SteveHof

2004 C240 4matic with 80k miles. Reduce engine oil level message has blipped on randomly for a moment or two on occasion over the last year but to no detectable detriment.

A few days back a muffled flapping noise came from the engine compartment for a few seconds while under acceleration at 40 -60 mph. Didn't last long enough to discern the source precisely, but sounded much like a crank RPM-synched leaky exhaust manifold gasket "Pffft." Engine power seemed fine until it stalled, no error messages or check engine light.

Last night the noise began again at 60 mph or so, increased in intensity although no power loss noted, did not stop, and a half mile later, engine dies. A mild (electrical) burning smell was observed while rolling to a stop, and maybe a slight whiff when popping the hood open. No visible signs of any problem. There was a blip of a check alternator message when rolling to a stop on the stalled engine (new alternator a few months back and I'm confident there's plenty of charge and battery amps at this time). However attempts to restart cranks slowly - as if engine is partially seized - and starter just can't crank at regular or uniform speed. Ignition tries to catch but will not. Same symptoms after it cooled down and still no error messages. Going to connect an OBD reader this afternoon to see if any codes are stored.

Any thoughts, guys? Sorry I don't have anything more to go on.

Glyn M Ruck

Are you sure that the engine oil level is not too high. Check it. You might have a leaking injector & have partially hydrolocked the engine. Remove all plugs & crank over to check.

SteveHof

Well, oil level measurement is a sore subject on this car. I've hated the automated monitoring since I've owned it precisely because I can never be sure if the sensors and ranges are correct. I always meant to find a dipstick for it. But based on what I read here, it's pretty common for an occasional high level message blip. Because it's so occasional and because I've done the oil changes, I'm pretty darn sure oil level is ok.

But tell me more about the partial hydrolock - would it give me a sudden hard spot in the starter crank speed after the highway stall? My OBD check resulted in no error codes whatsoever. And I'm haunted by the short whiff of something burning (more electrical than anything). I can't place that or the odd engine noise at all. Thanks!

Glyn M Ruck

Hydrolocking is if something that is not compressible like water or oil gets into one or more of the cylinders. In the worse case this will bend a conrod when you try & crank. A drastically overfull sump can do this. The oil will either force past the rings or up a captive breather or out of the crankshaft seals. This is unlikely but removing plugs will soon tell you.

It could also be a partially seized accessory like the alternator or HVAC compressor. I would expect the Poly V belt to complain but if it's well tensioned it might not. Remove the Poly V belt & try & crank.

SteveHof

Good insight, thanks. Will do what you suggest. The belt is well tensioned and that scenario actually addresses every symptom. But no engine error codes in all that? I know nothing about how robust OBD data is.

Glyn M Ruck

OBD will not catch the problems I've outlined.

SteveHof

Glyn, et al,

Well after an arduous week of choosing a shop to marry for diagnosis and repair, I've been told that the engine is trashed. It wasn't hydrolocking, but rather failed lubrication - a large amount of sludge in the valve covers and oil filter housing, a lot of varnish on components, and from what the mechanic says, main bearings that are so damaged that he could feel play in main shaft when turning it. The cam turns but many valves do not cycle, suggesting severe valve and guide damage. While I'd prefer to have him rebuild the engine I have (only 58k miles), he says it will very likely be too cost prohibitive in replacement parts. He's located a used engine, which is all that seems to be available.

My question is, how does this happen on a modern, softly driven engine in a non-dusty climate using synthetic oil? And it happened fast - within the last 8k miles or so since this sludge is all over the oil filter. No symptoms prior to the noise that intermittently occurred just prior to failure, and no warning or malfunction messages. Clearly the random high oil level messages were a result of sludge affecting a sensor.

I see some posts for sludge problems on earlier years and models, but it doesn't appear the '04 C240 was affected. I've used other brands other than Mobil 1 on my changes, 5W-30 weight as I recall. And I've used standard Rock Auto supplied filters. Hard to imagine that these products could be the cause. Any thoughts? And does anyone know about the MB extended warranty on sludged engines?

samaritrey

Well sludge is not Mercedes fault on any engine after say 99. They did have issues with clients using dino oil and running for 10,000+ miles but they fixed that practice and I have never heard of a sludge issue on a m112 engine in a w203. You said you used other brands other than mobil 1. Were they approved 229.5 spec oils? Mercedes is very specific on what oils to use for the extended oil changes and there are not many oils that are approved. Also the rock auto filters were they paper or fleece. For the m112 engine you can get the fleece ones and should always use them. Have you owned the car for its whole life or did you just recently get it?

