My First Leak Down Test Results (1 Viewer)

[Steamer]

Hi all. Asking for Opinions on my results as I’ve never done a leak down before. I think it’s obvious, my rings aren’t well but wondering just how bad they are. Should I be considering a re-bore for this off-road only rig. When I got the rig in 2000, I pulled the pistons out that had broken and frozen rings. I couldn’t measure the cylinders accurately but could tell they were a bit out of round with a slight ridge on the thrust side. Not financially ready for a rebuild I honed the cylinders till the ridge was gone and installed new standard size rings. New rod bearings also. I’m not using oil, smoking or fouling plugs. I just got my first leak down tester and did a compression & a leak down test. Comp test was done hot. Leak down was done warm as I discovered a leak in the tester and had to re-test after fixing it. For the leak down, each cylinder was tested @ tdc on compression. Test pressure was 100psi. The second gauge on tester reads in percent of loss.
And for hearing air in the exhaust I really couldn't tell if I was hearing air passing through valves or just hearing the hiss in the crank case. Air out of the dip stick tube was definite. TIA.

 

[snaggletto]

Looks like you have some lost performance but no real problems. Unless you have $ to burn, run it and monitor the leak down #'s over time. You may try some seafoam snake oil stuff as an additive over time to clean carbon deposits and see if you get lucky. Or trade engines with me and then you will think again about your problems! Everybody needs a little perspective.

 

[SteveH]

IMO, leakdown tests make every engine appear to be a wreck . If you are happy with the performance and the oil consumption, I wouldn't worry too much. Just drive it. Your compression numbers are world class. If it burns more oil than you'd like, or puffs blue on startup, you might consider replacing the valve stem seals, which will likely be shot after 18 years. This can be done with the head in the truck, if you use compressed air to hold the valves shut during replacement.

 

[Steamer]

Thanks, Snagletto & Steve H for the replies & vote of confidence. Just lately it’s been running poorly with erratic and low vacuum and wouldn’t idle. I dis-assembled the TH carb and cleaned. Helped considerably but still running very rough. I was thinking of putting the head in the shop, (guessing) but got the leak down tester first. I think it shows the valves are fairly good and better off than the rings. So I guess I’ll forgo any machine shop work and figure that my problem is carburetion. I’ve purchased a Sniper 2300 but have been sitting on it while I try to figure things out. I just pulled the manifold to thoroughly check the intake for cracks or leaks. Looking good there so I guess the next move will be the sniper.

I’ve had a couple of excellent experiences with SeaFoam so I am a believer. The valve seals were done in 09 and no indication that they’re not still good. I did use the compressed air method & it worked great.

Thanks again.

 

[1911]

Leakdown tests are more for finding where a real problem is, than as a measure of wear or performance. So you have a little wear in the valves/guides and rings; no big deal. These are low-revving, low-compression tractor motors designed to last a long time with third-world gas and maintenance, not some fine-tolerance race engine. It will probably run another 20 years without a major rebuild just fine.

 

[snaggletto]

You may check for air leaks around carb and intake manifold, vacuum lines, plugs, wires, ignition stuff etc. The carbs are easy to rebuild, but would eliminate the basics first. The EFI kit just adds a million more variables. Stay away until you get the motor running as it should.

 

[Whiskerz]

I would not worry much yet. Just plan of freshening it up in the future. Those static compression test numbers are good. Instead of the dipstick open the oil fill cap. Checking with the engine warm may also change these results on the leakdown test.