Overheating on the river but not at house?

Ok so when we are in th driveway with water hose connected never gets over 160 degrees. I just bought the boat and replaced water impellar. Thinking she is good to go, take boat out at river and within 5-10 minutes overheated. Where do i start and what else do i need to change out? I own a 1976 Ski Tique. How can i test to make sure the water impellar is priming the system out of the lake? Any help would be greatly appreciated. Trying to get this running right before season is over lol

if it was the t stat woudnt it overheat in driveway too?

Bucket test.

there is a slight drip of water coming from water impellar pump. but its not that much and its been leaking at this spot for about 2 years with no issues before.

plugged the water hose into a fitting rigged up, opened the valve

MarauderMatt wrote: plugged the water hose into a fitting rigged up, opened the valve

When you connect it up like that you dont even need the raw water pump! That is why you see water leaking too,any leak with pressure will be sucking air when under suction. Take a glass of water and a straw,cut a hole in the straw an inch higher than the water and try drinking it. That is what your pump is trying to do,thats you at the lake. If you were able to pressurize that straw,some water will leak out but the engine would get enough to keep cool while it ran,thats you at home on the hose.

since the Raw Water Pump has a slight leak, do i need to replace the whole unit? is so whats the part number? i hear they are expensive

looks to be coming from a tattletale, maybe from the shaft? ill have to take a closer look when i get a chance

Gary S wrote: This way the system is not pressurized by the house pressure,the engine pump must do the work just like at the lake. This is why I asked how you hooked it up at home---

+1

That screw holds the cam in place inside the pump. Placement of the cam determines which way the water flows thru the pump. The position of that screw facing in or out depends on the rotation of the engine. Facing in for a left hand engine,out for a right hand engine. Your engine is a lefty which is a whole nother story--- glad you figured it all out.

Careful Gary, you're assuming he has a PCM. Commanders and Escorts were available in the mid 70's and they put the pump on the other side of the engine. Pictures woul help here.

This is for PCMs, but gives you an idea of what's happening inside a RWP anyway.

TRBenj wrote: Careful Gary, you're assuming he has a PCM. Commanders and Escorts were available in the mid 70's and they put the pump on the other side of the engine. Pictures woul help here.

pump is on driver side of engine, i believe its a PCM engine,

old pic but should be able to tell if not i can get more later when i get off work

Ill leave the fuel line and filter for you guys.