Practically Classics Forum

Could one of the sensor wires be shorting out on those anti-rattle shims?

Still better than my old Alfa 156 where after a few weeks the sensor wire detached from the new pads .. and both sides .. the wire just corroded and fell off! Luckily I am not the type of owner to rely on warning lights for brakes, etc!

I figured that the issue with the brake pad warning system had to be an issue at the wheels. The logic behind this was that the light would come on solidly only when the brakes were applied, it could be made to flicker by rocking the steering too.

The wiring to the sensors looked sound and wasn't shorting out on the anti rattle springs or anything obvious like that.

All four of the pads on the front brakes have a wear sensor in. This is essentially just a wire that's inserted and glued into a void drilled in the brake pads just proud of the backing plate, so that it completes a circuit via the disc to light the warning lamp when the pads have worn down. You can see the hole for the sensor just to the right of the central groove in the friction material of the pad below.



For those not familiar with the brake warning light on the dash of a Merc T1, it performs two tasks. One is linked to a float in the fluid reservoir as on any vehicle. The second function is the brake pad wear indicator. The light only comes on if either the fluid is low or if the pad wear sensors are triggered (and during a self-test when the ignition is turned on, extinguishing when the engine is started). It is NOT a handbrake warning light.

The wear sensors are not fitted to the pads from the factory and have to be inserted and glued in place when the pads are fitted. Now, this hole is blind on proper OEM pads like these (made by Ferodo in this case), but I have seen "off brand" pads where that hole goes all the way through the friction material. What can happen then is that the wear sensor can go all the way through, poking out the other side, meaning the sensor can wind up touching the hub of the disc, giving a false reading to the monitoring system.

Given the behaviour I was seeing I had a sneaking suspicion that this was going on in my case. Should be quick to check at least.

The old "wedge a bit of wood between the brake pedal and steering wheel" trick was used to ensure the light stayed lit until I found (or failed to find) the offending sensor.



While I was situating the pedal wedging device I noticed something odd on the back of hand.



Blue tinted water... there's only one place that will be coming from, the cooling system...and suspect number one is right in the neighborhood.



Figures I found that less than an hour after ordering a bunch of parts from Mercedes (more on that later).

Unplugging the first three pad wear sensors did nothing, however when I unplugged the last one the light went out and stayed out. We have a false positive from the last sensor. I have temporarily disabled it by putting an insulating sleeve over the pin in the connector. I've still got three working sensors, and it's not hard to keep tabs on pad wear. I imagine they will last a decent length of time anyhow given the relatively light duties she's going to be doing compared to normal commercial use a van might see. Will be really nice to drive it without a little red light flickering at me the whole time.

I'll hopefully get her booked in for an MOT in the next day or so to *hopefully* confirm that I don't need to buy anything else.

I made a trip over to my local Mercedes dealer for some parts. They have always been really helpful before, and we quickly tracked down the parts we were after. I was expecting these bits to be a little more expensive than normal car items as they're quite a bit beefier.

The track rod ends were £48 each, yet the whole steering tie rod (which comes with the track rod ends as a unit) is £132. Given they've most likely been on there for 29 years I was rather expecting a bit of a fight to get them off the tie rod...so deleting half the rusted together parts I need to get moving was worth a few quid extra I thought. Likewise the drag link was available as a whole assembly for not a huge amount more than the two ends.

I decided to get the new fan belt while I was there. Yes I do know I could probably have got that a bit cheaper elsewhere but it seemed the right choice given the huge pile receipts for parts during the life of the van for genuine Merc parts.

Not a cheap trip!



On the plus side hopefully these should all be the right parts so should just fit.

The one concerning thing though was that their parts desk has been told that strictly speaking they really shouldn't be selling parts to me because it's a van. I should instead be directed to a commercial vehicle specialist down the road. I've tried to buy parts from them before, however they made it quite clear that because it was registered as a motor caravan rather than a goods vehicle their system couldn't look up parts for it. Oh, and they didn't want my business anyway as private individuals are "too much trouble" which really gave a good impression. Nor did their comment about how daft I was to be expecting a commercial vehicle specialist to have parts for an ancient camper.

