There has been alot of discussion about valve guides on M103 engines on this board.

I recently spoke with a mechanic about an oil consumption problem on my 1989 260 E with 76,000 miles on it. The car burns about three quarts of oil every 3000 miles.

He told me that the valve guides are absolutely bad on the car and that I must do a full valve job on the car to solve this problem.

Another mechanic told me that, yes, M103 engines do have valve guide problems, but that at only 76,000 miles, more likely than not, the valve guide SEALS have gotten brittle and that the guides are not yet bad. He said that he would just replace the valve guide seals and check the guides for play when he did this and that if they did not have play, it would be a waste to do a full valve job at this point in time. His price to replace valve guide seals only: $300.00

The first mechanic's price for a full valve job $1500.00

I told the first mechanic what the second mechanic had said, and he said that the second mechanic did not know what he was talking about and that the reason the valve guide seals would have gone bad in the first place was BECAUSE the guides had so much movement against them.

Both of these mechanics have worked on Mercedes-Benz for over 15 years each.

My questions are as follows:

1) Is it possible that my valve guide seals have gotten brittle but that my valve guides are fine?

2) Can a valve guide with play really cause a valve guide seal to go bad?

3) Is the first mechanic just trying to sell me an unnecessary valve job?

4) In what years did MB modify the valve seals and/or guides in the M103 engines? I read somewhere that 1986 and 1987 engines had valve guide seals made of one material and that 1988 and newer seals were made of more durable viton. I also have been told that the valve guides themselves to the 1991 and 1992 engines were stronger than in previous years.

5) Do M104 engines have weak valve guides and seals as well? (Since the head is totally different, I didn't know whether these engines shared the same valve guides and seals.


Thanks in advance!

In regard to your questions:

1) Is it possible that my valve guide seals have gotten brittle but that my valve guides are fine?
Yes, this is possible, but with 76k the guides are not far behind, usually need to be done at about 100 to 150k. The newer guides are made of a stronger material than the originals.

2) Can a valve guide with play really cause a valve guide seal to go bad?
Yes, but the wear would have to be significant. Valve stem seals usually succumb to heat cycling and get brittle and are unable to seal properly.

3) Is the first mechanic just trying to sell me an unnecessary valve job?
No, but I wouldn't totally dismiss his advice. $1500 is about average for this type of work. I would try a compression test, if that's OK, then try just the seals. You may be able to buy some time, but the guides will have to be done eventually.

4) In what years did MB modify the valve seals and/or guides in the M103 engines? I read somewhere that 1986 and 1987 engines had valve guide seals made of one material and that 1988 and newer seals were made of more durable viton. I also have been told that the valve guides themselves to the 1991 and 1992 engines were stronger than in previous years.
I believe that in late 1989 they changed the material for the guides. Don't know about the seals.

5) Do M104 engines have weak valve guides and seals as well? (Since the head is totally different, I didn't know whether these engines shared the same valve guides and seals.
Don't know this one either. Maybe Benzmac has the answer. I beleive the valves in the 104 were a different size. Anyway you've got a 103, so it really doesn't matter. Good luck...



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Jeff L
1987 300e
1989 300e
1987 BMW 325

I have not seen any oil consumption issues with the 104 yet. They have been really durable. The reason they don't wear the guides like the 103 is because of the geometry of the head. The 104 uses a cam over valve design. This allows the valve to be pressed on straight down. The 103 has a rocker set at and angle, this pushes side pressure and allows for some wear.


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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

ebardzik,

I have an '88 300E with 170K miles. I would have to go back to my records to know for sure, but it had valve seals and only valve seals sometime before about 80K miles. It still uses absolutely NO oil between 3,300 mile changes.

Hope this helps,

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles