Need some help. My son has a 2001 Rancher 4x4 which was rebuilt at 2100 miles by a local Honda dealer. There had been a piston failure which happened immediately while being ridden. The repair was relatively minor with just a piston and ring replacement. They said however, they took the engine all the way apart, which the bill would reflect---it was $950. I was out of the country at the time so taking it to an authorized Honda shop made sense to my son, though now he wishes he had done something different.

After about 8 hours of operation the engine started to smoke indicating burning of oil. It was minor at first, but soon became obvious that perhaps the rings didn't seat right. I told him I would look at it when I got home.

I have fair experience rebuilding engines of all kinds as a 35 year farmer---surely this can't be a difficult situation? We took the engine back apart and found some carbon deposits on the exhaust valve indicating oil burn, though the piston was still very clean with no staining yet. So we concluded that the 1) rings didn't take and put in new rings, and gasket set, or 2) there was an issue with valve guides which I took the head to a respected machine shop to check them out---they were reported tight and in excellent condition.

Of no consequence now, but the reason we tried to do it ourself first was that the Honda dealership went out of business shortly after they had repaired the machine. No recourse with a closed dealership.

Now the problem. With the change of rings and gaskets, the engine still is burning as much oil as before. I took it back apart and observed some oil accumulation around the oil port from the crankcase to the head. That would lead me to believe that there might be some warping in the head that is not allowing the head to seat properly with the jug. But I'm looking for other answers as well. Have I missed something where oil could be getting to the top of the piston?

Any ideas will be appreciated!! Otherwise I'm headed back to another repair shop, but certainly not a Honda dealer!!

 

You dont mention what caused the first failure, that can determine what happens later on.

If there were a piston failure, was there damage to the cylinder? was it then bored to the next size over? When you removed the rings install at the Honda shop did you check their end gap? excessive eng gap on those rings would show accelerated wear from something.

If an ATV gets submerged in nasty waters and is then rebuilt without being disassembled it will fail again in just a few hours.

 

First, thank you for replying. I've done alot of larger engine work, but this one has me baffled.

Of course, I didn't see the piston damage, nor did the son, but he was riding it in some hill country when it started smoking and losing power. He's very conscentious so he stopped riding, loaded it on the trailer and headed home before it completely quit. I'm having my son ( he's 21 and in college) look at the bill to see if it was bored, but I couldn't detect that it was. No indication on the piston that it is ten over. I mic'ed the cylinder to check if it was ovaled and it's within .002. The son did say that there was some water in the oil when he loaded it on the trailer, but it was very slight. He hadn't ridden in any water that day so it had come from previous activity.

I did notice when I pulled it back apart the last time that there was oil around the oil port coming from the crankcase to the head. A small amount of oil was even leaking to the outside of the head and pooled on the crankcase cover. That indicated that the oil port wasn't being sealed off properly. That's when I put a new head gasket in, which was not done at the dealership in the original overhaul. There was a black residue that looked like a gasket sealer between the cylinder and head. I cleaned all of that off, put in a new head gasket and thought that would fix the problem, but it's still losing enough oil through the piston from somewhere that it will exhaust unburned oil out the exhaust pipe.

My next thought is that the head and cylinder aren't true enough to allow a tight seal around the piston and oil port. I've had warped heads on six and eight cylinder engines, but wasn't believing that was possible on a single cylinder. I can take it to a machine shop to get that planed out, but I'm trying to collect ideas of what else it might be. Perhaps I'm missing some minor detail of the Honda over head cam engine? Is there something else that seals that oil port besides just the head gasket? I haven't seen anything in the parts detail, but perhaps I missed it.

Any additional ideas will be appreciated. Thank you!!