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.