Re: engine compression

[Joshua Van Tol <jjvantol@uswest.net>]

>I bought myself a compression tester to check the compression in my
>engine, which I did, but other than finding references as a ratio (8.5:1
>or whatever) I don't know what the readings mean.  I only checked 2
>cylinders so far, then the battery started getting run down (yes I do
>need a new battery!).  I got 95 psi on each cylinder.  Is this good?
>bad? what should it be?
>
>The patient is a Canadian 1986 (mid 85 manufacture date) 5KTQ 5cyl
>5speed trans with no modifications at all (yet).
>
>TIA
>Stephane Livolsi
>180 Yorston St
>Williams Lake, BC, V2G 3Z1
>ph 250-392-2637
>fax 250-392-2693
>
>'86 5KTQ stock (if you don't know what it means, you aren't in the club)

Sounds a bit low, but it also sounds like the test conditions weren't 
ideal. To do it properly, you need to do the following:

1. Warm the engine up.
2. remove all the plugs, and disable the ignition
3. prop the throttle open
4. test each cylinder in turn. Make sure to get a consistent # of 
compression strokes per cylinder. 6-8 is usual.
5. make sure the battery is good whilst doing this, a booster might 
be necessary.

I would expect you should be seeing > 120 psi on all cylinders, 
probably more like 150 psi.


Joshua Van Tol -- jjvantol@uswest.net