Strange issue with cooling.

agallant80

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Oct 25, 2010
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On the way up to Wilmington I ran hard aground on a sand bar. Like an idiot I put her in reverse and gunned it off the bar sucking up sand. The boat started to over heat so I shut her down. The sand was pretty big and a bunch of it was clogging the water intakes on the outdrive. I cleared the sand that was blocking the intake turned her back on and revved the engen. The temp came right down.

Im thinking I got lucky, I did not destroy the raw water impeller and everything is all good. Not so fast, no my temp gauge is reading at 100. I pulled over several times and checked the motor, the motor and manifolds were cool to the touch, thought the oil filter was hot. I made it up the river to the docks at Wilmington. I pulled one of the drain plugs (the one on the top of the block) cranked her over and water shot about 6 feet in to the air, so I am sure the raw water pump is working. My theory for the temp gauge being at 100 is that there is a rock of some sand keeping the thermostat open. Any thoughts would be appreciated.
 

HT32BSX115

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Re: Strange issue with cooling.

On the way up to Wilmington I ran hard aground on a sand bar. Like an idiot I put her in reverse and gunned it off the bar sucking up sand. The boat started to over heat so I shut her down. The sand was pretty big and a bunch of it was clogging the water intakes on the outdrive. I cleared the sand that was blocking the intake turned her back on and revved the engen. The temp came right down.

Im thinking I got lucky, I did not destroy the raw water impeller and everything is all good. Not so fast, no my temp gauge is reading at 100. I pulled over several times and checked the motor, the motor and manifolds were cool to the touch, thought the oil filter was hot. I made it up the river to the docks at Wilmington. I pulled one of the drain plugs (the one on the top of the block) cranked her over and water shot about 6 feet in to the air, so I am sure the raw water pump is working. My theory for the temp gauge being at 100 is that there is a rock of some sand keeping the thermostat open. Any thoughts would be appreciated.

Yeah......you ingested a fair amount of sand. It will go anyplace the water goes for the most part.

Use your imagination.
 

agallant80

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Cooling System questions

Cooling System questions

Hello,

After sucking in some sand and sea shells this weekend my boat is not cooling properly (running too cool). I think I have some junk holding the thermostat open. I want to take apart the cooling system and inspect the thermostat, temp sensor and impeller for the raw water pump. My questions are:

1. Does anyone have a diagram where the thermostat is?
2. What size bolts does the raw water pump take?
3. Where is the temp sensor located?
 

QC

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Mar 22, 2005
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22,783
Re: Cooling System questions

Re: Cooling System questions

Closed (fresh water) or open (raw water) system?
 

QC

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Re: Cooling System questions

Re: Cooling System questions

Here's this:

attachment.php


If I recall the seawater pump bolts are 9/16 head. That seems pretty simple to solve. Have you searched the Adults Only section for this stuff?
 

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tpenfield

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Re: Cooling System questions

Re: Cooling System questions

For the future, you may want to install a sea water strainer before the sea water pump. That way, you will avoid sucking things into the cooling system and you will add life to the impeller.

They have them here in iBoats . . .
 

agallant80

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Re: Cooling System questions

Re: Cooling System questions

Thanks, I thought the thermostat was in part H. I will take it off. As for the temp sensor where is that located? I don't see it in the diagram.
 

QC

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Re: Cooling System questions

Re: Cooling System questions

Should be right there too (H). Only thing with a wire to it :)
 

Bondo

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Re: Strange issue with cooling.

On the way up to Wilmington I ran hard aground on a sand bar. Like an idiot I put her in reverse and gunned it off the bar sucking up sand. The boat started to over heat so I shut her down. The sand was pretty big and a bunch of it was clogging the water intakes on the outdrive. I cleared the sand that was blocking the intake turned her back on and revved the engen. The temp came right down.

Im thinking I got lucky, I did not destroy the raw water impeller and everything is all good. Not so fast, no my temp gauge is reading at 100. I pulled over several times and checked the motor, the motor and manifolds were cool to the touch, thought the oil filter was hot. I made it up the river to the docks at Wilmington. I pulled one of the drain plugs (the one on the top of the block) cranked her over and water shot about 6 feet in to the air, so I am sure the raw water pump is working. My theory for the temp gauge being at 100 is that there is a rock of some sand keeping the thermostat open. Any thoughts would be appreciated.

Ayuh,.... Due to gravity, I'd pull the block's drain plugs, 'n run it, observin' the water leavin' the drains,...
It's the lowest point, 'n Always loads up with rust, sand, 'n crud,...

If the temp don't start workin' Right, pullin' the T-stat will answer whether is jambed up,...

Whether ya swap out the impeller is up to You,...

I would just to dig the sand outa all the crevices in the lower unit's hidden areas, like 'round the impeller pump,...
 

Bondo

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Re: Strange issue with cooling.

Ayuh,.... Let's not start 2 threads in 2 forums 'bout the Same subject, Ok,..??

It makes for a Strange read when fixed,.....
 

agallant80

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Oct 25, 2010
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Re: Strange issue with cooling.

Does this have a normal thermostat like in a car? I took off the cap on Part H and there was a ball on a stick with a spring in there. Is that some sort of new style thermostat or is the thermostat between part H and the block?
 

QC

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Re: Strange issue with cooling.

Normal Thermostat. Under H. Go to the Adults Only section, Mercruiser Information, Service manuals, #31, section 6.
 

agallant80

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Oct 25, 2010
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Re: Strange issue with cooling.

Ok I give up. I looked at service manual 31. I can't figure out what the part number is for the thermostat housing (part H) gasket. Anyone know? I tried going to the auto parts store but it looks like GM chaned the gasket on the cars.
 

Bondo

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Re: Strange issue with cooling.

Ok I give up. I looked at service manual 31. I can't figure out what the part number is for the thermostat housing (part H) gasket. Anyone know? I tried going to the auto parts store but it looks like GM chaned the gasket on the cars.

Ayuh,.... Click here, 'n pick the 1 ya need,...
 
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