M103 170kmiles, 1quart oil /600miles, stem seals only or valve job?

[Bruno_300TE]

Hi everybody
My 300TE from 1992 burns too much oil (about 1 quart in 600 miles), also there is plenty of gray smoke upon hard acceleration (eg when resuming speed after toll stations). I know the manual says up to 1 quart in 600 miles is ok, but my bet is that's because of the liability issue.
PO had the headgasket done and valve stem seals at 100 kmiles. I plan to keep the car "forever". Engine starts well all the time (max cranking 1 sec), mileage is good, runs a bit rough at high RPMs, power seems good too.
I am tempted to have a valve job done (seats, valve guides) instead of just replacing the stem seals.
What is the board's opinion, is this foolish overkill at this mileage or a reasonable job at this mileage for a keeper?
Your opinion is welcome!
Thanks, Bruno

[Rick76]

Your guides are probably worn so replacing just the seals may only help for a short time. Apparently the replacement guides from MB are a different material that lasts longer than the originals. My wife's 89 M103 (2.6) was using about the same amount of oil (or more). Previous owner had replaced the seals. Did the guides a couple of years ago and now don't have to add oil at all between changes.

[wheeels]

i agree youre guides are poss worn out (to queensway--pete tech

[gavinbr]

Hello,

I had a similar issue with 300ce equipped with 103 engine, 230k miles.

My solutions was to us use 20/50w oil.

This dramatically upped the miles per quart.
Try it and see!

May not work for you though?

Brian

[gmercoleza]

I would do seals and switch to 20W50. Sure, it may only last a year or two, but what a great year or two it will be! Honestly, the valve stem seals require very little in the way of effort and parts, probably $30 total. Worth a shot in my opinion.

[dkveuro]

Never found a 103 with worn guides.
I've done about 30 or more...
Replace the guide seals...use OE only.
You'll need a valve cover kit too, and replace the cam oil seal.
Replace the rotor, if you haven't already. They burn.

Being as head gasket was done, it is 'possible' new valve seal/s popped off
the guide and no longer seals.
Ask me how I know

Origonal seals go hard and no longer grip the valve stem.
Simple job....well, reasonably.


.

[Kestas]

Originally Posted by Bruno_300TE

... I know the manual says up to 1 quart in 600 miles is ok, but my bet is that's because of the liability issue....

I'm guessing the reason has technical merit. Once an engine starts burning too much oil, there are long term issues that start to develop, such as heavier combustion deposits, catalytic converter fouling, spark plug fouling, O2 sensor fouling, not to mention the cost of oil itself. Plus, unike the rest of us here on the board, many car owners are prone to neglecting their oil level, and easily get caught starving their engine of oil.

After this threshhold has been reached, it's more economical to rebuild the head or engine than continue burning oil if the car will be kept "forever".

[lee polowczuk]

I am running into this problem with our 300CE... a quart at 8-900 miles...runs great, still.

i have the parts ...a little antsy about losing a valve... may or may not do it myself..

i use 20w-50 now..when i get them changed..it will still be 20w-50 dino maybe 15-50 synthetic if i can get it on sale.

[Bruno_300TE]

Ok, I will do valve seals and switch to 20W50. I'll report about the outcome.
Leak-down test was ok.
Bruno

[kchemers]

Can you use the 20W50 in cold climates. I live in the chicago area and winters can be a bear 0 to -10 below is not uncommon. I have an 89 300TE with 115000 miles on it

[Bruno_300TE]

Regarding the oil, I asked the mechanic (who did the valve seals and recommended me 20W50) the same question. He said that he would not expect this winter to get much colder than 30deg, and therefore such oil would be ok.
I will give it a try with synthetic oil. Synthetic oil of the same weight than dino has a lower cold cranking viscosity. I will see how good starting is and how fast oil pressure will build. I bought 6 quarts of 20W50 Schaeffer oil which is a synthetic blend. The tech specs suggest it might work also in cold climates.
Bruno

[Bruno_300TE]

Hi
Valve seals have been a success. After 500 miles I cannot detect any chance in engine oil level. Smoke is gone as well. I do not run 20W50 though. After wading through some oil threads I decided to use 5W40 from Mobil1 instead of 20W50 which is too thick for a New England winter (although it has been very mild so far).
As usual though, the little diva needs attention again: the rear wheel bearing is about to fail.
Thank you for your comments, Bruno