What can make abnormal noise under the valve cover? - Page 4 - PeachParts Mercedes-Benz Forum

dieseldan44 · #46 01-26-2009, 06:20 PM

Quote:

Originally Posted by jt20

I was thinking that. But assumptions get us big trouble.

Its like when you're in a car, and another nearby starts moving your brain tells your body that you are moving... wiiieeerrrd

thats exactly what happened.

ill try pushing down on the assembly when i resume my efforts in the morning.

there is no mention of this calamity in either the haynes manual or in the FSM in any of the parts where valve springs are removed. is making sure a piston is under the valve just mechanics common knowledge?

dd

jt20 · #47 01-26-2009, 06:26 PM

compressed air is often used.

I personally would have used the firing order to determine when #5 was @ TDC by dividing 360*/5 and matching the angle zone for that cylinder.

Common?... I'm sure there are plenty of tricks but some still make mistakes.

jt20 · #48 01-26-2009, 06:31 PM

Just some food for thought:

How certain are you that this is the issue?

How critical do you think it is?

Are there any other symptoms or clues?

dieseldan44 · #49 01-26-2009, 11:17 PM

Quote:

Originally Posted by jt20

Just some food for thought:

How certain are you that this is the issue?

maybe 50%. the spring is loose, and it is the same area where i hear the noise under the valve cover. the other 50% is because i am unlucky.

Quote:

Originally Posted by jt20

How critical do you think it is?

No idea. The problem itself does not seem critical. it is not deteriorating or getting worse. this is just a guess though, i wanted to do as much work as i could up front to determine what the noise is and hopefully, get rid of it.

Quote:

Originally Posted by jt20

Are there any other symptoms or clues?

None. Other than the noise itself the car runs great, with great power. Starts near 0 degrees no problem. Starts first crank at 25 degrees. Does not seem to burn much oil (only driven 700 miles or so).

After this investigation is complete, if the noise is still there, Ill probably take it to a reputable benz place and see what they say.

One other question, will I need to take the valve stem seal off to get at the rotator for inspection / replacement? If I take the seal off, i probably need to put a new one on, and they only come as a kit, right? I don't think the car needs new valve stem seals at 150k.

tomorrow will tell me a lot. i'm hoping its just a busted or worn out spring. im putting a new one in no matter what.

thanks jt20,
dd

jt20 · #50 01-27-2009, 12:39 AM

Quote:

Originally Posted by dieseldan44

One other question, will I need to take the valve stem seal off to get at the rotator for inspection / replacement? If I take the seal off, i probably need to put a new one on, and they only come as a kit, right? I don't think the car needs new valve stem seals at 150k.

Forgot about that. Yes, you may have to - but when the time comes, try the rotocap before removing the seal. Just be prepared to deal.

Its cheap enough to buy the set in case the removal of the seal eff's it all up. But there is a way to remove it w/o causing harm if you do not have the patience to wait for a new set to arrive.

final word - replace it if you have the time to wait. It is old and brittle despite mileage. You'll see the difference when you have a new set in your hands.

Quote:

tomorrow will tell me a lot. i'm hoping its just a busted or worn out spring. im putting a new one in no matter what.

dd

I did not realize you were already prepared with a new spring in hand. That is perfect.

glad we are on the same page with regards to the legitimacy of this project.

dieseldan44 · #51 01-27-2009, 12:03 PM

So I got the spring out. My heart has never beat faster than when I was unsure if the piston was below the valve. I held the valve stem with a pair of slim pliers juuust in case, and put the locknut back on. I took the spring out, and then verified, with the locknut in place, I indeed has a piston there - which I did.

The spring itself, of course, hold no smoking gun. Its in one piece. It does have wear at the top mating surface to the keeper, but nothing I would consider alarming.

I am hoping that the spring itself had a rate below spec, allowing it to move more than it was supposed to between keeper and rotator, causing the noise.

I am choosing not to take the rotator or stem seal out. The rotator can only be had from MB Germany, 4 week lead time. Even if I took it out, I dont know what I would be looking for.

Any good way to test the rotator in the interim?

I am getting a sinking feeling I will be right back to where I started when I button this back up. I just need to be careful to make sure I dont make a mistake in the interim that will make me a poster child of 'if it aint broke...'.

Or maybe not. But i havent heard of worn out springs causing noise, so we shall see.

dd

jt20 · #52 01-27-2009, 12:12 PM

the rotocap may fit over the seal. Theres no harm is trying - it just sits in that bore.

To test it - put the spring on and apply pressure while spinning (it should spin freely)

Apply pressure with the spring and rock back and forth to observe excessive play.

If you get the rotocap out - spin it by hand and ensure the relation of the two halves is constant - Post a picture so we can compare the reveal of the lower half.

You should definitely compare the two springs and measure them.

dieseldan44 · #53 01-27-2009, 04:12 PM

jt20,

No go on removing the rotator over the stem seal. It just doesn't make it over the rubber. I tried rotating it with the spring, it seems fine. No binding or noises or anything like that. No what I would term excessive play, but of course I have nothing to compare to. Any play just seems to be the gap between the rotator and the hole it sits in.

New valve spring should be here thursday (had to purchase from MB dealer). I will evaluate the situation then when I see the new spring if the rotator is worth removing the stem seal to inspect. I cant do much until then.

I took some good pics and will post them later on tonight.

dd

jt20 · #54 01-27-2009, 05:31 PM

its the best you can do.

Good idea to leave the stem seal alone. If you were able to visually inspect the rotocap in its entirety, that should do.

dieseldan44 · #55 02-06-2009, 10:04 AM

Problem solved.

I put the entire thing back together and have now run it in for about 200 miles. The noise under the valve cover that I was hearing before is now gone - it was the worn valve spring after all. Under the valve cover now sounds like a sewing machine on all 5 cylinders.

Thank you everyone, especially jt20, for all the help. I learned a lot on this adventure which will undoubtedly prepare me for the inevitable next one.

Im going to post a summary in post #1.

dd

UriahT · #56 02-06-2009, 10:32 AM

Really glad that you solved your problem. Nice to hear that sewing machine clacking away like normal.

Don't know if you'd feel up for it, but a brief write up on this procedure might come in handy for someone with this specific problem in the future. Most mechanics would not have been as thorough with diagnosing your engine as you were.