Force 120, pumps water but overheat buzzer is going off

[HMC49]

Anybody else have this issue. I can lots of water pumping but the alarm went off. I shut down the motor and started it again and the buzzer stopped. A little while later, the buzzer went off again. Is it possible to overheat if you're pumping water.

 

[81 charger]

Re: Force 120, pumps water but overheat buzzer is going off

maybe your thermo switch is bad. if so could be sending a faulty signal. do it go to slow mode?

 

[HMC49]

Re: Force 120, pumps water but overheat buzzer is going off

Is there a way to test the thermo switch. Plus can the motor overheat if if is pumping water?

 

[Frank Acampora]

Re: Force 120, pumps water but overheat buzzer is going off

Yes, it can overheat and be pumping plenty of water. Remove the back cover at the top of the head and check the thermostat. It may be stuck closed, partially open, or broken.

I just went through this on a Chrysler 105--the one in the avatar. It would overheat at idle but cool down at full throttle. The thermostat was broken on top where the bar from the expanding pellet pushes. Since the *&^%$ cover would not come off, I had to replace the head. Since the only head I had was off a 140 with a 3.375 bore, compression dropped from 135 to 120. Now my project will be to drill out the bolts and re-tap the holes so I can re-use the smaller combusion chamber head.

 

[HMC49]

Re: Force 120, pumps water but overheat buzzer is going off

Frank, thanks for the advice. Just found there is no thermostat in the engine. Could that be the problem, water flowing through too fast maybe

 

[Frank Acampora]

Re: Force 120, pumps water but overheat buzzer is going off

NO! I would strongly suspect that the previous owner removed the thermostat because of a heat problem. Now it is yours to diagnose.

Before you start though, run the engine until the overheat alarm sounds and then a little more. Dribble some cool water on top of the block. If it rapidly boils off the engine is overheating. If it gradually evapoates, then the buzzer is bad and the engine is running at its correct temperature. Can you smell hot paint when the buzzer is sounding?

If the engine is really running hot: Remove the lower unit and try to blow water up the brass tube. If it is free and water flows freely out the thermostat hole then you need to remove the exhaust cover and check for sand or corrosion build-up inside the exhaust jacket. While you are at it you may as well remove the head and check the cylinder water jackets too. Check the cooling jacket inside the head for build-up.

Before starting be aware that you most likely will snap a couple of bolts unless you are very lucky.

 

[HMC49]

Re: Force 120, pumps water but overheat buzzer is going off

Hey Frank

Ran the motor on a set of muffs for 15 minutes and the alarm did not go off. I sprinkled cold water over the top of the block anyway and it did not boil off or look even remotely affected. I touched the block and id did not feel to warm. Yesterday it went off in about in about 5-10 minutes of use on the river. I have a thermostat ordered, but am not sure of the right way to put it in as there isn't one in there to tell the correct way. All of the pictures in my manual show different direction. Thanks again for the help, you really are the Force guru.

 

[emoney]

Re: Force 120, pumps water but overheat buzzer is going off

As a side note, Harbor Freight sells a digital, infrared thermometer for $20.00 ish and it's handy to have to verify thins like this. You just point and shoot....instant temp. Saves from an overherat possibly. Good luck.

 

[Frank Acampora]

Re: Force 120, pumps water but overheat buzzer is going off

Sounds like the thermoswitch on the head is too sensitive. As faras the thermostat, USUALLY, corect installtion is with the pellet toward the hot side, the block However, on olde Chrysler engines there was not enough room and it went in opposite. If you have enough room install it with pellet toward hot side, if not, put it in the other way. In either case, there will be a bleed hole either in the thermomeer flange or a small notch cut in the hole where the center seats. Install with this bleed hole up so hot water will tend to wash over the pellet.

 

[HMC49]

Re: Force 120, pumps water but overheat buzzer is going off

Do you have to take the head off to replace the thermo switch? I took off the lower end and poured water down the opening for the thermostat. The water flowed freely through with no sign of debris. I guess this is good.

 

[Frank Acampora]

Re: Force 120, pumps water but overheat buzzer is going off

No, you do not need to remove the head. There are two types of switches: One on early Force engines screws into the head next to the sparkplug. Later Force engines used a switch that plugged into a hole (well) in the head. It is held in with a rubber plug and circlip.

 

[Jiggz]

Re: Force 120, pumps water but overheat buzzer is going off

Just a thought on the temp sensor, it's almost standard method to test t-stats using hot water (with controlled heat) and a portable thermometer. I wonder why you cannot do the same with a temp sensor. I'm quite sure the temp setting is higher than a standard 130 or even 140 t-stat. I believe most temp sensors are set to go off at 160F or maybe even 180F.

 

[Frank Acampora]

Re: Force 120, pumps water but overheat buzzer is going off

If you don't mind dipping your VOM or continuity meter leads in hot water then yes, the sender can be checked. Clip one lead to the orange wire terminal and the other to the body of the sender. Set to minimum ohms reading. Dunk in cold water with a thermometer and heat it. If it shows continuity at 180 or less, it is too sensitive.

 

[Jiggz]

Re: Force 120, pumps water but overheat buzzer is going off

If you don't mind dipping your VOM or continuity meter leads in hot water then yes, the sender can be checked. Clip one lead to the orange wire terminal and the other to the body of the sender. Set to minimum ohms reading. Dunk in cold water with a thermometer and heat it. If it shows continuity at 180 or less, it is too sensitive.

Or you can use extension wires with alligator clips . . .

 

[HMC49]

Re: Force 120, pumps water but overheat buzzer is going off

You've guys helped a lot. Really makes this forum great.

 

[ahickman]

Re: Force 120, pumps water but overheat buzzer is going off

Did you ever resolve/identify your overheating issue?

 

[cmclane28]

Re: Force 120, pumps water but overheat buzzer is going off

I just went through this on my 1994 Force 90. The overheat buzzer would go off after only a few minutes of running it in the water under load. Not sure exactly which of these two fixed it, but I replaced the head gasket and the thermoswitch. Very easy to do and pretty inexpensive. No more overheat problem.

 

[HMC49]

Re: Force 120, pumps water but overheat buzzer is going off

I out in a new thermostat but not have been out on the river as of late, been really busy at work. I poured drops of water on the block when the alarm went off like Frank suggested and it did not boil off. It was warm to the touch bu not overly hot. If it goes off again next time on the water, I'm gonna replace the thermoswitch.