Using plastigage on main bearings

[Mtjohnso]

I have my tractor engine and sitting on wood blocks on end. It’s on its end because the other surfaces currently do not have good places to support it.
I am using plastigage as a beginning point of determining bearing wear. Since I have the engine sitting on its end I put a dab of grease on bearing surface to hold the plastigage in place.
Question will the grease affect how the plastigage spreads out? I know they recommend a very clean surface.

 

[Jim.ME]

It appears a small smear will not hurt. The instructions below are from the Plastigauge site. The issue I see may come if the other bearings are loose, the weight of the crank may not settled down into the journals as it would be if the engine was horizontal with the crank side up.

Plastigauge how it works

 

[Dick L]

I have my tractor engine and sitting on wood blocks on end. It’s on its end because the other surfaces currently do not have good places to support it.
I am using plastigage as a beginning point of determining bearing wear. Since I have the engine sitting on its end I put a dab of grease on bearing surface to hold the plastigage in place.
Question will the grease affect how the plastigage spreads out? I know they recommend a very clean surface.

I always snugged all mains. Snugged does not mean just finger tight but only wrist tight on a short wrench. Then I check each main one at a time.
If your checking an engine with shims I only snugged the first check to see if I needed more shims before torquing to spec with the plastigage.

 

[docmirror]

I don't know if it's in the instructions, but I always clean the bearing outer shell in the block, clean the bearings, clean all journals and put a strip of plastigage on each journal. If it doesn't stay well I use a very tiny amount of spit, and that usually works. The spit will not affect the crush of the plastic.

I do all journals at once, and I always torque the cap bolts very near full value. If the torque is listed at 80, I put at least 60 on the cap bolts. I've had good luck with accuracy doing it this way. The crank doesn't care if it's vertical or horizontal.

 

[Stan Coryell]

If it were me trying to measure to the ten-
thousandth: Clean all surfaces, ratchet strap the crank to the block, leave the plasti-guage long and tape it to the outside of the cap, and torque (or near) the mains.

 

[oliverkid]

You’re going to have a hard time getting an accurate reading across all the mains with the block sitting on end.

 

[Fixingfarmer]

It’s unusual but I think docmirror and Jim.Me both have good points. Generally it should be fine unless it has a TON of wear it won’t be accurate but it sounds like if it is that sloppy you would be considering a different plan?

If they vary wildly the engine is out and a micrometer could be used on the crank instead would probably be my plan

If you don’t want to or don’t have a micrometer set your plastigauge plan likely is fine

 

[Harry in Ky]

As usual, a number of different thoughts come up. Some probably more valid than others, but all deserve consideration. Personally, I've never done this with an engine standing on end, but it wouldn't scare me. I think I would remove two of the main caps (which two would depend on the total number of main bearings) Insert a small piece of cardboard on the bearing surface and install them back into place. Tighten the bolts just enough to hold the crank back against the inner bearing shells. Then do the plastigage treatment on whichever ones are left. I can't see how that would adversely affect the outcome.