25 HP 1981 rod bearing failure

[G DANE]

Put a 25 HP powerhead i had in shopcorner for years on a 35 HP midsection, for my brotherinlaw. Maiden voyage showed it had a clicking sound. The screwdriveron- pistontoptrick-, showed something like 1/64" play in lower connection rod. Before I even waist time to pull everything apart: Has anyone experienced a rod bearing failure that was fixable without changing cranckshaft and connecting rod or even connecting rod. Im' running out of parts for these, I repaired quite a couple thru the years. Only bearing failure I've seen was including chewed up cranckshaft journal. Worth the time ??

 

[DJ]

Re: 25 HP 1981 rod bearing failure

Gdane,

Before I would go changing con. rods, I would be looking at interference issues with the powerhead swap.

Plus, that 25 powerhead may just need a serious decarb.

 

[Lubosleftboot]

Re: 25 HP 1981 rod bearing failure

Is connecting rod failure common on Johnson and evinrude motors?I am asking as there seem to be a lot of very old OMC motors on here that are still giving good service to their owners.


LLB

 

[tashasdaddy]

Re: 25 HP 1981 rod bearing failure

81 is not old for a johnny/rude, i'm still running a '55 15hp every weekend the head has never been off, i did Joe Reeves, carb adjustments to it and it runs like new, i also keep it decarbed.

 

[KYHunter2]

Re: 25 HP 1981 rod bearing failure

Im sure you know this .

But , a motor sitting around for along time .

May get some rust on the bearings , and crank journals.

It doesn't take alot , to lead to premature bearing failure.

KYhunter

 

[G DANE]

Re: 25 HP 1981 rod bearing failure

Well this one sat inside in shop, it sat for 4 years at me and many years at the previous owner. When I bought it for parts originally, it turned freely, I measured compression, it was right on 128 on both, so I decided this powerhead was worth saving for a runner some time. Usually when you shake flywheel forth and back a little on those, you hear clacking and clicking, this one was smooth and silent. Then I stumpled ower a mid section and a lower unit last year, and I had the parts. Honestly the only 20 - 35 with bearing failures, newer than 75 i've seen were both previous swimmers. Maybe this one sunk on a boat once, who knows. I guess I will open it up any way, just to know. It starts in first pull every time, a shame.

 

[G DANE]

Re: 25 HP 1981 rod bearing failure

to lobosleftboot. No usually they are put out of service because of overheating and scored cylinders, or salt water corrosion. My old mechanic, who are no longer once said to me: An evinrude cant wear out. They can be damaged by mistreatment or lack of preventive maintenance, but with the right maintenance, propeller and use, they never wear out. I knew a dealer who had a 1965 he used on his dighny for more than fourty seasons, every summer. It was never rebuild, just had the preventive maintenance.

 

[KYHunter2]

Re: 25 HP 1981 rod bearing failure

It is a shame , and I'm sorry for your misfortune.

KYHunter d

 

[G DANE]

Re: 25 HP 1981 rod bearing failure UPDATE

Re: 25 HP 1981 rod bearing failure UPDATE

Had half an hour tonight so I removed silencer, carb, intake and reed assembly, which gives limited access to lower connecting rod bearings. I tried to press and rock with them. No sign of any unusual play, at all. Rods had that shiny golden colour from hardening, like new, no sign of rust.. I guess I maybe just moved the piston in bore, then. Thought a bit of possibility of a broken pistonring. Measured compression, cold. Both dead on 115 ( i had oil in bores when 128 ) Can it have a broken ring, or sticking ring, and equal compression at same time ? Could sound come from lower unit ? It jumped out of gear, and propshaft was bent a bit. It iddled low, and would die sometimes while shifting in gear. Lots of power though. Plugs were whiteish, and fuel pump was pumping weak, had to press primer now and then to keep carb bowl full. What else could produce that clicking sound, not like poston slop rattle, a lighter sound.

 

[wilde1j]

Re: 25 HP 1981 rod bearing failure

A worn main bearing could do that ... easy to check crankshaft runout with a dial indicator.

 

[G DANE]

Re: 25 HP 1981 rod bearing failure

wouldnt a broken ring affect compression ? Headgaskets are clost to 50$ here, so you dont just pop heads to see, unless neccesary.

 

[Scaaty]

Re: 25 HP 1981 rod bearing failure

Could be a wrist pin/piston prob

 

[R.Johnson]

Re: 25 HP 1981 rod bearing failure

With a damaged gearcase, and a bent prop shaft, my guess would be the noise is coming from the gearcase. Probably a damaged forward gear, and pinion, Take it apart, and look. With a bent propshaft, It has to come apart anyway

 

[G DANE]

Re: 25 HP 1981 rod bearing failure

Popped the head of tonight, and guess, it ate something hard, chewed a couple of edges on the intake port, and banged up a piston and the head. I think it will be fine with a new piston and maybe another head. I will consider making it a part motor however as the lower needs repair too.