Can regular compression tests (say annual) be used to monitor the condition of the coolant/side seals and predict engine life? Do rotarys lose their compression steadily as the soft seals get closer to failure, or is it kind of unpredictable?

(Assuming the driver continues taking care of the engine and doesn't get unlucky and pop an apex seal).

Dave

 

Unless you have a huge coolant seal problem, you won't see it in a compression test. What you will see is the condition of the apex and side seals.

 

Uhh, that's not comforting to hear. I've never been comfortable with all the white steam in my exhaust (last ab. 5 min), and after a compression test last year I quit worrying (all 8.5s and 8.6s).

My prior research suggested compression tests were vital for measuring coolant, side, and apex seals, so what you're saying flies in the face of my understanding.

So has anyone had great compression numbers and start the coolant seal death signs shortly afterward?

 

The key to whether this is a problem with the coolant seals is whether you are losing coolant, not attributable to bad fill or AST caps. If you are not losing coolant at all, you are probably OK.