GT-40 fresh water pump

[richard]

To day I checked hight temp problem (180F) of my 01 SAN,GT-40 engine,I use fake a lake and run the engine ,I open the collant cap,I notice the coolant very quiet inside, I think the freh water don't work,later,when temp. going up ,the coolant level going higher,I stop the engine, before I want change a new thermatat, but now I think I should check the fresh water pump first, any one had experience on this,I love to hear.

[Jesse1]

RE: GT-40 fresh water pump

I install a new raw water impeller each spring. It's not hard to replace. If you ever run the engine without it being in the water it will damage the impeller very quickly.

[richard]

GT-40 fresh water pump

My problem is fresh water pump, raw water pump impeller change already.

[ffmedic74]

RE: GT-40 fresh water pump

Also try your water strainer towards the rear of the boat. 1. make sure its clean. 2. Make sure the gasket is still inside the threaded flange of the clear plastic stainer bowl. People have had these missing or not tight and suck air causing the raw water pump to have problems.

[pj]

RE: GT-40 fresh water pump

Total rookie question here. On a closed cooling system boat, what is the raw water that's getting sucked in from the lake do? Is raw water still used to cool the exhaust headers or what?

[DavidF]

RE: GT-40 fresh water pump

Yes, raw water is for exhaust system and heat exchanger for closed system.

Slim to no chance of circulation pump problem unless the shaft seal is leaking and then it would still circulate water. I would start with the thermostat.

[richard]

RE: GT-40 fresh water pump

I just check and feel the coolant pump don't function,next step I'll disasemble the coolant pump for check, hope this right,about thermostat ,even it don't open,it should have pass hole to let small volume coolant flow,but I don't see any little flow when see in coolant tank,seems the coolant pump no funtion atall,I pay too much concern to raw water pump.(coolant pump may means close system water pump)

[nms1991]

RE: GT-40 fresh water pump

Richard are you talking about the circulating pump on the front in the middle above the crank? easy way to see if it is working remove the belts and then take off the thermostat housing(when engine is cold)and rotate the pump to see if it moves the coolant. Also try to pull the pulley side to side and in and out to see if you have any play in it.

[richard]

RE: GT-40 fresh water pump

nms1991:
Your are right,I'm talking about,and the sytom very like the fresh water pump don't funtion,or the the coolant path can't flow through the engine,it's not very to take out the fresh water pump,you know inside how works? use impeller?

[nms1991]

RE: GT-40 fresh water pump

The circulating pump uses a cast steel impellar to move the fluid around while the raw water pump uses a rubber impellar to move the fluid. It would not hurt to recheck your raw water pump impellar to see if it has any damageon any of the blades. Have you replaced the impellar before? If you had did the impellar have any missing peices and did you find all of the peices before you reassembled the parts on the engine?

[richard]

GT-40 fresh water pump

nms1991:
I did change 2 time the raw water pump impller,and find no lost blade peice,they lokks good, now the problem remain is the coolant don't flow,so it can't do heat exchange,now I want to see what happen w/the fresh water pump, before take out it ,(quite difficult) if some way to pre check the fresh system is usful for me.

[richard]

Fresh water pump ok

I change the 147F thermostat instead the old 170F thermostat ,high temp. (180F)solved,i t keeps on 160F, freshwater pump works regular.