86 3 Liter OMC Overheating

[jsurr]

I have a 1986 3 Liter 140 HP OMC that overheats. It stays 170 to 175 degrees (160 degree thermostat) forever w/rabbit ears and varying RPM. I will run at 2500 to 3000 RPM in the water and it stays the same. Within 10 to 15 minutes of running above 3000 RPM the temp will increase to 250+ if I let it. Shut down immediately, let cool for a few minutes, then start up and the temp will decrease immediately.
I have changed the thermostat, cleaned the thermostat housing, replaced the impeller and cleaned/flushed out the exhaust elbow. On my test run the same results, only this time it blew the themostat to waterpump hose. Which BTW my water pump is working great from the gush of water coming from the busted hose.

Thanx in advance for your input

jsurr

 

[chiefalen]

Re: 86 3 Liter OMC Overheating

Do you have a flapper that came loose.

When you took of the riser did you look in the tube.

It might have gotten all the way down.

You got power steering in that boat or any heat exchanger those are known to clog up.

 

[jsurr]

Re: 86 3 Liter OMC Overheating

chiefalen, I did look down into the tube. Nothing looked out of the ordinary. There is a pin across the top of the opening. However, none of the drawings or the SELOC repair manual mentions a flapper. There is no oil cooler nor power steering.

Thanx

 

[drrm123]

Re: 86 3 Liter OMC Overheating

first i's check fan belt to make sure it's not slipping (try spinning water pump pulley or altenator)( or if pulleys are rusty and chewing up belts)

second thing you can try is remove inlet water hose from thermostat housing get a 1 gallon container run engine(in water) at idle should take about 25-30 to fill container

third thing i'd check the timing on boat to be sure it correct intial and advance(you'll need a dial back timing light)

sounds like everything you replaced should be ok you can open manifold drain screw too to make sure water comes out and not plugged up

 

[chiefalen]

Re: 86 3 Liter OMC Overheating

Part # 81 is the flapper in the link.

You have a stringer or cobra?

http://www.dougrussell.com/partscat...7,135,136,200,201,202,140,204,205,206,144,207