Should there be a difference? I just got a compression tester from Harbor Freight the other day. It so happend that the engine was hot when I was testing...tester screwed right in no problem. Later, I wanted to double check..engine happend to be cold...the tester just wouldn't thread up in the plug hole. Does the head expand that much? Is the $5 tester from harborfreight that bad...should I even take the readings I got seriously?

 

bump

 

I've never seen that problem before...it should screw in just fine. Did you try the same plug hole? One could be fine but the other could have messed up threads or something.

 

All four worked fine with the motor hot. All 4 won't work at all with motor cold.

 

The bad news is you get what you paid for. For $5.00 I am suprised you got all 4 cylinders. I hear Snap-On is a good company.

 

I've heard the same . While that would be nice, what is a decent brand for a low-income college student just trying to maintain the car he's got? Actron, Matco, etc perhaps?