743 over heating

[mkueffler]

I have a 743 that all of the sudden starting running on the hot side at full throttle. I looked it over and discovered that the top radiator hose was colapsing at the 90 degree elbow right above the thermastat housing. I took some 12 guage electrical wire and rapped around the hose there to prevent it from colapsing and took it for a spin, it didnt overheat and ran much cooler. So i baught a new upper hose and installed it. now it dont overheat but it sure runs hot, right on the edge of overheating. Plus the new hose is trying to collaps but the wire inside is preventing it. Does anyone have any idea why its running so hot and why the hose is colapsing?

 

[wings5j]

I had this happen once on an old Dodge car. The water pump was in great shape but the radiator had gotten mostly plugged up so instead of moving anit-freeze, the water pump would suck the radiator hose shut. Of course, a plugged radiator will make the engine run hot.
There could also be some other flow restriction (bad thermostat, etc.). At idle, my flow seemed normal but adding throttle was when the problem showed up.
John

 

[under the bus]

I had this happen once on an old Dodge car. The water pump was in great shape but the radiator had gotten mostly plugged up so instead of moving anit-freeze, the water pump would suck the radiator hose shut. Of course, a plugged radiator will make the engine run hot.
There could also be some other flow restriction (bad thermostat, etc.). At idle, my flow seemed normal but adding throttle was when the problem showed up.
John

5j pretty much laid out the possibilities.

 

[mkueffler]

5j pretty much laid out the possibilities.

hmm, well when I pulled the upper radiator hose off to install a new one about 5 quarts of antifreeze drained out that hose quickly. So that leads me to believe it isnt restricted in the radiator, the hose is being sucked in so then the thermastat must be opening up. the pump must be working good to colaps the hose. so im not seeing how there is a ristriction anywhere! any insite to this info?

 

[Fishfiles]

hmm, well when I pulled the upper radiator hose off to install a new one about 5 quarts of antifreeze drained out that hose quickly. So that leads me to believe it isnt restricted in the radiator, the hose is being sucked in so then the thermastat must be opening up. the pump must be working good to colaps the hose. so im not seeing how there is a ristriction anywhere! any insite to this info?

radiator plugged up externally on the under side you can't see without removing the covers behind the engine -----------run a paper napkin over the face of the oil cooler to see if there is good air flow going in over the fins

 

[OldMachinist]

radiator plugged up externally on the under side you can't see without removing the covers behind the engine -----------run a paper napkin over the face of the oil cooler to see if there is good air flow going in over the fins

"the hose is being sucked in so then the thermastat must be opening up"
Not necessarily, the water pump sucks coolant from the bottom of the radiator and if the thermostat is not opening properly it will pull a vacuum on the top hose since the it can only suck so much thru the bypass.

 

[mkueffler]

"the hose is being sucked in so then the thermastat must be opening up"
Not necessarily, the water pump sucks coolant from the bottom of the radiator and if the thermostat is not opening properly it will pull a vacuum on the top hose since the it can only suck so much thru the bypass.

good point, I wasnt sure which way the pump pulled the antifreeze. I think I will put in a new thermostat, I should have done that when I replaced the upper hose I guess, lol. Thanks for the help!

 

[mkueffler]

good point, I wasnt sure which way the pump pulled the antifreeze. I think I will put in a new thermostat, I should have done that when I replaced the upper hose I guess, lol. Thanks for the help!

after starting to replace the thermostat I noticed the water pump pully would not turn. I took it off and it turns the bearing was bad. it would turn for a while then lock up and then turn for awhile. that must explain the power loss every now and then.

 

[Tazza]

after starting to replace the thermostat I noticed the water pump pully would not turn. I took it off and it turns the bearing was bad. it would turn for a while then lock up and then turn for awhile. that must explain the power loss every now and then.

That could be the issue indeed. Its weird that if it locked up, it would burn the belt out.
Hopefully it will fix all your issues.

 

[mkueffler]

That could be the issue indeed. Its weird that if it locked up, it would burn the belt out.
Hopefully it will fix all your issues.

yes it did fix the problems. it runs great again! thanks