Hi, I'm new to the Forum. I am having an issue with my 1995 F250 with stock 7.3 Diesel. Yesterday I noticed my Engine Temp Light was on. I looked at the gauge and it was reading normal. I pulled over and checked the Coolant level and it was about 2/3 of gallon low so i added some. While I was waiting to see if the engine temp light would go off I started feeling the hoses to see if they were hot. I noticed that the top hose was cold. I ran the truck for several more minutes and the hose never did warm up. It was evident that the coolant wasn't moving through the system but the heater was working great ? I assumed I had a bad thermostat and installed a new one today and took the truck for a drive and when I returned the top hose was still cold. The coolant isn't moving through the system ? The heater gets hot and the temp gauge reads normal but the engine temp light is staying on even when cold. My question is, Have any of you ever had a water pump go bad without leaking or the bearings going bad ? It was suggested to me that the impellers could be worn out but that seems like a far reach to me. The truck has 150,000 on it and has never had any cooling issues. Any suggestions would be much appreciated and if anybody has ever actually heard of impellers wearing out I would like to know. I suppose if I don't hear anything I will pull the water pump and check it out. Thanks

 

You should check the radiator as well as the pump, there could be a blockage not allowing the coolant to pass.

I would def not drive the truck at all until you get this sorted.

 

Thanks for the reply.

 

Well, you are in Ohio and not working the truck. I would not expect the stat to open much due to it being pretty chilly out, as it will bypass internally to flow to your heater core. You could have air in the system still. My pump gasket leaked, so I just replaced it instead of only the gasket. It was cheap enough. Hell, I would block the radiator mostly off if I was in your shoes. Part of mine is and I am in Texas.

I would not pay much attention to the dummy gauges. Could just be grounding out on something. Pick up an IR thermometer and check temps.

This may help:

Thermostat, Water

A poppet-type water thermostat (8575) is used with all engines (6007).When the water thermostat is closed, coolant flows to the water pump (8501) through a bypass passage at the front of the engine. When the water thermostat is open, coolant flows through the coolant outlet elbow (thermostat housing) to the radiator (8005).The water thermostat used in production is a high temperature water thermostat for use with a mixture of water and permanent-type antifreeze. A low temperature water thermostat should be installed if a non-permanent type antifreeze and water coolant solution is used.

 

Thanks, That helps a lot. Yes the dummy gauge has never seemed right to me and the engine temp light came on Sunday morning when it was 3 degrees outside and has stayed on so I figured that was a seperate issue also. Your info about how the heater core still getting coolant thru it explained a lot to me. Thanks Again.

 

There are 2 sensors on the temp circuit. 1 for the gauge, and 1 for the light. I would say the light sensor needs replaced.

 

Unless there is something wrong with your stock gauge then I have found them to be accurate. What my added on gauge does, my stock gauge does.

 

Thanks for the info.

 

 

Thanks for the reply. Its sounding like I am worrying about nothing :-)

 

As stated , change the light sensor. If it is coming on dead cold it is probably a short in the 20 yr old sensor

 

Where is the lite sensor [for water] on the engine? I can see the 1 sensor on the thermostat housing but do not know where the other one is. Thanks Friskyjake

 

Temp gauge one is on the water pump, other on the head I recall. Passenger side somewhere. Follow the harness.



OP - I also have a 203F thermostat. I tow 10k or less and haul more than tow. If this is you, highly consider that stat...and go with the purple Fleet Charge coolant. It is prefilled with SCAs which your 7.3 needs. Seriously, block off most of your radiator. Plug in when you can.

 

Thanks for the reply. I will do that.

 

Overheat sensor correct location is about 10-11:00 of water pump. On timing cover.