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So while out for a lunch cruise the other day, our temps spiked at idle speed, 196 was highest observed temp. Cut the motor and threw the anchor immediately. I pulled the raw water pump to effect a repair on water, since I had a spare and tools in the boat. Impeller was completely shredded. I pulled the discharge hose from the pump to the v-drive inlet and flushed out some more impeller pieces. We collected what we thought to be roughly 80% of the impeller chunks and I also disconnected the inlet to the thermostat housing then fired the engine up for about 30 second to flush out anything to that point.
I also removed the strainer bowl to inspect that since I had beached up the previous day. Light debris noted, nothing major.
Fired it up and the temps were climbing at Idle, so I put it on plane, Temps dropped dramatically, down to 140 actually, then increased slowly to 155 where they stabilized, which is where my boat normally runs. Perfect, job done then...
Entering the channel we dropped back to idle speed, when temps began to rise again rapidly. Shortly reached 190 where the alarm went off and I once again shut it down immediately. Managed to get it trailered since the boat ramp was close by and put it in the driveway where I continued testing off the hose. Reading all the threads I could find I double checked everything from the impeller direction to pump orientation, to the strainer gasket.
1-Established what I think to be good/normal flow all the way to the riser inlets through the cooling system, at idle RPM. Replaced thermostat somewhere in there with a 140 since that's all they had at west marine. Stock is 160, but we run in bathwater down here in Houston anyway. Should be fine right?
2-Air bubbles observed in strainer bowl. All inlet fittings and strainer assembly itself seem to be tight. While checking for leaks I closed the though hull valve to pressurize those fittings with the hose, no leaks observed.
3-Removed strainer assembly to place inlet hose in bucket and check for bubbles. Attempted to start motor for this test and it locked up.
4-Removed all plugs, Cylinder 5 full of water.
5-Purge water, compression check.
Cyl 1-185
Cyl 2-190
Cyl 3-180
Cyl 4-190
Cyl 5-180-Water
Cyl 6-185
Cyl 7-180
Cyl 8-190
6-Reinstalled plugs and proceeded with bucket test. Air bubbles still observed, suspected bad strainer housing at this point.
7-Plumbed strainer back up normally and hooked up hose to run motor. Engine locked on startup again. Pulled plugs, more water out of Cylinder 5.
One theory is that I popped an intake gasket with water hose pressure...this seems thin to me. Possible?
Another theory is that we blew a head gasket resulting in identical compression numbers on 3,5,7 with 5 being the flooded one.
A slightly more grim theory that I cooked up is that perhaps some of that impeller made it's way into the block and is clogging something internal, thus resulting in my still climbing temps at idle. Further, with observed ET climbing to 180 prior to me shutting it down in the driveway I have to wonder, if a journal is clogged in a water jacket somewhere, is one section/cylinder of the block getting super heated, while the rest remains relatively cool?
Leak down test is next on the list which should tell us if it's the head gasket or just the intake gasket. I suppose at that point I can return to troubleshooting the climbing temps at idle issue.
If anyone has any suggestions, tips, input, ideas, experience, theories, clever jokes, positive vibes or Houston locality and a willingness to turn wrenches, I am 110% open to all of the above.
Here are some pictures of my predicament.
Thanks for tuning in.
I also removed the strainer bowl to inspect that since I had beached up the previous day. Light debris noted, nothing major.
Fired it up and the temps were climbing at Idle, so I put it on plane, Temps dropped dramatically, down to 140 actually, then increased slowly to 155 where they stabilized, which is where my boat normally runs. Perfect, job done then...
Entering the channel we dropped back to idle speed, when temps began to rise again rapidly. Shortly reached 190 where the alarm went off and I once again shut it down immediately. Managed to get it trailered since the boat ramp was close by and put it in the driveway where I continued testing off the hose. Reading all the threads I could find I double checked everything from the impeller direction to pump orientation, to the strainer gasket.
1-Established what I think to be good/normal flow all the way to the riser inlets through the cooling system, at idle RPM. Replaced thermostat somewhere in there with a 140 since that's all they had at west marine. Stock is 160, but we run in bathwater down here in Houston anyway. Should be fine right?
2-Air bubbles observed in strainer bowl. All inlet fittings and strainer assembly itself seem to be tight. While checking for leaks I closed the though hull valve to pressurize those fittings with the hose, no leaks observed.
3-Removed strainer assembly to place inlet hose in bucket and check for bubbles. Attempted to start motor for this test and it locked up.
4-Removed all plugs, Cylinder 5 full of water.
5-Purge water, compression check.
Cyl 1-185
Cyl 2-190
Cyl 3-180
Cyl 4-190
Cyl 5-180-Water
Cyl 6-185
Cyl 7-180
Cyl 8-190
6-Reinstalled plugs and proceeded with bucket test. Air bubbles still observed, suspected bad strainer housing at this point.
7-Plumbed strainer back up normally and hooked up hose to run motor. Engine locked on startup again. Pulled plugs, more water out of Cylinder 5.
One theory is that I popped an intake gasket with water hose pressure...this seems thin to me. Possible?
Another theory is that we blew a head gasket resulting in identical compression numbers on 3,5,7 with 5 being the flooded one.
A slightly more grim theory that I cooked up is that perhaps some of that impeller made it's way into the block and is clogging something internal, thus resulting in my still climbing temps at idle. Further, with observed ET climbing to 180 prior to me shutting it down in the driveway I have to wonder, if a journal is clogged in a water jacket somewhere, is one section/cylinder of the block getting super heated, while the rest remains relatively cool?
Leak down test is next on the list which should tell us if it's the head gasket or just the intake gasket. I suppose at that point I can return to troubleshooting the climbing temps at idle issue.
If anyone has any suggestions, tips, input, ideas, experience, theories, clever jokes, positive vibes or Houston locality and a willingness to turn wrenches, I am 110% open to all of the above.
Here are some pictures of my predicament.
Thanks for tuning in.
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