how long to change valve guide seals?
 

I have an 87 300E and my seals are over 100K miles old. I am watching the oil consumption. How long does it take to replace the seals and how hard is it? I could not find any one describing how to do it on the forum.
thanks.

I had cars that put out a lot of visible smoke from leaky valve guides/seals which didn't burn a lot of oil between oil changes. I imagine you would have to see quite a bit of blue smoke coming from the tailpipe before oil consumption becomes significant.

there is no smoke
 

There is no smoke out the tailpipe

If the valve seals are leaky, you will see the smoke primarily at startup.

If they have already been replaced then you have gotten rid of the factory seals and most likely replaced them with updated versions. As I recall, your car is a later model anyway. I think the offending seals were only on the '86, '87 and possibly '88 models.

How much oil is it using?

Have a great day,

I don't recall seeing alot of smoke on startup on the 103's I've replaced valve stem seals on. The best indicators are the "false start" or stumbling on cold startup, and spark plug condition.

Gilly

It will take about two months.
 

Well, at least mine has. But I had to detour and remove the cylinder head since the guide broke and I dropped a valve in the cylinder. I still have to do the right side guides (4.5) when I get the other head back on.

You haven't found anything from a search? There's been a lot of discussion of how to do this. It isn't hard but you must not drop a valve into the cylinder or you will be doing a head job.

To prevent losing a valve, simply rotate the engine to move the piston to the top at the cylinder where you are about to change the seal. Takes a little more time, but a lot less time than pulling the head as I'm sure Josh would confirm.

Good luck,

Very little smoke on modern motors with working cats. They clean it right up, except when cold. I doubt they leak as much on a cold motor though.

The best way to determine the condition of VG seals on 103 motors is with oil consumption as that is always the problem. They are simple to do and although the book probably says 3-3.5 hours a good tech can probably do them in 1-2 hours.

The debate here is always wether to do guides. My advice is to do seals at any milegae untill they don't last 20k. Then do guides. Even if they only last 20k they are still a bargain against the cost of a complete head job.

I consider this as a temporary fix, and it may not be for every situation, but thought I would share it. My 560sel has this oil comsumption problem as well - about a quart every 500 miles, until I tried using Lucas Oil stabilizer. Oil consumption is now about a quart every 1500 miles. I guess there is not much pressure up in the valve cover area that this additive is able to slow down the leak past the stem seals....

My '87s valve guides and seals were done about 100K miles ago. Present mileage 325K. Had done seals earlier too.
Oil consumption- not quite sure. It seems to be a quart every 500-1000 miles. I regret sounding like an idiot but it that is exact as I can get now. I like getting 1500-2000 miles per qt.
We have a tech session coming up this weekend and if it is a 2 hr job with a tech nearby I might go for it.
I have not found a good link on how to do it. I like to have studied before asking for help.
Thanks for the help.

psfred on 4-20-04 (88 300 sel question)mentioned that significant loss of oil can occur from the oil filler cap. Do others agree and is there a way to check the cap? In the same link someone reported that we should keep are oil level between the marks-not at the upper end. Stu Ritter said something similar in the Mercedes Club Mag-does everyone agree with this? If so my oil level light will intermittently come on at this level. I have ordered a new sender already.

i agree look for all other sources of leaks before doing anything else.other sources of potential leaks,oil filler cap,valve cover gasket,timing chain cover gasket.this subject is well covered on this site