compression test at home?

No-but make sure you get a diesel compression tester instead of a gasoline compression tester so you dont kill the tester. They are more expensive, but they also go up to the pressure that you need it to go to, and they are the correct thread.

Compression spec. is 319 - 348 psi with 44 psi allowable variation between cylinders. Be sure your tester has that capability. Test is done at glow plug hole (thread M12 x 1.25).

Since you will be removing the glow plugs you may as well install new Bosch or Beru (may be misspelled) glow plugs - about $10 each but good for 100K miles.

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Hi,

Still looking for a car to join the diesel club, so sorry if this may sound ignorant:

Are the threads "standard" (as w/ spark plugs in gas models) or make/model/engine dependent?

Also, I assume one installs the tester in place of a glow plug? Or some other plug? What must be done to prevent the engine from starting--simply remove all the plugs at once (emulating gas engines: no compression=no fire) or are their additional precautions to watch for?

Thanks for helping to educate us "newbies!"

Rick

Agreed.

On Mercedes, you remove all the injectors and test compression that way. On the 4 and 5 cylinder engines, the last glow plug is behind the oil filter housing.

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What is the best procedure for using the compression tester? Should I let the engine get up to temp or should I just do it cold? Should I wait a certain amount of time before I move on to the next cylinder? any other tips would be helpful.

I truly appreciate all the experienced people out there who are so nice to share their expertise with all us beginners.

Thanks a million! Jeff

Cold or warm, does not matter. Just move on to the next one. No waiting required :)

What you might want to consider is that after you take a reading on the cylinder squirt in some oil and see if there is a significant change.

cheers

Squirting oil alters your reading... more false reading of actual engine condition... People do this only to test real bad cylinders.

It gives a crude idea as to the location of the poor compression. If it increases after oil is injected then it's likely that the piston rings are shot, if the compression stays the same(ish) then top end is more likely at fault.

sure, but it's easy and locates the problem a 'bit' better. ie if there is no significant change, look somewhere else (ie top) if there is whoa nelly, you've confirmed your trouble

cheers

... exactly, especially if it's an easy and cheap procedure. Every bit of info can help.

cheers

If you actually wanted to do, that you would be switching to differential pressure to check for leaks on the rings,valves,etc. More expensive than compression and you need an air compressor as well. A good mechanic can tell what needs fixing without even stripping the engine down. Which was the point ,on aircraft and other expensive engines....