I just did a compression test on TT
Using the battery and turning her over 4 times I got 49 - 47 - 47 - 49.
So I decided to try it with the hand crank. The readings were in the mid-20's.
The readings were all taken with the spark plugs and carb removed.
This is a mystery to me. What am I doing wrong?
Should be the same either way.
I thought they should be the same.
The engine was cold.
I checked by cranking with the battery, then with the hand crank. I did not remove the compression tester or change anything between the tests. I got a much lower reading on every cylinder using the crank.
I have since done a search and found the following:
Beg, steal or borrow a battery and recheck - you'll probably be pleasantly surprised by the readings.
Are you cranking over the engine with the starter Susan or just using the hand crank? You may get lower results with the crank.
If you have leakage(rings or valves) it would be lower when hand cranking I would think.
You are most likely cranking slower by hand. If you had bad rings or valves you wouldn't be getting #'s in the high 40's. You're OK. Don't sweat it.
What matters is that you got excellent numbers. The high 40's are great and may even improve a little once you get some time on it.
Because on battery you are going rurr-rurr-rurr-compression, rurr-rurr-rurr-compression, rurr-rurr-rurr-compression, rurr-rurr-rurr-compression =47. By hand it's like; ug,ug,ug, comprssion, ug,ug,ug,comprssion (dripping sweat about now) =20's LOL
I was surprised how fast compression drops. Got a gauge with a hold feature and now I can crank faster and still get a reading. I also use the crew in adapter.
When I tried running back and forth to the gauge, the readings were very low.
Has anyone else tried checking compression both by hand cranking and using the starter? If so, what were your results?
On my freshly rebuilt engine in my 16 coupelet via handcranking I achieved 50psi cold.
My compression tester is inherited from my father--he had a service station before WWWII (and one when I was first married in '76)--yep, I was a "Petroleum Distillate Transfer Engineer"!.
Anyway, back to my compression tester; its a Boyce Compresso-Meter and has a valve that keeps the read compression on the gauge, then you push a little button to release it. Very handy for checking compression by oneself.