BRITCHEFLEE Leak Down Test

Thank you for the question. I think the leak down test was worth running. I used a Harbor Freight Leak Down Test and then did the listening test at carb intake, tail pipe,and the oil fill tube. Also check radiator for signs of leakage ie bubles.
#1 had a 15% rate, #2 had a 10% rate, #s 3&4 were very low. No bubles in the radiator. All exhaust valves showed no leakage, Intake valves showed a very small amount of leakage on cylinders 2,3&4. # 1 was tight. #1 showed a moderate amount of air in breather. 2&4 showed very little, and 3 showed a little more than 2&4.
I plan to pull the head next, measure the bores. Then I plan to remove the pistons/rod aseemblies and look the rings etc over.
Hopefully, I can then determine what I need to do. The engine is burning an excessive amount of oil. It goes through about a quart an hour.
I had done a compression check first. Numbers for dry and wet tests were #1 103 then 105, #2 112 then 115, #3 107 then 119, and #4 118 then 125.
Oil pressure is 25 cold and 20 hot.
I would appreciate any thoughts you might have.
Thank You for any thoughts you might have.

Just a guess, but as you have good compression numbers, and good oil pressure, I would suspect valve seals.

If your oil control rings are stuck in the lands, the oil they pass will increase your compression reading numbers as you have indicated.

Not sure what the history is with the engine - I'd try running ATF through both the fuel and crankcase before tearing into it in an attempt to free up the stuck rings.

Your call.

(quoted from post at 18:21:31 09/24/12) Thank you for the question. I think the leak down test was worth running. I used a Harbor Freight Leak Down Test and then did the listening test at carb intake, tail pipe,and the oil fill tube. Also check radiator for signs of leakage ie bubles.
#1 had a 15% rate, #2 had a 10% rate, #s 3&4 were very low. No bubles in the radiator. All exhaust valves showed no leakage, Intake valves showed a very small amount of leakage on cylinders 2,3&4. # 1 was tight. #1 showed a moderate amount of air in breather. 2&4 showed very little, and 3 showed a little more than 2&4.
I plan to pull the head next, measure the bores. Then I plan to remove the pistons/rod aseemblies and look the rings etc over.
Hopefully, I can then determine what I need to do. The engine is burning an excessive amount of oil. It goes through about a quart an hour.
I had done a compression check first. Numbers for dry and wet tests were #1 103 then 105, #2 112 then 115, #3 107 then 119, and #4 118 then 125.
Oil pressure is 25 cold and 20 hot.
I would appreciate any thoughts you might have.
Thank You for any thoughts you might have.

Click to expand...

Thats a lot of oil you are burning through - I assume it is smoking like crazy and your plugs keep oiling up?
All I can tell you is that my 8n was eating up oil, the oil was always black and smoked like a chinese factory chimney - pulled the head and replaced sleeves, pistons and rings with a kit from here and with a new head gasket it ran without burning a drop of oil and no smoke.
I am not that much of a mechanic and got stuck on the valves as no matter what could not move the darn things - I now regret not going a bit further and taking the block down to have that done for me - my bearings looked to be in good shape so actually just bought a new set at the same size - might want to do the plastigauge test if yours look bad.
There was a member here who sent me a really good step by step description as to how to replace sleeves etc - sadly I have misplaced that.
If you have the head off I would definately take the thing to local machine shop to check for warping etc mine was only about $40 to get nice a flat again - just make sure it is not touching before you tighten it down by doing the grease trick.
I am sure others with far more experience will give further advice and comment on the oil pressure which to me seems low at start up cold.

comp numbers are good and don't change much wet.

if she's smoking like a train.. I'd wager to say that all the tests were wet cuz she's pumping oil.

either stuck or bad oil control rings....

With it going through a quart an hour I'd say that you did a wet and wetter test. That would account for the very small difference in the numbers. How much of a ridge in the liners? If it were me I'd just go ahead and bite the bullet and rebuild it.

I have 2 8N's. One I rebuilt this spring and the other I got in Aug. I really like getting on the rebuild because I'm confident of the engine. Not real sure yet of #2. Really haven't run it much yet bebcause of the dry year. Looks like it's slobbering a little oil but starts and runs well and isn't using oil much. Think that I'll keep an eye one it and put some AFT in the cylenders over winter. If it's still slobbering after that I'll rebuild that one too.

Rick

Thank you all for the wonderful suggestions.
The history on the tractor is intesting. I bought it from a friend who could not rebuild it for health reasons. He was going to scrap it so I bought it from him. It was a real smoker.
I soaked the cylinder every week for about three months. It really helped. The tractor did not smoke and it used very little oil for about a year.
When I started using it this spring it really smoked and burnt considerable oil. This has continued all this year. I have done some ATF soaking but it did not help. About six applications.
I have the head off now and starting measurements.
Interesting enough, the plugs never fouled out. They got black and oily but never did foul out.
I do not believe the engine has ever been rebuilt from looking at bolts, nuts, parts etc.
I will post what I find as I go along.
Many Thanks for all the help.