My 89 560sel runs great but has consistently been increasingly using more and more oil. I religiously change oil every 1,500 miles however the engine is up to 1 quart every 250-300 miles. The car has 214,000 miles. The engine may need a rebuild however I have been told that it may be just the valves blowing by oil. I checked the compression and all cylinders are at about 175 psi and each are within 5 psi of each other. Is there a way I can check to see if it is valves? Thanks in advance! I love this forum.

You have valve seals leaking too much.
It is not a big job...most shops will run $400.00.

Only use OE from Mercedes. Some people like the white Teflon seals others say they cause guide wear.

It is not uncommon for the V8 at this age.
Nothing you can do to confirm guide seals but with that volume of oil disappearing and all compressions good as they are, this would be the next step.

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It is a valve guide sealing problem. Even at that mileage just seals may fix it for a significant period. Significant would be over 30k.

My procedure is to pull all the plugs and look for a specifically heavy carbon buildup. If there is one then do the guide seals on that cylinder first and check the tightness of the guide in the head. If its tight install the seals. It is a 5.5 hour job. If a guide is loose then stop and decide whether to pull the heads now or dump it. A valve job is all labor but it is a bunch of it and the cost will be $2500 -$3000 maybe more depending on a lot of parts issues.

The bottom ends are indestructable. Got a customer with over 900,000 miles on a 91 420SEL (same basic stuff). Two valve jobs the last about 500k ago and numerous valve guide seals but not using oil.

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Continental Imports
Gainesville FL
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Great thanks for the reply!!

Time to have the heads done. Valve guides are Toast as mentioned above. Valve guide seals will band aid the problem for a little while.

@ this mileage when you do heads I'd wager you would be in for a fresh chain/injectors/intake manifold/CIS rebuild etc, etc.. In our shop that usually comes in around the 4-5K range.

Also a great time to swap out your manifolds for Euro's and let another 20 or so RWHP out of the engine!

Jonathan

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Jonathan Hodgman
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Enthusiast Service, Restoration & Tuning.
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If its burning a lot of oil you should be seeing smoke out the tail pipe, either all the time or just when starting or accelerating. Or maybe you just have a bad leak. First you need to figure out which is the cause. If it smokes out the tail pipe all the time then you could have sticking oil rings, then there is something you can do that doesn't involve a lot of money or disassembly. Go buy a quart of Marvel Mystery Oil and dump half in the gas tank and half in the oil. Go drive it for 15 minutes or so, then shut it off over night. If the rings are sticking this will free them up. If it just smokes when starting or accelerating, then you probably need valve stem seals. The Mystery Oil will soften them up and they make start sealing again if you get lucky. If its a bad leak, then thats a whole different story.