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Discussion Starter #1
Flyfisher and his mighty misdiagnosis:
So I was out 4X4 ing on Saturday with a friend and his 2002 Jeep. (the wife wouldn't let me take hers:confused: ) We were mudding around for about 3 hours got it stuck a bunch of times, you know the usual stuff. As we left the mud hole and got on the road, the Jeep overheated. I was convinced it was the thermostat. We got it towed the two hours to my shop and on Sunday I changed the thermostat. Still overheated. I noticed the rad was plugged solid with mud from the engine side and took the next 15 minuites to clean it with a power washer. Seems to be fine now, but I have a question regarding thermostats.

I replaced the stock one with a fail-safe thermostat, but it doesn't have the little ball checked valve orfice above the actual valve like the stock one. Is this a valve to eliminate air and possible cavitation in the system or what purpose does it serve? Is there any danger to replacing it with a thermostat without this tiny passage? Finally, why don't fail-safe thermostats come stock with all vehicles?
 

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Hmmmn, I thought the fail safe feature was the little ball check valve. If you installed a fail safe thermostat without one, what makes it fail safe? Sounds like the old "right box, wrong part" trick we see more and more from the cheap overseas labor that hasn't got a clue as to what is is going in the box. The fail safe thermostat is for motors that do not have a by pass hose, such as most Small block Chevys. I have alwas made mine fail safe with three 3/32 holes in the flange of the stat. Don't worry about it in my little 289 powered Bronco.

Trees
 

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Man 4x4ing is fun.. especially mudding. My friend has a 2000 Jeep and when we go mudding it always over heats. So he took it to his dads shop who is a GM mechanic and had him look at it. The problem wasn't the thermostat. It was all the mud caked onthe bottom and sides of the engine. It actually keeps the heat in puts a lot of stress on the engine. We actually spray the sides and under the engine with a PAM cooking spray so the mud won't stick. Beleave it or not it actually works pretty good.

James
- Drive it like it's stolen -
 

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Discussion Starter #4
I'll try the pam trick. When I go mudding, I usually go close to home so I can wash the engine after it cools. This time we were about an hour from home (two hours by tow truck). The truck started pinging about an hour or two into the forray, probably for the mud caking on the engine as you suggest.

The fail safe thermostat has two brass pieces that hold the valve in place I would assume (I've never had one fail) that they give way (either by pressure or temperature or both) and force open a second valve surrounding the main valve, allowing coolant to pass. Once the second valve opens, the thermostat is junk, but it fails open so the temperature gauge will read cold rather than result in an overheat condition. It's a pretty nifty idea. I can appreciate drilling holes in the thermostat but wouldn't that result in a longer warm up time? If the stat were to fail closed, wouldn't it still overheat?

Thanks for the info. I'm still wondering about the ball check valve, the ball is on the engine side of the stat and therefore would not allow coolant to pass while the engine is running/hot. It seems to be a valve to allow coolant to pass when the engine is on cool down, more like a refil for air pockets that may have developed in the head. It's a directional stat, the ball check valve is on the top of the stat and the stat is marked "top".
 

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Fail safe

Doc here:pimp:

I install Fail-safes on all the Vettes, mine (Napa Auto parts) have the little brass ratchet looking linkage on the top side, that ratchet up and lock when Failed..

I think Fail safes are relatively New, and Car manufactures are like the F.A.A. ... It takes years of testing, mounds of paperwork, and an act of god ... To Officially make it a good idea...Besides...they have all those Head/rebuild gaskets to still sell...wouldn't want to cut that market too quick..LOL:D

The little "Ball" you are talking about, I think, does the same thing as Drilling holes in the Stat...EXCEPT the ball acts as a one way pressure valve, allowing flow in one direction, into the block. Where the stat, with holes in it, will allow back-pressure and boil over easier into the top hose, in a "Locked closed" position.

The PAM idea is a good one on not only the radiator/engine, but on the rims, fender-wells and anything you want to easily clean off after mudding...you can use WD 40 , house wax just about any thing oil based,that won't stick,stain or burn...makes clean up simple!

Doc:pimp:
 

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Discussion Starter #6
It must take a long time, I used my first one in or around '92.

I'm wondering if I should pull out the fail safe stat and drill a hole in the top of it.
 
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