Overheating 7.4 bravo 3..
 

My boat has an overheating problem.

I just had a new impeller installed and exhaust flappers and manifolds and risers. At idle the temp if fine once moving it goes up around 175 and the beeping starts. I can slow down and will go back down to around 165. The manifolds on the other engine are cool to touch and the manifolds on this one are hot(not scolding hot but too hot for normal)

I have a perko flush unit and when I use it it leaks water around the hose fitting on the unit itself, down in the bilge. Could that same leak cause air to enter the system?

The manifolds would not be getting hot if it was not an raw water intake problem correct? The water goes directly to the manifolds all the time so the thermostat should not be the problem. Does the water route itself through the coolers then to the manifolds or is it a direct path to the manifolds?

I'm guessing either perko flush bad or allowing air into the system or bravo 3 hose crushed somewhere at the transom.


Let me know what you think?

The water goes to the cooler first, you should pull the hose of the cooler and and look inside for dirt, ect. Some coolers have a lot of little holes on the inside and some just have a big hole on the inside, Most of the time the little holes get cloged up.

Thanks for the reply boatek!!

Should I take the hose off of the thermostat housing that comes from the coolers and unhook the outlet hose at the pump housing and backflush it?

Do that to, But you want to try to SEE if it is cloged so you don't feel like you are wasting time and guessing if you got it all out or not.

If that flush unit is leaking then you need to fix that as well.

Well I found the problem. Impeller pieces stuck in the oil cooler.

I have a powersteering cooler and a fuel chiller set up nothing was stuck in those but the honeycomb design on the oil cooler trapped all of the pieces. Got all of them out and also changed the thermostat while I was working on it.

I ran it at 3000 rpms and it ran at 160-170 never got to 175 degrees. The engine manifold was way cooler on the port side. I stopped the engine and checked for a restriction there but it was good. Maybe thats normal.

I felt a few bubbles on the intake hose at the thermostat housing through the hose and the perko was still leaking small drips. Im guessing its sucking air bubbles through that leaky fitting. I've got one on order and will put it on next week.

Thanks for all the help guys.