ParadiseMJ Posted February 9, 2013 Posted February 9, 2013 My MJ set-up: 88 Pioneer 4.0L, AW4, Open cooling system, HD tranny cooler, etc. I have a ZJ HD fan clutch, and my e-fan on a switch in the cab. I have a 195 t-stat (Stant) and a 16# (NAPA) CAP It's been pretty cold here this winter, cold for here 20-30 lows. My truck is running ~160 under most driving conditions. If I am pulling a load, uphill, in 3rd, at ~45-50 mph I might get it up to 200 or so. As a test I put a piece of cardboard over the mech. fan side of the grill and took a little 10 mile round trip drive. It did get up to almost 210...but when I took the cardboard off...it cooled right back down to ~160. Is this a sign of a stuck open t-stat?? My heater works great, the coolant is nice, clear neon green, the overflow tank cycles properly from hot to cold, no leaks.
mvusse Posted February 9, 2013 Posted February 9, 2013 Could be, simple to tell for sure: remove the thermostat housing and take a look. But the dash gauge is inherently unreliable.
ParadiseMJ Posted February 10, 2013 Author Posted February 10, 2013 Could be, simple to tell for sure: remove the thermostat housing and take a look. But the dash gauge is inherently unreliable. Thank you. I know I could go out and remove the two bolts and check the stat...problem is, I'm old and lazy. I don't want to go pull the cover unless I have to. I've never had a problem with any of my gauges on any of my Jeeps. Can anyone comment on the symptom??
Alexia Posted February 10, 2013 Posted February 10, 2013 Usually that indicates the thermostat has failed and stuck open. The Stant Superstat is designed to do that.
gogmorgo Posted February 10, 2013 Posted February 10, 2013 Yeah, better to have it stick open than closed. The bit of cardboard over the grill raising the temperature definitely shows it's overcooling. Most often it's a stuck thermostat, but it could also be a fan clutch that doesn't disengage or an auxiliary fan that won't shut off. Cardboard over the grill is a pretty common sight around here. It's what we liked to call a Saskatchewan thermostat. It's not used as a solution for stuck thermostats so much as it is for straight up decreasing the amount of cooling, so you get more hot coolant into the heater coil so your car warms up inside faster.
ParadiseMJ Posted February 10, 2013 Author Posted February 10, 2013 Saskatchewan thermostat. I have a buddy from Saskatoon :yes: When I'm wearing gloves and a hat...he's in shorts and a t-shirt. Thanks all...I guess I'll go get me a t-stat today
danbyrambler Posted February 10, 2013 Posted February 10, 2013 Good heater output pretty much normal run time? - - My 87 4.0 TG always read a little onna low side & more so in winter - - Low 20s is starting to get with it tho - should be able to see TG needle move a little as TS opens/closes/operates whatever - - Had a Triumph Spitfire once & did the cardboard thing when it got down there - TG pointer swung like a clock pendulum almost - - - Lazer temp readers are neat tools - - Will be able to do a fast & dirty under hood ck with one - - :thumbsup:
jeepsouth Posted February 10, 2013 Posted February 10, 2013 My mj did the same thing the fix was a new thermostat...took trying two of them to get a good one though.
cruiser54 Posted February 11, 2013 Posted February 11, 2013 I have a buddy from Saskatoon :yes: When I'm wearing gloves and a hat...he's in shorts and a t-shirt. Thanks all...I guess I'll go get me a t-stat today Exactly why I only use the factory stat for $23.35 at the dealer. 83501426AC. I went through 3 Stants before biting the bullet and getting the factory one. I'm not freezing my butt off to save $12.
Eagle Posted February 11, 2013 Posted February 11, 2013 If the thermostat was stuck open I doubt very much there would be normal heat coming out of the heat vents.
ParadiseMJ Posted February 11, 2013 Author Posted February 11, 2013 If the thermostat was stuck open I doubt very much there would be normal heat coming out of the heat vents. Thanks. Thus my confusion. Heat is HOT when called for.
Alexia Posted February 11, 2013 Posted February 11, 2013 If the thermostat was stuck open I doubt very much there would be normal heat coming out of the heat vents. My heater in the LJ puts out hot temperatures at 150F.
gogmorgo Posted February 11, 2013 Posted February 11, 2013 Yeah, I can get "heat" out of my vents before the engines warm enough that the gauge starts registering. Air at 70F still feels a lot warmer than the ambient -20F.
ParadiseMJ Posted February 12, 2013 Author Posted February 12, 2013 It's a frigid 48F here tonight :thumbsup:
gogmorgo Posted February 12, 2013 Posted February 12, 2013 It's a frigid 48F here tonight :thumbsup: Actually, today was nice and warm. Only needed a light jacket, no gloves or toque. A balmy 20F.
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