jdubslopro
Petty Officer 3rd Class
- Joined
- Mar 5, 2010
- Messages
- 91
Re: 5.7 Mercruiser MPI won't stay running
Update. They put a new map sensor and tps into it. Running with no codes. But they informed me of a new issue, one that is preventing the motor from idling properly. Cylinders 2-7 are at 180psi, but cylinder one is reading at 90psi. They advised that its a blown head gasket. Now, I rebuilt the motor less than 10 hours ago (done exactly to spec sequence at exact torque lb-ft and even degrees with a fancy $500 snap-on tech wrench).
When I first got the boat back initially from the first time of tps IACV replacement, I put the boat in the water and from the minute I launched it wouldn't run, had to restart multiple times. In a matter of minutes it was hydro locked (water in all cylinders). I cleared all the water out and restarted it. My guess is that since I removed the flappers (originally one had come loose and was lodged in the exhaust--I believe this to be the initial cause of overheating my v6, blowing intake mani gasket and allowing water into the block) I experienced some reversion backing the boat into the water. I didn't really think this would be an issue, but it must've been the cause to my hydro lock.
So now I have to pull the motor and do a head gasket and new head bolts...and haven't even gotten to fully break in the motor from the initial rebuild.
Is this the same diagnosis (bad head gasket) that you here on the forum would give? I didn't realize a hydro lock at low rpm (idle or lower) would cause a head gasket failure, but I just want to make sure I'm replacing what is most likely the culprit rather than wasting money or time pulling the motor without actually replacing the faulty part. I also just paid for them to reseal my outdrive, so there's another gasket wasted. Gahh!! I just want to be done with this nightmare!
I suppose while the head is off I will check for bent valves, but wouldn't the valves hit the piston if they weren't fully closed?
Update. They put a new map sensor and tps into it. Running with no codes. But they informed me of a new issue, one that is preventing the motor from idling properly. Cylinders 2-7 are at 180psi, but cylinder one is reading at 90psi. They advised that its a blown head gasket. Now, I rebuilt the motor less than 10 hours ago (done exactly to spec sequence at exact torque lb-ft and even degrees with a fancy $500 snap-on tech wrench).
When I first got the boat back initially from the first time of tps IACV replacement, I put the boat in the water and from the minute I launched it wouldn't run, had to restart multiple times. In a matter of minutes it was hydro locked (water in all cylinders). I cleared all the water out and restarted it. My guess is that since I removed the flappers (originally one had come loose and was lodged in the exhaust--I believe this to be the initial cause of overheating my v6, blowing intake mani gasket and allowing water into the block) I experienced some reversion backing the boat into the water. I didn't really think this would be an issue, but it must've been the cause to my hydro lock.
So now I have to pull the motor and do a head gasket and new head bolts...and haven't even gotten to fully break in the motor from the initial rebuild.
Is this the same diagnosis (bad head gasket) that you here on the forum would give? I didn't realize a hydro lock at low rpm (idle or lower) would cause a head gasket failure, but I just want to make sure I'm replacing what is most likely the culprit rather than wasting money or time pulling the motor without actually replacing the faulty part. I also just paid for them to reseal my outdrive, so there's another gasket wasted. Gahh!! I just want to be done with this nightmare!
I suppose while the head is off I will check for bent valves, but wouldn't the valves hit the piston if they weren't fully closed?