Overheat anytime I hit 4800 rpm or above

[Buda13]

I have a '97 P150TLRV with an interesting problem. I can run all day below 4800 RPM with no issues however once I hit anything above that mark I cant make it a mile without the overheat alarm going off. The thing is I can pull the cowling imedietly and the heads are just warm to the touch, not HOT. The motor has been to 2 different certified mechanics that cant seem to pin it down. They have been through everything including pulling the heads, compression check, water pump and impeller, de carb, you name it! So they replaced the overheat sensors and fuel line and the problem went away for 6 months and has just started surfacing again. I was told by a mechanic that '97 was the first year Skeeter and Yamaha were partners and that there were some after market wiring harnesses that caused this problem to occur in this year model. I dont know if he just gave up or what, but I have yet to find anyone that can do anything for me except offer to rebuild the powerhead. That seems to be everyones response when they cant determine what the problem is, all of them have said something like " Well, all thats left is to rebuild it and see if that fixes it." Thats a pricey "guess" at the problem!! PLEASE HELP!!

[Buda13]

I forgot to mention that this motor has only been used in freshwater.

[Mike E]

Do you have a water pressure gauge?

[Buda13]

Yes, water pressure is good.

[jb123]

changeout waterpump AND housing, replace thermostats, and replace prv parts and let us know how you make out. if it was used in fresh then there should be no water jacket corrosion. do you know the history of the motor, as in prior usege? could also be light blockage in the water tube impeding flow. what is your trim level when this occurs, try it fully down and also you can try to drop the motor one hole to see if this helps.

[Dennisg]

HI Buda, this sounds to me like you have a blockage in the water pump/water inlet tube, somewhere in the water pump area. I say this because you say that 6 months ago you changed the watr pump impeller, Etc. and the puroblem disappeared now it has resurfaced. I am betting that a piece of your impeller is broken off, and is not causing a problem untill RPM gets high enough to suck the broken piece into a position that it interfeares with the water flow. This senario has happened to me. Drop the lower unit, and replace the water pump, completely, not just part of it, as your mechanic probably did, they like to chance out only parts that look bad, when for a few more dollars you can change the entire pump assembly. Do it yourself, it is easy, and you can buy the pump kit at this website(best price that I have found)Only when you do it your self, do you know it was done correctly and complitely,and for a lot less money
have fun, Dennis

[slim]

has anyone pulled the outer covers on the heads off? run into instances that sounds just like this many times and it was corrrosion inthe heads not allowing the water to cool the metal. you would be suprised how much a little bit of corrosion could cause this problem.