I just returned from a week of wheelin' in Death Valley. My YJ and I did everything imaginable and I couldn't have asked for it to run any better.
The only thing I've noticed is that the temperature gage now sits a notch lower than it did before I left. Of course, I'm hoping that the 1200 mile trip cleared out something in the cooling system, and the engine is better than ever. Unfortunately, I have a feeling that I've burned out something and my temperature is incorrect.
Does anyone have any ideas on this problem?
Thanks
ds
PS -- Has anyone every gone to Harvey's Complete Jeepshop in Long Beach, CA? How is their work?
There is a chance that your thermostat is stuck open. A quick way to tell is to start up the engine when cold and hold onto the upper return hose. If you feel heat within 30-45 seconds, that means water is flowing through it before the engine is up to temp....meaning the thermostat is stuck open.....happens all the time...at least it's not stuck closed.
As for Harvey's....they do great work...they know their stuff....but man, are they expensive....not only for labor, but parts too.
Sounds like the thermostat might have broken.
To test...
Take the radiator cap off, and make sure the radiator is topped off with antifreeze.
Use a $3 candy thermometer (available at any grocery or discount store) in the antifreeze, and try to seal the radiator neck with a rag.
Wrap the rag around the thermometer as tight as you can get it.
Drop the thermometer into the antifreeze, and slide the rag 'knot' down into the radiator neck to fill the hole.
Start the engine, and let it get all the way to operating temperature....
(The top radiator hose will be very hot, and there will be more or less constant circulation through the radiator)
See if the candy thermometer and the heat gauge agree on what the water temperature is...
If they agree, it's probably the thermostat.
If they don't agree, it's probably your gauge or sending unit...
--------------------------------
ABOUT the candy thermometer...
The glass candy thermometers are a lot more accurate, and usually cheaper than the metal meat thermometers.
The glass is more fragile, but the candy thermometers will stay accurate for a lifetime.
Look for one that is all glass, with as little plastic on it as you can get,
with a metal tip protector if possible.
The ones the Wal-Mart store here carry have plastic top caps, and no metal covers for the tips.
The best all glass one I have found was at the grocery store.
All glass, with stainless steel clip for holding it on the side of the pot, and stainless steel tip protector... It was about $5 though...
I found out that the candy thermometers are within two degrees when compared with my digital pyrometer.
Pretty accurate, and not $500....
I keep mine in a big, fat, metal cigar tube for safe keeping.
The hard plastic cases that hold machine tool bits or large drilling tools would work just fine also, and they can be had for little or nothing at any machine shop.
Tape the tube in the lid of the toolbox so it doesn't get crushed by junk...
What can go wrong with a jeep that runs to cold?? I have two electric fans and no thermostat, but i have one to put in, when i have time, The Jeep runs at about 120 degrees. Is this too cold for the jeep. It does seem a little more hesitant when i have it that cold.
Thanks for any info.
Dan Stewart 1963 CJ5 "Caloosa Jeepers" member
The engine is designed to run at 180 degrees or hotter. Below that the gas does not atomize as well and effeciency sucks. Put in the proper thermostat and you will see the gas mileage go up...and your engine will last longer. What is not apparent is the fact that when its cold, some of the gas gets by the piston rings and over time dilutes your oil....which will increase wear. We could write many pages in regard to thermal effeciency in internal combuston engines....
I wouldn't worry too much about that, I just got back from a 4 hour trip, and my 79 cj-5 was running at about 235 degrees the whole time with a new thermostat. Figure that one out.
If the thermostat is stuck open, there is an easy way to tell. Let the jeep set long enough to get completetly kool. I suggest over night. In the morning, remove radiator cap. Start jeep. If you thermostat is open, the water pump will shove water through radiator right from the start. As soon as the engine cranks. All you have to do is look in the radiator. The water will be flowing.
Water will flow all the time anyway, most AMC engines have a built in water bypass...
That's why holding the upper radiator hose to see if the warm water passes right away won't work very well either...
If the temperature gauge doesn't agree with the thermometer, but neither says you are getting up to operating temperature, then the thermostat is likely stuck open.
It's a 50/50 toss up if it's the gauge or the thermostat, but the second temperature reading will settle things once and for all.
It will also give you peace of mind that the gauge is correct if it turns out the be the thermostat...
I always go for the verification....
Later folks,
Aaron.
"I Have The Body Of A God... Buddha"
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