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sharp9700

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"Hi Folks,
I’M new to this

"Hi Folks,
I’M new to this forum and at the same time, I have a big problem. Last week I had a severe over heating problem whit my 1988 merc 5.7 whit Alpha-one 1e gen.. The temp. Gage run at top. I shut of the engine right away. i.l make some test after cooling down, and a found that the engine over heat at low RPM an ru OK when I run somthing like 10 mph and more. I don’t try WOT....I was thinkig tha was my water pump was burn. I remove my lower unit to fix the problem, and I found a lot of thing bizzare. First, The upper part of the water pump is completely melted. The small pastic tube that connect the water pump end the copper tubing was melted to, But my impeller is in great shape, like a brand new (all of my Alpha-one (Sierra brand) is brand new from last summer. Is not normal. Yesterday night, I had a flash tha the only thing that can make that, is the hot exhaust. This morning, I look in my upper unit to find something wrong. I found a half piece of water shutter. I unassemble the exaust in the engine compartiment and found that my two water shutter is burn.

My real problem is WHAT HAPPENS TO MAKE THAT???? Is it possible that it was only the t-stat that grip or something else?
For sure, is not the water inlet cloging because my impeller is in good shape and before, i’d never had that king of problem.
Please help me, my holliday began last Friday, and the boat is in the driveway......

Phil"
 
"Phil:

Your thermostat may

"Phil:

Your thermostat may have stuck closed, the water shutters melted from hot exhaust and engine water and so did the water pump top. Change all of them including the old impeller. Remove the water pocket where the plastic and copper tube insert and check it for heat damage. Is the belt tight on the circulating pump on the front of the engine? Check all your hoses for kinks or bends."
 
"Thank Guy for fas answer,
I

"Thank Guy for fas answer,
I don't know if you can tell me that the number under the t-stat, one is the temp, and the other one looklike to be the date of manufacturinG . Am i right? I have a brad new T-stat tha is a 160 deg., the old noe is an 140 deg., what do you think about that?? My old T-stat run very stiff compare to my new one, I thing is the problem.

Thank"
 
"Hi Guy,
If we look how the w

"Hi Guy,
If we look how the water flow in the system, it's logic tha it was the t-stat that stuck close. I put a brand new one yesterday, a brand new complete water pump, and I wait my water shutter this morning from the Merc dealer. I will install it and try it on the ear muff and let you know. Do you think I have something else to do????

Thank
Phil

P.S. Sorry for my english, I'am a frecnh Canadian..."
 
You speak the enlish languaqe

You speak the enlish languaqe better than many people I know; they butcher it!

Did you take care of the melted plastic part in the OD? Was the shutter bad?
 
"Thank you Guy,
The shutter w

"Thank you Guy,
The shutter was all burn, I put a pair of brand new one. I clean the OD and exhaust pipe of all melted plastic. I start the engine on the muff and all looklike to be OK. Just one question, I have a small hole(+ - 1/4") at the back of the right side of the lower unit. when I open the water, it saw a jet of water going out by this hole. Is it normal, I don't remember if I've already seen that????

Thanks"
 
"Now It's the time to find

"Now It's the time to find a truck to put it on the water,because I'd blown a piston and a connecting rod on my Durango 5.7 Hemi when I pull out the boat off the water last week. Very bad begening of my hollyday...
not to bad, My boat is fix, and the truck is under warranty. I just don't have it.....

Thank you very much for the help

Phil"
 
"Hi Guy,
Sorry for no news si

"Hi Guy,
Sorry for no news since last post, but i'm very busy. I'd drop the boat in the water the 2e of august for test run. It run great at every speed. I'd make a ride a week later with 7 peoples in it for 3 hours and the temp gage stay around the middle. a little bit over at low speed and a little under at high speed. i think all is runnning normal and ok.

Thank for all your help.

Phil"
 
Phil:

Good to hear from you

Phil:

Good to hear from you. The rise in engine temperature at slow speed suggests that the 160 deg. thermostat you installed is to high. You removed a 140 degree thermostat and should put the same one back. Make that part of your engine service before next season. Happy boating.
 
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