Mercruiser 5.0 250hp Engine overheating above 3000 rpm, please help....-gctid383674

[Guest]

Hi,

my port side engine is overheating when it gos above 3000 rmp, I have changed the manilfolds/risers, termostat, water pump impeler and housing, also I checked the water flow coming from the outdrive and the water flow is fine I am getting a lot of water coming in, but it still overheating, could anyone give me any idea what else could I check on it to repair the problem.

Thanks

Welberson

2000 Bayliner ciera 3055

[Chief_Alen]

Heat exchanger.

[TerryW]

wnunes wrote:
Hi,

my port side engine is overheating when it gos above 3000 rmp, I have changed the manilfolds/risers, termostat, water pump impeler and housing, also I checked the water flow coming from the outdrive and the water flow is fine I am getting a lot of water coming in, but it still overheating, could anyone give me any idea what else could I check on it to repair the problem.

Thanks

Welberson

2000 Bayliner ciera 3055

Did you do anything that may have provoked the issu e.g. just had the outdrive serviced?

Is this a raw-water cooled engine?

Here are some additional things to try. . . . .in the order I'd do it based on cost and effort:

1) the engine temperature should be read with an IR gun (held about 2" from the engine) in the thermostat area. Make a heat map on a scrap of paper and see where it is hotest. This can give valuable clues such as whether the engine is really over-temperature (my 5.0 runs at about 160 degrees F or 80 C measured at the temperature sender on the brass body). You can watch the thermostat opening and closing using the gun.

2) Gauges can be dodgy as can their connectors. Does the overheat temperature warning buzzer come on? If not it may be the temperature gauge sender being over-zealous.

3) The flappers in the exhaust can get stuck closed; Take off the large rubber connectors on the risers and visually inspect the flappers and make sure they "flap" reliably in the right direction.

4) The hose from the circulation pump to the thermostat housing has a metal spring inside it to stop it collapsing. Is this ok?

5) The engine water circulation pump (not the impeller in the outdrive) can go wrong in strange ways. The internal impeller can slip on the shaft under load.

6) Look at engine tune if the engine tune is way out (timing and carburation). I have never known this affect temperature without performance being hopeless;

Hope this helps. . . .

Terry

[Guest]

Might also be worth checking the in-line oil cooler as well

[Guest]

Ohana5 wrote:
Might also be worth checking the in-line oil cooler as well

And heat exchanger (if equipped)