desyfering1
New member
"Okay so I bought a nice 84 Do
"Okay so I bought a nice 84 Doral 15' boat for $500. It needed a motor.
Took the motor apart and found it had a broken piston (number 3) and a bent rod and scuffed up cylinder wall.
Took it a rebuilder, claims he only rebuilds MARINE blocks. He bored all 4 cylinders to 30,000 over and put new pistons, rods, lifters, machined the cam, new oil pump, all new bearings and seals etc. etc.. Supposed to be like new.
Put the motor in, went out for 10 minutes, water temp read 180 degrees, got some blow back, and then KNOCK KNOCK KNOCK.
Pulled the motor out, took it back to the guy. He said it had a bad piston (number 4) WRIST PIN WAS SEIZED.
I put it back in. Took it out for a day, it ran at 180 again. Next day KNOCK KNOCK KNOCK.
This time I opened the motor, saw another WRIST PIN seizing up (number 3). I changed the piston, honed the wall. This time I changed the water pump, the impeller, and thermostat (I know I should have done that the first time).
The exhuast manifold was all cleaned out, the carb rebuilt, I went over everything with a fine tooth comb.
I thought NOTHING could go wrong.
Sure enough the 3rd time, 30 minutes in, we got the knock, ran at 180 (which I don't know how).
Got into shore, took the thermostat housing off, steam was coming from the engine. We checked for lots of water flow from the impeller, no problem. The thermostat was opening up as it should at 160. The water pump is brand new.
I took the thermostat right now and it was running at 110 or 120 if that helps.
So here we are again. This time it sounds like # 2, I imagine it is the wrist pin again. I will be pulling the motor again today. I cannot afford to continue to put new pistons in.
Is this a sign of overhearing? Or an Oil flow problem? I didn't think 180 would be enough to cook a piston, I thought it would blow a head gasket before this.
Was there a mistake when the engine was rebuilt the first time?
Any help on this subject would be appreciated."
"Okay so I bought a nice 84 Doral 15' boat for $500. It needed a motor.
Took the motor apart and found it had a broken piston (number 3) and a bent rod and scuffed up cylinder wall.
Took it a rebuilder, claims he only rebuilds MARINE blocks. He bored all 4 cylinders to 30,000 over and put new pistons, rods, lifters, machined the cam, new oil pump, all new bearings and seals etc. etc.. Supposed to be like new.
Put the motor in, went out for 10 minutes, water temp read 180 degrees, got some blow back, and then KNOCK KNOCK KNOCK.
Pulled the motor out, took it back to the guy. He said it had a bad piston (number 4) WRIST PIN WAS SEIZED.
I put it back in. Took it out for a day, it ran at 180 again. Next day KNOCK KNOCK KNOCK.
This time I opened the motor, saw another WRIST PIN seizing up (number 3). I changed the piston, honed the wall. This time I changed the water pump, the impeller, and thermostat (I know I should have done that the first time).
The exhuast manifold was all cleaned out, the carb rebuilt, I went over everything with a fine tooth comb.
I thought NOTHING could go wrong.
Sure enough the 3rd time, 30 minutes in, we got the knock, ran at 180 (which I don't know how).
Got into shore, took the thermostat housing off, steam was coming from the engine. We checked for lots of water flow from the impeller, no problem. The thermostat was opening up as it should at 160. The water pump is brand new.
I took the thermostat right now and it was running at 110 or 120 if that helps.
So here we are again. This time it sounds like # 2, I imagine it is the wrist pin again. I will be pulling the motor again today. I cannot afford to continue to put new pistons in.
Is this a sign of overhearing? Or an Oil flow problem? I didn't think 180 would be enough to cook a piston, I thought it would blow a head gasket before this.
Was there a mistake when the engine was rebuilt the first time?
Any help on this subject would be appreciated."