Compression test recommendations

[elongest]

OK, I don't have my manuals with me. I just did a compression test on a new to me 59 Cub. The tractor starts and runs OK but it had been setting for about 30 days. I pulled the plugs and used a HF compression tester. The rear valve on cyl.2 was stuck open. Shot some PB Blaster and Marvel Mystery oil by the valve and got it freed up with no big issue. All four cylinders the compression was an even 80 PSI dry and 90 PSI after wetting with oil. The spark plugs had a little black soot on them, and the exhaust pipe inside was black. I have no experience working this tractor. What would you do?

[Bill V in Md]

The compression numbers are a little low, but not terrible and on the plus side they are consistent. If the oil pressure was good, I don’t think you need to do anything drastic. If it were mine, I would check and adjust the valves as needed. I would add sea foam to the gas and run it for a while to see if the compression comes up a little. As for the sooty plugs, make sure the carburetor float setting is correct.

[Eugene]

Yup what Bill said. I wouldn't consider an engine over haul. Just use the tractor as it is.

I would add the Sea Foam to the gas and engine oil. Work the tractor hard for a total of 10-12 hours. Then another set of compression tests.

[elongest]

Thanks for the replies, I was thinking about to letting it keep on running. Working alone I just needed a second opinion, since I had the hood off and the Touch Control out.
Thanks Again, Eddie

[Glen]

Hi,
Some things that can affect the compression test numbers are,
remove all 4 spark plugs, so they are out of the engine at the same time.
Open the throttle fully, so the engine can get air for the test.
Charge the battery fully before doing the test.

[Gary S.]

I'm a fan of Harbor Freight because no one is going to use this stuff when I'm gone- so no sense investing alot of money on name brand tools at my age anymore.
That said I have not had good luck with their leak down testers or their compression testers. I would seriously look into getting a second opinion with another tester,places like O'Reilly's rent them.

[Nosparkplug]

It is my understanding that the active ingredient in most gas treatments is Techron. You can buy it everywhere. On my Cub it had numbers similar to yours. What I did was brought mine up to temp and pulled the plugs then pour some in each cylinder, turned it over by hand then let it sit for 30 minutes. Crank it up and let it run for 30 minutes then do it again. My numbers are back up over 100 and have been a while now. YMMV. Charles

Edit to add: my float needed adjusting BADLY.

[elongest]

I was thinking about doing what you did with the Techron. Glad to hear the treatment worked out.