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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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.


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.


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.


...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.


All this faff so I could do this.


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.


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.


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


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...


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.


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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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?


It almost looks like an engine bay again.


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...


And a water leak from the thermostat housing...


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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