98' 120 Force "tone"

[mberns]

finally got my boat ready, new gelcoat, new carpet...now the outboard is giving me a hard time..

Once we got it started, idled well for about 10 minutes (back yard on the water hose) then we got the over heat tone.... Talked to my local guy, he thought we weren't getting enough water through the ear muffs to the motor....took it to the lake. While idling to wait on the trailer to be parked.. Got another tone. Turned it off, fished the cove. Tone cleared, we took off. Ran fine. Got back to the cove to trailer boat. While idling waiting on trailer we get the tone again.

Called my local guy back. He said check the idle RPMs. Was idling low around 600, bumped it up to 800, sounds better anyway. Ran it in the back yard on the muffs again (without the cowl) and we didn't get a tone. Took it back out yesterday and we're getting the same problem. Off the trailer, idling waiting on the other passenger, over heat tone... Repeated the loop around the cove with the troll motor, Cooled off tone went away. Took off, ran fine at full throttle. On the way back, it stalled in the middle of the lake, went to restart and we got the over heat tone again...

While trailing my boat, another guy was having a problem with his force..lol.. He said he used to have problems with over heating as well. Said he put vents in the cowl and it took care of the problem... Does this make sense? Does anyone know if the sensor is actually on the block? Could the temperature inside the cowl have anything to do with it over heating?

I just want to go fishing!!! Any ideas would be great.

thanks,
Mark

 

[pnwboat]

Re: 98' 120 Force "tone"

Sounds like maybe a simple mater of changing your water pump impeller?

 

[roscoe]

Re: 98' 120 Force "tone"

heat sensor is oN the head between the sparkplugs.

Common for a failing water pump impeller to give low water flow at low rpm.

When was the last time the impeller was changed?

I think its time.

 

[moparman]

Re: 98' 120 Force "tone"

Ditto to the above post

 

[mberns]

Re: 98' 120 Force "tone"

has a new water pump....wouldn't they have changed the impeller at the same time? I'm gonna give em a call.

thanks guys..

I have to take off the lower unit to get at the impeller don't I?

 

[pnwboat]

Re: 98' 120 Force "tone"

Yes, you have to take the lower unit off to change the impeller. If they changed the water pump, I would expect them to have changed the impeller too. Have you ever started or ran the motor out of the water for a short period without muffs?

 

[mberns]

Re: 98' 120 Force "tone"

no I haven't.

We ran it with the muffs again tonight. It starts up great now that we tweaked a few other things. Hardly pulls any water at all. Once we throttle it up it starts spitting some, but not much at all. On the water at full throttle pulls alot of water.....

Question, after letting it idle in the back yard for a bit. We cut it off and there is smoke coming from the exhaust holes...

 

[pnwboat]

Re: 98' 120 Force "tone"

It's kind of hard sometimes to get good water flow on muffs with a garden hose. Real test is out on the water.

It's normal for a smoke to come out of the exhaust holes after you shutdown the motor.

 

[mberns]

Re: 98' 120 Force "tone"

ok so the impeller is brand new. Took off the lower unit and everything is good. Any more ideas?

 

[pnwboat]

Re: 98' 120 Force "tone"

Since you have the lower unit off, take the thermostat out and back-flush through the thermostat opening with the garden hose. Use some rags to get a good seal around the end of the hose in the opening in the head where the thermostat was located. Water should flow good and strong out of the water tube that connects between the lower end and block.

You can check the thermostat itself by heating up some water in a pan. Observe the thermostat closely. It should start opening at around 130 - 140 degrees. As temperature increases, it should open all the way.

You could also just try and run it without the thermostat as a temporary test to see what kind of water flow you get. NOTE: I would advise against running it without a thermostat as a permanent solution. The motor needs to get to proper operating temperature to achieve full power and efficiency.

 

[maverick974]

Re: 98' 120 Force "tone"

One other thing you might check? If the old water pump broke off any of the wings off the impeller, pieces of those may be clogging the water jackets just enough to slow the flow of water. It happened to me. As mentioned above, I use a hose at full pressure to force out the rubber pieces. Backflow with the lower unit off. Mine spit out some pretty large pieces of rubber from the old impeller.
It's a longshot but it's worth a try if nothing else works.

 

[mberns]

Re: 98' 120 Force "tone"

We replaced the thermostat. Still overheated. We ended up making 3 different size restricters instead of using the thermostat. At high RPMs, revving the engine on the hose it didn't overheat. While the lower unit was off we did push massive amounts of water through the thermostat area down the midsection and nothing but good water flow came out...

Took it to the lake yesterday, overheated again idling in the cove..... Fished for a bit, cooled off, started it up and took off, pulled good water, no problems, went down the lake a ways, stopped fished for awhile, started it up took off again. Fished more no problems. Coming back, while trailing it (low RPMs) toned in route to the trailer.

Two questions

1. Does this motor have a poppet valve? I was told the larger Mercury motors have this valve to control water pressure around the heads.

2. Is there any reason the cowl would be not vented properly, storing heat, and causing me to over heat? I ran into a guy with a 125 Force that said he had over heating problems. He put 4 in vents (2 in front, 2 in back) and the problem went away. I just hate to put holes in my pretty cowl...


As far as running this thing with restrictors instead of a thermostat, I've been told as long as I'm not fishing in the winter when the water is under 60 degrees I should be fine...


Anybody know where I can find a 150 Mercury engine cheap like? lol

 

[pnwboat]

Re: 98' 120 Force "tone"

Cutting holes in the cowl is not the answer. I would check for blockage in the intake area of the lower unit. Probably have to take the lower unit and water pump off and back flush from where the water pump picks up the water.

Also may have a bad thermoswitch. Could be triggering the alarm prematurely. You should be able to test it with some hot water and a thermometer. Only problem that I can see is at what temperature should the thermoswitch activate? I would guess in the 160 to 180 degree range, but that's just a guess.

 

[mberns]

Re: 98' 120 Force "tone"

yea, we checked for blockages when we checked the impeller. We're gonna pull off the heads to see if there is any crap around the heads..

Took it out again yesterday, with NO thermostat, engine ran like crap, stalled out at full throttle, re-started it, stalled out again, then wouldn't restart. It acted like the battery was dead....alternator problem we thought. We fished for a bit, then the motor started right back up. Since it started right back up we think it's just the continuing water flow problems..

Planning to idle this thing today without the cowl in the back yard and see what happens....

pnwboat, I know it sounds crazy, my cousin is an outboard expert (but he lives 200 miles away) went to some expensive school in Florida to get certified, and he's saying the same thing as you are....but, but, I ran into another Force owner on the lake and he swore it fixed his problem..lol...but for now, I'm listening to you and my cuz.

 

[mberns]

Re: 98' 120 Force "tone"

Does anyone know where I can find a service manual for this motor?

 

[pnwboat]

Re: 98' 120 Force "tone"

They are available on line. Ebay, some local marine stores etc. Original Force repair manual, Clymer are the preferred publishers.

You can order one from here too.

http://www.clymer.com/Book.aspx?bid=621&title=Force+4-150+HP+Outboards+%28includes+L-Drives%29%2c+1984-1999