I thought it was the other way around? Can you think of reasons why?

Background:

I've put about 40k on the 300DT since I bought it and did a (hot) compression test for the first time last week:

#1 200
#2 325
#3 325
#4 300
#5 325

Noting #1 being low I took a reading again on #1 the next morning (cold) and it was 260!

I have repeated the test on #1 both hot and cold and results are the same.

What can you think of that would cause that?

Valves have been adjusted. Battery is a year old and tested good.
Not sure about starter motor. May have a problem cranking slow.

I am going to repeat the test but add another cyl to see if it's doing the same as #1.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

It could be an affect of oil dripping into the cylinder via the valves when it's sitting and creating a false seal with the piston rings when you test it cold. And when it's warm it's burn that oil out and your getting a true compression number.

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If oil was leaking into the cyl overnight, wouldn't I see the oil burning as smoke out the tail pipe when started in the morning? There is no smoke whatsoever at cold start.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

My guess is that the valve adjustment might be too tight. edit: (but I see you say the valves have been adjusted.) Not sure what else it could be.

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-Louis

'87 300D Anthracite

You don't say when the valves were adjusted, so I'd say adjust the valves again. The valves grow when the engine is warm, that is why the cold adjustment and hot adjustment specs are different.

valves were adjusted cold before I did the compression tests.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

maybe, try checking the valve clearances again when the engine is hot and see if you have any clearance.

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'82 240D 224K miles manual transmission
mods: wooden 4by4 bumper, EGR delete and older EX manifold without EGR port, glass pack muffler (cheapest replacement muffler), rebuilt bosch injectors with Monark nozzles

working on: aux electric fuel pump, coolant/fuel heat exchanger/filter head, afterglow, low oil pressure buzzer/LED

I don't believe it is valve clearance. I've checked it twice. I didn't mention (in this thread) that I put in new injector nozzles. Is it possible that the prechamber coller may have been disturbed and is leaking more when it is hot than cold? Same with the injector heat shield. I am going to use some soapy water on the coller threads and see if I find bubbles.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked