jonnyjeep

Problem now sorted hopefully... Before I go into details, I would like to quote the old saying 'buy cheap, buy twice, buy thrice' as all brake pads are not equal & all brake pads do not fit as properly as OEM pads....especially if they are produced in China for the EU. My problem was brake knock/rattle over bumpy roads at low speed & it was indeed the pads. It wasn't the height of the pads that was the problem (183.4 mm), it was the width of the pad ears. The pad ears on cheap pads are not wide enough, hence they rock back & forth, which causes a clunk/rattle on rough ground which goes away when you apply the brakes. I bought some NAPA 'proformer' pads & they have ears that are (and I've measured them with a micrometer) 0.9mm wider, which pushes into the caliper clips alot tighter, thus stopping them rocking back & forth and preventing the brake pad from rattling....at last I'm a happy 300C driver

After my last posting a few months ago that concerned clunking brakes that were all but sorted, I have a new woe ! Back in December '23 I fitted a pair of new front brake calipers on my 2007 300C CRD as the old ones were seizing up when hot. ........and thats when the rattling started ! Since then I have tried a couple of different makes of pads, new slider pins & new pad carrier clips.....but only on uneven roads at below 20 mph, I have this rattling noise coming from the brake area. I have narrowed it down to the inner brake pads & have concluded that the twin pot floating brake caliper design on the front of this vehicle is not really fit for purpose. There is nothing to hold the inner brake pad to the caliper piston...hence it rattles at low speed. Previous vehicles that I've owned have only had single pot floating front calipers & the inner brake pads always came with a backing clip that pushed into the caliper piston to stop it moving up & down. The workshop manual states that the pads are interchangeable inside to outside. Is there a reason for this ? Until they produce front inner brake pads for the 300C with clips that fit into the caliper pistons (to stop the pads moving), then there will always be a rattle problem with the inner front pads on the 300C

Still no oil soaked EGR, firewall, engine cover etc since sealing the turbo outlet pipe, but a little turbo flutter occasionally when letting off the accelerator....seems normal for a turbo diesel

Water ingress on the brake pads makes the problem worse, so obviously a washout issue with how the pad ears & clips are greased. Copper grease of now seems to be different of copper grease of old & doesn't seem to be up the job anymore. Tried lithium grease... no better. Tried ceramic grease...no better. Tried CV joint grease...PERFECT !! CV joint grease....that black stinky stuff that smells like hydraulic fluid is perfect for brake pad ears & clips. Super lubricating & doesn't wash out. No more creaking & clunking when braking for 3 months now, even after driving through numerous deep puddles.

I fitted a swirl valve bypass & found that the light does stay on. If you have a scanner or laptop software then you can turn it off. Or simply, just disconnect the battery negative for 30 seconds (standard PCM reset time) & it will reset to it's parameters & the PCM will be fooled into thinking that the swirl valves are still connected

Hi there, if you have a code reader, then you can try to delete these codes, as they may have been stored by the PCM if the battery wasn't disconnected when the work was done, or the engine was started without the MAF sensor being plugged in. If you don't have a code reader, then just disconnect the battery negative terminal for 30 seconds (standard reset time) & reconnect it. This should clear all fault codes & reset the PCM. The PCM should re-learn all it's parameters in less than 5 miles. If the fault codes re-appear after that, then you have permanent faults I find that glow plugs are always an issue with the CRD OM642 engine & even though it says it's a 'glow plug control module' problem, it's usually just one or two glow plugs that are at fault. A proper scan will tell you which plugs are a bit iffy. There is another consideration....did you have NGK glow plugs fitted ? The reason I ask, is because I fitted a set of 6 NGKs a couple of years ago & after about 100 miles I had multple fault codes. When removing them, 4 of them were bent..... alas, they were fake NGK plugs (there are alot out there) & the dodgy ebay seller did not refund my money. Went to local motor factors & bought some genuine Bosch glow plugs for not that much more than what the NGKs were on ebay & they were great. Three years later, two of them have failed, but doesn't really affect car. Will get two new Bosch ones before the cold weather sets in Hope this helps

Thanks for the reply Bignev, sorry to take so long to reply as I haven't been on here for a while. I did hit another 6K miles on the 300C a couple of weeks ago, but the oil light hasn't come on yet since the last oil change. I'm tempted to leave it until it does come on at high speed, just to see how many miles it takes. Engines like this should do at least 10K miles before an oil change, especially as it's fully synthetic. I also don't use expensive brands...I've been sticking with Granville hyperlube VL 5w30 for years & it's always been good & it's British ! An engine like the Mercedes OM642 needs better oil filtration. A single filter that is the same size as a 2.0L engine is not enough for the oil capacity of the engine. I will change the oil & filter soon though, as I don't want to tempt fate. I think Mercedes cut costs when they made this engine. Proper efficient German engineering would have put a bigger filter, or even two filters

