Donzi26ZX

I have a 1999 Formula 330SS with 7.4 MPI motors. One of the motors is over heating, here is what I have replaced on the motor. Last year I put new exhaust on and a new impeller (entire kit) and thermostat. This year I put on the entire sea pump and again a new impeller kit because the pump rotted out completely and fell apart. Here is what the boat is doing now, at idle it is fine, once you put a load on it the boat over heats so obviously I have a restriction some where. Today I checked the pickup for blockage and took off the hose from the inside on the elbow from the transom and water comes in from that..... nothing, I also took off every hose and made sure nothing was clogged and flushed out the oil cooler, nothing!!! I Also took the thermostat out completely and ran it same problem. The only other thing that is what related would be the circulating pump, what are your thoughts???

Back4More

When you flushed the Oil Cooler did you back flush it? Meaning to the pump conection.

Donzi26ZX

Yes I did back flush it. Also when you take the hose off on the transom how much water should come in the boat, it comes in but with a steady flow? I just wanted to make sure that there wasn't a restriction. Any suggestions?

BY U BOY

Check The T-stat Housing You Could Have A Piece Blocking The Thermostat.

Donzi26ZX

I checked it and there is nothing blocking it, I even ran the boat with no thermostat and still had the same problem???? Anything else???? Would you think it would be the water pump on the motor?

BY U BOY

DO YOU HAVE WATER COMING FROM THE WEEP HOLE?

nordic95

You need to take this transome hose off and remove the plastic 90 elbow and check there.Over time the rubber hose collapses as the transom aluminum corrodes.I have see this many times,water will flow but the volume gets really restricted.


Nordic95

Donzi26ZX

Yes I do have water coming from the weep hole but I am not sure how much should be coming out??? So you are saying that it wouldn't be the water pump???

jeff32

Nordic95, you are right. We had almost the same problem this year on a 29 outlaw. The inside of the hose was like separated in many different layers, probably because the hose dried out. so under load, not only the multiple layer were obstructing the flow, but as you said the hose would tend to squeeze together. Changed that it helped a lot, but also changed ALL water temp sensors (tstat, sensor on block and dash gauge) it worked!

Donzi26ZX

Thanks, the season is over not worth hauling the boat to change the hose for only a few more weeks if that!!! I was hoping that it might be something where I wouldn't have to haul the boat, thanks for all the help everyone!!!