Who doesn't like an overheating thread!

[thejeep007]

I'll keep this short, 89 mercruiser 3.0 overheats after high rpm, clear tube attached no air can be seen entering system. Water pump is new, base looks a little chewed up. Hose from lower to transom replaced last year. Riser is new. When it manifold is warm front top cold bottom rear , Riser is cold, thermostat housing is cold, hose is warm to hot. Starting to think it could be temp sensor but the large hose and felt gurgling and could see air bubbling in clear hose like the water in the block is boiling. My automotive background me the circulator pump, look rough but should be enough to water. Disconnected the large hose on the lake tons of water out of thermostat housing and nothing from circ pump. I stumped! Thanks everyone!

 

[Bondo]

Ayuh,.... I'd spend money on the raw water pump base 1st,.....
It needs to be in Perfect condition,....

Disconnected the large hose on the lake tons of water out of thermostat housing and nothing from circ pump.

Water flows through that hose, To the circulatin' pump, not from it,....

 

[thejeep007]

Could it be a blocked manifold? What has me confused is the riser is really cool when my temp is reading hot. Watching the burping in the clear hose when the engine was turned off that be from the water in the block boiling? If I bump the idle up after gets warm the temp drops right back down. Also the top front of the manifold hotter then the rest of it, is that from a blockage? Every season I am chasing something!

 

[flipbro]

That base and pump are SHOT. Replace them and I bet the problem goes away.

 

[thejeep007]

Going to try and buy one now thanks. What on the pump is showing it's bad? Just for my education

 

[flipbro]

The impeller looks very rusted and for sure don't circulate the water as it should. The base is melted showing its got very hot at one time.

 

[thejeep007]

That is the circulator pump with rusted fins

 

[thejeep007]

No Title

Alright just got the wrong pump base, pulled the riser what do you guys think?

 

[thejeep007]

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[Bondo]

Ayuh,... The riser looks fine on that end, what about the water dump holes on the other end,..??

 

[thejeep007]

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[Bondo]

Ayuh,..... Nothin' wrong with that,....

 

[thejeep007]

By that picture think I should pull the manifold?

 

[Bondo]

Not from what I can see,...

 

[thejeep007]

I can't figure how the block is getting hot and not the riser and manifold!! Brand new t Stat and the old one tested good. Flapper intact! Going to get the correct pump base now hope it's what's causing this. Thanks everyone for your input. I like I have a circ pump from. You old engine might as well swap em out

 

[flipbro]

Yes that is a circulating pump but that piece thats rusted up is also called an impeller..and yes the rubber one in the leg is also an impeller.and with the combined two will cause an over heat. Do you have an IR gun

 

[thejeep007]

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[achris]

Go up into the sticks and hunt out my videos. I have one on servicing Alpha One raw water pumps (in the drive). Look at that video and you'll see why the pump base in your drive is shot. Other than that, the circ pump was shot, the exhaust elbow is fine (is an 'elbow', not a 'riser')...

Chris..

 

[thejeep007]

No dice still overheats, can feel air when my hand on big .. Hose....

 

[thejeep007]

One thing though, the brass hose that goes into the water pump pump pulled out with the pump. Is that normal?