OMC TurboJet 115 Over Heating Problem

[klawunf]

I have an OMC 115 Turbo Jet in a 14 ft Four Winns Fling. The motor works fine when I am running the boat and cruising at moderate and high speed. If I slow down to an idle or very slow speed the engine will over heat. I have completely flushed the cooling system and disassembled all the hoses and I cannot find any problem. I replaced the spring and ball check valve on the out drive. I replaced the thermostats and the pressure relief valves. What should I do next ???

 

[OBJ]

Re: OMC TurboJet 115 Over Heating Problem

Lugs....what year is the engine?

 

[klawunf]

Re: OMC TurboJet 115 Over Heating Problem

1995. I've exhausted the manual.

 

[OBJ]

Re: OMC TurboJet 115 Over Heating Problem

Lugs....is it really heating up or is the horn just going off? Have you replaced the water pump impeller?

 

[klawunf]

Re: OMC TurboJet 115 Over Heating Problem

The horn is going off. The engine is hot enough that I cannot keep my hand on it.

 

[klawunf]

Re: OMC TurboJet 115 Over Heating Problem

The Turbojet does not have a water pump. It gets water from the jet drive.

 

[OBJ]

Re: OMC TurboJet 115 Over Heating Problem

Well Lugs.....that means all my parts manuals are in error. <br /><br />Your post indicates a classic impeller problem. The impeller housing should set right on top of the pump housing. An impeller that has "lost it's memory", meaning the blades stay bent and fail to meet the sides of the impeller housing will cause symptoms as you have indicated.<br /><br />Are you using a OEM service manual or generic?

 

[klawunf]

Re: OMC TurboJet 115 Over Heating Problem

I have the OEM Service Manual for the Turbo Jet 115. This is a 115hp 4 cyl Outboard power head mounted on a jet drive.

 

[klawunf]

Re: OMC TurboJet 115 Over Heating Problem

Maybe the jet pump is shot and not supplying enough pressure at low speed. What do you think?

 

[OBJ]

Re: OMC TurboJet 115 Over Heating Problem

I think I'd be looking at the section on the jet pump again. Tell ya' what, I get to the shop tomorrow, I'll take a look at my manuals and drop ya' line here on the forums. All I got here at home is an electronic parts manual. But the parts manual does indicate a water pump for cooling. Could you post your engine model number real quick if ya' have it?

 

[klawunf]

Re: OMC TurboJet 115 Over Heating Problem

Sorry, The boat is 100 miles away from me. The only numbers I have at home are TurboJet 115. The parts book says 115 jeer on the front cover

 

[OBJ]

Re: OMC TurboJet 115 Over Heating Problem

Hmmmmm.....just thinking here.....I've been looking at jet outboards parts breakdowns. Dang I could be wrong. Now my intrest is really gone into overdrive. I'll get back with ya' tomorrow soon as I get a look at my manuals.

 

[seahorse5]

Re: OMC TurboJet 115 Over Heating Problem

Because the cooling water is from the jet pump, the engine idle, in the water in neutral position, should be around 1200 rpm. If it is set to a lower rpm like an outboard, it will overheat. Make sure the hoses and the fittings,that come off the top of the cylinderheads are not plugged with sand or salt.

 

[woodlark]

Re: OMC TurboJet 115 Over Heating Problem

I had the same problem with my 1994 OMC Turbojet after sucking sand into the heads. I flushed till I was blue in the face and flow looked good but the problem still persisted. I finally bought the head upgrade kit for this motor, since I was planning on taking the heads off, I figured I may as well replace them with better ones at the same time. When I took the heads off I found a pebble lodged in the head water channel... hehe just enough to let water circulate enough to keep it cool at higher speeds but at lower speeds it would over heat. I have'nt had a problem since.<br />James.

 

[woodlark]

Re: OMC TurboJet 115 Over Heating Problem

Ohh yeah one more thing ..make sure you have that "OPTIONAL" sand filter installed. Of all the stupid things to make optional for a river boat.<br />James.