Is a leak down test even needed ?

[erniefish]

My neighbor has a f115txry, he asked me to look at it ,( has been sitting for 2 years ) Motor does not appear to have gotten wet , but a few things do not work , as well as it was frozen, so maybe it did . I (soaked cylinders for a week in various formulas , got motor freed up , compression is as follows top to bottom 160,115,120 ,55 , do I try to get it running ? Is a rebuild worth it ? Thanks for any advice , Eric

[ausnoelm]

Leak down might be good, maybe a valve was stuck open, and the piston might have pushed it shut, but not sealed, but then, possibly nothing like that happened, it might be shot, you need to sort out why one cylinder has very low compression, and before everyone gets in, I doubt a decarb is going to fix it.....

[Sequoiha]

You could also just have a stuck ring, I would try to get it running, let it reach normal operating temp. And check it again, nothing to lose and everything to gain.

[erniefish]

Thanks guys, I will get it running , and check back

[99yam40]

3 of the cylinders have low compression.
leak down will tell where it is leaking to on each and how bad.

I would think past rings due to rust in cylinders and rings, but it could be else where.

if it is the cylinders then you need to find out how bad they are pitted.
then worry about the shiny places like bearings, crank journals,wrist pins,seal surfaces,valves, etc.

[rodbolt17]

cause some engines if a valve is stuck open and you crank it or run it you destroy that valve.
a leak down test will show if it is a valve or a ring or a head gasket that leaked water in and allowed it to lock up.

[erniefish]

Got it started

After much soaking of cylinders , got it started, now oil alarm is going off ,I know to check with manual gauge , any suggestions other than that , thanks Eric