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ML 350 CDI
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Discussion Starter #1 (Edited)
If you experience extreme engine rattle on start up that you've never heard before, or even noisy engine at start up (which I've had since I bought the car three years ago) seeming to come from the top and front end of the engine, this will be of interest to you.

Low oil pressure (or none on start up like me), evidenced by the aforementioned noises, or nil oil flow to the engine on visual inspection, may be caused by the failure of the non return valve that fits between the oil pump and the engine.

This part (47 on the diagrams, P/no: A611 180 01 15) is a particularly poor piece of design work on the part of MB. At least the one in my car is..... The plastic valve is within a plastic shaft tube/housing where it runs up and down multiple times throughout the engines life. In my case, the valve housing has worn so much it has permitted the shaft of the valve to cock slightly sideways, preventing the valve from opening, restricting oil flow to the engine.

This particular part is in ready supply at my friendly dealer, suggesting this may be a commonly replaced part. As far as reasoning for failure, the engine is clean and has a full service history. The vehicle has travelled only 47,000 miles and was in storage for a year and a half. Failure seems (upon considering the design of the valve) a matter of time, not an unusual occurrance. Dealer stock also seems to suggest this is the case too......

To replace, jack up your car and place stands under the chassis.

Remove the front plastic tray from under the front of the engine, the one that mounts to the subframe and the front bumper. Pop out the centre of the plastic clips and they'll just fall out. I used a door trim remover tool.
Drop the engine oil. As you know, these things have a LOT of oil in them so use a large container. :D

Undo the two engine mount bolts on the RHS of the car. Placing a jack under a steel support/piece of square fencing tube from the local hardware store solidly and carefully into the engine housing, where it meets the engine mount, gently lift the engine off the mount.

Remove the transmission cooling pipe brackets where they bolt to the lower subframe so the pipes can be lowered closer the the ground, making it easier to remove the sump from the car and preventing you from having to jack the engine up too high. Don't want to bend any pipes, etc.

Remove all of the torx bolts securing the front lower sump housing only. The sealant used sticks like poo to a blanket, so VERY gently lever the sump housing (LHS front has a tab that will accept a large screwdriver) so a safety knife blade can be slipped into the join to cut the sealant. Very gently pry the sump. it can even be a good idea to squirt a little kero around the joint to soften it, leave it for a good hour to penetrate and dissolve it. Be very careful not to bend your housing. MB silicon sealant is the BEST.
Gently and carefully remove the lower sump housing through to the front of the car.

Remove the three torx socket bolts holding on the oil pump. Note more oil will fall out when the bolts are loosened. Being careful to not drop the offending valve (note its orientation, so you don't stuff up putting it back in) while removing the oil pump from the engine. You do not need to remove the drive chain.

Clean the pump, and all mating surfaces of all parts removed, get your butt over to your dealer and buy the valve (for around twenty bucks) and a tube of recommended MB sealant. When you buy the valve, the valve will not operate freely and will seem slightly open. Using your finger, press lightly on the valve and rotate the inner workings fully counter clockwise. It leaves the manufacturer in a jammed open position so as not to have the valve pushing on its seat while in storage.
Reverse the procedures above to get your car back on the road.

Having had this happen to me (luckily in the driveway at home), I'd recommend doing it when you buy your car. If you've not done it yet, put it on the to-do list. Nothing would suck harder than being in the middle of nowhere and having this little turd of a part stopping you dead........


REMEMBER: There is a real danger of a crush injury, or damage to your oil pump, if whatever you're using to jack up the engine is flimsy or not stable. If the engine falls when you're not expecting it to, that would be bad.....


Thanks to Witek M for the part heads up.
Picture courtesy of 43sqd
 

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99 ML320 2000 ML55 AMG... miss my 84 500sec AMG
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if this part can restrict oil to top of engine, then why couldnt this be a thing to look at if you get the oil light?
 

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99 ML430, 00 ML320, 05 E500 4matic Wagon
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The oil light is triggered by the sensor in the pan as to the oil level.
It monitors other things, but oil level is one of them.

In this case the oil pump problem would leave plenty of oil in the pan and not trigger the low
oil light to come on in the dash lights.
 

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Discussion Starter #5 (Edited)
if this part can restrict oil to top of engine, then why couldnt this be a thing to look at if you get the oil light?