One of the big perks of having this van so far has been the incredible parts support from Mercedes...will be really disappointing if that ceases to be possible down to some manager meddling with things... Especially as the staff actually on the parts desk really do want to help.

Assuming that Parcel Force don't foul up this delivery (they have managed to mess up all three this month so far so I'm not holding my breath), my new exhaust for the van should be here tomorrow.

Another brief car-less tangent. Only a brief one-post one this time.

Got slightly sidetracked today by another project while it was raining. Another one of those things spotted at the side of the road which I had decided required investigation before it was either rescued or getting put in the electrical equipment bin at the recycling centre (rather than dumped at the side of the road).

It had actually been forgotten about in the boot of the Activa for a couple of weeks. I had clocked that it was A: an audio amplifier of some sort and B: that it weighed a tonne. That was as far as my observations at the time had gone when I tossed it (with difficulty) into the boot.

First look today revealed is to be a rather more businesslike amp than anything else I've had. It's a Spectra 90/D power amplifier...400W stereo or 800W bridged...

Let's have a look shall we. I'd already got the (seriously scruffy) cover off by this point while I was checking for any signs of damage or distress.



No obvious signs of the magic smoke having escaped, though I wasn't really expecting much to be honest. Most amplifiers like these usually have a plethora of protection circuits that usually prevent major meltdowns unless it's something blindingly obvious like the mains transformer having overheated. Usually if something has gone awry you'll just find that one channel is shut down or the whole thing will refuse to power up. This can actually make fault finding an absolute nightmare sometimes as they will often trip out before you can get any useful readings.

Couldn't see anything amiss. It was quite dusty in the case (as is pretty inevitable it seems for any electronic equipment with a fan in) but not too badly really. No signs of any overheating anywhere, no signs of water ingress (despite the case being quite rusty on the surface) or anything like that.

The only signs of trouble I could see were that the volume control pot for channel 1 had become detached from the front panel (sorted by doing the nut on the spindle back up) and that the nut holding the wire on to one of the speaker output posts had come off. This was found rattling around in the case and was reattached.

Was a dead channel due to that nut having come off the reason it had been binned? Well only one way to find out. Plug it in and see what happens!

Okay, not quite. A couple of sanity checks were done - checked the earth bonding was good and checked there was no leakage to earth with the Megger. All seemed good.

Turning it on resulted in an almighty "thud" from the huge toroidal mains transformer (I don't want to know what the inrush current is - the 40,000uF of smoothing caps probably have something to do with it), the fans starting up nicely and after a second or so a couple of relays clicking purposefully.



While I had it powered up this gave me an opportunity to check that there was no DC present across the speaker terminals (that's a quick way to kill speakers). Absolutely nothing according to either analogue or digital meters...this is good.

Couple of lights to tell me it's alive but that's about it. I took that opportunity to take it outside to blast as much of the dust out as I could. It's a substantial bit of kit...



I needed an audio source and some speakers. Specifically I needed some speakers I didn't care about in case there was a fault present that resulted in them being blown into the next county.

Conveniently I remembered having bought a set of speakers something like ten years ago for a project I had never got around to doing...not exactly hifi but they'll prove if it works or not.



The input is via either 1/4" jack's or XLR plugs. I'll just go grab some connectors from Mapl...oh. No I won't because they don't exist any more. Great! Amazon it will be then. In the meantime I came up with a truly diabolically dodgy aux cable adaptor to plug an iPod in.





Horrible hack. This is all signal level stuff though so there aren't any safety issues at least.

Let's stuff some audio in and see what happens.



It appears to work absolutely perfectly. Obviously it's barely ticking over here driving a pair of speakers rated to 70W RMS/120W peak at volumes limited so my ears don't bleed, but it played happily for a couple of hours.

The case however was a mess.



I didn't bother doing anything about this earlier as it seemed daft to spend time on it in case it turned out to be a very heavy door stop.

Now it's proven to be working it seemed worth tidying it up a bit.

Hit it with the carbide mop...



Nice fresh coat of hammered black paint.



All back together, looks rather nicer I think.



Never ceases to amaze me what people throw out! This took all of two minutes to fix, and half of that was opening the case.

Now I need to find some speakers to go with it, then we can really rattle some windows...

That's brilliant! A quality piece of kit that, well worth saving, well done.

