compression on a 240D
 

Hello,

Does anybody know what the miminal compression should be on 1982 240D?

please advise

brian

I think it's suppose to be 400 PSI. I believe 250 PSI is about the lowest you can expect it to run. I'm not sure these are the specs, but I have read these numbers on this forum. Do a search and you will probably be able to find more.....

One of my 240s, my '77 has 300 across all cylinders and it smokes big time--need of rings. I had read new these should have a reading of 400 but do not know this to be true as I am not a mechanic and never saw it writing. My engine has seen its better days due to the lack of maintenence by a prior owner who ran it as a farm vehicle.
:(

compression on a 240D
 

Hello,

further to my compression question

if you have low compression how do you check whether its valves or rings.

before it died on me[wouldn't start] it ran strong?

my 240D has 250k miles and which i have owned since new, and have carefully maintained it over that period, changed the oil every 3000 miles. i'm surprised that it hasn't lasted longer?

any help would be appreciated.

brian
1982/240D/auto/calif car/250K miles

If I may ask, why are you focusing on the compression?

Was there a deterioration of performance over time, or did something happen "all of the sudden"?

- Patrick

Brian, Do a search for " leak down test".....

17 Bar minimum: 255psi

This sounds like more of a fuel problem than a compression problem. Smoking is usually related to fuel, particularly white. You might even have "critters" (algae) in the tank. Fuel leaks, of any kind, could mean air in the fuel system.

Do the easy things first.

Check the fuel filters. When were they changed last? What do/did they look like? Have you used any Biocide? Have you checked the filter screen of the fuel tank?

Check the fuel system and let us know what you find.

compression on a 240D
 

Hello again,

Maybe i should start over from the begining again.

My 240D/auto was running great, smoked a bit and used oil, and has been a wonderful car for my wife and i.

Then suddenly it started to run rough at idle, still ok at speed, 50~70.

I left it over night and came out to start it[we live in N Calif]. Never have to use the start knob on the dash, just let it glow through its cycle and it always started. This time it wouldn't even fire a cylinder.

Sooooo i thought time to check the valve gaps etc. and i was going to do the seals at the same time

Adjusted the valves some were a bit tight. Ran a quick compression test[not the final because i have a push and hold compression tester] and i got 120,150,90 and 62, its hard to get the thing in the holes, using the glow plug holes for the test. According to some of the posts i have read this car should never have run, supposed to be 300 psi average. I will do another test. Interestingly i noted a while back that the valves for cylinders 3 and 4 were pretty oiled up, thats looking through the air intake and exhaust manifold holes. I was changing the exhaust gasket at the time. I thought its time for the seals to be replaced.

My original post was to find out what the compression should really be.

I'm at the point now of determining whether its rings or valves. My manual says use compressor to check for leaks in the combustion chambers, either though the rings or the valves.

I'm suprised that this car has not gone longer before having to do these kind of repairs. I hope its going to be valves, rings could also be a bore out job.

Any comments about mileage versus repairs. Mine is at 250 K.

thanks for your comments

brian

There have been some long and hard discussions on doing leak down tests.... which is the same as you are referring to concerning the compressor but without the guage attached...
There are also some safety concerns which have been written about...