Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

Post pictures and stories about your cars both present and past. Also post up "blogs" on your restoration projects - the more pictures the better! Note: blog-type threads often get few replies, but are often read by many members, and provide interest and motivation to other enthusiasts so don't be disappointed if you don't get many replies.
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Zelandeth
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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1041 Post by Zelandeth » Tue Oct 12, 2021 11:18 pm

Today has been at times frustrating but overall was productive.

I didn't actually have much work to do in terms of cleaning up the mating surface of the new head. This is what it looked like when I first looked at it. Reckon someone had already made a first pass over this before I got it.

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Likewise the block actually wasn't bad at all. Didn't take long at all to get it all cleaned up - though I failed to take a photograph of that stage for either head or block at this stage.

Before I could start building things back up I needed to reset that blasted ratcheting timing chain tensioner.

First step of that is to remove this huge great bolt-like thing, which requires you to remove all but one of the alternator bolts so it can be swung out of the way.

This required the biggest socket in any set I own, but thankfully I did have one big enough.

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I had assumed this would bring the whole tensioner out...no, it retains the spring and forms the outer oil seal...but the core of the tensioner (and the bit I needed to remove) was completely separate.

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...Which required a 17mm hex bit to remove. Which I didn't have. Biggest I could find in the garage was 12mm. Biggest I could find separately anywhere locally in stock was 12mm...so ended up having to spend £20 on a whole set of 10 sizes just for the 17mm one which was annoying.

It was also biblically tight. Though after hanging off the end of a breaker bar - which was bending worryingly itself - it eventually gave in and came free and could be unscrewed from the block.

One timing chain tensioner assembly.

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All this faff so I could do this.

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The way it works is that the plunger can move freely from frame right to left, but cannot move the other way. So the only way to back it off is to pull the plunger all the way out and insert it back into the other end of the body. When you screw the outer cap back on with the spring under it, that then applies the correct amount of tension to the chain. In addition to the spring tensioner, there's also a hydraulic circuit built in to push the plunger out...so basically there's a layer of redundancy there in case either the spring or hydraulic system were to fail.

If it didn't involve having to remove the alternator to get at it and require tools beyond what the average DIY mechanic are likely to have to hand I'd call it clever.

Having just got that sorted out it looked like we were making good progre...Oh.

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Yeah, then the weather decided to play around which lost me about an hour.

Undeterred though once the skies cleared I got back at it.

No pictures from when I was actually wrangling the new head into position as you'll understand it was quite an awkward job to do myself.

The head bolt torque specs and the bolt tightening sequence were helpfully included with the gasket. Nice touch - I did check online too and they matched up.

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However as soon as I dug out the torque wrench I realised I had an additional problem.

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Yep...Torque wrench is 3/8" and the Torx bit I had for the head bolts is 1/4". Back out to Halfords *again* to get an adaptor. I knew from prior experience that I didn't have one in the garage...so bought all of the usual suspects suspects so shouldn't run into this problem again.

After what felt like an eternity...

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I tell you now though, that last 90 degrees nearly killed me. I was near enough *hanging* off the end of the thing to get there. I will definitely be feeling that from my back in the morning.

Head is torqued up, timing chain sprocket, guides are fitted and the tensioner has been refitted.

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I was pretty beat at this point from torquing up the head bolts but wanted to get one last thing done, even though I knew there was no way I'd be getting to a test firing today. I wanted to verify the engine would actually turn over through a full revolution without valves hitting pistons. I had followed the instructions (crank pulley to the O/T mark and the notch on the camshaft level with the head), so it *should* have been fine...but this is the sort of job where I really do feel out of my depth so am questioning everything.

I dumped a pint or so of oil over the camshaft so everything was lubed up (in addition to the smear of grease I put there when I put it together), then got a socket on the crank pulley...and it turned over absolutely fine. No unpleasant noises, binding or anything...so there's hope for me having got that bit right.

Next up:

[] Set ignition timing (as I suspect it's a mile out now as I'm sure the chain jumped a few teeth while it was loose.

[] Check and adjust valve clearances. I did ponder doing that before it went on the car.

[] Put the spark plugs in.

[] Bolt inlet manifold to support bracket.

[] Reattach exhaust.

