I would agree with that if I hadn't had it gone through 2 of them getting it replaced when it first started to overheat. Also, the warm up went really close to its normal rate, except it didn't quite make it up to 190 until I slowed down below 40 mph, then it went up above 190. I hope that I haven't had 2 bad thermostats put in.
I would be looking at the t-stat again, take it out and place in a old pop can (empty) then pour some boiling water into the can right out of the kettle, if the t-stat opens fast and smooth then you can eliminate the t-stat. You can try running without a t-stat to see if the vehicle over heats, my money is on it won't. That will only help eliminate the t-stat from your problem. You may have a collapsed hose that is reducing flow through the rad.. or yes even a bad water pump. Water pumps are silly things, some last only a couple years and then some (like on my 57 Pontiac and 54 ford , both Canadian models) can last for over 50 years (the ford water pumps leak if I let the system pressurize, shaft seals are weak and failing). For the few bucks it costs for another t-stat, I'd change it out and I would even look at buying or having the work done at a different place, just in case the place that the current one and previous one came from received a bad batch, or to eliminate the same goon from possibly installing it incorrectly.
Snow...
Okay, It will cool properly at road speed but not at idle would indicate fan failure to move enough air as a primary concern. If you can send me an e-mail address I'll forward you some Jeep Cooling System info.
Overheating In Traffic (Stop and Go, Low Speed Driving) Overheating in traffic and low speed driving has one common cause: the fan. During stop and go, low speed "creeping" and low speed driving, there is not sufficient flow of air through the radiator. Therefore, the engine has a fan to draw air through the front of the car. This fan operates off of a viscous fan clutch. Basically, the fan clutch is mounted between the fan and the engine. As cold air flows over it, the clutch loosens up, allowing the fan to freewheel on the shaft of the engine. The fan then hardly turns. As the air flowing over the clutch heats up (as the engine transfers more heat to the radiator) the clutch tightens up, spinning the fan faster and drawing more air through the radiator. The cycle continues as long as the car is running. Over time, this fan clutch can wear out, causing the fan to freewheel whether it is hot or cold. This causes reduced airflow through the radiator, and therefore high operating temperatures during low speed driving. This theory is easy to test, because once you get on the highway the car will cool right down. Testing the fan clutch is pretty easy. Simply start the car and allow it to warm up to normal operating temperature. Shut it off, then give the fan a good flick with your hand. If it rotates more than about 1.5 turns, then odds are the fan clutch is worn. However, I have found this test to be a very bad indicator of the true condition of the clutch. A much better test is to simply pick another one up and swap it on. If this solves your problem, then the fan clutch was obviously the culprit.
"YouGoFirst" wrote in message news:x6TDe.460690$ snipped-for-privacy@bgtnsc04-news.ops.worldnet.att.net...
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Your thermostat could be stuck partially open.... too much cooling at first, then not enough later. Or it could have been put in backwards... the sensing part should be toward the block (spring out). Did the symptoms start after the maintenance, or were they happening before? __ Steve .
I took it in to the place where I had the fan clutch replaced, and the owner said that he has owned several Jeep Grand Cherokees, and that they all run hot. He said that as long as I am not getting above the 235 mark I should be ok. Is there anybody out there who has owned a 1993 V8 Jeep Grand Cherokee that can confirm that it can get that hot when running the AC while it is 100 degrees outside?
I can confirm it though not a 1993 - I have the 1997 w/ v8 - was the next notch up last week while driving in 90+ heat a little over 100 w/ heat index in stop and go Philly driving for about 3 hours. I was worried for a bit, since the all the xj(s) I've owned never went above 210 (unless you count when the electric fan went)... but it never went above the next notch, just stayed there all day...
Paul
We have a '93 JGC Limited with 90,000 miles. With ambient running 100 to 105 lately, the Jeep runs at almost 210 degrees while moving at least 40 mph. If I do a lot of stop and go driving, it will go over the 210 mark. I let it sit and idle yesterday for about 10 minutes with my wife in the car, and when I returned it was just below the red line. As soon as I got the car moving above 40 mph, it came back down to 210. My thermostat is less than 6-months old. Original water pump. Seems like it has always run pretty hot. I have had to turn the A/C off when in Phoenix at about 115F. The engine pinged so back I thought it would blow up. Turning off the A/C stopped the pinging, but darn near melted us.
Dick
Thanks, I guess the mechanic wasn't full of crap.
Some things to consider:
With the stock 190-degree thermostat, that's the minimum temperature in the radiator. It can go higher and still be "normal."
Make sure your radiator cap is in good condition. The system depends upon pressure in the radiator to increase the boiling point of the liquid.
Make sure your lower radiator hose is not soft. This would allow it to collapse from the water pump suction thereby reducing fluid flow.
Dick
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