Oil consumption
 

I have a 89 300E recently purchased with 130K. I believe it has 20-50 oil in it. What rate of consumption should I expect per quart to be acceptable? 500, 700miles per quart before I have to consider valve guides.

That sounds about right. If oil consumption is around there i would start with the valve guides and seals to reduce it.

Oil Consumption
 

Your post made me think of how much my Honda consumes oil at 267,000 miles....about 4 quarts per 100 miles:D

I have to check the gas and add oil just to drive it:D

I'm sure my 2.6 Mercedes with a new head will be satisfactory to the Honda oil consumption!

But.....I have a beautiful new-looking Mercedes in the yard so when I come home I don't feel too bad....knowing that one day....I will be able to drive it, even if I have to gut the engine compartment and put a 1970 340 Dodge engine under the hood! Then I'll call it a 340E!:D LOL!

500 miles per quart is the factory threshold for what's "acceptable," if you get close to that number and are starting to look to make it higher, I would start with the seals and see if that helps enough. A lot less $$ and time, and should be worthwhile on an older engine.

With 130k miles,


The M103 engines were weak on Valve guides. I don't know when a change in materials was made- maybe your 89 has them. They are also weak with headgaskets.

I would go to about 700 miles/quart and start saving up some bucks. If you DIY the head, I suspect the cost could be 200-300 for parts and machine work. I've drilled out the guides and installed new ones by chilling. Worked like a charm and the lapped the guides. But, on a better day, I would install the guides and take it to a machineshop for cleaning up the valve seats.
My 86 model is going to be in the same boat soon. It's got 75,000. I was thinking that excessive oil consumption might lead to an earlier cat failure.

Michael

130,000 miles is in the ballpark for valve guides on the M103, early version.

Symptoms are excessive oil consumption and blue smoke on startup, and idle problems from excess air going down the guides. Valve job time.

My TE had a valve job at 160,000 for this reason (before I got it).

Peter

Before you run out to have the valve guides replaced, consider what Steve Brotherton had to say in this post.

http://www.peachparts.com/shopforum/tech-help/28450-average-price-valve-job.html?highlight=valve+guides

An independent Mb tech in my community who spent the better part of 20 yrs. in an MB dealership told me that he's seen many 103 motors go well past 200K before needing guides.

I had a consumption problem that was cured by new valve stem seals. The motor had close to 100K on it.

Oil Consumption
 

I agree with Mike in replacing only the valve stem seals. The rubber seals get brittle and crack or the sealing lip wears and that is what causes oil to leak into the cylinders. The seals can be replaced without removing the head and parts will probably be less than $20.

I replaced the valve stem seals on my '92 300e and oil consumpion went down from a quart in 750 miles to a quart in 2000 plus miles. I also replaced them in my '88 260e and the results were not so dramatic but still a great improvement.

You noted that 20-50 oil was used in the engine. I have found that the grade of oil really doesn't make much difference as far as consumption is concerned.

John

Your right!


I bet a 89 is late enough.... I understand that *earl* M103's had a factory campaign on excessive oil consumption due to valve guide wear.

It is a hugely easy job to do seals, the compressed air trick and a spring compressor. Pretty darn simple. If you have a manual and can rent or borrow the tools... it would be $20 and 6 book hrs for a pro(something around there if memory is not completely dead). Maybe you could do it in a day.

I have no idea how many years were considered early....

Sorry if I cam off fast and harsh earlier.


Michael