robin 295 tight rod to crank

[chris3353]

Hello all,

First post here thanks in advance.

I have a 295 engine,, The rod bolts loosened on the # 1(? farther inside the case, clutch side). I read in post that is common.. The piston was slapping the head, the bolts were 1/4 out. can not believe it did not break the rod.

I pulled the motor, broke it down. Everything looks in surprisingly good shape. Polished the crank on the bench,, took scotch bright to the connecting rod and going back together it is tight... Will not turn over once the rod bolts are tight at all.

I read a few other post but they never had a follow up/ solution. Yes they are in the same order, same parts, checked for burrs,, Even used Dykum on the surfaces to look for hard contact, Nada,, nothing..

THe only thing i see a little a miss,, and it could just be my eye,, is the rod does not look perpendicular to the crank when tightened.. I feel the side of the rod is dragging on the crank. The cap has plenty of clearance but the rod it tight..

Any ideas,,, I can order new rods but thought i would throw this out there before i was time and money.


I build a lot of motors but this is my first Golf cart.

Thanks,
Chris

[CP241]

I’ve had a few of them that same rod loosens itself. But caught it early enough that I just retorqued them and they were fine.

If it was knocking around enough for the piston to make contact somewhere it shouldn’t, I’d say that rod is distorted and should be discarded. It only takes a couple thousandths of an inch to make it not fit right…

I’d buy new rods and whatever else is needed to rebuild it.

[chris3353]

Originally Posted by CP241

I’ve had a few of them that same rod loosens itself. But caught it early enough that I just retorqued them and they were fine.

If it was knocking around enough for the piston to make contact somewhere it shouldn’t, I’d say that rod is distorted and should be discarded. It only takes a couple thousandths of an inch to make it not fit right…

I’d buy new rods and whatever else is needed to rebuild it.

I just put my Fowler dial indicator on it best i could,, The crank is ~1.380"

the rod that did not loosen, and operated smooth is 1.370-1.380.
The rod that came loose is 1.378-1.385.

Both are to tight to move once on the crank.. everything is out on the bench. I surfaced the sides of the good rod a few thousandth in case there was a burr hitting the crank . Seems to have helped.. I think someone has been in here before me so I will start back with the basics like any other motor.

[chris3353]

Figured it out,,

The pistons are in the same cylinder as they came out but I flipped them 180 from how the came out.. I can see where both pistons were hitting the new spark plugs and i reinstalled them the same way and it was too tight. I flipped the rod/piston on the crank (opposite) of how they came out and it is smooth.

The crank radius must be a little different on the front/rear side of the journal??

Anyhow, It appears to be smooth now even though it is not how it came apart.

[CP241]

The rod should be marked fan on one side. Obviously that side goes towards the fan
The piston should have a DF marking on it. Make sure that side goes towards the fan also.

Maybe they were backwards before?

[chris3353]

Originally Posted by CP241

The rod should be marked fan on one side. Obviously that side goes towards the fan
The piston should have a DF marking on it. Make sure that side goes towards the fan also.

Maybe they were backwards before?

I pulled it back apart last night, I was not comfortable with changing the orientation of parts.
I went back to the crank and gave it another quick redneck polish.

I was going to order rods ~200$ so i thought i would try a backyard rod conditioning.. It wasn't pretty but seams to have done the trick. I used scotch bright, a #2 square bit klein tool and my drill.

I ran the scotch bright back and forth until all the aluminum looked new again.

I am a .0025-.003 cleanance which is a little still in spec for a used engine.

The pistons and rods are back in the correct way, torqued and all feels good.

Chris