Grampaw

Over this past weekend, the wife &amp; I took a trip in the truck to an RV Show (about 75 miles), and while driving, I noticed the heat guage would raise to about 190* and then drop to about 150*. I checked the coolant level in the recovery bottle, and it was fine. I could not see any leaks either. :'( Does anyone know what might be causing this? Could it be a faulty thermostat? ???<br><br>Thanks in advance<br>Grampaw

Shovelhead

Sounds like you might want to change to the 180* thermostat. <br><br>I helps keep the temp fluctuations down.<br><br>Ed

Grampaw

Thanks Ed,<br>But I'm wondering why it just started. I've had the truck since September last year and done some towing with it and never had this problem? Doesn't there have to be something wrong to cause this? Is it just that the thermostat may be going bad?<br><br>Grampaw

GrandpasRam

Grampaw, there are a few things that can cause that. The thermostat could be sticking intermittently, or you could have reduced airflow through the radiator. When the radiator cooling fins get plugged with road grime, bugs, etc. it can begin to cause the symptom you describe. Using a degreaser conpund in a hand pump tank sprayer at low pressure and letting it sit 10 minutes or so before flushing with water can clean much of the gunk out of the cooling fins; as for the thermostat, if you don't know if or when it was last replaced, it might be a good idea to replace it and flush and refill the radiator as you do. It could give you a chance to inspect the inside part of the coolant hoses for potential replacement need.

BigBlue

Mine just started doing the same thing. Except it only bounces between 195-185. ???

HC

Short version:<br>Replace the thermostat.<br><br>Long version:<br><br>During initial warm-up, it's very normal for temp to overshoot your normal running point, then drop back maybe 50 degrees, then overshoot again maybe one more time. After 10 minutes, you should see a steady number.<br><br>You never said, what is your normal, light load, steady running speed temperature, near 190? Or near 150? And were you going up or down any significant grades while all this was occurring?<br><br>I would expect maybe a 5 to 10 degree rise going up a two mile long grade, or a 5 to 10 degree drop going down one. A 50 degree swing does not sound normal after that initial warm-up swing.<br><br>If you are seeing a rise ABOVE normal operating temperatures going up hill, followed by a quick return to normal when you crest the hill, then I would expect the dirty radiator is the main cause. If you are seeing fluctuation both above and below your normal set point, or dropping below normal on any downhills, then a sticky thermostat is the likely source. You're a '95, the thermostat is probably &lt;$20, I'd put in a new one regardless and see if the problem goes away.<br><br>On my 2001, the thermostat is the most simple &quot;do it yourself&quot; item you can imagine. Two bolts, remove old one, drop in new one (make sure you get it rightside up by looking at old one before removal). Gasket is built-on to the thermostat, so you don't have to use sealant or anything messy at all. Just be sure to scrap any pieces of the old gasket off the seating area before dropping in the new one. Replace bolts, start engine, top off antifreeze and you're done. You can even just add some antifreeze to the overflow bottle the next day if you prefer, you probably won't loose enough to matter but it will suck the overflow bottle dry on your next cooldown. <br><br>Somebody with a '95 needs to chime in here and let us know, is it harder on the older models, or the same?<br>

Lary Ellis (Top)

The cooling system in the 2nd gen trucks like yours are very efficient and unless you are working the truck hard, will seldom get very hot.<br><br> A common problem with them has been the fluctuation of the gauge as the engine heats up enough to open the thermostat then the rush of cool water shuts it down again.<br><br> This is very common for a 95 truck and it causes no damage at all. My 96 has done this since I bought it new. My guess is that it has warmed up enough since when you bought it in the fall, and you are just now noticing it.<br><br> Chrysler put out a bulletin on this and their fix is to install the 180 thermostat as Ed stated, and this keeps it from being so noticable on the guage.<br><br> It is not really a problem though, just one that you notice and if it makes you uncomfortable, then by all means go for the cooler thermostat. Most of us get used to it being the nature of the beast and just forget about it.<br><br> 106,000 miles on mine and it still does the very same thing, no problems with the engine at all, Just about 5 pounds too much weight on the accelerator pedal though ;D

BigBlue

I'm going to swap to a 180* 'fore to long. I'm tired of listening to my fan kick on all the time. It's noisy and kills the power. What is the deal with how the fan operates? I know on my dad's vette, if you swap in a cooler T-stat, you have to reprogram teh computer to kick the fans on at a lower temp (they are electric fans though). Do you have to do that on ours also?

BigBlue

I just called Napa, O'Reiliy's, Carquest, and Dodge, and none of them have a 180* T-stat for my truck. What's the deal? Where can I get one? What would happen if I were to completely remove the T-stat all together? Or maybe put some shims under it? I know I can put shims under my dad's t-stat and cool it off some. When I talked to Dodge, putting a lower T-stat in would void the warranty unless, and I quote, &quot;You swap in the factory one before service.&quot; ;D. He also said that it would affect the 02 sensors in our trucks. When did our trucks come with 02 sensors? Thanks for the help yall.

phox_mulder

Local Cummins distributor is the best and possible only place to get one.<br><br>http://www.cummins.com<br><br>to find the nearest.<br><br><br>phox

BigBlue

Thanks. I really want to get the temps cooled down on this thing. It bothers me that it is running this warm. It never did this last summer. I've flushed the fins out (even took off the fan shroud to get at them better). I sprayed Simple Green on them and let it set for a while and it didn't help.

Stamey

[quote author=BigBlue link=board=8;threadid=14127;start=0#135916 date=1052341317]<br>Thanks. I really want to get the temps cooled down on this thing. It bothers me that it is running this warm. It never did this last summer. I've flushed the fins out (even took off the fan shroud to get at them better). I sprayed Simple Green on them and let it set for a while and it didn't help.<br>[/quote]<br><br>BigBlue, <br>How hot is your engine getting? You WANT it to run around 200 degrees. Right at 200 is best. I wish I could get mine that high. I am hoping that my gauge just reads a little low and it really is at 200. ;D I don't even start worrying until the temp approaches 230.<br><br>Chris

BigBlue

It runs over 190 and I'm tired of hearing that blasted fan kick in. That thing kills the power and mileage. Plus it's really loud and annoying. That's really the only reason why. And electric fans are not an option.

BigBlue

Maybe my fans just like to kick on. I don't know. I'm going to find a 180* T-stat and see if that helps.