Valve Stem Seals - DONE!

[jaymanek]

Well the 7 months in a body shop did my valve stem seals no good.. I found I was getting a lot of smoke when hot at idle or pull off.

With some special tools, this job can be done without taking the heads off.

This is only a job for a professional IMO and I called in some help for this one.

General outline:

First you need to dismantle the top end and remove the cams. Lock the engine to stop it turning later..

Then you need to remove the plugs and use a compressed air line with a special adaptor to fit in the plug holes. This keeps the valves tightly closed. Engine may turn here if not locked.

Then you need compress the springs using a special valve spring compressor and then they can be removed... Dont lose the little half moon retainers otherwise you will be in trouble!

The old valve stem seals can now be seen and can be removed.

The new ones have to be treated very carefully, a slight nick in the rubber will mean all this hard work to be for nothing. You have special tube come with the kit from MB which you slide the seals over. We also lubricated them with some oil..
They can be pushed home with the correct sized socket and a light tap with a hammer.

Once all 16 are done, re assemble..

One of the old ones, had gone very hard compared to the andrex puppy soft new ones.

Didnt get a pic of the new ones... a bit tricky to be holding a camera...

A job I wont want to do again.. im sure it would have been quicker just to transplant engines from one of the donor cars I have!

 

[rf065]

A job I wont want to do again.. im sure it would have been quicker just to transplant engines from one of the donor cars I have!

That explains why Mercedes were so reluctant to do mine under warranty! I wonder how much it cost them to do them.

Russ

 

[Druk]

Quote : "First you need to dismantle the top end and remove the cams" /Jay.

Do you mean just the followers Jay and not the actual camshafts. Is there a special tool to compress the springs to remove these or do they slip out after a retainer is removed?

 

[rpe2]

I've done this before without removing the cams, but if I did I'm sure it would make it easier.

One thing I made sure I did (on advice from somebody who had done this umpteen times before) was before starting up, double check the timing as the sudden jolt from the air in the cylinder could cause a sprocket to jump the chain.

Good write up Jay and totally understand why you wouldn't want to do again..

Cheers

Richard

 

[jaymanek]

We removed the complete cam shafts otherwise you cannot get the spring compressor in.

Im sure there are umpteen methods but this is the one my friend uses.

All is not good though as one of the chain guides got broken, so now will have to wait for the part to arrive from MB before we can put it all back together.

 

[unitfreebie]

Good Job!!!

Say, how did the chain guides get broken while replacing the valve seals?

The Dealer, I believe, is reluctant to replace valve guide seals on older engines with high mileage because the job would only be temporary due to the increased valve guide clearance would prematurely wear the new seals... then the owner would come back and complain in 20-30,000 miles!!!

The only permanent cure in that case is a complete top end with new valve guides.... This is one of the reasons Mercedes went to the 0-40W synthetic motor oil to keep oil in the valve guides during the cold start ups in the mornings.

 

[jonnyboy]

i remember when i did a 300se as part of a replacement camshaft. bought the snap-on spring compressor and all the associated stuff, air line adaptor etc.

Forgot to only lightly tap the valves with a mallet to check the collets were seated, bent a valve on last cylinder, so the head had to come off anyway.

A lesson learned...

 

[jaymanek]

Good Job!!!

Say, how did the chain guides get broken while replacing the valve seals?

Well on the first one or two we forgot to lock the engine and when we connected the compressor the engine turned whilst the cam pulley had been taken off the cam shaft... this snapped two guides..

 

[jaymanek]

then the owner would come back and complain in 20-30,000 miles!!!

Well ill be ok until 2039 then!

 

[tromppost]

Had the same done to my 420 SEC years ago, stopped the smoking and ran well till I got ride of it. It was in for a couple of days as there were some other bits that broke like the plastic tube that feeds to oil.

 

[jaymanek]

Guys dont do this job unless you have to!!

After replacing all the guides etc, the engine started fine but cylinder number 6 was misfiring... after messing for ages found that it had low compression... more test to find that exhaust valve is not closing properly..

Cant understand it as everything went back where it came from.. we labelled everything..

Anyway so now it means the head has to come off to examine whats wrong with the valve..

arrhhhh

I have a 560 engine that i could have transplanted in this time!

 

[jonnyboy]

Guys dont do this job unless you have to!!

After replacing all the guides etc, the engine started fine but cylinder number 6 was misfiring... after messing for ages found that it had low compression... more test to find that exhaust valve is not closing properly..

Cant understand it as everything went back where it came from.. we labelled everything..

Anyway so now it means the head has to come off to examine whats wrong with the valve..

arrhhhh

I have a 560 engine that i could have transplanted in this time!

You obviously felt that you had to emulate me see above lol

Seriously, I really feel for you though...

 

[jaymanek]

I know... We are sure its not bent, maybe some carbon has got in the wrong place.. who knows, can only tell by taking the head off now..

 

[Rockyview]

W108 Valve Stem Seals - Which way is up?

Re: 1966 250S

Hi everyone: I'm replacing the valve stem seals and I have new Victor Reinz seals - the exhaust ones are black (I believe) and the inlet ones are white. This is all great and everything but there is a brass band on one side of the black seals. The other side is slightly narrower but with no band. Which way is up (to the sky) on install? Same question for the white ones, the narrow end up?

Lastly, can someone tell me (using the attached "no-seal" picture) how far down do you push the seals? Is the intent to have the base on the valve guide and the top narrow part on the valve?

I've included a pict of the valve with seal before I removed it, but since I'm new to this job I'm not sure it is in the correct spot anyways. Thanks.