Over heating

Hey all, I am working on my 58 and seem to be having a thermostat sticking problem. To start with the jeep did not have one. I put a new one in and started it, waited for the temp to get up to 160 where it should open. But at 180 then 190-200 :evil:and shut it off. Tapped on the housing and it opened. I ran it for a while and it stayed right at 160. Let it cool then started it again temp came up and everything was fine. The next time I started it when it was cold it did not open and over heated again. So long story short three new thermostat later it is doing the same thing. Once in a while it works, some times it overheats. It is starting to be a PITA !!! I don't dare drive it anywhere because I cant trust it. Once it opens and is warm it works right. Any suggestions ?? Thanks in advance, Harlan

 

Is it possible that you are installing the thermostat wrong side up. The sensor needs to be towards the block. This would explain why it works fine once it opens any amount allowing heated coolant to touch sensor. Some thermostats come with "vent" holes always allowing some coolant to pass through event when cool. Don't know if that would help if you are installing them right side up. Smoke

 

"Some thermostats come with "vent" holes always allowing some coolant to pass through..."

If you don't see one, try drilling a 1/8" hole. It will allow the the heated water (or any air bubbles) from the block to flow past the thermostat's temperature sensing mechanism, otherwise it will open late. Sounds like once your thermost opens and allows circulation, it runs at the right temp, so this seems like the problem.

 

Are all 3 thermostats from the same source?
Have you tried other brands?
On both of my Jeeps, the temp guage seems to go above the normal temp area while it's warming up then drop back to it's normal place.

 

Smoke, Yes I did verify the sensor is toward the block every time I replaced the thermostat.

Pete, No, The thermostat did not have a "Vent" but I did drill a small Vet hole to allow air / coolant to pass by the thermostat on all of them. I will try a bigger hole or possibly two to see if it makes a difference tomorrow.The thermostat I am using is the one the FLAPS stated is used on the 58 134 F head. I actually went to two different parts stores just to see if a different manufacture would help the situation.

Thanks, Harlan

 

Get a pan of water boiling on the stove. You can use an oven thermometer to monitor temperature. Watch the thermostat in action back and forth multiple times. If it works fine there, check for binding or rubbing on a gasket when installed. Just for giggles, install it the other way around.

Bill

Sent from my SCH-I535 using Tapatalk 2

 

Are you sure your temperature gauge and sensor are accurate, not giving erratic readings?

 

It is unlikely that the thermostats are all bad. Drilling a larger hole will probably have little or no effect unless the hole gets so large that you are bypassing the thermostat entirely.

Well, there are a couple of possible situations here.

It is likely that the jeep overheated all the time and that's why the thermostat was removed. I'd suspect that before anything else. Take a look at the hose that goes from the radiator to the thermostat housing. It should be rigid enough to keep its "roundness" at all times.

A very common problem here has a very simple fix.. stand to one side and look at the hose in relation to the top of the radiator. That hose MUST have a generally downward slope as it goes to the T housing. If it goes upwards at all it'll trap air and you'll get overheating -- even if it is level it can trap some air. This is common in applications where the correct hose may not have been available and a substitute hose was fabricated in. You might even need to raise the radiator a little... I've had to simply trim off some of the hose (at the T stat end) to generate that downwards slope.

Another simple fix could be the relationship of fan to radiator. The fan should be close to the rad, and if it isn't you might need a spacer to push the fan forward, or fan shroud, or both. Jeep made a six blade fan and a spacer for their industrial engines to get additional cooling. The fan is fairly easy to find, but you might have to fabricate the spacer. The 'stock' spacer is around 2 1/4 inches long. The last spacer I found was at a swap meet on a scrap engine.

If the engine had been rebuilt and bored over .040 it might need some extra help in cooling in terms of an additional electric fan.

If that isn't a problem then it could be a partially clogged radiator or heater core or hoses. Could be a marginal water pump. Look for something marginal rather than completely bad, othwise the jeep would overheat without the thermostat too.

I wouldn't think about taking anything apart until I'd made sure that it must be something internal to the engine and not part of the stuff mentioned above.

 

Ok, here is an update.
The radiator hose had been repalced with the first thermostat. It is sloped like Kemel stated with a slight rise from the bend to the radiator. No place for an air bubble. I noticed that when the engine was overheating water coming out the overflow, (new cap) block to hot to touch. (200 on the gauge) The area just below the thermostat, the housing and the upper radiator hose were all cool to the touch. So, to get some water flow I drilled a second hole. Now there is water flow but not enough to stop the thermostat from opening. Only enough to get the hot water to the thermostat. It now opens at 160 and will stay there and cycle a little bit on the gauge. So it appears the thermostat is working. I am still working on why that area would not heat up at the same rate as the the rest of the block and head. But through 5 full heat cycles it never failed to work correctly.

I wonder what the next item/problem/challenge will be ?

Thanks

 

Glad you got that part figured out...