Zelandeth wrote: Wed Apr 24, 2019 11:30 pm I'll just go grab some connectors from Mapl...oh. No I won't because they don't exist any more. Great! Amazon it will be then.

Tip for the future, rather than feather the nest of yet another huge American corporation, can I strongly recommend RS Components for this sort of thing? I gave up using Maplins ages ago, 'cos RS Components are so much better - a huge range, and excellent web site, VERY good prices and brilliant service, stuff arrives very quickly and I often wonder how they can do it for the price. I have far more confidence that I'm getting quality stuff than I ever would with Amazon.

Example - I recently bought a BMW 330d for pocket money, apart from rusty wheelarches the only fault is that the on-board computer didn't work. It was a faulty switch in the end of the indicator stalk that prevented you from changing the OBC display on the dash. Replacing the stalk (or even investigating it to fix it) means removing the steering wheel, mucking about with airbags etc. so I decided to just put a small press-switch in the side of the steering column cowl and wire that up to the OBC. RS Components supplied a perfect miniature black push switch, £4.04 delivered, arrived in 24 hours and it looks so smart you'd think it was an original BMW fitment. And, of course, it works!

Nice one, keep up the good work.

Luxobarge wrote: Thu Apr 25, 2019 7:32 am That's brilliant! A quality piece of kit that, well worth saving, well done..

Agreed! That's one mightily impressive spot of rescue work.

I too am recommending RS as they can still get some of the more obscure components in values that are rarely found in more modern equipment than I tend to work on. High WV values on caps, for instance, are still useful to me for those occasions when I find myself guilt tripped sweet talked into fettling older TV sets and similar things where EHT supplies are found. They're very fair on price, quick to send and will exchange quickly too, should any problems occur with purchased components.

RS was a site I used to use a lot. Especially back when I was at college. The killer used to be their delivery charges for small orders - spending £5 to get £0.50 worth of resistors delivered used to be annoying. When I started at college they had an agreement in place where students were allowed to get items delivered to the Trade Counter (which was literally about 500 yards from the college). Overnight one day they rescinded that agreement without any prior discussion with the college, and I discovered this when they extremely rudely refused to allow me to collect the order I had in place for a major project. This resulted in them essentially having £150 worth of my parts held hostage - which RS HQ decided had "failed to be collected by the customer." I wound up significantly out of pocket and about a week behind schedule thanks to that nonsense.

Farnell/CPC are my usual go to for stuff when I know I need it - Maplin were still really handy when you had a moment like "Oh, I need an XLR jack now..." or random stuff like that.

This morning (astonishingly, exactly when it was meant to) a very large, heavy cardboard box arrived.



Now I've been here before, so made a point of assembling everything on the floor before going anywhere near the vehicle. Especially on bargain basement eBay specials like this.



This showed a few things. Firstly that the downpipe is indeed different to the one on the van. A little annoying as I was kind of hoping to avoid touching that based on the pain and suffering I've been through trying to get downpipes separated from manifolds in the past. Secondly was that the slip joints were really tight so would definitely need spreading out a bit before putting them together. That's definitely something I was glad to discover inside rather than while trying to slot things together on the van.

Well let's make a start then. First contact with the enemy...



Astonishingly, five minutes later this was in front of me.



The bolts just...unbolted. No heat, no power tools, no fuss. I'm slightly baffled by the concept of a downpipe to manifold joint coming apart without hassle! Not going to complain though.

A large amount of faffing around then ensued while I figured out which hangers went where (as this system is a significantly different layout to the one which came off), figured out exactly what order I needed to put things together in, and battered things with a 4lb lump hammer to correct a couple of bend angles.

Pretty much what I expected from a cheap exhaust to be honest...three hours of *making* it fit followed by twenty minutes actually putting it together.

Eventually we got there.



Had to alter the tailpipe to sit a little lower on account of the grey water tank. Just need to get a bracket put together for the last hanger there...had hoped I could do without it (the system is plenty well supported) but the tailpipe vibrates and buzzes like mad at idle, so it's needed to help damp that vibration.

Starting it up astonishingly revealed it to both be gas tight and to not be touching and buzzing against anything. Was rather surprised though when I touched the throttle and was presented with a very throaty exhaust note. I have a sneaking suspicion that this bargain basement silencer doesn't actually contain any baffles.

