When I was younger I had no air compressor so never needed it. Never changes the valves stem seals on other gazers unless I had the head off for some other reason.

Most diesels are not overhead cam engines and I don't recall any of the Diesel Engines I worked had valve stem seals or even the gasser types that are simply deflectors.

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84 300D, 82 Volvo 244Gl Diesel

Good Morning all!

I started the procedure to replace the valve stem seals on my 1978 240D yesterday and need a bit more guidance regarding cam vs. piston positioning. I have removed the rocker tower assemblies already, and before I start removing valve retainers and springs, I want to ensure that the pistons will hold up the valves as I remove them from each cylinder.

I was trying to verify where TDC for cyl.#1 is on the crankshaft dampener and was confused about the degree markings vs. the scribe mark that is on the dampener. Should I disregard these markings totally and just go by the camshaft lobes?

Thanks to whoever may have any input.

The firing order is 1 3 4 2.

When #1 is at TDC #4 is at TDC.

When #2 is at TDC #3 is at TDC.

#1 is at TDC compression stroke when the #1 camshaft lobes are on the flat part/base circle and the high points/lobes of the #1 camshaft lobes are completely opposite of opening.

At the same time both #4 camshaft lobes will be teetering on opening the valves.

Do #1 and #4 first and then rotate the crankshaft 180 to put #2 and #3 at TDC.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Since the rocker arm assemlies are coming off the cam postion dose not matter concering the seals. What does matter is that the Piston needs to be up at top dead center so there is no cance a valve will drop down inside of the cylinder.
The piston is coming up on the compression stroke and when the the exhaust valve cam lobe and the intake valve came lobe form a V pointing straight upwards you are at least close to top dead center on the compression stroke of that cylinder.

use your crankshaft damper timing marks ant the pointer to get number one cylinder at top dead center and with the camshaft lobes in a V and you will understand it.

This may help concerning finding Top Dead Center on number 1 cylinder. Not that top dead center is marked OT.

Well peach parts won't let me post a compeitors site. Do a google image search for: camshaft lobe position on a OM617.952 at top dead center

Go down to the pic with m e r c e d e s o u r c e dot com OM617 internal engine timing marks under it.

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84 300D, 82 Volvo 244Gl Diesel

Well a very good day to you all!

I managed to get all 8 seals replaced over the last few days, and have yet to install the rocker towers, carry out valve adjustment, and install valve cover and everything else. Thanks to EVERYONE for all your help on this FANTASTIC site.

One thing that concerned me though was the valve guide wear I noticed . I was able to visually see slight axial play in most valves. Should I be concerned? I am not in the position to dig into this engine any further.

Car has 130000miles however unsure if they are legit miles or not.

Wouldn't be concerned over the guide wear if it runs well. Worst scenario is it may wear the new seals a little faster. If there is a compression problem and the head has to be removed, then replace all of the guides and seals otherwise drive on! Since all was just apart I'd do another valve adjustment/check in 1k miles and if all is well go to 10-12k.

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Thank you very much!

I too think you should drive it and see how it goes .

You'll know if it allows too much oil past as it'll create tiny little dots on the left side of the trunk lid .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Nate,
We both know that's a built-in feature...
rust proofing!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Not for me they aren't .

When the engine was failing in my 300CD I had to clean them off at least once a week ~ I kept that car clean as a whistle and regularly waxed .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better