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8.1 horizons running hot... any input please

A

avian22

New member
Engine was overheating when I got it.

After inspection I found badly corroded manifolds and check valves. replaced them all.

Also acid washed heat exchanger and the reservoir that the heat exchanger sits on because they were clogged.

New thermostat.

Verified that all coolant flow through the Eng. Is solid .

Not overheating anymore. However, it is running hot. Will go as high as 198. 192 at idle.

Any suggestions?
 
Thermostat Temp? I'd also change out the Temp. Sender. They are known to register a wide range of readings. As stated, you need to confirm there is actually a problem before looking for one. IR gun is a good start. Al W.
 
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@wmlaks - Vdrive, however raw water pump is new w/new impeller

@makomark - Risers are new /

@Wickeral - hit it with the temp gun several times. especially right at the sensor and thermostat and the reading pretty close (within a couple of degrees). will def. replace anyway. just to eliminate any chance.


This thing is taking me for a ride man. At this point, I am thinking that there is air getting into the cooling system some where. Maybe the rubber grommets that seal the heat exchanger into the reservoir it mounts on. I don't know! Maybe the there is a restriction inside the block. I am just praying someone can suggest something that I overlooked. At a wall right now!
 
avian22 said:
@wmlaks - Vdrive, however raw water pump is new w/new impeller

@makomark - Risers are new /

@Wickeral - hit it with the temp gun several times. especially right at the sensor and thermostat and the reading pretty close (within a couple of degrees). will def. replace anyway. just to eliminate any chance.


This thing is taking me for a ride man. At this point, I am thinking that there is air getting into the cooling system some where. Maybe the rubber grommets that seal the heat exchanger into the reservoir it mounts on. I don't know! Maybe the there is a restriction inside the block. I am just praying someone can suggest something that I overlooked. At a wall right now!
Click to expand...

Ayuh,.... Have ya Verified that water is flowin' Into the heat exchanger, 'n Out through the risers,..??
 
I am thinking that there is air getting into the cooling system some where.
Click to expand...
Install a 2' length of clear water hose between the water inlet hose and the heat exchanger. If you don't see air bubbles reinstall it between the heat exchanger and the water outlet hose going to the exhaust mans.
 
@Bondo - Getting good water flow through risers

@guyig - Good idea! Will give that a try

Question :

while I was checking good water entry through the seacock and raw water strainer, I noticed that the raw water strainer is installed above the water line. Therefore, when you open the lid on the strainer no water comes in by itself. The raw water pump is actually priming itself when the enging turns on. It looks like the water pump is going to take a 15 second gulp of air before it actually primes. Plus, while the engine is running the water that is coming out of the side boat seems to be a surging type of flow and not a solid continuous flow.

I haven't given it allot of thought because the strainer on the other engine is the exact same way and it doesn't heat up.


Question is :

Are the strainers ok up above the water line like that?

And


Is it normal for the water to surge like that with 8.1's?
 
Old rule of thumb, if one overheats an engine, replace the thermostat. Theycan have a tendancy to get "erratic" if stressed too badly, sometimes sticking closed or hanging open.

Also, when opening the strainer, close the sea cock 1st. When done in the strainer, refill the strainer with water, with a bucket or something, then replace the cover, then open the seacock. That way water in strainer will be full when pump starts sucking water, eliminating any loss of suction by a big slug of air. If water disappears from the strainer when you open the seacock, then there is an air leak into the suction side somewhere, which can kill the pump suction and output of the pump.
 
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