Valve Problem
 

hi guys! i changed my spark plugs today and found some unused oil on the one closest to the radiator. and just a tid bit on the next one. the other 2 were clean. the plugs burn was normal it just looked tired already. i called a local Mb shop they said it might be a valve guide. it a $6 online if i DIY. but the shop said usually they just replace the whole valve. $2,500. duh im not buying it. what i want to know is has anyone had this problem? is it the valve guide or something else? maybe coz its right beside the engine oil filler cap thats why theres oil? also as you can see in the last pic the oil looks unused/new thanx for the replies.

just incase your wondering the numbers on the coils are the firing order.

ok i did alittle research and seems like im not alone with this problem. all the threads ive read were unanswered. please someone help us. also hope these pics help.

the spark plugs all look alike upclose.

BUMP

Need more info. What's the year/model of your car? How many miles? You should update your profile with year/model and location.

Valve guides are cheap, but you really need the valve job gasket kit, it's about $100-120 or so sice you will need that odd assortment of gaskets when you try to put the pieces of that puzzle back. Then you just pull the heads, take them to a machine shop and have them install the valve guides, probably just a whole valve job while there. I would think a good MB shop would only charge you about $1,500.

Before you do that, to a leak down test to see if the oil is coming from the rings or if it's something else.

Doesn't Mercedes do a procedure for cleaning valve guides by running the engine at 3-4k rpms for like 10 minutes? If so, is that supposed to prevent this stuff?

There seem to be lots of M271 issues lately. I'm nervous.

Listen to Buell. Give us more detail. How much oil does this car use? If you run down hill against compression and then floor the throttle does the car blow a cloud of smoke out of the exhaust & then stop smoking? Do a leakdown test & wet & dry compression test.

its not really using oil. i dont have to add oil at all. and no it does not puff out smoke. although this morning i started up the car watched the exhuast blow out some whit smoke for a few secs then nothing just the normal moist dripping of the exhaust. i was thinking maybe the smoke came from the anti-seize on the spark plugs. im gonna observe again tom morning. all i noticed is my car is drinking more gas. and no i dont use cheap gas. i wanna do a test on it. i dont have the tool. any links to a good set of testers?

oh also as you can see i did update my profile

Yup, 2003 was the worse year, or at least the first year to have this problem. What happens, and cylinder #3 seems to be the common theme is the exhaust valve gets carbon buildup to the point it can't seal anymore. So what happens is you get misfires. So you want the easy fix or the cheap fix. But seriously, before you spend any dough, get a leak down test, it takes 1/2 to an hour and you'll know what is wrong. What you will likely hear is when you applied compressed air to the faulty cylinder, you'll hear a hissing coming out of the tailpipe, that's the exhaust valve.

The easy fix is what dealers do, put in a new head, it's $2K for the part and about 12 hours labor, figure $3,500.

The next best fix is to pull the heads and do a valve job like I mentioned before, why throw away a perfectly good head that just needs rebuilding. Typically (dont' know specifically on this motor), they'll pull the valves, clean and grind them, put new exhaust valve seats, install new valve guides and put it all back together. Gave you what that should cost above.

The cheapest thing to do and it worked for one person here is to use what I recomended to him, GM Top Engine cleaner. You get at any GM dealer, it's like $10 and you pour it in your intake a little bit a time while the engine is running, enough make the engine run rough but not so much it stalls. Instructions should be on the can. Don't get the spray, get the liquid. He had to do it twice before it cleared the problem but heck for the few bucks, do it a bunch of times. $50 of magic potion is better than a few thousand of surgery. My guess is that it's a bandaid fix but time will tell. Like I told him, you gotta try it first, nothing to lose at this point.

cool method on the GM top engine cleaner. can i just do this or should i do a leak test first?

