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overheating, need urgent help.

hougie

Well-Known Member
Joined
Aug 8, 2010
Messages
153
Location
Alberta, Canada
Occupation
municipal worker
hi guys,

ive got a 301.8 cat. been using it the last three days diggin. it's running in the red on the temp guage except when the rear door is open, Then it runs just under red. I'm going to clean rad tonight but does anyone else have any ideas? Maybe pull thermostat and leave it out for time being?
 

shopguy

Senior Member
Joined
Jul 2, 2011
Messages
502
Location
Alabama
Did it start with you or did you buy it doing it reason I ask I bought a Hatchi that had the fan blade installed the wrong way. very hard to spot if you are not looking for it. If it dont lose any water or boil over I would do as Nige said and look at all the airflow stuff first & then again.
 

hougie

Well-Known Member
Joined
Aug 8, 2010
Messages
153
Location
Alberta, Canada
Occupation
municipal worker
it seems to be losing water shopguy. I re-cleaned the rad and topped it up again, There was some blockage built up behind the hydraulic rad but i got it cleaned out of there. The operator said it was in the red and when he got out and shut it off he could hear it boiling. It's hard to find good help :(
 

Shenandoah

Well-Known Member
Joined
Nov 15, 2012
Messages
205
Location
Virginia
If you suspect it's your thermostat get yourself one of those infrared thermometers that can read temp at a distance. What you will be looking for is a large difference in temp between the radiator and the block/heads of the engine. If your thermostat is working correctly the difference will be small, and there will also be a difference in temps between the input hose going into the radiator and the output hose going into the engine.

Additionally, removing the thermostat can cause an overall rise in the fluid temp because it will no longer have the cycle time in the radiator required to cool it down. A lot depends on the ambient air temp. Obviously in an arctic condition this wouldn't happen.
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,979
Location
G..G..G..Granville.........!! Fetch your cloth.
If you suspect it's your thermostat get yourself one of those infrared thermometers that can read temp at a distance. What you will be looking for is a large difference in temp between the radiator and the block/heads of the engine.
I second that. If your rad is working correctly and you shoot the temperature of inlet versus outlet with the coolant at normal operating temperature you should see a temperature difference of at least 7-8 DegC between the two. Less than this and your radiator is plugged internally.

Could be something like a water pump (back to fan belts again) or also the thermostat. Try shooting the temp of the hose where it comesout of the stat housing when the machine is started up from cold. That hose should not start to get warm until quite a while after engine startup. If it starts to get warm immediately your thermostat is most likely stuck part-way open, which would in turn explain your overheating issues.
 

imtools

Member
Joined
Dec 8, 2012
Messages
6
Location
United States
Occupation
Mechanical Engineer
If you suspect it's your thermostat get yourself one of those infrared thermometers that can read temp at a distance. What you will be looking for is a large difference in temp between the radiator and the block/heads of the engine. If your thermostat is working correctly the difference will be small, and there will also be a difference in temps between the input hose going into the radiator and the output hose going into the engine.

Additionally, removing the thermostat can cause an overall rise in the fluid temp because it will no longer have the cycle time in the radiator required to cool it down. A lot depends on the ambient air temp. Obviously in an arctic condition this wouldn't happen.

A shorter cycle time in the radiator also means a shorter cycle time in the engine and it won't pick-up as much heat. Since it is flowing faster, overall heat removal is almost the same. The thermostat is there to help the engine reach proper operating temperature sooner at which it runs more efficiently.
 

Shenandoah

Well-Known Member
Joined
Nov 15, 2012
Messages
205
Location
Virginia
A shorter cycle time in the radiator also means a shorter cycle time in the engine and it won't pick-up as much heat.

True. The coolant will not see the optimal time to be able to absorb heat as it would when the thermostat is closed.

Since it is flowing faster, overall heat removal is almost the same.

This would be true if the pressure build up in the engine due to a closed thermostat remained the same at the pump impellers in a no thermostat condition and the pump worked at the same efficiency. I'm not sure it does. I'm also aware that there is lot of conjecture on this topic of which I'm adding to. :)


The thermostat is there to help the engine reach proper operating temperature sooner at which it runs more efficiently.

True. True. True.
 

Delmer

Senior Member
Joined
Jan 3, 2013
Messages
8,865
Location
WI
Removing the thermostat is a test only. Better to test the thermostat out of the engine than the engine without the thermostat.

Most thermostats open and close two openings, the one to the radiator is closed to warm up faster, but the one back to the engine is closed when it is fully warm, so the water goes to the radiator, not just through the engine. That's why the engine may run hot without a thermostat.
 
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