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Old 08-12-1999, 04:08 AM
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86 300E 160,000 miles. Can I replace the valve stem seals myself? If so, what else should I do to the engine at this time?
Old 08-12-1999, 09:48 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
You need specail tools to do this and compressed air. You have to take off the valve springs and blow compressed air into the cyls to hold the valve up. It takes a qualified tech at least 2 hours to do this with the right tools. I wonder how long it would take to do this for a DIY'er.


Old 08-13-1999, 07:07 PM
Chris C.
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Valve stem seals are pretty easy to replace as Benz stated you need compressed air, a fitting for the spark plug hole, a KD valve spring compressor and a few hand tools.
The job is pretty straight forward, if you'd like I can give you all the details.
Understand this YOUR GUIDES ARE GONE! seals will help w/ oil consumption but you really need a valve job, I did the same thing at 149,000. It made a huge difference in oil consumption. (1qt. per 1,000 miles to 1qt.per 3,000)But I really need the guides replaced, too much $$ right now.
See Ya,
Chris C.
Old 08-13-1999, 10:44 PM
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Join Date: Jul 1999
Location: CT, USA
Posts: 2,699
I've got a '88 300 TE with 145k on the odo. Burns maybe a quart every 3-4k of Mobil 1 15W-50 (run it year-round in New England). Runs like a top. What are the first signs that the seals (and probably guides) are it solely oil consumption? And if doing the seals, do you pretty much always do the guides since they have about the same lifespan? Or, if you do the seals can you get away without doing the guides for awhile?

Also, the guides involve pulling the head on an M103 motor, right?

Thanks in advance for any input.

Regards, Michael
'92 500E
'88 300TE

Old 08-14-1999, 05:52 AM
Posts: n/a
If I remove the head myself, can I take it to any machine shop to do the valves, a garage that works on MB or should I take it to the dealer for this? I am assuming I need a press to replace the valve guides and the valves will need to be reseated. Can I save money by removing the head and replacing it myself. I have a tork wrench and quite a few tools. Larry
Old 08-14-1999, 01:39 PM
Chris C.
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I have R&R over a thousand cyl. heads myself so Yes when I am ready to do my Valve Job I will remove & replace the head myself and allow a machine shop that does Mercedes heads all day long do my machine work. Now I am willing to take on the responseability of possable head gasket leaks, tweaking the head, or any of the many other things that can go wrong on the removal & installation of the cyl. head, you have to ask yourself, Am I a good enough mechanic to rip into the top end of a Mercedes and know all the little tricks so as not to screw up a perfectly good valve job? If yes, go for it. If "well I think so" then you'd be better off with the warranty for the Valve job including the installation. I think my machine shop gets about $1200, complete, not bad. They also replace all exhaust valves regardless, and head bolts.
I do all work on my cars, truck,and motorcycle. But I was also a mechanic for 15 years. Even with the experiance I have eaten a few jobs, somtimes dodey just happens, then it's nice to have a warranty!
Old 08-14-1999, 02:01 PM
Chris C.
Posts: n/a
If I remember correctly the 86 thru 88 103's had some reaally crappy guides, in 89 they changed material so now even the 86 get's the upgraded guides.(somthing for you to think about).
On what to look for on guide or seal replacement, most notice oil consumption, lower gas milage, loss of power, rough idle, and on closer examination inconsistant compression tests, due to guides allowing the valve not to seat perfectly in it's seat.
Yes, you have to remove head to do the guides.
At 145k, you would not be waisting your money on a valve job, although if you have no symptoms...
Hope this helps,
Chris C.
Old 08-14-1999, 03:09 PM
Posts: n/a
While not exactly on topic, if one is going to go to the effort of having a valve job done anyway, are there any recommendations to add some tweaks to gain a little, or a lot of performance???

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