[] Reattach fuel flow and return lines.

[] Hook back up 384756392 vacuum lines.

[] Reconnect gearbox kick down cable (NOT throttle cable, it has to go on after the rocker cover).

[] Cobble together a throttle return spring (I mangled the original one removing the head).

[] Clean antifreeze crud off water pump & any other areas where it's an issue.

[] Bolt thermostat housing back on.

[] Reattach alternator & set belt tension.

[] Check torque of camshaft sprocket bolt.

[] Bolt the suspension hydraulic pump back on.

[] Temporarily hook up HT leads (they'll need to come off again to refit the rocker cover).

[] Replace oil filter.

[] Flush out any debris in the sump with some diesel.

[] Refill engine oil.

[] Refill cooling system.

[] Refit battery.

Then we should be able to see if it will run and confirm we've got good oil flow to the camshaft and no nasty noises.

If all seems well with that brief test...

[] Refit rocker cover.

[] Reconnect throttle cable.

[] Refit HT leads and their guide channel.

[] Refit air cleaner.

Plus probably half a dozen things I've forgotten.

...Then we should be able to do a proper test.

Between the original problem possibly not being the head and my own cack handedness there's plenty of scope for us being right back where we started.

Place your bets!
My website - aka. My *other* waste of time
Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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Zelandeth
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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1042 Post by Zelandeth » Wed Oct 13, 2021 11:05 pm

Today I spent a good solid six hour stint working on this. The result?

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It almost looks like an engine bay again.

https://youtu.be/zCzaN7n7O9w

Apparently I'm not a *completely* cack handed idiot either and must have done a reasonable job of getting the timing right. Given this was the first time I'd ever had the head off an OHC engine unsupervised that felt like quite an achievement. Initially getting it started took a little coaxing but I think it may just have been flooded/the plugs oil fouled. Took me about half an hour of fiddling before I realised that the throttle cable wasn't hooked up yet so my holding the pedal down while cranking wasn't going to help. Idiot.

Sadly as you can probably hear on the video she still sounds pretty rattly at higher revs. This was pretty much impossible to hear before because there was so much of a racket from the top end. Hard to tell too much from blipping the throttle when stationary, should be more obvious if there are any untoward noises when we take an actual test run.

However I need to sort a pretty major oil leak from the timing chain tensioner...

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And a water leak from the thermostat housing...

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Before we can do that. The tensioner is leaking I'm guessing because the metal O-ring it seats against is intended to be a single use item, and the thermostat housing just needs a gasket. I did order one but what turned up was totally wrong for this engine...tried to get away with instant gasket and it didn't work. I don't actually have any gasket paper in stock at the moment...might try making one from card just as an experiment while I wait for the proper one to turn up.

The only real own goal I had to sort was initially bolting the brake servo vacuum hose bracket on backwards...which by my standards is pretty good going!

Even if we do find ourselves back where we started after this, I still feel it was a worthwhile exercise. The alternative would have been to pull the engine out of the car for inspection...which I really don't have the space to do and would have needed to buy quite a few new tools to undertake. This has taken a couple of afternoons and probably £50 of parts/sundries. A T12 Torx bit and 17mm hex key were the only tools I needed to pick up for the job.

If we'd gone down that road and found the bottom end to be stuffed I'd have a dead engine sitting in the middle of the front lawn to annoy the neighbors (even more) and a now engine-less car sitting there being a large white paperweight unless I spend a small fortune on a replacement power unit. This way we will have discounted the top end as a possible issue, but have at least ended up with a car that runs and drives until we decide exactly what to do.

That path may well be looking to sell it on as a project as I'm just not sure I can summon the enthusiasm to justify spending the sort of time, effort and expense of replacing the engine. If one turned up cheap and local, maybe. However the only ones I've found so far have been anything but cheap and would require shipping...if she was a tidy example maybe, but without spending thousands on bodywork this is always going to be a bit of a rough car cosmetically.

