Well, I thought I had this problem fixed but I guess not.
I replaced the riser gaskets, thermostat and raw water impeller. I did a compression check and all looked good. I changed the oil and saw no signs of water. I've used the boat a few times since then with no problems.
So yesterday I launch from the ramp and made it about 500' before the alarm went off, we never got on a plane, just idle speed. Temp gauge read about 205. Shut it down and checked the engine. Everything looked normal and the cap was on the engine flushing hose. So I hit the key to restart it and it's hydro locked again.
Put it back on the trailer, bring it home and remove the water from all 8 cylinders. Checked the impeller and it's still good. Hook up the hose and run for a good 30-40 minutes with no problem. I was able to get the temp up to about 175 with the engine running about 2500 rpm.
The only thing I noticed was the little O ring on the cap for the flushing hose looked slightly deformed like maybe it was a little loose and got pinched when it was installed on the hose, but there is also a second O ring of the type you use on a garden hose that I would have expected to provide a good seal.
So I have two problems.
1) Why the overheat? Would a very small leak in the flushing cap be enough to cause the overheat? It ran fine on the garden hose. At this point I am going to cap the flushing hose permanently and go back to using the ear muffs to flush the engine.
2) Why the hydro lock? I have overheated the engine twice because I forgot to put that stupid little cap back on, once resulted in a hydro lock, once did not. That was my own stupid mistake. But yesterday the cap was on. Do you think the hydro lock is caused only by the overheating or is there some other cause that I should be looking at?
I'm thinking that 2 out of 3 times it's overheated it has hydro locked, so maybe I just got lucky that 1 time it did not hydro lock??
To save you having to read through the old thread the engine is a 2005 5.7L Gi-E serial number 4012150295
Thanks for any help.
Chris
I replaced the riser gaskets, thermostat and raw water impeller. I did a compression check and all looked good. I changed the oil and saw no signs of water. I've used the boat a few times since then with no problems.
So yesterday I launch from the ramp and made it about 500' before the alarm went off, we never got on a plane, just idle speed. Temp gauge read about 205. Shut it down and checked the engine. Everything looked normal and the cap was on the engine flushing hose. So I hit the key to restart it and it's hydro locked again.
Put it back on the trailer, bring it home and remove the water from all 8 cylinders. Checked the impeller and it's still good. Hook up the hose and run for a good 30-40 minutes with no problem. I was able to get the temp up to about 175 with the engine running about 2500 rpm.
The only thing I noticed was the little O ring on the cap for the flushing hose looked slightly deformed like maybe it was a little loose and got pinched when it was installed on the hose, but there is also a second O ring of the type you use on a garden hose that I would have expected to provide a good seal.
So I have two problems.
1) Why the overheat? Would a very small leak in the flushing cap be enough to cause the overheat? It ran fine on the garden hose. At this point I am going to cap the flushing hose permanently and go back to using the ear muffs to flush the engine.
2) Why the hydro lock? I have overheated the engine twice because I forgot to put that stupid little cap back on, once resulted in a hydro lock, once did not. That was my own stupid mistake. But yesterday the cap was on. Do you think the hydro lock is caused only by the overheating or is there some other cause that I should be looking at?
I'm thinking that 2 out of 3 times it's overheated it has hydro locked, so maybe I just got lucky that 1 time it did not hydro lock??
To save you having to read through the old thread the engine is a 2005 5.7L Gi-E serial number 4012150295
Thanks for any help.
Chris
