1996 E300D Intake valve seat/sealing issues? - PeachParts Mercedes-Benz Forum

RyanCooper · #1 10-06-2023, 10:08 PM

So i've had this car a while now and have been replacing lots of neglected maintenance items (like all the plastic fuel lines, the main fuel feed/return lines under the intake, all the breather parts, delivery valve seals etc) and noticed the first time i ran it with the intake off, it makes a popping sound like air leaking past a valve.

put my hand up to the ports and sure enough i feel air pushing out of the second intake valve on cyl #1. at first i assumed this was due to carbon buildup, but its actually not near as bad as i thought or others i've seen, or even other cylinders that aren't doing this. i read about valve seat recession issues on early 606's? but everyone says they've never heard of it/or its on the rear most cylinders due to lack of cooling. but this is cylinder 1 and to my knowledge this engine has never been overheated.. idk what to do? it doesn't misfire (at least yet) but im worried about it since i had plans for this car...

Sugar Bear · #2 10-07-2023, 10:20 AM

Is there any access to rotate the valve several times by hand in both directions and re-test? Rotating it may clean the sealing faces.

If that doesn't work replacing that valve spring might help and if not, I've no good news...sorry.

87tdwagen · #3 10-07-2023, 02:37 PM

I agree with Sugarbear on seeing if you can rotate the valve. If not, try turning the engine to close the valve and use a 50/50 mix of acetone on marvel mystery oil or ATF and soak the port a few times to see if that cleans up the mating surfaces.

Good luck

Diesel911 · #4 10-08-2023, 12:24 AM

If the valve is actually leaking, putting some liquid in the port is going to find it leaking on down into the Engine. Maybe someone can recommend some spray that you can use sparingly.

Otherwise, what Sugar Bear said.

87tdwagen · #5 10-08-2023, 09:23 AM

You can use just acetone as it will evaporate quickly if its a concern. Typically, brake parts cleaner in spray cans is acetone. So an option for cleaning any carbon build up.

Sugar Bear · #6 10-08-2023, 03:46 PM

If using a liquid I'd try Marvel Mystery Oil.

RyanCooper · #7 10-10-2023, 07:57 PM

Thanks for the replies, sorry for my late reply.

i initally tried using some carb clean to clean that port and around the valve and it did leak down some, i even recorded a video where you can see a sliver of orange when that cylinder fires through where it's not sealing... valve from the angle i can see doesn't appear to be burnt. is it possible to spin the valve with everything assembled??

im beginning to wonder if the previous owner overheated it enough to hurt that valve or seat... when i cleaned it it almost made it worse as it was after i cleaned it, i saw the combustion event, last time i had the intake off and ran it, it was dark outside and i don't remember seeing that (I.e it was blocked enough to not see but still let air pass)

GregMN · #8 10-16-2023, 03:27 PM

Go to this thread: IP Swap: 603 IP into a 606 engine

Read posts #7 & #9 to see my problem and solution to sticking valves.

It may or may not help with your issue. I have read that in europe the 606's had valve seat ware and seating problems.

RyanCooper · #9 10-18-2023, 07:50 PM

Quote:

Originally Posted by GregMN

Go to this thread: IP Swap: 603 IP into a 606 engine

Read posts #7 & #9 to see my problem and solution to sticking valves.

I may or may not help with your issue. I have read that in europe the 606's had valve seat ware and seating problems.

hmm interesting idea/solution. ill give that a try when i have the intake off again to fix more fuel leaks. i think i have a borescope around somewhere i can maybe try to see if the valve is not seating all around or just in the one corner at the limited angle i can see. and also get closer to it etc.

RyanCooper · #10 11-12-2023, 04:20 PM

Little overdue update, finally was able to order the rest of what i needed to fix my fuel leaks. so while i had the intake off again i ended up spraying wd40 on the valve stems while the engine was running, thinking it would do similar to the marvel spray idea.

noise didn't go away but i noticed it helped clean some of the valve stems, and i don't see combustion "light" through any valves now (nor air pushing back like before).

now i just gotta fix my flaring trans (or manual swap lol) and other little issues on the car like my turn signals and more lol