Probably absolutely a worthwhile project for someone so inclined to drop a new engine into, or strip this one down for a proper rebuild, just don't think that person is me. Especially as this whole experience has been a bit of a sledgehammer to the enthusiasm for the car. I'd been planning to pick away at improving it overall, but really hadn't planned on much mechanical work beyond routine servicing and the usual maintenance projects which older cars bring with them - a major mechanical issue like this wasn't really in the plan, and is an area where I just feel a bit out of my depth. Especially when it's a car we're talking about that I'm really not all that familiar with. Doesn't help that whenever you search for "how do I <insert task here> on a Mercedes M102 engine?" The first page of results is entirely comprised of answers for the six cylinder or diesel engined cars. That gets annoying quickly.

Guess we will see what happens once we've done a proper test run. Had to abort things today due to the amount of oil and water that was pouring out of it (very glad I just put water in for testing).
My website - aka. My *other* waste of time
Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1043 Post by Dick » Thu Oct 14, 2021 5:25 am

Good luck mate! :thumbs:

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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1044 Post by Zelandeth » Fri Oct 15, 2021 9:26 pm

Thermostat housing gasket and timing chain tensioner outer oil seal have both now been ordered from the dealer and should be here Monday or Tuesday.

Think I may have confused the folks at the Mercedes dealer slightly when I parked an Invacar in their car park...

Hopefully should be able to give the Merc a proper test run once they're fitted.

Annoyingly I'll need to unthread the belt and half detach the alternator again to fit the seal for the chain tensioner...for all it's a 30 second job in itself!
My website - aka. My *other* waste of time
Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1045 Post by Zelandeth » Mon Oct 18, 2021 6:01 pm

While waiting on parts from Mercedes for the S123 I figured it was a good opportunity to get a service item on TPA I'd been putting off done. Gearbox and diff oil change.

What came out was quite grim, not glittery though, just very degraded. Was really thin and seemed to have lost a lot of its lubricity. The oil that went in last year was from a very old container, and even though it was still sealed I think it may have broken down over time on the shelf. The new oil that went in today was actually new and hopefully will fare better.

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While I was in there I took a look at the condition of both CVT pulleys and the belt - these items live quite a hard life so it's worth checking for any signs of distress whenever you're in the area, especially as we've been experimenting with a current belt type rather than the exact one originally specified.

Everything looks fine though, looks like the Dayco HP2020 belt is able to stand up to the job.

It's been on there since last August and has about 1500 miles on so far.

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Main reason I had been putting it off was that getting to the level plug for the diff is an absolute pain in the tail. It's not quite so bad now I've done it a few times as I know where it is (you can see it or touch it, but not both at the same time), but is still bloody awkward. I'm sure the intended way of changing the oil was to have the car on a lift in which case it would be dead easy. Having the original seat would make it easier too actually as the backrest can be easily removed from that, not possible on mine so you're working around it.

I've found that cracking the level plug off from in the engine bay but then unscrewing and removing/refitting it from in the cabin and then doing the final tightening from the engine side seems to be the easiest solution.

The "light scattered showers" the weather forecast predicted this afternoon proved to be anything but. "Persistent and mostly heavy" was a better description. So we got a few more typical photos of her out and about rather than just when it's nice and sunny for a change.

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My weatherproofing improvements have definitely helped, though I do still have a little water getting in around the offside of the windscreen occasionally.

Somewhat to my surprise, the demister actually does just fine when you're on the open road so long as you keep a window cracked slightly - problem is that as soon as you drop below about 50 it basically ceases to have any effect whatsoever - and the cabin being so small means that it fogs up very quickly. Obviously there's no way to direct air to the side windows either so you really do need a demisting cloth to live in the car.

Windscreen wiper does a better job of clearing the screen than you'd think with how tiny it is, though an intermittent wipe function would be nice...you really want two hands on the handlebars whenever possible so having to keep turning the wiper on/off gets a bit tiresome after a while.

Not that I generally plan to use the car regularly in monsoon conditions, but if I get caught on a longer run in poor weather it's nice to know that it's not a huge problem.
My website - aka. My *other* waste of time
Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1046 Post by Zelandeth » Tue Oct 19, 2021 10:03 pm

Today has been frustrating.

Started out well enough, with these picked up from the Mercedes dealership.

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That's a gasket to go between the thermostat housing and the cylinder head and the seal that goes between the outer cap of the timing chain tensioner and the block.

