258 running at 230-240. Is this high??????

Take out the t-stat, throw it on the stove in a pot of boiling water and see if it opens.

 

Thanks for all of your help. Sorry it took a little bit. I tried drilling a hole in the 195 t-stat last night and it still ran too hot. Today I bought a new 180 t-stat and made sure it opened in boiling water and it does. Then I also drilled the hole in the top of the actual t-stat housing to be sure and now it runs up to a little hotter than 100C or 212F. This is still hotter then what it used to run at. It used to run at about 190 and if it would heat to about 200 you would see it cool down. What else could it be? I also replaced the radiator cap. When it is running around this temp I can still open the radiator and no pressure. Any ideas?

Thanks in advance.

 

Is there any excess steam coming from the exhaust pipe?

 

I didn't really notice any excess steam from the exhaust pipe. I'll have to go buy a thermometer that goes that high so I can check the coolant. Could it be the water pump? Thanks for the help.

 

While it COULD be the pump...It would be highly unlikely....Not that water pumps don't fail...just that they "normally" do not fail in the manner....
This may have been mentioned earlier...but are your belts good and tight

 

All the failed waterpumps I have ever had to replace have failed because of a leaking mounting gasket ,leaking shaft seal or worn out shaft bearings , never heard of one not pumping so long as it was turning and had fluid to pump. At the start of this thread you made referance to a "new mojave heater". Other than changing the T-stat has any other part of the cooling system been worked on or modified in any way? Maybe there is some other variable that we are not aware of that could be causing the problems. Was the water pump working okay before you changed the T-stat the first time?

 

Even if that thermostat is new, replace it.

 

Thanks for the help guys. I did replace the new 195 t-stat with a new 180 t-stat which the old t-stat was a 180 and always stayed below 200 but now it stays between 210 and 220. I haven't put the new mojave heater in yet. The only thing I have done to the cooling system was replace the t-stat and I raised the radiator about 1-1 1/2 inches up because the coupler between the steering shaft and the steering box somehow started rubbing the radiator and put a hole in it. I also fixed the crack with quicksilver epoxy. The radiator was also too low that it had been pushing down on my power steering lines and also caused those to crack. Please let me know what you guys think. Thanks.

 

Okay...what kind of fan are you using, mechanical or electric?

 

Though it is not common, and it happened to me once and nobody else I know of, the impellers on a water pump can rust away. I had it happen and only found the pump was bad after going thru the entire cooling system. The parts guy left it on the counter for several month just for the novelty of it. '73 Scout II, btw.

 

I went through somethin similar on my 75. Finally replaced the sending unit and all was good. Now lemme ask about the gauge: Is it the stocker? or a calibrated unit that has actual marks on it with degrees? I am wondering how you are getting a firm temp reading if you are going by the stock gauge..

And is it possible that the epoxy got into the rad and is causing a restriction someplace?

 

Hey guys thanks for the help. The fan I am currently running is a mechanical fan. The belts also seem to be tight. The guage I am running is an electric guage and it has the degrees marked on it. The guage is only about two or three months old and was working fine before. Before I took it apart this thing would not pass 200 on the guage. The radiator doesn't seem to build pressure at all. The fluid level raises and leaks out with the cap off but when I close the cap and open it after a while there is no pressure. There is also coolant leaking out of my overflow tube and I replaced the radiator cap thinking that was the fix but it still leaks. I am also pretty sure the epoxy didn't get in the radiator because it was a very small crack and the epoxy was like a clay. Thanks for all of your help again guys.

 

JC Whitney also sells radiator caps with temperature guage in it- kind of a neat back-up.

 

Okay lets see...water expands about 4.3% when heated from 40*F to 212*F(you may have anti-freeze mix in it too?). When the heated water expands in a closed radiator it will build pressure and continue to do so up to the cap pressure value at which time the cap will release and send the excess fluid out the overflow tube.You know its expanding by your own observation with the cap off,this is when it would be handy to check the actual fluid temp with a thermometer in the rad neck and then you would be able to validate the dash temp reading. If no pressure builds up the first thing suspect would be the cap, and you indicated that you have have replaced it.So.. you know its heating up and expanding so where is it going? If you dont see it going into a catch bottle (or on the ground) it suggest that its leaking internally.You can take it to an auto shop or possibly rent the tool that they would use and check the cap and cooling system yourself. The tool is an adaptor that connects to the neck on your rad(cap off )and the tool has a hand pump and pressure gauge.You stroke the hand pump building pressure in your engines cooling system up to the normal cap pressure, then you sit back and wait a while and hope that the pressure gauge reading does'nt drop.If it does and presuming that the tool or its connection is not leaking and you dont see any other external leaks then that would indicate an internal leak(head gasket ?) The tool usually comes with an adapter to test the cap too.If you rent it the instructions should come with it although its fairly simple to operate,just dont overpressurize the cooling system , only take it up to the normal cap pressure.I hope that you dont have an internal leak but I dont think you are going to be comfortable at this point untill you find out for sure.Also remember that if the cap is left off and not put on untill after the fluid has heated and expanded then ther will be little or no pressure buildup,you got to start with a cold engine and the cap on for pressure to build up.

 

I can see the coolant dripping out of the overflow tube onto the ground. Maybe the surface that the radiator cap mates to is eneven because when I open the cap when it is leaking out of the overflow there does not seem to be 16 lbs of pressure there. Would this leaking cause it to run hot like this?? Or should I look into a water pump? The next time I heat the jeep up I will check the coolant temp. Would the temp of the coolant be the same as the motor even if the water pump is not working properly????

Thanks in advance.

 

If everything was okay with the waterpump before the T-stat was changed for the very first time I cant understand how it would fail by changing the T-stat. You mentioned that you moved the radiator ,when the radiator was repositioned up the 1 1/2" you did'nt by chance pinch the lower hose thus causing a restriction? Tell us your location ,maybe there is someone here that is close to you and could drop by to take a look what you got going on.Sure would like varification that the dash gauge is accurate...maybe its not really getting that hot,maybe the dash gauge calibration is drifting.

 

I will try to check the actual coolant temp. I still don't understand why the coolant would be dripping out of the overflow though. thanks for the help guys I will let you know my findings after I heat it up again.

 

These cooling systems are designed to have an pocket of air at the top and will puke out the excess coolant till it reaches the proper level. I noticed this only happens when i have added more coolant.

 

Thats good to hear. I was almost thinking that because after everytime I fill the radiator it does this. Okay guys I had to drive the jeep 2 miles to my house because my jeep was at my mom's house. When I got home I checked how hot the coolant was and it went to just barely more than 150 and the temp guage said about 195 to 200. As I was driving the jeep home it reached 212 degrees and I did not want it to get any hotter so I shut the motor down for a little bit. It does sound like something is squeaking a little bit in the front of the motor but not majorly loud. I checked the belt again and it is tight. Thanks again guys. Let me know what you think.