1989 Johnson 110 overheating diagnose help please

[NAVY LIFE]

I finally took the new to me powerhead out to the river today to test run. Overheat buzzer after 10 min.
History: New water pump kit, thermostats carbs rebuilt, comp test 90psi on all cold. Overheat on muffs pulled thermostats cleanedsand and gunk out, flushed from under while L.U. was dropped. put all back ran for 1hr on muffs no horn. Took out for live test idle good good throttle resp. fisrt time gave half throttle primer ball was collapased on self - reprimed ball it took off ran great. I started slow gradually increased rpms then the buzzer went off. Shut her down. Total time running in river 15minuts. One half hour later started it back up put it on the trailer. I tried to pull cyl. head covers last week co check for blocks but broke the second bolT then stopped.

My plan is to Pull thermos. off again PITA see if more debrees are in there.

If more junk on t-stats not allowing them to open should I run without untill all junk is flushed out of motor?

pulling cyl. covers seems to be useless 1 of two bolts broke. Should I pull heads?

Next step please help

 

[NAVY LIFE]

Re: 1989 Johnson 110 overheating diagnose help please

Ok pulled thermostats, some gunk (bits of shels, and black grime)collecting around springs but not like last time.
I think I will run w/out thermostats till shes all cleaned out.
water temp is about 80-83 degs. right now.
any thoughts?

 

[emdsapmgr]

Re: 1989 Johnson 110 overheating diagnose help please

I know you don't want to, but I'd pull the head covers. Your shells are migrating to the thermostat housing from the block and a visual inspection of the head water passages is probably necessary. If you find a lot of crud, then it is also possible there is some in the cooling cavity between the two heads. Did you have it off and visually inspect that cavity during overhaul? You may have to pull the regulator/rectifier off to top of the block and have a look inside for additional debris. I'm not a fan of running without thermostats-they help insure that the block fills completely with cooling water before it lets any out of the powerhead at idle. A cold-running engine tends to accumulate more carbon around the ringsets over time than one with functioning stats.

 

[Haffiman]

Re: 1989 Johnson 110 overheating diagnose help please

Running without thermostats increases the risk of burning down your rectifier/regulator. With no back pressure, an air-bubble normally builds up on top of the cylinder block and the regulator looses cooling.
One danger when running the cross blocks full of mud or whatever is that the deflectors that regulate and directs water flow in the cylinders may catch a lot.
In your case I would have pulled the heads and cleaned out manually .

 

[NAVY LIFE]

Re: 1989 Johnson 110 overheating diagnose help please

pull starboard head not too bad deflectors looked good put hose on to wash out junk behind top cover. Still do not want to break bolts off that thing.

There was some pitting on the lower cyl. wall?? how long till failure??
last comp. test 90psi on all.

 

[emdsapmgr]

Re: 1989 Johnson 110 overheating diagnose help please

Can you post a picture of the pits?

 

[NAVY LIFE]

Re: 1989 Johnson 110 overheating diagnose help please

heres picture of the pitting.