S50 misfire on cyl 1 - help

[chris dunlap]

I have an S50US that has no compression on #1.

cyls 6-2 = 175 to 185psi.

10k on complete rebuild. new rings/valve guides/seals/bearings/etc

It runs GREAT at high load and rpm but poorly on low rpm/low load.

If a ring was bad wouldn't it run poorly all the time? I'm stumped. I'll do a cold compression test with some oil in the cylinder next.

The leakdown test I did - I can hear air coming from the timing chain area. No air gets out from the intake/exhaust valves. Bad head gasket - leaking into the timing chain area maybe?

at 20psi - I do not see any air bubbles in the coolant. It does not use oil - the coolant looks fine also. No signs it's mixing coolant/oil. Odd.


Any ideas?


Chris