I GIVE UP! Engine overheat again

[redneck wakeboarder]

I have run out of things to check. Since June I have burnt 4
impellers on my 98 Legacy. They separate from the metal
splines and the engine runs hot from lack of water.I have check every inch of hose,trans strainer,done a volume test on the raw water pump,and replaced the thermostat. What else do I need to look for to get this beast to run? I would like to know if I am the only one with this problem.

[cryonchick]

Have you ran the boat out of the water with the assist of a fake-a-lake or some other method? If so, are you getting any water out of the exhaust? Maybe the shredded impeller pieces are blocking the passages. If you get water out of the exhaust you know that it is pumping water, if not then it isn't getting through and will eventually burn up the new impeller after awhile. When replacing the impeller make sure that you coat the impeller and housing with a lubricant, I used vasoline, and plenty of it. Made it easier to put it in and doesn't give it a dry start.
When mine went I had to pull hose before and after the raw water pump. Check all of your housings. raw water, circulating water, etc.. Good Luck........

[uuhyeah]

I had a similar problem with my 90 sunsport. I checked everything and replaced the manifolds. Nothing seemed to help. I checked the water filter next to the intake and found grass. Cleaned it out and it runs cool now.

[barrey]

In my '87 comp the impeller disintegrated and left pieces of itself in the thermostat, after replacing that it was still overheating, and I found that there was a piece of the impeller lodged inside one of the tubes leading from the thermostat housing to the exhaust manifold, blocking it somewhat. It took a length of coat hanger to dislodge it. (This was on a PCM Ford 351, BTW).

The weird thing for me is that it would run fine for 20-30 minutes at a time in the driveway, hooked to a hose. Whenever I got it to the lake, it would overheat within 3-5 minutes.

Looks like the pressure from the hose got past the (partially) blocked opening enough to cool the engine, but the pressure from the supply pump drawing from the lake wouldn't do it.

Runs great now, just in time to replace the floor at the back on the driver's side. That will be fun... (NOT!!)

[dndsam]

This might be rather odd, but do you have the hoses correct on the waterpump housing. I have had them on backwards before and was actually trying to pump out of the crankcase instead of the lake. It does make a difference .

[jsrasband]

I didn't have hoses hooked backwards,I had the pump turned upside down.It took me a while and a lot of frustration to figure that out.Check inside pump for a burr or anything that could be eating up the impeller. Good luck