Looked thru the FAQs, and did a search, but I didn't find a definitive answer

My folks buoght a '98 E320 about 5 years ago with 80,000 miles on it. My dad, living in farm country in Southern VA never saw fit to actually use the synthetic oil that Mercedes calls for, and instead used regular Penzoil Dino oil. Now its got 139,000 on it, and it's smoking like a freight train. I'm pretty sure its the valve seals, as it seems to be dumping the oil under decelleration, building it up in the catalytic converter, and then letting it go in huge puffs under hard acceleration.

My question is, is this a job that a fairly competent shadetree mechanic can do (I've done timing belts on numerous VW TDIs), or do I really need to take to an experienced Mercedes tech? I'm trying to help my folks out and save them some dough, but if it'll cost more in the long run, i.e. too many special tools, more time than its worth, etc., I'd rather
just take it to a competent shop.

It was your dad trying to save money that created this problem in the first place.

Bear that in mind when you're looking for a cheap mechanic.

Go to a specialist.

@JK

If you wait a little while, you'll probably get more helpful input.

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2007 C 230 Sport.

Not really a matter of him trying to save money, as him not really knowing any better. I never thought to check on what oil he was using, or what the car was supposed to use, as I'm 4 hours away, and he just takes it to the same shop he's always taken it to.

As far as me doing this job, its a matter of me just enjoying being a shadetree mechanic, and its a job that I feel pretty comfortable I can do, I just want to do due diligence and research before digging in to it.

I'm sure you guys get a bunch of cheapskates in here just trying to get quick fixes, so I'll excuse your sarcasm, but I am generally interested in what is wrong with this car, and what needs to be done to fix it.

Does my diagnosis sound correct?

Have a cylinder compression/leakdown test done before you decide on a course of action. Diagnosing internal engine problems by taking an educated guess is asking for trouble. In my experience, problems with M112 valve stem seals are virtually non-existent. The only time I've ever replaced them was as a pre-caution, when the motor was torn down for other repairs. All the oil burners I get at my shop end up needing new piston rings, at best. I've seen plenty that needed engine blocks/pistons too.

Make sure you find someone with experience at re-ringing these engines, if that's how it ends up. Otherwise, you may wind up spending a lot more than you need to. Good luck, and let us know what happens.

Aren't the 1998+ models with FSS covered by the class-action lawsuit extended warranty (I believe it guarantees replacement of the engine from damage done by sludge/oil consumption until 150,000 miles). Does anyone have a PDF of the letter...I lost mine but thought I saw one on the internet.

Does that only cover original owners, or does it cover any owner, up to 150,000 miles?

I am not sure that the 1998 is covered. The owner's manual for my 1998 E320 clearly states to use synthetic oil. And in the engine compartment there is a very visible sticker that also mentions the use of synthetic oil.

I too have seen the letter that you mention, but I can't remember what it says about the 1998 MY.

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Current Benzes

1989 300TE "Alice"
1990 300CE "Sam Spade"
1991 300CE "Beowulf" RIP (06.1991 - 10.10.2007)
1998 E320 "Orson"
2002 C320 Wagon "Molly Fox"

Res non semper sunt quae esse videntur

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Not in this weather!

The synthetic oil was to prevent oil sludge which does not seem to be the problem here. The settlement is bound to cover non-original owners. You need to get a copy of the settlement. If you can't find it anywhere you should be able to get a copy from Mercedes, they were afterall a party to it.

My understand is that dealers were using dino oil and changing per the FSS. This was causing problems which lead to the lawsuit and settlement etc.

However I doubt that say 5w30 Pennzoil changed every 3k miles would do harm. Or did your dad follow the FSS?

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

See http://www.benzworld.org/forums/w163-m-class/1183834-10-year-150k-miles-extended-warranty-class-action-lawsuit.html?highlight=fss+lawsuit

Mercedes won't cover it. Partly due to their lack of willingness, partly due to poor documentation on my father's end.

I am going to go ahead and re-ring the engine, and replace the valve seals while I have it apart. I have a few questions based on research that I have done.

Does this engine have the aluminum cylinder sleeves?
Are these a replaceable item, or should the cylinder walls be re-honed if they are scored?

Who publishes the best shop manual for this car?

I know practically nothing about cars, BUT, since you are saying you are going to change the rings, am I correct that you think its a stuck or broken ring? If its just a stuck ring, my uneducated opinion would be to buy a couple of bottles of AutoRx and run through their procedure. It seems to increase compression by unsticking the rings.

I wouldn't consider doing this job without a FSM, ie Factory Service Manual. Your local MB dealer sells them, or you can order them through this site.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

My local dealer told me to call 1-800-FOR-MERC to order a copy.