I was getting a knocking noise when the motor was hot. After removing the 2 sumps, with out removing the motor again (yes that was fun). I found that the con-rods on piston 2 & 3 are being chewed out for some reason, after only 4000KM. The motor has been totally hand rebuild and the bearings where hand fitted to the correct clearance. I've check and it isn't a bent con-rod. The motor revs during running in, never went over 3000rpm and after never went over 4000rpm.
The reason for the motor rebuilt was because the motor showed low compression. While I dismantling the motor I noticed when removing the sump I found metal shavings and pieces that came from piston 2 & 3 con-rod bearings that had been chewed out. I thought the motor ran out of oil so the oil pump was also stripped down and didn't show signs of wear. Also the relief valve was check for wear and obstructions, which there wasn't any.
I believe the problem is the hole in the main bearing should be larger to allow more oil as the crank shaft and block has larger oil holes. Also the oil grove in one half of the main bear cap should be in the other half as well and larger to allow more oil to be feed into the crank shaft main bearing con-rod feed holes, which will allow more oil to be feed into the can-rod bearings. As number 2 and 3 main bearings each feed 2 con-rod bearings and number 1 and 4 only feed 1 con-rod bearing. 2 and 3 main bearing oil hole and grove is not big enough to feed these to con-rod bearings, because main bearing 1 and 4 only feed 1 con-rod bearing each, they don't have the same lubrication problem.
I was getting a knocking noise when the motor was hot. After removing the 2 sumps, with out removing the motor again (yes that was fun). I found that the con-rods on piston 2 & 3 are being chewed out for some reason, after only 4000KM. The motor has been totally hand rebuild and the bearings where hand fitted to the correct clearance. I've check and it isn't a bent con-rod. The motor revs during running in, never went over 3000rpm and after never went over 4000rpm.
The reason for the motor rebuilt was because the motor showed low compression. While I dismantling the motor I noticed when removing the sump I found metal shavings and pieces that came from piston 2 & 3 con-rod bearings that had been chewed out. I thought the motor ran out of oil so the oil pump was also stripped down and didn't show signs of wear. Also the relief valve was check for wear and obstructions, which there wasn't any.
I believe the problem is the hole in the main bearing should be larger to allow more oil as the crank shaft and block has larger oil holes. Also the oil grove in one half of the main bear cap should be in the other half as well and larger to allow more oil to be feed into the crank shaft main bearing con-rod feed holes, which will allow more oil to be feed into the can-rod bearings. As number 2 and 3 main bearings each feed 2 con-rod bearings and number 1 and 4 only feed 1 con-rod bearing. 2 and 3 main bearing oil hole and grove is not big enough to feed these to con-rod bearings, because main bearing 1 and 4 only feed 1 con-rod bearing each, they don't have the same lubrication problem.
- icepick, Balhannah, Australia