Cooling issues...in Havasu...need help.

[havasurat27]

Thanks in advance! Heres the deal......502 w/new IMCO powerflow manifolds, new impeller, completely troubleshot cooling system. Starboard side manifold is hot enough to burn the powder coat off. Big issue. I have checked everything that I can think of! Today I had another boat follow and check the water flow from the exhaust underway. The waterflow seems to go away and steam sets in after 45mph or 3000rpm. I am running a recirc. pump with the mercury style t stat housing that has... IN from the sea-pump ad OUT to the recirc. pump, and lower water inlets on the manifolds. Also has a hose each side that runs to the exhaust risers from the t stat housing. I have checked for restrictions everywhere from the inlet of the sea pump to the flapper on the outside of the boat. I have have many opinions from many mechanics and nothing fixes this neverending issue. Any thoughts would be great as I really do not want to take this heavy thing back to Cali.

[Trailer Park Casanova]

I had a similar problem once.
Re-routing the cooling hoses cured it.

[cola]

What about the thermostat. Is it new ??? if it is where did you put it. It doesn't in the manifold. It sets up in the housing. One of the Merc drawings is wrong. I don't remember what year, I know it was on the 502. Good luck. I will check back in the AM.
Mike
http://www.marinepartsexpress.com/Merc_Schematics/500%20GEN%20PLUS%20GM%20502%20V-8%201999/0L414639_0L601036/THERMOSTAT%20HOUSING.pdf
http://www.marinepartsexpress.com/Merc_Schematics/500%20GEN%20PLUS%20GM%20502%20V-8%201999/0L414639_0L601036/THERMOSTAT%20HOUSING.pdf

[clusclan]

Hey Chris you need to sell that and buy a new magic

[C-2]

Have you tried Fred at IMCO directly? If there is anything he knows, it's his exhaust and Hallett's. Maybe eliminate that possibility.
--
I once had a 6-pack dually with only 16K miles, a 454. Same thing, out of the blue and while towing , it heated up. Replaced everything, added a large custom radiator, two oil coolers, completely rebuilt eveything. Nobody could ever figure out why it did that.

[havasurat27]

Hey Chris you need to sell that and buy a new magic
Clu..thanks for the advice! Sounds expensive though. Call me if you have any ideas or if you have a few spare minutes on your hands Sunday. Good little cash job for you if you can sort it out? Check your pm for my number.
Chris

[havasurat27]

Hey Chris you need to sell that and buy a new magic
I guess you cannot recieve private messages yet being a newbie to this world..my number...909-208-7016. HELP!