Compression test cold?
 

It's a long story but I would like to do a compression test cold. Will this work at all or must the engine be warm? Would there just be reduced target compression numbers? This is on my '87 300sdl.

Yes, just inaccurate numbers. Probably best to crank the engine for a few revs after you have the injectors out to get the oil circulated.

Looking for a major problem?

Hopefully nothing major, it runs/ran fine, I just took it apart for maintenance- vac pump, timing chain, water pump, thermostat, etc.. Now I find that the tranny needs to come out (leaking front seal) so I'm debating on taking the whole powertrain out if the compression is low. But, it did run fine so I think I'll just pull the tranny. Besides, I can do a valve job with the engine in.

my chiltons foreign car manual lists cold numbers for the older 115 cars but i think the fsm recommends testing hot, definately for your newer 124 car.

tom w