Replacing the gasket for the thermostat housing was precisely as awkward as I remembered (because I didn't want to remove the stubby hose between the block and the stat housing as it's a pig to refit), but uneventful. If I do keep this car something I will probably do is go through the engine bay and replace ALL the hose clips as most of them are either half seized or have stripped heads. It's overkill I know, but I far prefer Mikalor (other brands are available, but that style), I'm used to them from having messed about with a lot of ancient commercial vehicles when I was younger, and they're just so much less hassle in the long run.

Things then rapidly went downhill from there. Firstly it turns out that Hermes have apparently lost a parcel which contains the replacement alternator for the Jaguar. Wonderful. Their system shows it as having been delivered...whereas it definitely hasn't been. Not to us, any house on our (short) street, or the same number on any of the surrounding roads. Great. So that's about £300 worth of alternator that's just vanished into the aether as far as we can tell.

Step two for the S123 was pulling things apart again so I could replace the outer oil seal on the timing chain tensioner.

It's the thing which looks like a huge bolt head in the photo below, slightly above and left of the centre of the frame.

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This is where the real headache started.

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Those two washers should be the same size...they clearly aren't. New one is a couple of millimetres smaller - sufficiently so that it won't fit over the body of the tensioner.

Heading back and talking to the dealer revealed that that washer doesn't actually exist at all on their parts system...so we're not totally sure where the one they gave me came from!

I spent a good couple of hours driving around to everywhere I could think of and couldn't find anything even close to the right size anywhere.

Typing "Mercedes M102 timing chain tensioner oil seal" into Google revealed that it was paying attention to the words "Mercedes" and "timing chain" and completely ignoring everything else. I'll do battle with that when I'm sitting at an actual computer...I just don't have the patience for that nonsense when I'm using my phone.

I'd really hoped this would be ticked off today but it looks like I'll be having to order a stupid washer and wait for that to arrive before I can make any progress.

I have a feeling someone mangled this washer somewhere in the distant past as it was absolutely slathered in instant gasket when I removed it...and I find myself almost wondering if that may be responsible for the historic oil flow issues we've clearly had to the head. Coincidence or causality? Either way, I'm fixing the problem rather than bodging it.

Having been a few hours since I fitted the thermostat housing I went to fill the cooling system...and went and made myself more work. Apparently when I threw everything back into the garage a few days back I threw the wrong cap on a couple of bottles...and the one with the cap which said A/F Blue was in fact not blue antifreeze...it was 20W 50 oil. So a good slosh of oil went in the radiator before I spotted it. This is the curse of Motorserv having NAPA everything now...all the bottles are identical! System was going to need flushing anyway as there was some oil contamination from when the head came off...but there's more in there now! I did manage to skim *most* of it off as it hadn't mixed, but I'm sure there will be more slime to come out.

Moral of the story: When you're shutting up shop, no matter how knackered you are, don't cut corners. You'll end up making yourself more work in the long run. Probably in a way which will make you feel like an absolute IDIOT as well.
My website - aka. My *other* waste of time
Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1047 Post by Zelandeth » Thu Oct 21, 2021 12:25 am

Found two local independent hydraulics specialists today...first one barked "we don't do car ***!" at me, second didn't even look up from their phone for more than half a second before muttering that they didn't do stuff like single washers any more.

Step forward Pirtek. Who immediately said "That's an odd one..." and went rummaging.

Couple of minutes later:

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It's copper rather than aluminium, but I don't think that will be an issue, it's just sealing between two pretty smooth metal surfaces.

The outer diameter isn't that important as there's plenty of room around it, the inner diameter was the important one and that's spot on. They wouldn't even take anything for it.

Did it fit?

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Like a glove...

Problem solved it looks like.

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After a good half hour of running...no leak present.

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Not by any means the first time that Pirtek have saved my tail either.

I did completely fail to remember to pick up the hydraulic hose for the suction line to the SLS pump though...will need to go back tomorrow for that.

I'm sure the hex head is actually a metric size, though I don't have a clue what size it is...none of my metric sockets are big enough...this worked fine though!

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Evidence of my "mishap" with mislabelled bottles yesterday.

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The good side of this is that it never really mixed, so I've managed to skim I reckon 95% of it back off the surface. There's a slightly oily film in there now but I don't think much worse than from the head coming off.

