How to install main and rod bearings. Case 1370

Henrik Jansson · Apr 16, 2015

Should I have some grease or oil on the backside of the main and rod bearings?
Some people say that it has to be dry and clean.
What happens if it is engine oil on the backside?

I slipped in the main bearings without removing the crankshaft. It was some oil on the bearings. Shall I remove them and try to get them dry?

oldproudvet · Apr 16, 2015

Absolutely dry on the backside, use laquer thinner, carb cleaner anything to insure dryness! Any residue of oil will create a slight film that will prevent the bearing shell from remaining firm against the iron rod or main cap. It will allow the bearing shell to "walk" or wiggle that will soon have it spinning inspite of the captive tab. Examine the surface the bearing is going to seat against it should clearly show honing marks, if not, it probably will almost appear polished, which indicates the shell is walking. The bearing MUST be a crush fit, in other words, you have to push it into the rod or main. If it drops in, the bore is not round, it's stretched or enlarged and it must be addressed. VERY critical to have those brg shells snug..........

How to install main and rod bearings. Case 1370

Henrik Jansson

Member

oldproudvet

Well-known Member

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