$4000 later

[Awill10291]

I bought a 1986 Supra Beast. It has a 460 ford inboard motor that has been marinized.

-replaced impeller
-replaced thermostat
-replaced regular water pump ($50)
-replaced hoses
-took heads off they were severly WARPED had machine place grind down installed all new gaskets was told this was likely the problem. IT WASNT!!!
-replaced all other water pumps (I believe raw water or sea water pump?)
-Place that has done all this work says WATER FLOW IS GOOD.

What the HECK could be next? I bought this boat for $1500, and for the first week it ran fine. NOW IT RUNS AT 220 OR HIGHER after over 4000k of labor and parts. Does anyone have any idea on what could be causing this? When i feel the hose that takes water into the motor, it is cool. When i touch the hoses that the water comes out of the engine they are HOT and you can barely touch. The big silver exhaust manifolds? are always too hot to even touch as well. Was told you should be able to rest your hand on those! Any help would be great. Thanks guys! ((((((((((

[Jetlink]

Did you install the raw water pump to flow water the correct way? That is easy to fix, check and easy to mess up the first time. Take a picture of the front of the engine, then a close up of the raw water pump and also tell us what the rotation is of the engine as I am not familiar with a Ford 460.

[Wulphie]

Check the thermostat cover. They can get severe rust build up and constrict flow to the exhaust manifolds and through the thermostat housing. Also remove block drains and run water through the motor. Some times you can get rust and sediment build up in the cooling jackets.

Also check that you have a 140 degree marine thermostat. Depending on your exact cooling system the t-stat may require a bypass hole in it.

[wotan2525]

Try to run boat with raw water intake hose in a bucket full of water NOT using a hose to feed it. If the engine does not SUCK through this hose (and quick!) then something is wrong.

If the mechanic is "pushing" water through the engine with a hose, this is your problem. My money is on the raw-water pump being backwards or the impeller being roasted. And the raw water pump is NEW? Not just serviced?

Also -- pull the thermostat out. No reason to even have it in there until you get the engine running cool.

[Awill10291]

The boat is back with the mechanic. WOTAN- Impeller been replaced for the second time this summer. He said he replaced the raw water pump, not just serviced. JETLINK- I would assume this boat mechanic who has fixed many boats on my lake (much newer) put the raw water pump on the right way. I can't get any pics right now because it is back at the shop. Will try to later next week. WULPHIE- I was told by several boat fanatics that thermostats are to make sure the boat runs smoother, and also make sure that the engine doesn't get too cool, SO at one point I actually removed the thermostat to make sure water flow would be sufficient. The boat STILL OVERHEATED. Since then a new thermostat was installed.

[Jetlink]

Man, what you are describing leads me to believe that the pump was installed incorrectly and therefore is not able to draw water to the engine and cool it. Your mechanic might be the best out there but he is like the rest of us, human and we are prone to making mistakes. If the impeller is cooked for a second time already, that is where my money is going. Just as an example, I am now on my second impeller in my raw water pump since I took ownership of my boat 5 years ago and I replaced it only because it came in the new pump like that.

[Wulphie]

The boat is back with the mechanic. WOTAN- Impeller been replaced for the second time this summer. He said he replaced the raw water pump, not just serviced. JETLINK- I would assume this boat mechanic who has fixed many boats on my lake (much newer) put the raw water pump on the right way. I can't get any pics right now because it is back at the shop. Will try to later next week. WULPHIE- I was told by several boat fanatics that thermostats are to make sure the boat runs smoother, and also make sure that the engine doesn't get too cool, SO at one point I actually removed the thermostat to make sure water flow would be sufficient. The boat STILL OVERHEATED. Since then a new thermostat was installed.

This is why I said to check the system for obstructions, rust etc. If the t-stat housing is constricting the flow from rust it doesn't mater if the t-stat is installed or not. Same with rust/sediment build up in the block.

The only reason the engine will overheat is because it is not flowing water. By eliminating the probability of the pumps not working and t-stat not opening then there has to be a blockage.