SteveHof

Thanks samaritrey. The 229.5 spec is not something I ever paid attention to, and I blindly assumed that all synthetics were the same as long as they met the standard manufacturer grades. And I've always run paper filters, which I believe the dealer also installed when under their warranty maintenance. I've had the car since 6k miles, it actually has just 58k, not 80k as I mistyped.

In any case, I'm struggling with how much damage there really is. Could the main bearings have spun out so badly that there was play in the front drive pulley? I got a look at the valve train when he had the cover off, and everything seemed wet and lubed up there, but the mechanic said he concluded the cams, valves and guides were damaged beyond repair. Hard to believe with an engine that exhibited less than 45 seconds of theoretical oil depletion. I just hate installing an engine of unknown history with 20k more miles on it.

Glyn M Ruck

Petrol engines suffer from low temperature sludging & diesel engines from high temp sludge. A lot of stop start in-town driving will promote this.

You must use 229.5 oils with Fleece filter on the M112 engine. Mobil 1 0W-40 Euro formulation being the most commonly available in the US.

We had one lady with a C240 a long while back that was sludged due to poor service practice & light use frequently not at full operating temperature. If memory serves me correctly we cleaned it up with a couple of oil changes back to back at very short interval.

The simple check of damage is to do an oil change & try & get the thing started & measure oil pressure, blowby, leakdown. Otherwise it's teardown & examine which might be throwing good money after bad.

You got any pics of the sludged cam & tappet area?

SteveHof

Glyn, I wish I had progressed this dialogue before committing the car for engine replacement. Your idea about the oil change and restart is sensible. But he's got the old one out and the replacement coming in tomorrow, so there's no turning back. C'est la vie. I'll get a few pics and post them though, I told him I want to spend some time with the core before he returns it.

So yes, it looks like the fault lies with me on the particular MB oil spec and filter type. And yes, my wife had a very short commute for most of the car's life. My bad on the oil, but if the M112 really has to have the fleece filter, it's fair to expect that's all that should be made available for it.

Separately, he says the inner CV joint boots are cracked - is 8 years about the life for them?

Once again, thanks for the helpful insight, guys. This straight-up, unpretentious forum is the best thing about my MB ownership lately!

Glyn M Ruck

All I can do is wish you good luck!

Presume you mean inner front plunging CV joints? Those things work hard on a 4 Matic. Get them cleaned, greased & new boots.

samaritrey

Well I wish you luck as well. BTW how long were you going between oil changes? The paper filters are not the end of the world on the m111 or m271's can't remember which you can only get the paper filters and they seem to be ok for the full 10k but that scares me personally. My m112 in my car has 176,000 miles on it have always done oil changes when the car says too so anywhere from 10k to 13k miles and it still runs like new. Of course I only use the proper oil and fleece filter as recommended. Keep us updated and if you do manage to get us some pics of the old engine that would be interesting to see as well.

SteveHof

Thanks samaritrey, I'll likely need it. Hate the feeling of being at the mercy of an unknown shop. Guy seems pretty competent and straight, but you never know.

I too followed the A&B intervals roughly, about 10k, and sometimes changed the filter out between oil changes. The dealer did the first two under warranty maintenance.

I think it was the oil spec that got me, and perhaps that I didn't have a dipstick - I only saw/smelled/felt the oil when I was changing it, rather than keeping up with it on the dipstick. The oil always drained very dark on this car - I've been using synthetic in all my cars since the early 80s and never saw it get very dark. But something else happened in there the last 8k miles - the filter was completely loaded up - that's what baffles me most.

I'll get some pics. Thanks again for your consult.

Glyn M Ruck

Analysing an oil sample from the engine would be interesting. Sounds like it polymerised, goo'ed up the filter & would not pick up from the sump in the end.

LILBENZ230

You can keep up with the levels in the instrument cluster via dyno mode. That's how I do it.

To clarify what Trey was saying, the paper filters work fine for the M271 even the 13k drain intervals. I run them. But that is neither here nor there for you with the M112. In the future make sure you use 229.5 spec oil only.

SteveHof

Glyn, I may do just that. The oil seemed fine in terms of lubricating ability, albeit quite dirty. I'm guessing sludge built up quickly once the filter gummed up and went to bypass.

Lilbenz, thanks for the clarification and recommendation. I'm still stunned that this engine would be so particular as to fail with an API SN oil and a paper filter. Sometimes sophistication isn't a good thing.

So my indy tech has quoted me US$340 to change out all 4 axle boots along with a full cleaning. Does that seem right with the motor out?