1985 Johnson 140 overheating problem

[stephenhudack]

Hello all i recently bought a wellcraft center console with a 85 johnson 140 on it. I start it up in the driveway it will run for a while at idle then the over heat alarm comes on. The cylinder heads feel hot and i believe the alarm is correct. I dropped the lower unit the other day and replaced the water pump, changed both t-stats and put it all back together. (what a pain it is to line that shift rod back up!) I started the engine and have the same problem. I have a couple questions.
1. On the new water pump, when i was done installing it, i put the hose on the outlet tube to make sure the o-ring sealed to the metal plate, and i noticed a small hole in the plastic housing on top and water came out of it. Is that a tell tale for something?
2. If there was a head gasket leak wouldnt the engine run poorly? becasue the engine runs great the overheat buzzer just comes in.
3. When i shut the engine down after the alarm comes in water continues to poor from the tell tale, but when it stops you can hear water gargling almost like its boiling cominng from the tell tale. Is this normal?

Any help would be greatly appreciated!

Thanks
Steve

 

[HighTrim]

Re: 1985 Johnson 140 overheating problem

1. That is a vent hole, normal

2. Depending on compression, may not even start

3. Normal

Are you running on the muffs or in a barrel? Is it actually overheating? An infrared thermometer would solve this.

 

[stephenhudack]

Re: 1985 Johnson 140 overheating problem

Im running the engine on muffs, and i ran it up the river for a test run as well. Both times i had the same problem. Im going to bring home a temp gun on monday and double check it. The only other issue i had is when i removed the lower unit i put the hose on the copper pipe and was not gettting anywater out of the tell tale. I didnt hold the hose there too long because i was afraid to damage the engine. Should i have seen water coming from the tell tale?

 

[HighTrim]

Re: 1985 Johnson 140 overheating problem

Yes you should have.

You will have to drop the gearcase, to flush/backflush the cooling circuit. You will not damage anything.

I find it a little easier to use compressed air to ensure the circuit is clear.

Would have been the best to do it when the t stat were removed. Flush water or compressed air up from the water line, then backflush from the t stat housing.

Was the impeller damaged when you removed the old one?