I recently rebuilt a 2003 txrb 150 and followed the service manual instructions on installing the prv (poppit) in the wrong direction. The direction in the manual says long side towards the block but I have learned through iboats that Yamaha made an error in their publication and the short side is supposed to go into the block.
The first test run seemed ok, got up to 3000 rpms no problem, although did notice a surge but it corrected itself. I thought to myself, that didn't sound good, but it only lasted a couple seconds and everything returned to normal. Came to an idle and remove the cowl...everything looked ok, put cowl back on and resumed test run for another few minutes. No overheat alarms during the high speed test. I didn't have a lot of time to play so I returned back to the lift and began the flush with the hose attachment. I noticed water coming from under the cowl so I took the cowl off. Once removed, it was obvious something was leaking on the motor. I removed the oil tank and found a pin sized hole in the block on the top cylinder. The hole only seemed to penetrate from the water cooling passage as a compression check tested ok at 115 - 125. I'm thinking when this hole was created, water under the cowl caused the motor to surge.
I've tested the motor at idle for hours before the high speed test and the cooling system seemed to do it's job...no overheat alarms and strong tell tale. So I'm basically assuming what happened was too much pressure built up in the cooling system and pierced a hole in the block? My first question is, why didn't the gasket go before an aluminum block?
So I've spent the last week thinking about what could have gone wrong...It could be corrosion has clogged a passage somewhere, or the prv was sticking, or maybe the gasket maker on the crankcase covered a cooling passage hole, or exhaust gases getting into the water cooling system, or...well that's about it. The overheat temp switches work as I tested them the weekend before, so I'm thinking this wasn't an overheat issue it was a over pressure issue. There was some corrosion, salt build up, calcium, or whatever the white stuff is within the water passages, but nothing that seemed to prevent water flow. I did clean the water jackets on the heads before reinstalling. The old tstats weren't completely covered with corrosion, just some light coating...enough for me to not take a chance so I did replace those.
I haven't checked the torque on the head bolts yet as the manual suggests to retorque after break-in period.
I don't think the crankcase gasket maker would have affected water passages would it?
So I'm left wondering if installing the prv in the wrong direction could have caused this?
Tonight I removed the prv and tstats, did a quick flush to see if water was flowing through those areas. As far as I can tell there isn't a clog in the cooling system. The tstats were wet, the prv was too. Lots of water coming from the exhaust.
Tomorrow I'll switch the direction of the prv and flush with vinegar.
I patched the tiny hole with marine tex and seems to hold up to the 40 psi water hose so that's a good, but still a little worried about the original cause of the pressure build up. Could a prv installed the wrong way allow that much pressure to pierce an aluminum block?
The first test run seemed ok, got up to 3000 rpms no problem, although did notice a surge but it corrected itself. I thought to myself, that didn't sound good, but it only lasted a couple seconds and everything returned to normal. Came to an idle and remove the cowl...everything looked ok, put cowl back on and resumed test run for another few minutes. No overheat alarms during the high speed test. I didn't have a lot of time to play so I returned back to the lift and began the flush with the hose attachment. I noticed water coming from under the cowl so I took the cowl off. Once removed, it was obvious something was leaking on the motor. I removed the oil tank and found a pin sized hole in the block on the top cylinder. The hole only seemed to penetrate from the water cooling passage as a compression check tested ok at 115 - 125. I'm thinking when this hole was created, water under the cowl caused the motor to surge.
I've tested the motor at idle for hours before the high speed test and the cooling system seemed to do it's job...no overheat alarms and strong tell tale. So I'm basically assuming what happened was too much pressure built up in the cooling system and pierced a hole in the block? My first question is, why didn't the gasket go before an aluminum block?
So I've spent the last week thinking about what could have gone wrong...It could be corrosion has clogged a passage somewhere, or the prv was sticking, or maybe the gasket maker on the crankcase covered a cooling passage hole, or exhaust gases getting into the water cooling system, or...well that's about it. The overheat temp switches work as I tested them the weekend before, so I'm thinking this wasn't an overheat issue it was a over pressure issue. There was some corrosion, salt build up, calcium, or whatever the white stuff is within the water passages, but nothing that seemed to prevent water flow. I did clean the water jackets on the heads before reinstalling. The old tstats weren't completely covered with corrosion, just some light coating...enough for me to not take a chance so I did replace those.
I haven't checked the torque on the head bolts yet as the manual suggests to retorque after break-in period.
I don't think the crankcase gasket maker would have affected water passages would it?
So I'm left wondering if installing the prv in the wrong direction could have caused this?
Tonight I removed the prv and tstats, did a quick flush to see if water was flowing through those areas. As far as I can tell there isn't a clog in the cooling system. The tstats were wet, the prv was too. Lots of water coming from the exhaust.
Tomorrow I'll switch the direction of the prv and flush with vinegar.
I patched the tiny hole with marine tex and seems to hold up to the 40 psi water hose so that's a good, but still a little worried about the original cause of the pressure build up. Could a prv installed the wrong way allow that much pressure to pierce an aluminum block?