Overheating problem-more challenging than usual
 

i have whipple supercharged 598 in my single engine cat. it has a single teague adjustable bottom pick up, hardin sea strainer, and hardin dual stage water pump.

if water is sucked from a hose connected to the bottom pick up and a 5 gallon bucket, the engine will slowly heat up climbing to 190 b4 i shut it down. if i pressurize the 1 1/4 hose, it does not overheat and a lot more water goes through the cmi headers.

i thought i had this fixed when i found a small zebra mussel shell caught in the sea strainer pressure relief valve. since it did not overheat after removing the shell while under pressure, i tested at the lake. the temp climbed while idling at the dock so i went home. that is when i decided to test from the bucket rather than under pressure.

water flushes through the entire system both from the pick up to the header or from the header to the pick up w/o the engine running. i have removed the side covers from the hardin pump and inspected the impellers which show no damage.

i am now thinking of finding a way to test the water pump, either by volume or maybe suction. when i feel the pick up hose in the bottom of the bucket, it doesn't seem to suck as hard as it should. this is purely a subjective judgement as i have no specs. hardin does not seem to have even volume specs. i suppose i could just double the mercrusier single pump spec which should be about right. i may also block the sea strainer pressure valve just to make certain that it is not allowing any air to enter.

does anyone have any troubleshooting suggestions?

thanks,

dave

Definitely sounds like a suction problem. Check every connection on the suction side of the pump, and any places a hose might be kinked slightly unless it is pressurized and pushed open.

good idea, but i replaced the hoses from the pick up to the sea strainer and from the strainer to the pump input. i said it was challenging1

Are you sure you have the inlet / outlet correct on the pump? May wanna just do a quick swap and see what it does. If hoses are good to the pump then has to be a problem with the pump. Do you have a plain old reliable single stage pump laying around you could put on and try? I had a similar problem last year with my dual stage pump and I took it off...

when i i installed the pump, i looked at impeller rotation to determine in/out. also, this setup worked well for one season and then i got mud and dirt in the pickup and throughout the system causing the overheating. i had to tow the boat back to the dock. later, after flushing and checking everything, i found a small piece of shell in the pressure re-leaf valve in the sea strainer causing a vacuum. i thought i had found the problem, but there must be another problem source as well.