Refreshed Cooling System - Now immediately overheating. A little help?

[Stinkbug]

I recently began having trouble overheating my 1997 with a 4.0 on the trail on occasion. I attributed it to an aging system that had not been touched in the 20 years I’ve owned it. I probably went overboard by throwing parts at it, but here’s what I did to refresh an aging system

I flushed it thoroughly and I used the following replacement parts:

• Kyorad Radiator
• OEM water pump
• After market thermostat housing
• USMW Fan clutch
• Robert Shaw 195 degree thermostat
• MatsterPro temperature sensor (The only one I could source locally)
• New Gates Hoses.

I put it together and filled it with distilled water through the heater hose at the thermostat to hopefully avoid excess air in the system and allow me to check for leaks, so far, so good, no leaks.

Now the bad news… It came up to temperature quicker than I expected and within a few minutes I heard the ding on the dash, walked over to watch it rapidly overheat and into the red on the idiot gauge.

I let it cool down, checked the radiator and it and the over flow bottle are at the full mark. I fired it up again to move it storage spot on the other side of the but this time I paid attention. It was already warm so it quickly came up to 210.Then it began to steadily climb towards the red on the dash gauge for 30-45 seconds then the now familiar “ding” and it pegged the temperature gauge at 260 within 2-3 seconds.

My gut is telling me it is either a bad thermostat that is not opening or it’s a bad temperature sensor.

I would appreciate any suggestions about how I spend my Sunday trouble shooting this…

 

[GregBelleville]

I recently began having trouble overheating my 1997 with a 4.0 on the trail on occasion. I attributed it to an aging system that had not been touched in the 20 years I’ve owned it. I probably went overboard by throwing parts at it, but here’s what I did to refresh an aging system

I flushed it thoroughly and I used the following replacement parts:

• Kyorad Radiator
• OEM water pump
• After market thermostat housing
• USMW Fan clutch
• Robert Shaw 195 degree thermostat
• MatsterPro temperature sensor (The only one I could source locally)
• New Gates Hoses.

I put it together and filled it with distilled water through the heater hose at the thermostat to hopefully avoid excess air in the system and allow me to check for leaks, so far, so good, no leaks.

Now the bad news… It came up to temperature quicker than I expected and within a few minutes I heard the ding on the dash, walked over to watch it rapidly overheat and into the red on the idiot gauge.

I let it cool down, checked the radiator and it and the over flow bottle are at the full mark. I fired it up again to move it storage spot on the other side of the but this time I paid attention. It was already warm so it quickly came up to 210.Then it began to steadily climb towards the red on the dash gauge for 30-45 seconds then the now familiar “ding” and it pegged the temperature gauge at 260 within 2-3 seconds.

My gut is telling me it is either a bad thermostat that is not opening or it’s a bad temperature sensor.

I would appreciate any suggestions about how I spend my Sunday trouble shooting this…

Do you have the old temp sensor to swap?

 

[User4574]

Do you have the old temp sensor to swap?

This. Or you still have air in your system. You tried to limit the air, but did you burp it?

 

[Stinkbug]

Do you have the old temp sensor to swap?

That’s my Plan A… hopefully I can get it out of the old thermostat housing without destroying it. I am also going to check where that needle starts when it is stone cold.

 

[Stinkbug]

This. Or you still have air in your system. You tried to limit the air, but did you burp it?

How do I go about that? BTW the thermostat does have a small holy that I was sure to orient to the top on installation.

 

[B1Toad]

Are you 100% sure the thermostat is installed with the copper pellet facing in to the cylinder head? (spring facing out) My second guess would be the after market housing somehow pressing/pinching/holding the stat from opening due to incorrect machining.

edit: I just saw the sender is after market as well and suspicious of that as @GregBelleville alluded to.

 

[L J]

How do I go about that? BTW the thermostat does have a small holy that I was sure to orient to the top on installation.

I've always parked on an incline (or put the front end on jackstands) and let it come up to temp and run (without the radiator cap on).

 

[User4574]

How do I go about that? BTW the thermostat does have a small holy that I was sure to orient to the top on installation.

After it is full of coolant let it run with the cap off and circulate. Level will rise and fall a bit as the air gets a chance to escape.

There is a burp kit available (Amazon, harbor freight, etc) that is handy because you don't make as much of a mess.

Radiator Kit

 

[Stinkbug]

Well it looks like the problem is solved. I touched the top of the radiator and it was cool, touched the heater hoses they were warm but not hot. I touched the lower radiator hose, it was cool, I touched the head, uncomfortably warm but not hot. The gauge was still reading 210ish. I pulled the sensor and it was just warm. It certainly was no where near 220 degrees.

I was able to wrestle the old sensor out and swap it in. I took it for a drive down the highway. After about 10 minutes it never budged outside the normal range of 210+/- a few degrees on either side.

I just cleared the over temperature code and should be good to go….

Edit: Fixed a typo.

 

[mrblaine]

Well it looks like the problem is solved. I touched the top of the radiator and it was cool, touched the heater hoses they were warm but not hot. I touched the lower radiator hose, it was cool, I touched the head, uncomfortably warm but not hot. The gauge was still reading 210ish. I pulled the sensor and it was just warm. It certainly was no where near 220 degrees.

I was able to wrestle the old sensor out and swap it in. I took it for a drive down the highway. After about 10 minutes it never budged outside the normal range of 210+ miles a few degrees on either side.

I just cleared the over temperature code and should be good to go….

That is blasphemy for the Mopar isn't special, aftermarket is just as good folks.

 

[mrblaine]

I've always parked on an incline (or put the front end on jackstands) and let it come up to temp and run (without the radiator cap on).

I've never cared and in fact, the part of the driveway where we do most of our radiator work is slightly higher at the back of the rig.

 

[Stinkbug]

That is blasphemy for the Mopar isn't special, aftermarket is just as good folks.

Along those lines… I originally attempted to put the highly reviewed Hayden 2737 fan clutch in as part of this project. However, the receptacle on the clutch for the nub on the front of the water pump was slightly undersized and it would not slide on. Had I forced it, it would have been a pressed fit that would never again separate from the water pump.

I am sure it’s a great fan clutch but my one and only experience with Hayden is less than satisfactory.