W124 200E exhaust fumes inside car

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djf01

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Oct 6, 2008
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7
Hi there,

I've been looking after a 1990 W124 200E with 102k miles on the clock for the last three years and kept up with routine fluid and filters servicing for the last 30k miles.

After I changed the air filter a couple of weeks ago I have noticed strong smell of exhust fumes inside the car when stationary or in slow traffic.

I've checked the connection of the breather tube to the air filter and it seems secure, but I noticed that there is some oil leaking from this connection, also oil has entered (and drained out of) the resevoir inside the air filter housing.

Does this mean that the pcv valve is faulty? Should I just change this or should I do this plus replace the breather pipes. Or is it likely that the fumes are something else?

There are some other related symptoms like; oil leaks around gaskets, sometimes lumpy idle (but better since new air filter); but obviously the fumes are the main concern. Pretty sure its not the exhaust pipe as that's new and it sounds ok.

My haynes is particularly vague in this area...

Thanks in advance.

Dan
 
The "exhaust smell" may come from an exhaust leak-manifold/down pipes/exhaust itself. Easy to check up on a ramp. If you partially block the exhaust outlet with a rag( watch you don't burn your hand) any leaks should be evident by a hissing noise from any leak. Do this with the exhaust cold and hot. It's more likely the smell is coming from oil leaking on to the exhaust manifold and burning off. you won't smell it when the car is moving because the slipstream is sweeping it away. You could try renewing the cam cover gasket and the breather pipe leading to the air filter-these get soft with age/oil contamination and can leak. If you remove the air filter you will see the airflow sensor plate-if this gets crudded up that can lead to a lumpy idle. gently depress it and clean the "THROAT" of the airflow sensor with carb cleaner. It sounds as if your engine is getting a bit of piston "blow by" which is pressurising the crankcase and blowing a bit of oil out the cam cover vent. This could be just down to engine bore wear and you may just have to live with it. You could get the cylinder compressions tested to get an idea of how bad this is.
 
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It sounds as if your engine is getting a bit of piston "blow by" which is pressurising the crankcase and blowing a bit of oil out the cam cover vent. This could be just down to engine bore wear and you may just have to live with it. You could get the cylinder compressions tested to get an idea of how bad this is.

Bore wear on a 102k engine?

This is a Mercedes engine, not a Ford.
 
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If the 102 miles are genuine? Not wishing to cast aspersions on the posters car but seems lowish for 18 year old car. :confused: Other things can also effect premature piston ring wear like a previous overheating incident/ blown cylinder head gasket etc :eek:
 
If the 102 miles are genuine? Not wishing to cast aspersions on the posters car but seems lowish for 18 year old car. :confused: Other things can also effect premature piston ring wear like a previous overheating incident/ blown cylinder head gasket etc :eek:

It is a little low, but they do exist and come up on eBay and the classifieds now and then.

I suppose it would really depend on how well it has been maintained.
 
Thanks for the replies guys I appreciate your thoughts.

I'm pretty sure the 102k is genuine as I've got the MOT certs going way back. I've put 30k on in the last 3 years and it's been fine. I've done oil and filter changes every 6k.

Going back to the problem, I guess it could be an exhaust or manifold leak but it seems a bit strange that I only started smelling the fumes after I changed the air filter? Also the sound of the car hasn't changed at all - wouldn't I hear if the exhaust was leaking?

The oil leaks are seeps rather than drips - I only lose 1 litre of oil every 6000 miles so I dont think it is oil burning off the exhaust manifold - plus the fumes are the killer headache/wind down the windows and shut all the heating vents kind...

So this is why I thought pcv valve which I understood if faulty can cause the oil to come into the air cleaner enclosure. I presume that is connected to the breather pipe going from the rocker cover to the air cleaner somewhere. I think I will replace the breather pipe as I guessed if this pipe isn't airtight that this could be where the fumes are coming from?...
 
2 things you said---the exhaust was "new"---- not disagreeing with you--- but that's something else that's been changed recently as well as the air filter??
Did you use a bona fide mercedes/mann/knecht/hengst air filter in case there's a problem there.
As a test you could try routing a temporary breather pipe of similar bore from the camcover gasket to a temporary catchpot mounted low down on the chassis to see just how much oil vapour is coming out of the engine. Block off any other connections necessary in the emission pipework. http://www.detali.ru/cat/oem_mb2.as...+++717.412&CT=M&cat=504&SID=09&SGR=060&SGN=02
If this helped and your engine is blowing a lot of oil you might think of a permanent set up plumbed in - not too expensive- well cheaper than an engine rebuild anyway. ;) http://www.fordmondeo.org/forum/showtopic.php?tid/785586/
 
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thanks Graeme,

Well the exhaust is new as in not old and full of holes - it went on about 6 months ago. The air filter is from dealer and matches the old one.

I think I'll get it on a lift in the week to rule out exhaust leak like you said then I'll look at your ideas about the catchpot idea and do a compression test.

I'll be really dissappointed if the engine is worn though as I was hoping to get another 100k out of it...

Does 1L of oil every 6000 miles sound high in your experience?

Thanks again I'll let you know how I get on.

Dan
 
OK fair do's that seems to rule out the exhaust and filter- still worth checking the exhaust tho as you have suggested. A litre of oil every 6k seems quite a reasonable oil consumption to me and quite a hopeful sign that things are OK bore wear wise. Time for a recheck of all those emission control hoses in case any oil vapour is escaping into the engine compartment.
 

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