The vast majority of the bottles are labelled both on the lid and bottles, like so...

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The one that caught me out was very much an outlier! Definitely won't make that mistake again though.

Before I set about running tests I sorted out the other coolant leak I'd noticed, one of the washers was missing from this coolant balance pipe.

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I'm not proud of the bodged throttle return spring... I'll be getting a proper replacement for this if the engine is staying with us, but it does work.

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Aside from a few plastic covers for the HT leads everything is now back in the engine bay.

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Finally meant I could let the car warm up properly until the fan was cycling (which it was also nice to see was working as the switch came with the new head so was untested until now).

So how's our oil pressure looking?

In gear right at the point when the fan is cycling, about like this.

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Though the idle is definitely a bit low which won't be helping - at 1000rpm it seems reasonable.

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Deliberately checking for it at a set engine speed as that will make it far easier to tell if it's getting worse over time.

Here's a quick look at how it tracks with engine speed.

https://youtu.be/gVEGt8-F1mA

Definitely sounds a lot better than she used to.

https://youtu.be/fgo95uJMnmE

By the time I got to this stage we were well into rush hour so no proper test runs were going to take place...an unproven car and rush hour Milton Keynes traffic just sounds like a recipe for disaster. We did however go for a gentle bumble around our local estate...and it seems to be working okay. Not able to give her enough revs to really tell much though - but we'll do a proper test tomorrow.

It's definitely very noticeable that the engine is running cooler while bumbling around town...would previously have been sitting around the 100C mark, whereas it now seems to sit about halfway between the 80 and 100 marks.

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Not reading too much into it, but it seems to suggest the engine may be running more efficiently.

Only a *little* bit of a mess left where I was working...I did try to catch as much as I could in a catch tank, but there's only so much you can do.

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I think the vast majority of the oil came from the initial leak we had from the timing chain tensioner. Slightly puzzled as to where the exhaust manifold gasket came from as I'm reasonably confident that two went back on each of the runners...

Let's see how the actual test run tomorrow goes...

At least today was less annoying than yesterday!
My website - aka. My *other* waste of time
Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1048 Post by Zelandeth » Thu Oct 21, 2021 8:44 pm

We've been out and done a bit of driving around today.

Nothing has blown up yet at least!

About 30 miles done, all keeping close enough to base to hopefully be able to limp home if something went awry.

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Horrible photo. I'd left the flash turned on on the camera. Derp.

I definitely need to bump the idle speed up a bit, I'm pretty sure that the IAC valve isn't doing anything...I have a spare so I'll probably thoroughly clean that then just swap it over. The one currently on there is the one that was on the spare head, so has probably been sitting disused for many years.

I had the car stall on me twice going into gear, and it didn't really want to restart on those occasions, sounding like the engine was kicking back against the starter.

Figured the ignition timing was most likely out there, especially as performance had felt a bit "flat" even keeping in mind I've been being pretty gentle so far.

You can tell the timing light isn't a tool that gets used hugely frequently from how dusty it is!

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Correct setting is 13 degrees BTDC +/-3 at idle (850rpm). Yeah...it was at roughly 38 degrees advanced, so that won't have been helping. How I wasn't getting pinking with it that far advanced I've no idea. I will recheck it once I've sorted out the idle speed/IAC issue as it's difficult to get it spot on right now as the idle speed changes with the setting and is wandering enough to make it tricky to judge. It's at least close-ish now though.

Haven't been for a proper drive since, but on a quick run round the block the engine felt smoother.

Something which definitely is not smooth however is the gearchange. It feels like gears are being changed with a sledgehammer. The box has always been a bit clunky, especially 2nd-3rd and when cold, but every change at the moment is totally devoid of any slip. To the extent it's honestly painful. Definitely can't be doing anything any favours. It's either going to snap something in the drivetrain or my neck...one of the two.

There's no adjustment I'm aware of on the kickdown cable I removed, but I'll definitely double check that tomorrow and make sure I've not routed it wrong so it's binding or anything. I thought it was just a case of unclip the cable and hook it back up, I may have missed something though.

I did note the fluid level was quite low, so topped it up. Well...aside from the half pint or so I felt it necessary to dump over the exhaust manifold...you know, it just seemed like a good idea...or I'm just that clumsy an oaf. Yes...that was it.

