Best way to to tell TDC on Compression Stroke
 

85 300D 0M617

Sorry, I am not a mechanic, but am learning. I understand that I have to have the engine at 15 degrees after TDC and that the 15 degree mark can be either the exhaust or compression stroke.

Can I tell if the engine is on the compression stroke by removing the number 1 glow plug somehow?

I can't beieve I have to remove all of this to fix this... man, what a mess

You won't see anything in the prechamber (injector or glow plug). It's actually very easy to tell if it's on the compression stroke because when you look into the oil filler cap AND it's at 15 degrees neither of the first two cam lobes should be touching the valves. If one of them is touching the valve then you know that valve is open.

-Rog

Remove the oil cap. Most forward cam lobe (exhaust) should point (generally) toward driver's side of car. Next one back (intake) should point up (more or less.)

Which is also what you sometimes get when you start multiple discussions about the same issue.

To make it easier, use the bolt on the p.s. pulley to turn the engine over. I have the large metric box wrench set from Harbor Freight (26 mm fits, I recall). Some say not to use that, but I never heard why it could cause a problem.

Get a compression tester, take off the compression tester gauge, attach a balloon to the air hose, when you see the balloon puffing up you're getting close to TDC.

How to exactly at TDC???