Yep, you're right. I may have been totally unlucky and experienced a random failure. But my dealer had 17 of these valves in stock.
If you're lucky, it won't fail.
If you're unlucky, who knows where you might be if it does? At home? With your better half down at the market? When you're on a road trip interstate and have stopped for fuel?
 

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Discussion Starter #6
Update:
The engine was slow to get up oil pressure, so I left the oil filter carrier out of the engine until it quitened down. Then installed it once it was quieter, indicating it had pushed up oil.
After going for a fair run, the engine is nice and quiet.
More telling is that on cold start, the engine no longer has a 'noisy start' like it used to.

The very same part that makes sure your engine doesn't rattle on start up will actually make it rattle on start up when it starts to fail. Remember, your engine is not supposed to be noisy on start up. If it is, you may have this valve issue.
 

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Hi Aussie,

I think I have the same problem on my 2006 ML500. I live in FL, so most of the time I can barely hear the valve train noise. As matter of fact when I switched to lighter weight oil 5W-30, noise was gone at start. Only time I heard the noise(slight knocking) was upon deceleration after cold start and only for the minute or so. This has been going on since 15K miles.

This AM when I started the car, there was NO MISTAKE in the noise. I am up in VA (colder weather), my car was not getting any oil in the top of the engine. This was loud. Noise went away after 20-30 seconds. I am going to have the valve replaced when I get back to FL. Thanks for your detailed write up. I'll update in couple of weeks after I get it done.

PC
 

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I had the same problem in my w 210 E 55 Amg (278000km) replaced idraulic lifters (24 lifters) no result , then valve replaced, finally no more noise!
Thank you very much for this very helpfull post.
 

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So I have a 2005 S430. Having problems with rattle at start up and noisy valve train. The noise would go away if you raised the engine RPM to 1000.I replaced all the lifters but yet the problem remained. I hooked up an oil pressure gauge it the car and was getting just barely above 1 bar at idle,which is within spec. However, when I revved the engine up to 2,000 RPM, the oil pressure rose but it was delayed. According to WIS, there should be no delay.

I came across this thread and noticed had similar symptoms. So I decided to pull the pan and see what I found.

My old valve was not stuck open like the orignal poster had stated. But the rubber seal that comes with the pressure valve was totally distorted. When installed in the engine block it was flush with the block. Im thinking there was no longer a seal between this part and oil pump, possibly causing the oil pressure to squirt out back into the oil pan instead of where it needs to go. It's late, so I will be finishing the job sometime tomorrow and will update with the results.
 

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1991 300D, 2001 E320, 2006 SLK280
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So I have a 2005 S430. Having problems with rattle at start up and noisy valve train. The noise would go away if you raised the engine RPM to 1000.I replaced all the lifters but yet the problem remained. I hooked up an oil pressure gauge it the car and was getting just barely above 1 bar at idle,which is within spec. However, when I revved the engine up to 2,000 RPM, the oil pressure rose but it was delayed. According to WIS, there should be no delay.

I came across this thread and noticed had similar symptoms. So I decided to pull the pan and see what I found.

My old valve was not stuck open like the orignal poster had stated. But the rubber seal that comes with the pressure valve was totally distorted. When installed in the engine block it was flush with the block. Im thinking there was no longer a seal between this part and oil pump, possibly causing the oil pressure to squirt out back into the oil pan instead of where it needs to go. It's late, so I will be finishing the job sometime tomorrow and will update with the results.


Hi there! How did your repair go? I also have to do this job as I suspect this is my issue.

When removing the oil pump, does it come off the chain easily when the mounting bolts are removed or does the chain have to be dissembled in order to remove the oil pump?
 

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Unfortunately it did not. I ended up replacing the engine because I was tired of dealing with it. Once you unbolt the pump the chain easily comes off. Make sure you release the new valve when you get it. It comes from the factory stuck open halfway.
 

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Unfortunately it did not. I ended up replacing the engine because I was tired of dealing with it. Once you unbolt the pump the chain easily comes off. Make sure you release the new valve when you get it. It comes from the factory stuck open halfway.
Thanks for that updated info.

Sorry to hear you had to replace the motor ($$$$). At least you wont have to deal with that annoying noise.
 
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