35 hp Evinrude 1982 piston rod end caps - I need help from the outboard guru's

[DetRvrRat]

I bought a 1982 35hp evinrude 7 years ago. Before i could even get it on the water the motor locked up. I then decided to tear down the entire motor to find the problem. It turned out to be the piston rod end cap bolts had come out of the rod. I installed new pistons, rods, bearings and bolts. The motor was then put back together very carefully making sure that I torqued all the bolts to spec. Over the last 5 years the motor has run like a champ until just this last weekend when once again the bolts loosened and locked the motor in the middle of my vacation. What can I do to rid myself of this during the next repair? What is causing it to last 5 years then coming loose? Is there a better way of keeping those bolts from doing this again? Any input is much appreciated.

 

[F_R]

Wow, you have some kind of luck (bad). That is extremely unusual, especially happening twice. You did the best you could with new parts and proper torque. I really hate to suggest it, but I suppose you could put a drop of Loctite on the bolt threads. The next guy to tear it down will cuss you though. I wonder, is there something unusual about the use of this motor, like too-high RPM or constant idle? It should be able to take anything within normal bounds.

 

[racerone]

Where the caps properly lined up ?----What torque was used ?

 

[racerone]

There are millions of these connecting rod screws in use.---When torqued properly with oil on them they do not come loose.----Oil on them is per the factory manual !!!----Alloy steel bolts with a tensile strength of 180,000 PSI and torqued to 370 INCH LBS.

 

[jrs_diesel]

Dumb question, but did you use the lock plates under the bolt heads? When assembled, the tabs on the lock plates are bent up against the bolt head to keep them from doing what yours did. Sucks that it happened twice. Hope you get it back on the water soon.

 

[Chinewalker]

No lock plates on these bolts. Just torqued...

 

[DetRvrRat]

Thank You! I guess when I get to doing this (hopefully for the last time) I'll triple check the installation. I am usually quite confident when I tear something down and rebuild. For the time being I have a 25 hp power head that will fit it while I rebuild the 35. Just seems strange how it would hold for 5 years and all of a sudden do it.

 

[boobie]

Just remember the cap alignment is very critical and don't get the caps mixed up. There is a tool for the alignment but it can still be done with a sharp lead pencil.