Heat alarm after replacing Impeller

bkhealey

Seaman Apprentice
Joined
Aug 20, 2012
Messages
45
Hi, I have a 1992 Force 90HP. The impeller was trashed and pieces were missing so we replaced it. So when we run it, water does come out the two holes on the back of the motor but not a lot. After running it for a minute the over heat alarm goes off. I am thinking that there must be a piece of the impeller stuck some place. I have read on iboats of people doing a back flush of the cooling hoses. But that was for a different motor. Can someone tell me how to do this with a Force 90HP?

Thanks so much.

Brian
 

Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
Re: Heat alarm after replacing Impeller

Back flushing is mostly done through the thermostat well using a garden hose and an improvise method to hold it in place. If problem persists, you might want to double check the impeller again making sure it is properly installed especially with the key in place. With muffs most of cooling water from the engine will exit through the snout. If there is any debris caught in the system it will most likely be in the t-stat. Open and inspect the t-stat well first, then back flush and try again. If problem persists, re-check impeller.
 

bkhealey

Seaman Apprentice
Joined
Aug 20, 2012
Messages
45
Re: Heat alarm after replacing Impeller

Thanks! What did you mean when you said "double check the impeller again making sure it is properly installed especially with the key in place"? Not the best mechanic in the world. :) Also, I attached a picture of the Thermostat. There is a small round plastic bolt that is on top, Squirt water down that or take the Thermostat off?

Thanks again!!

BrianView attachment 210515
 

Jiggz

Captain
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Oct 23, 2009
Messages
3,817
Re: Heat alarm after replacing Impeller

Need to unscrew the t-stat cover (4 screws) and slowly remove the cover. Make sure you take note of the orientation of the t-stat for replacing later. Remove the t-stat unit and inspect for debris. If you push a garden hose in this well, you should see water run down the snout (engine not running or off). Be careful not to use too much water pressure for it could wet the entire engine and electrical ckts. Use some plastic bag to cover electrical parts. If water runs down the snout then there is no debris.

When replacing impeller and the procedure is incorrect, the woodrift key sometimes falls off or it could be the water tube is not properly aligned with the pump housing. However, if you see water generously coming out of the snout during engine runs, your problem is mostly blockage in the cooling system. And this blockage mostly happen at the t-stat.
 

bkhealey

Seaman Apprentice
Joined
Aug 20, 2012
Messages
45
Re: Heat alarm after replacing Impeller

There is a gasket there, Should I worry it will need to be replaced when I take it off? You can see it in the picture.

Thanks Jiggz!
 
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Jiggz

Captain
Joined
Oct 23, 2009
Messages
3,817
Re: Heat alarm after replacing Impeller

If you can remove the cover without breaking it you can reuse it. If it broke you can order a new one but you can reuse the old one temporarily using marine grade silicone sealant while waiting for the new one. You have to open and inspect the t-stat after an impeller get tattered into pieces. Just be careful to save the gasket for now. The gaskets are dirt cheap and available here at iBoats.
 

bkhealey

Seaman Apprentice
Joined
Aug 20, 2012
Messages
45
Re: Heat alarm after replacing Impeller

Ok thanks again, I will take it off later and let you know.

Brian
 
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