Hi all.
Im thinking about buying a compression tester, only a cheap bit of kit @ £13, It say's that when you have connected the tested to crank the engine, Firstly, I'm assuming that means to start the engine, and then second, it worries me that only 3 of the cylinders would be firing, Will it damage my engine if I did that?

Cheers, Jason

 

Get it warm, then remove all 4 leads and plugs. Put the compression tester in 1 cylinder at a time. Crank for 5s or so, the engine will only reach cranking speeds as nothing will be firing

 

Thanks for that

 

Just one other thing, I've read the in general, engines have 140 - 160lbs of compression with no more than a 10% difference.
Is that correct, and for a 1.25 Zetec?

Thanks again.

 

Sounds about right mate, main thing is that they're not far off each other

 

http://www.pumaracing.co.uk/comp.htm

 

thanks for the info too!