Have you done this yet....and was it a clockwise undo ? You'd think that as the belt runs clockwise, then all bearings & bolts would be right hand threads. They would undo themselves otherwise ? The only times I've ever encountered left hand threads was on rear wheel bearings on an old Ford & a chinese made parasol...lol

Chryslers' obviously bad attempt at trying to improve a perfect mercedes engine by adding new parts....or did the then Mercedes owned Chrysler try their best to sabotage Chrysler.....marketeering for their own future gains ?

Sorry for the total confusion...I got my inlet & outlet the opposite way round. The pipe I sealed was the turbo outlet pipe, but this was obviously the one that was causing the oil spray back onto the back of the engine, EGR & underneath of the engine cover.....blowback ?

Possibly a bad wheel bearing....makes sense as the sensor can sense a straight wheel, but if it goes out of true, especially when cornering, then the sensor may misinterpret the sensor ring. Defo something to do with the sensor or sensor ring though, as that is one of the main causes of the ABS light.

Hi all, has anyone ever had their oil light illuminate when motorway driving, but not when urban driving. A couple of times in the last month, the oil light has come on after doing 60mph+ for more than 10 minutes. I cannot hear any extra engine noise when this happens. The light goes off when I drop down to about 50mph. I've done a full diagnostic scan & although a couple of unrelated fault codes came up, they were nothing to do with the engine oil pressure or the sensor. Maybe an oil change is probably due because it has been 6000 miles since the last oil change....or should I say, possibly just a filter change ? I may have answered my own question....filter ? This OM642 mercedes engine takes 9.5 litres of oil at a change, which is pretty much double what a 4 cylinder 2.0 diesel takes, but only has a single oil filter the same size as a 4 cylinder 2.0. That is double the amount of oil being filtered through a filter that really is only build to handle half that oil. It's no wonder that this engine requires such frequent oil changes ! An oil change on this car requires 9.5 litres of fully synthetic 5W/30 oil & a new filter after about 5000 miles. Considering that fully synthetic oil is premium oil & in most cars is good for between 10,000 - 18,000 miles, then maybe it may make more economical sense to just replace the filter, as the oil should still be good....shouldn't it ?

It wasn't the dreaded O ring oil cooler leak and was actually a very cheap & easy fix. So maybe many others can possibly breath a sigh of relief. The spray was actually coming from the aluminium pipe that pushes onto the turbo inlet. Because this pipe is a push fit & there is no proper seal, then a small amount of oil gets forced out & sprays liberally about the egr area & soaks the back end of the engine cover insulation and cross member. I put a rubber O ring around the turbo inlet & also spread some black instant gasket around it (probably overkill, but just to ensure that it would seal), then pushed the aluminium pipe onto it and let it set for a couple of hours. I've had no oil fouling around the EGR area or engine cover insulation since I did this a year ago. I do wonder though....why is there no rubber seal on this pipe, considering the turbo pressure that is pulled through it ?......did a designer think that an aluminium over pipe with no vacuum seal would suffice ?

D Salmon cars in Colchester did this for me back in June 2020, just after they re-opened after lockdown. They are the only dealer I have found that can actually do this properly within 50 miles of me. I left it with them, went for a walk about around lockdown Colchester (everything shut) & it was done within a couple of hours....£95.00. There is a guy there that really knows his stuff.

Hi all, I've been here for a while, but haven't had too much input, as I'm much of a 'work it out myself guy'. But there is a problem that I do have with my 300C, that I can't work out regarding the front brakes. The damn things keep creaking & clonking when hot. New discs, countless new pads, new pad clips/old pad clips, copper grease, lithium grease on the ears & backs. New sliding pins & seals. Twin pot calipers are working fine. I strip the brakes down & re-copper/rubber grease them & they are fine for a month or so, but then they gradually get worse again, until the creaking & clonking gets to the point where you have to redo it again. I'd had this problem a few years ago on a Ford Scorpio & it was down to pattern brake pads not being made to original spec, so I suspect the same with the 300C. Rubbish Chinese made parts ?.....where can can I get proper orginal spec brake pads in the UK Or is it a case of glueing wraps of tin foil onto the backs of the rattle clips to make the pads fit tighter ?