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Cleaned as much of it up as I could, but it still stank for ages...guess at least it wasn't EP90!

Pirtek unsurprisingly had no problem picking out a suitable hose to replace the leaky suction line for the SLS pump. This has been sweating for ages and I think was responsible for a lot of the oil over the front of the engine.

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Definitely looks a bit tidier...plus will be nice to not get covered in hydraulic oil every time I accidentally brush against it. Was a bit of a faff to change it without draining the reservoir but I managed it. I didn't have any of the correct oil in stock so didn't want to drain it if I could avoid it.

Yes...the hose bracket is upside down. I'll sort that next time I'm working on the car...was just out of time today.

Doesn't look like we've had any more leaks present themselves during the day, so that's a plus. Just need to try to get to the bottom of the horrendously harsh gearchange (which is massively worse than before I worked on the car, so *something* has changed) and we can keep testing. Open to suggestions there.

I do have oil and filters in stock again now, so will do another oil change at the weekend. Still looks spotless on the dipstick but after doing work this major it just makes sense I think. Especially given we're still on the lookout for glitter too.
My website - aka. My *other* waste of time
Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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Zelandeth
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Re: Zel's Fleet Blog...Jag, Citroens, Mercedes, Sinclair & AC Model 70

#1049 Post by Zelandeth » Fri Oct 22, 2021 6:30 pm

Can anyone see the problem here?

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How about now?

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Yeah...that is going to be doing any good just flopping around underneath the inlet manifold. It's the line which goes to the shift modulator on the gearbox - and a lack of vacuum there would indeed explain why it's been changing gear so harshly.

Sneaky one too...every single other vacuum line is white plastic with a colour coded stripe on it...this is the only black one I've seen on the whole car.

The issue is though that I couldn't connect it without displacing something else...which tells me that something is hooked up wrong. There is a solenoid controlled valve which looks like it should have something hooked up to something on the second port, but it's not been connected since before I got the car... I'd assumed up till now it was a vent.

I made a best guess for what I think went where to give everything a home, but I really need to find a proper diagram to show were the lines are actually meant to go. There are just too many of them on this car to sort out by intuition alone.

This *has* mostly sorted out the gearchange though. Second to third is still a bit of a thump and she still doesn't want to use first gear unless you absolutely boot it from a standing start (not sure if that may be by design?) so I think some adjustment may still be needed, but it's a thousand times better and is entirely liveable with. I'm not honestly worried it's going to snap the propshaft UJ or the torque converter flex plate on a gearchange any more.

With a bit of poking around I ascertained that the IAC valve was doing nothing.

Pulling it off the car for inspection revealed it to be completely jammed up. I did free it off after a bit of effort and cleaning, but for now have put the one off the old head on. It turned out that an adjacent vacuum controlled valve which is something to do with the PCV/idle circuit was also stuffed, both being physically stuck closed and with a blown diaphragm.

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It's only moderately awkward to get to, though getting the first bolt out using only a stubby 5mm Allen key was a test of hand strength.

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I did come up with some quite colourful names for that bracket the kickdown cable sits in though.

Still doesn't seem like the IAC is doing much of anything... though see my earlier comments about vacuum lines possibly being hooked up wrong. This evening's task is going to be finding a proper diagram of the vacuum line routing. I know the idle should pick up (and used to, albeit only about 80% of the time) when you select a gear... doesn't seem to be happening now.

At least the car does feel driveable again now, I was really worried I was going to break something with how it was before. It looks like a bit of trim on one of the B pillars did succumb to the jolts though and is now being held on by the seatbelt...

Edit: I'm an idiot. That's not an IAC (Idle Air Control) valve... it's the Auxiliary Air Valve...which is used only during warmup from a cold start. I should have remembered that given it's the same injection system as used on the Saab 900s which I've had three of and have been messing about with since I was about 12. It's amazing what you forget after a couple of years! Thanks to the person who pointed that out, I really appreciate it.
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Current fleet: 73 AC Model 70. 83 Citroen BX 14RE. 85 Sinclair C5. 85 Jaguar XJ-S V12 HE. 86 Mercedes 230TE. 90 Mercedes 208D AutoTrail Navajo.

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