How hot is to hot

[Audiofn]

I have been running my boat for the summer and the temps have been at about 150 degrees all summer. Last evening I ran up for dinner with some friends and the boat was running at about 180-190. The water temp this week was warm (about 78-80 degrees). Is it the warm water temps causing the problem or do I maybe have another issue to look into. These are 420hp 454's and they both are kind of doing the same thing. The temp held steady no matter what speed I ran.

Jon

[DAREDEVIL]

I have been running my boat for the summer and the temps have been at about 150 degrees all summer. Last evening I ran up for dinner with some friends and the boat was running at about 180-190. The water temp this week was warm (about 78-80 degrees). Is it the warm water temps causing the problem or do I maybe have another issue to look into. These are 420hp 454's and they both are kind of doing the same thing. The temp held steady no matter what speed I ran.

Jon

Its a little hot,,but i think u still be fine. Whats your water press ???? should be around 15-20 PSI @ WOT !!!!
Maybe go ahead and xhange impellers and back flush the system to free it up ?!

[Steve Miklos]

I have been running my boat for the summer and the temps have been at about 150 degrees all summer. Last evening I ran up for dinner with some friends and the boat was running at about 180-190. The water temp this week was warm (about 78-80 degrees). Is it the warm water temps causing the problem or do I maybe have another issue to look into. These are 420hp 454's and they both are kind of doing the same thing. The temp held steady no matter what speed I ran.

Jon

If your are raw water cooled that is too hot. On a closed cooling system that is fine and can make good power.
Steve

[Audiofn]

Thanks guys. I did not have time to go down on Sunday to look at it. I am going ot see if maybe a sucked up some weeds into the water pickups and either clogged up my intakes or my strainers. Hopefully it is that simple.

[offthefront]

Something is up though ..... warm for carb motors ....strange both doing the same thing .....pull the incoming line from the oil cooler and back flush the system up to the raw water pump ....

[Geronimo36]

Do you have the gil exhaust system or the merc system on your 420's?

I'm with offthe front, something is up. You're most likely running a 140 t-stat so the highest I like to see is 150 deg. 180-190 is high for a 140 t-stat and could be a number of things including t-stat, rotted/restricted t-stat housing, grass, resticted flow, raw water pumps, blockage in exhaust etc...

[Audiofn]

I am running the Gill manifolds.

[Geronimo36]

ok, the gils usually gon't clog up from rot...

since both of them are doing it, have you recenlty opened your sea strainers? If you have the older perko syle strainers the cork might be dry and sucking air while you're underway.

Just throwing that out there!

[Audiofn]

Turns out it was an ellectrical issue. I drove the boat down to the resaurant durring the day and everything was fine. Service was slow so the motors had cooled off. When I went home I had the running lights and dash lights on. If I turn off the dash lights everything is fine. So with the dash lights off I am running 160 on one motor and 165 or so on the other. Maybe a tinny bit warm but about what it has been all year.

[Ratickle]

Turns out it was an ellectrical issue. I drove the boat down to the resaurant durring the day and everything was fine. Service was slow so the motors had cooled off. When I went home I had the running lights and dash lights on. If I turn off the dash lights everything is fine. So with the dash lights off I am running 160 on one motor and 165 or so on the other. Maybe a tinny bit warm but about what it has been all year.

Now that's a new one. Does that mean they share a common ground? Or something else?

[Audiofn]

I do not know yet. Once I saw what the problem was the solution was obvious, don't turn on the dash lights! The anchor light is enough to see the panel. I will take a look later. My guess is that there is a guage that is faulty or a bad ground.

[.38Special]

My boat does the same exact thing. 502 MAG MPI's. If I turn the cockpit lights on, both pressure guages immediately go from 40 to 60 and the temp goes from 150 to 180. This happens like clockwork everytime, since the day I got it.