MTFCA Forum

I have rebuilt engine that is stiff to turn over. I was thinking about pulling the spark plugs and squirting oil in each cylinder then
pulling the car around the yard to loosen up the engine.
Kind of like a poor mans engine run in stand.

My engines were all too stiff to crank start after rebuilds so I towed them in high gear until they started and then ran them for 5 minutes or until they started to overheat. I then let them cool down over night and repeated the process 2 more times. On the third start I let them run until they started to get hot or 15 minutes. After that I was able to crank start and ran the cars conservatively for the next 100 miles. Worked for me.

I would not allow a new engine to overheat.

A rebuilt engine should not be that tight. My experience is if you have to tow it to loosen it up you will score the cylinders, pistons, and bearings... whatever is too tight, and you end up with a worn-out new engine.

johnr wrote: ↑

Wed Aug 20, 2025 8:28 am

I have rebuilt engine that is stiff to turn over. I was thinking about pulling the spark plugs and squirting oil in each cylinder then
pulling the car around the yard to loosen up the engine.
Kind of like a poor mans engine run in stand.

johnr wrote: ↑

Wed Aug 20, 2025 8:28 am

I have rebuilt engine that is stiff to turn over. I was thinking about pulling the spark plugs and squirting oil in each cylinder then
pulling the car around the yard to loosen up the engine.
Kind of like a poor mans engine run in stand.

If its the Babbitt that tight, I dont like it, but ok. If its pistons too tight damage will ensue. Problem is you dont know?
Make sure to add oil onto the transmission thru the inspection cover. 2 quarts slowly over about a 1 hour period. Remaining 1 1/2 quarts in the front via the breather cap.

The motor should not have been assembled this tight. Only bad things can happen.
A well used babbitter near me made em to tight. My practice was to add 1 .002 shim from each bearing before finish assembly.
Now I timesaver everything to where there is 95%+ contact & the crank will move with one finger. Bonus - these builds have not needed bearings tightened yet.

Bottom line, I would disassemble the motor & get it right the first time, before starting.

A new rebuild shouldn’t be that tight to begin with. If you rebuild an engine and you build it fairly tight use some lubriplate , STP at least a coat of oil on all the bearing surfaces. A coat of STP on the bearing surfaces works pretty well. Just a little makes the surfaces really slick.