Turbo-Jet

..while the engine is still in car?

i spent the night laying under my car staring up at the bottom end. i have the pan off in order to replace the oil pump, which i beleive to be the original, even though the engine has been rebuilt.

i am trying to fix a low oil pressure situation, and hoping the oil pump is the the cause. but, while i'm in there i want to check the clearances of the mains. i am wondering if i can pull caps 2, 3 , or 4 and use plasti-gage. i am concerned that the wieght of the crank resting on the bottom on the caps will give false readings (normally the engine is upside down for this measurement, correct?). and what about any oil still in the bearing? can this be done with accurate results?


[Modified by Turbo-Jet, 9:01 PM 11/15/2001]

LT1driver

Check all the mains, ONE A ATIME, pull each cap, check clearance and retorque then move on to next cap. not a problem if one at a time. Good luck. :cheers: :blueangel:

lou

:yesnod: I'm withe LT1, IF you do one at a time it won't be a problem. Plastigauge is the only way to when building engines. I love the stuff. lou

Turbo-Jet

thanks. what numbers should i be hoping for?

green plasti-gage?


[Modified by Turbo-Jet, 8:23 AM 11/16/2001]

Matt Gruber

unless it knocks you are wasting your time

Turbo-Jet

why, will results not be accurate because crank is sitting on bottom of caps?

what if i use bottle jacks to push it to the top of its clearance?

BSeery

No it will be fine. Dont use the jack !!

WATTAC

I don't think you'll have a prayer of getting the correct numbers. Between the crank setting down on the caps, and this is questionable because all the rods are holding onto it also, the back of the crank is being held in some position by the clutch/transmission and the front is held by the timing chain. The use of plasigage depends on the crank being free to settle completely into the block and the measure the "gap" left between the crank and the cap. This is impossible with the crank fully installed. You won't even know if the crank is warped/bent.

If you have had a serious problem that points to the main/rod bearings then it's time to remove and repair as needed.

Oh, and by the way, ask me how I know this. Ten hours of working under a car with rod knock, replacing the bearings, and running the engine for only a minute or two before the knock returned. Not a happy moment.

Andy

74ZZ430

You can use plastiguage to check you main bearings clearance with in the motor in the car, I did. The instructions that come with the plastigauge tell you to remove the caps on each side of the one you want to check and insert a bussiness card or something about that thickness into the bottom of the cap and retorque them, this pushes the crank up so you can get an accurate reading.

Tom454

Plastigage is a nice toy. It will only "ballpark" the measurement. I use it occasionally. The only way to accurately measure bearing clearance is with the proper tools- micrometers. Inside micrometer for the caps, outside micrometer for the crank. Ask me (professional engine builder) how I know. I only use plastigage occasionally for ballparking when the engine is still together, or as a fast way to look for un-evenness or taper. By the way, if you do stick something in between a bearing and the crank, make sure it is soft.