This is the kind of observation which is worthless without evidence isn't it...

YouTube Link

Not that I'm complaining...

Yes she's a bit smokey, hasn't left the driveway since October so she needs a good run. Usually runs clean as a whistle.

Thankfully it's not boomy as that would get annoying in a real hurry I reckon on a long trip. I'll be curious to see how it actually sounds on the move though. Obviously that will have to wait until the trip to the MOT station as it's currently out of test so I can't exactly go out for a quick test run.

Wasn't actually that hard to fit really. Bit annoying that the fit needed a little "gentle persuasion" but not really surprising at this price point, and I don't think I've ever fitted an exhaust that was anything less than maddeningly awkward. Well...save for the one on my lawn mower maybe.

Feel confident enough to get it in for a test now, was a bit worried that the remains of the exhaust would wind up going through somebody's windscreen before. Plus a shiny new exhaust should hopefully show the tester I'm actually willing to put some work in to looking after the van...the invoice for £300 worth of genuine parts for the known fail items should give a decent impression too I'd hope.

That could have been a lot worse.



Failed on 2x TREs and drag link ball joint obviously. Also the prop shaft CV boot which was known but forgotten about going into the test, rear brake imbalance, high nearside headlamp aim and missing rear reflectors.

The missing reflectors is an odd one as they're integral to the tail light lenses...don't want to be seen as arguing with the tester...but sorry mate you're wrong there. The tail lights are configured right now exactly as they left the Mercedes factory.

Propshaft CV boot is a simple fix, tester confirmed that quickest way is to just unbolt the centre bearing carrier and lower the propshaft until the slip joint separates.

Rear brake imbalance...blarg. The garage can have that one to sort. I'm not faffing with brakes against the clock. Especially as I seem to remember the self adjuster on these being fiendishly complicated.

Headlight aim, fair enough. I fitted a new light a couple of days back and hadn't even looked at the aim so far (it's on the to do list for the weekend).

I'll do the propshaft CV boot, headlight aim, probably stick on a couple of trailer reflectors as it's easier than arguing with the tester, and will give the ball joints the opportunity to come apart. If they do I'll swap them, if they put up any fight though the garage can do it on Monday.

Looks like we've got a reasonable chance of being ready for Thursday.

The exhaust is frankly hilarious. It's a real proper old school "BraaaaaaaAAAAAAAAAAAAmmmm..." Through each gear just now...

Let's see what we can do to take a few chunks out of the MOT remedial work list.

First target is going to be the propshaft slip joint boot. It's been in the garage now for a few months waiting to be fitted...let's get to it.



Initially my plan had been to minimise the degree to which I had to dismantle things - hoping that I could get away with simply dropping the centre prop bearing assembly. Unfortunately it turns out that this doesn't give enough clearance to separate the splined section on the rear prop from the socket on the front section. Shame as I'd already removed a couple of bits of the exhaust (which I fitted a couple of days ago!) for access. So had to put them back together again. On the plus side, this did give me the ability to check the state of the bearing on the centre prop carrier - it's silky smooth and has no detectable play in it.

The reason I had really been hoping to get away with removing things from the front was that I really didn't want to have to try to get the bolts out of this.



There's no leak here - things had been sprayed down with Plusgas shortly before I took the photo. I was forced to pause at that point as the nuts on the rear flange on the prop were 15mm...a size which I knew for a fact I lacked a spanner in. No way to get a socket on there because of the proximity of the universal joint...You can *just* get a ring spanner onto the nut on four of them, but a socket was a non starter. This meant that I had to make yet another trip round to Halfords to pick up a spanner.

I wasn't sure whether the entire prop was balanced as an assembly or if the front and rear sections were done separately...so I marked the rear flange to ensure that it was reassembled in the same position as it was removed (I had the handbrake on and the van in gear to ensure that neither end could move).



Once all the bolts were removed the rear of the propshaft was lowered to the ground. It's heavy and especially in the confined space under the van is a bit cumbersome, but isn't impossible to manage single handedly. I did want to make sure that I didn't just whack the splined section on the brickwork of the driveway when I withdrew it though so grabbed an old cardboard box for it to drop onto.



