1988 Force 125 Overheating

[Justinde]

Hi All,

I return seeking some wisdom.

Since I bought my boat, I have replaced the exhaust cover and gaskets, as the previous one was full of very old sand ( hardened like concrete).

The boat has a new water pump and impeller, timing is correct, and link and sync is done. I went out on the weekend, and after about 5 minutes at 1/2 throttle, I had the overheat buzzer.

The only modification I have made is the pisser, running the hose from the top of the thermostat per an earlier post. Water flow is ok from here, but VERY hot.

Prior to installing the pisser, I only had an overheating problem before I changed the water pump. Now I seem to get it.

Is is there any chance the pisser is affecting the pressure, and therefore cooling system? Should I be looking elsewhere?

Any feedback is welcomed.

Cheers from “Down Under”

 

[jerryjerry05]

The water pump should put out enough water and the pee tube shouldn't hurt the flow, so
the pee tube shouldn't make a difference.

The "hardened like concrete" makes me think the cooling passages might be clogged?
You remove the head?
Test the thermostat? might be bad?
Test the temp sending unit?

Post pic f the install of the pee tube.

 

[Justinde]

Thanks Jerry,

The previous owner spent big $$$$ on the power head. It has one piston plus 20though oversize. It has been bored and honed, and has new pistons/rings. I had the head off when I first bought it. They didn’t do the exhaust because they didn’t want to risk breaking the bolts. I did it and broke only one, which took a LOT of patience.

That said, the water pump is 12 months old, and the boat hasn’t run since last weekend, but I wouldn’t have thought that a water pump would perish in 12 months?

Inhavent check the thermostat....How do I check the sender?

cheers again....

 

[jerryjerry05]

You need a meter to read the resistance.
Hook leads to the sender and put in a pot of water on the stove.
Don't let it touch the bottom or sides.
You need a candy thermometer.
Turn the heat on.
It should make the meter rise as the temp increases, your looking
for movement as the water reaches the operating temp.
It's about 145-150d

I could be wrong on the temps but it's close.

I also use a heat gun to measure the temp of the engine.
Bought it real cheap on e-bay.
One of the best tools I have bought.

 

[Justinde]

Hi All,

I am removing the thermostat this weekend to check, and I’ll check the temp sensor, however, should I take it for a run without the thermostat in to “ clear it out”?

For the $50.00 or so, I’ll replace the water pump again.

feedback and thoughts always appreciated.

cheers

 

[jerryjerry05]

It doesn't "hurt" the motor if you run without a thermo.

The thermos purpose is to maintain the correct temp.
Motors run better when they are hot.
They get better fuel economy and performance when running at the right temp.

Cleaning it out won't hurt a thing.
If there is any crud built up? It might help clear it out.

 

[Sea Rider]

If the thermo and sender are found doing their homework right and you have previously removed near like concrete internal salt formations expect to have same in the entire powerhead water paths specially being such an oldie OB and much worse if previous owner used it constantly in salt water.

When having a highly internal salted powerhead the worse thing to do is not to remove the cylinder head, exhaust covers, thermo bolts to mechanically scrape off internal salt formations for the fear of breaking bolts, on older and newer OB's running in salt water that issue will happen, it's part of the internal water paths clean out preventive maintenance.

You could flush any OB with muffs, run them on a barrel filled with vinegar for as long as you want but if having excessive hardened salt layers, crusts formations such practice will only be lavishing love. LOL Report if sender and thermo were found in excellent operating shape.

If such parts are OK and the engine is working with correct timing and carb synch that powerhead calls for a tear up ASAP if wanting to work and cool as when out of the box..

Happy Boating

 

[Justinde]

Thanks Sea,

The power head was rebuilt, other than the exhaust....??? I don’t know why.

I have had the head off, and there is no crud in the water vanes.

Ill run her with no thermostat, and if it overheats with no thermostat, then there is a serious problem.

Ill post back.

if she runs well, I’ll do the tests as suggested.....