Overheating at idle...

[Grand Larsony]

Just want to be sure I'm moving ahead wiht the right troubleshooting sequence.

1989 Sea Ray Sundancer 300 with twin Mercruiser 260 hp Alpha 1s. 750 or so hours, generally excellent condition, and marine mechanic maintained.

Port motor is overheating at idle but comes down to temp with a little throttle. I'm now in the water and trying to avoid a haul-out unless necessary.

Impellers were done 24 months ago by the PO (about 70 hours running time) but I don't know if housings were done as well. I had the exact same issue on the stbd motor last year and it was impeller chunks in the thermostat housing. I see no kinks in coolant hoses or anything else obvious on the port motor.

1. Check thermostat housing for debris, old impeller parts, or whatever else could be impeding water flow.

2. Verify the anti-siphon "ball thingies" are functioning properly.

3. Replace thermostat and gasket.

4. Pull boat and replace impeller and housing if necessary.

Anything else? Is this the right sequence?

Best regards -- I love this forum !!!

-D

 

[Limited-Time]

Re: Overheating at idle...

Has the classic sound of an impeller issue. Look like #4.

 

[Grand Larsony]

Re: Overheating at idle...

My thoughts exactly... weak impeller.

But, since I had same issue on other motor last year, I'm going to check the thermostat housing before hauling it out.

Will report back to close the thread once I get it resolved.

Thanks,

 

[Brentathon]

Re: Overheating at idle...

I had low idle overheating on my '91 Alpha, and it was the T-stat housing was so corroded that the white balls weren't sealing properly.
I got a new housing and it was fine.
They're to provide some restriction/back pressure, so cold water from drive doesn't simply go right out through elbows (without being circulated through block).

 

[Grand Larsony]

Re: Overheating at idle...

Update in case anyone cares... Pulled the T-stat cover and hoses on the housing looking for debris or impeller parts and to check the ball thingies... no luck.

Gonna get it hauled and replace impeller \ housing. Damn.

 

[Bondo]

Re: Overheating at idle...

Update in case anyone cares... Pulled the T-stat cover and hoses on the housing looking for debris or impeller parts and to check the ball thingies... no luck.

Gonna get it hauled and replace impeller \ housing. Damn.

Ayuh,... Has that motor got a P/Steerin' cooler on it,...

That'll catch the junk 1st....

I'm thinkin' it's gonna be 1, Through 4, anyways,....

 

[Grand Larsony]

Re: Overheating at idle...

Just to close out the thread...

Not the PS motor -- but did get it fixed.

Cost me a haul-out, impeller kit, housing, seals & gaskets for upper. All better (except my checkbook). Cost of doing business I guess.