It was then withdrawn from the socket in the front section until it dropped onto the box,



While being careful to protect the splined section it was a simple matter to then remove it from under the vehicle.



On the plus side, it's much easier to work on the prop with it actually free from the van. Especially getting the original metal sprung clip that was holding the remainder of the old boot on off.

Not much left of the old one!



The remainder I believe to be finely atomised and spread over a stretch of the A421 just outside Buckingham.

I then gave the splined joint a thorough clean to get rid of all traced of the old grease and any contaminants. Then it was given a liberal coating of CV joint grease (I must have had that pot going on 15 years now) and the new boot slipped into place.



I gave the bolts all a quick scrub with the wire brush to clean the threads up before getting ready to reassemble things. I'm pretty sure that there was some sort of thread lock used during the original assembly, so got mine out ready to be used during assembly.



It was a pretty simple (if slightly physically awkward) process to slot the propshaft back together and bolt the rear flange back together. By some complete fluke I actually managed to get it lined up perfectly on the first try!

The boot was then fastened in place. This would have been done using metal clips originally but I don't have the special pliers you need to fasten them so a couple of cable ties will have to do for now. I will look to get a pair bought in though as I'd obviously like to get the metal clips in there - they were supplied with the boot after all.



That done it was time to tick a few other things off.

The "missing rear reflectors" was a bit of a head scratcher as they're integral to the tail lights - though if the lights are on it would be easy to miss.



The reflector is plain to see if the camera flash is used.



I'd rather not argue with the tester though, for dug out a couple of reflectors that I had floating around in the garage and stuck them on the back.



The headlamp aim was unsurprisingly miles off given that I had fitted a brand new headlight to the nearside a few days ago. Didn't take long to adjust that back to something resembling a normal beam pattern.



One thing I was reminded of standing there with the engine running is that I really need to fix a proper patch onto the air cleaner assembly as there's a hole in it.



This is on the outside of the filter element so isn't important from an air filtration perspective - it does however result in a boomy resonance from the induction side of things which sounds like a blowing exhaust and is quite tiresome. Might see if I can get that sorted before we leave on Thursday.

Final thing I did for the day was stick a little trim on the exhaust.





A joint effort between it being because I thought the finish on the really cheap exhaust wasn't great so I wanted to tidy it up, and also to shift the tailpipe out slightly so it was venting slightly past rather than directly in front of the rear wheel. Not that the exhaust gas temperatures are particularly high from this engine, but I'd rather not cook the tyre.

Tomorrow I'll see if the ball joints want to play nicely...I'm guessing not given how easy everything has been so far...Karma is surely going to come back and bite me at some point soon!

Good stuff, I wonder why some other vehicles that have a splined propshaft joint, such as Reliant kitten and Fox do, don't pick up any comments about the absence of a rubber bellows there? It's a particularly hostile environment for a rubber sleeve that's expected to flex in so many directions and as long as the splines are kept clean and the grease nipple (as found on the Reliants, I'm guessing that maybe there's just a blanking plug on the Benz one, or maybe no external way of getting the grease in?) sees the gun from time to time, then surely all should be fine.
I would have pulled the tester up about their inability to see the reflectors' positions though, if only so that they don't make the same mistake again. I spent some time doing MOTs during my active years in the trade and was always pleased to have such a discussion with the customer regardless of the outcome. Assuming that the point is raised in a good humoured way and not aggressively, then a tester should be grateful for having learned something. That said, the extra reflectors can't do any harm but rather than let the tester put an erroneous failure point on the list, I'd say something along the lines of; "I've put a couple of supplementary reflectors up there, because if the original, perfectly functioning ones can be missed by an experienced tester, they could be missed by following drivers too, especially if their vision was impaired or they were texting at the time of the 'inevitable' collision!"

My guess with the boot on the propshaft is that it's just a "belt and braces" approach to lubrication. Pretty much everything about this thing is over engineered (only 78bhp from 2.3 litres yet still having a good sized front mounted oil cooler for a start) so my guess is it's just making *really* sure that it's not a possible failure point.

The splined bit is ridiculously long compared to the other few I've seen in person too.

There is a grease nipple on the rear section of the front propshaft, but I *think* that feeds the UJ rather than the splined part...could be wrong though...