1979 Evindrude 70 HP - Connecting rod binding after rebuild

[wisconsin_ninja]

I am attempting to reassemble the motor and I ran into a problem with the top connecting rod bearing. Currently the crankshaft is sitting in the block and all connecting rods are installed. When I place the flywheel on the shaft and turn it, there are seven distinct spots per revolution where it binds up a little bit. When I turn the flywheel backwards, it makes an audible click at each spot. If I only tighten the screws on the connecting rod cap finger-tight, there is no binding and the flywheel turns very smoothly. What could possibly cause this?!? The bearing needles, retainers, connecting rod bearing surfaces, and crankshaft bearing surface all look fine...

Summary-
- top piston's connecting rod bearing binds
- audible clicks when flywheel turned backward, no clicks (but still binding) when turned forward
- doesn't click or bind when finger-tight, starts to click about 10ft-lb (30ft-lb is spec)

 

[R.Johnson]

Re: 1979 Evindrude 70 HP - Connecting rod binding after rebuild

You realize the rod cap's cannot be interchanged, and they can go only one way back on the rod.

 

[wisconsin_ninja]

Re: 1979 Evindrude 70 HP - Connecting rod binding after rebuild

Yes I realize that the connecting rod caps only go on one way.

 

[wilde1j]

Re: 1979 Evindrude 70 HP - Connecting rod binding after rebuild

I'm guessing the cap on that rod is not correctly aligned, which would account for the clicking and the binding when torqued.

 

[R.Johnson]

Re: 1979 Evindrude 70 HP - Connecting rod binding after rebuild

I can only suggest you go over your assembly procedure again. What does the broken joint of the rod look like when they start to pull together. There should hardly be a hairline crack.If there is, you have the cap on the wrong rod, or the cap is turned around. These part's have to be spotlessly clean also.

 

[wisconsin_ninja]

Re: 1979 Evindrude 70 HP - Connecting rod binding after rebuild

Well after a few weeks of banging my head against the wall I realized that the connecting rod had a hairline crack in it. I couldn't see it when the cap was off, but it opened up a few thousandths of an inch when the bolts were torqued. The crack was on the outer part of the connecting rod between the tapped hole and then side. I ordered a new connecting rod and the rest of the powerhead rebuild went very smooth.