Please don't go chasing a problem that does not exist. If the car is not, using oil, misfiring, backfiring or blowing smoke there might well be nothing wrong. You are basing all of your worries on one discoloured/slightly fouled plug. Listen to Buell & don't tear down anything unneccessarily

In future run your car on Techron it will keep the valves looking like this.

https://mbworld.org/forums/attachmen...n-ichibans.jpg

i agree with glyn! dont be too worried. i can see on your third picture the oil look new/unused. probably the person who did the oil change was clumsy and spilled alittle then it ended up on the plug. try checking the plug again after a few miles and check if theres still oil. if there is then do a leak test. from there you'll probably know what to do.

I recall an old trick "back in the day" you would rev the engine,
and poor water into the intake.
Was that just stupid? I recall doing that when I was like 18 or 19 on an old
Ford..I think it was supposed to clean the valves.
Likely not a good thing to do on a benz? Or... ???

Reading the thread over again, I'm not clear...why do you think a valve is bad?
I recall there are seals between the head and valve cover that go bad
on M111 and cause this, maybe it's the same thing on M271?
emrliquidlife had a thread on this...
the spark plug holes were filled with oil.
It was not related to valves. Just some cheap seals easily, well relatively, replaced without removing the head.

I think someone spilt some oil & please don't go pouring water down the inlet of a modern vehicle - It's not a cast iron Yank Tank - you can do a lot of damage & could bend a con rod.

i am with glyn- it looks as though all of the oil you are finding is on the outside. i think some oil was spilled also.

i've heard of water in the intake. however, it was a very, very small amount. the idea was that the steam cleaned the carbon out of the combustion chamber. i've read about it several times, but never had any first or second hand experience with it.

I am a bit confused here. If there is a problem with the valves or valve guides, this should show up as deposits on the electrode of the spark plug.

What I think I am seeing in the photos is oil on the exterior of the plug(s). I don't see how this could be caused by valve or valve guide problems.

A common problem in higher mileage BMW's is the valve cover O-rings begin to leak around the spark plugs. The result is oil on the outside of the plugs. Replacing the valve cover gasket set cures this problem. I am wondering if the Mercedes M271 might be prone to the same (or similar) problem as it ages.
:zoom:

Hate to drag this back up but I noticed my car do something earlier that I've never noticed.

I was following it, allowing a friend to drive it while I drove her car to see if I could figure out what she was complaining about. We got to a passing zone and she went to pass a car and she must've gave it WOT but it blew a puff of black smoke out. Just a puff. I called her phone like 10 minutes later and requested she floor it again and it did the same thing. I drive the car pretty hard, but it's maintained really well, too.

Any ideas? Glyn? It doesn't smoke on start-up or at any other time. No codes, no misfires, runs absolutely great and isn't using oil. Always have Tier 1 gas, use Techron concentrate every 3-4 tanks.

My car has the same, exact issues. No spilled oil, and only the front two cylinders. No added oil between changes. 61,000 mi.

Matt,
Don't worry - Just slightly rich at WOT until the engine reacts. Remember at WOT the fuel trim circuitry runs open loop so you loose a bit of mixture control briefly. She probably floored it at fairly low RPM. If MB tune this out in the ECU mapping with a blower you would have a flat spot. Black smoke is unburnt fuel.

Think of throttle pump in crude old carburettor engines. Just gave the engine a shot of fuel.

Thanks Glyn.. I'm not worried then. I was kind of shocked at seeing it.

Bringing this one back from the dead to diagnose a misfiring issue. Can someone please verify this cylinder firing order for the M271 as being 2-1-4-3 (from firewall to radiator), as in the first picture? Just need to make sure, and flipping through my manual and Googling around have come up empty.

firing order usually should be on the engine itself. i.e. M112 and M113 firing orders are on the passenger bank valve cover.

I agree, that's where they usually are; that is the case with the V6 and V8 engines we have in the MLs (they're nicely embossed on the metal). I can't find them on the I4 anywhere though. It's possible they are there, just hidden behind the plastic fittings underneath the engine cover. All I see on the sides and top are part numbers for the head, engine block, and various smaller pieces.