[Mike]

i wanted to test the compression on my zook to see if the rings are going or if its the valve stem seals
what should the compression be on a 1.3 and what would be acceptable?

Cheers

[Damo]

Mike wrote:

i wanted to test the compression on my zook to see if the rings are going or if its the valve stem seals
what should the compression be on a 1.3 and what would be acceptable?

Cheers

As per the FSM, the standard compression should be 199 PSI. The service limit is 170 PSI. Maximum difference between any two cylinders should be 14.2 PSI.

[11_evl]

and thats pretty std figures for almost any N/A petrol engine around.

turbo can get away with a little lower pressures but still should be within the same range from cyl to cyl

and diesel is another story altogether

[Mike]

so 185 to 190 across all 4 cylinders is pretty good?

[Damo]

Mike wrote:

so 185 to 190 across all 4 cylinders is pretty good?

Yep, beautiful. Tell us how you did the compression test. And what's the problem you are having?

[Mike]

i disconnected the leads took out the plugs then screwed the compression tester into the first cylinder then turned over the motor a couple times
if the compression is good that means the rings are alright right?

[Scrawny]

I hope you disabled the ignition system somehow too. Did you hold the throttle open too? Sounds like rings and valves are ok to me. It won't guarantee non-leaking valve stem seals or anything like that though.

[Mike]

what would happen if i didn't disconnect the ignition system?

[Scrawny]

Puts massive strain on the coil. The spark still has to go somewhere and it takes a lot of effort to jump the spark to a ground

[Mike]

would disconnecting the earth off the coil be enough?

[Rockhopper]

Mike wrote:

what would happen if i didn't disconnect the ignition system?

from a safety point of view, a stray spark could also ignite any unburnt fuel that may escape the cylinder through the spark plug hole. Not saying it will happen, but it could happen (I have seen it before). If there is a plug on the distributor wiring, you could disconnect that or either the positive or negative coil connection.

[JrZook]

Mike wrote:

would disconnecting the earth off the coil be enough?

Yes

[rustylj]

opening the throttle is bullshit.the engine will draw enough air pass the
butteriflies,remember it's only winding on the stsrter motor.
compression testing won't tell you if the oil rings or valve stem seals
are worn.there the ones that cause oil usage.