blown headgasket or broken compression tester?

[jwahl16]

Well i just finished a compression test and something strange happened.

I first did a full dry test and came up with: 162,162,170,170.

I then started a wet test, cylinder 1 came up with 180-185. Then i accidentally put the spark wire back on the number one plug during my next test. The car barely idled and cylinder 4 started smoking after i tested number 2. I figured it was the oil burning off but i didn't like how it came out of a different cylinder (which had no oil in it at the time). I then tested all the cylinders again and the compression gauge read 0. I had my 5 year old nephew look at the gauge (so I have no idea how high it went) and he said it went up and then back down so the gauge isn't holding the reading.

Could i have done some damage by putting the wire back on to the engine and/or the gauge? The car still starts up fine, but i haven't driven it yet.

thanks

 

[Calan]

Start over.

Inject some air straight into the tester and see if it holds pressure, and then do the test again.

If you are worried that you may have damaged something (not likely based on what you said), do a leak-down test first.

http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

 

[jwahl16]

haha thanks. The main thing that had me worried was that smoke came out of the number 4 cylinder when i put oil in the number 2 cylinder. I know the pistons are at the same position but i didn't think they should be connected like that.

 

[Calan]

haha thanks. The main thing that had me worried was that smoke came out of the number 4 cylinder when i put oil in the number 2 cylinder.

If you cranked/started the car with one or more plugs not connected, you probably got some backfire...which could push oil from one cylinder up into the IM and then back down into the others. Or cylinder pressure alone may have pushed it back up through some open valves. (All kinds of weird things can happen when cylinders fire out-of-order or not at all).

If you did somehow blow the HG or cause other damage, the leak-down test will quickly show it.

I know the pistons are at the same position but i didn't think they should be connected like that.

Cylinders 1 and 4 will be at TDC together (but 180* apart on valve timing), and the same for 2 and 3. If cylinders 2 and 4 are at TDC at the same time, you have a serious problem.

 

[jwahl16]

If you cranked/started the car with one or more plugs not connected, you probably got some backfire...which could push oil from one cylinder up into the IM and then back down into the others.

If you did somehow blow the HG or cause other damage, the leak-down test will quickly show it.

ok thanks calan, i'll keep at it.

EDIT:

O yeah, your right, I don't know why i thought 2 and 4 were up at the same time!