my 1996 dodge ram 1500 is over heating sitting still and going down the road i have replace (in the past 3 days) radiator, water pump, thermostat, and radiator cap. i have rented a block tester from auto zone and tested to see if there was any combustion fumes in the radiator to see if a head was cracked or if a gasket was bad it came up negative so im clear as far as that goes (i hope) well since i have replaced all those parts we have tested it numerous times to see how far it would overheat and it still does but my brother in law seems to think that since we ran it hot again and again we mite need to replace the thermostat one more time see we will try that this weekend my dad seems to think that my radiator needs to be from the dealer ship i doubt thats the problem since i just replaced the radiator. so im asking if anyone knows or has a solution to my problem its still running hot hoses are fine all new parts (as in new cooling system) and it still wants to overheat. i have thought about this when we go to replace the thermostat again this weekend to take a water hoses and run it through the thermostat housing and see if it will push anything that mite be clogging the motor up is that safe and or ok? any help would be much appreciated thank you all for your time and advise
I’ll defer to the experts but I don’t think the thermostat is bad at all unless you got a cheapy one instead of a name brand. You can easily test in in a pan of water with a candy thermometer on the stove to note when it opens and when it closes. I always do this with any new one before going to the work of putting it in. One thing you could do is pull the thermostat as a trial to see if it still over heats to isolate the problem. Are your fans coming on? Is it really overheating or could the sender be bad. I guess you could still have some air trapped in the system or there may be a lot of gunk in the engine passages itself that need to be flushed out. Might have to try a mechanic with a temperature gun to determine the actual temp or see where the hot spots are.
Hoses are a good thought. The inner liners of coolant hoses can and occasionally do seperate from the outer structure and close when they heat up. Yours are old enough to make that a possibility. You’ve done the rest of the system, you may as well change the hoses too.
Yes, it is an excellent idea to remove the radiator hoses and the T-stat and flush the engine out with hosewater. Flush it in the reverse order in which it operates. Unless there’s a breech somewhere, you can do no harm, and if there is you should find out anyway.
first of all thank you for responding i was beginning to think no one would. my fans are coming on and feels fine plenty of tension when trying to turn it by hand. and its really over heating when it runs hot and we shut it off u can hear what sounds like boiling water near the thermostat.we have a lazer temp gun havent tried that yet but i feel like why when the water is boiling. would it still be necessary to use the temp gun?
lol i guess it wouldnt hurt to change the hoses. and i guess ill get out the and try and save the radiator fluid i just put in and take the hoses off replace them and try and flush the motor
but (not to be negative) what if the problem is not resolved any ideas from there? asking cause if im out there id like to have a back up plan instead of having to wait for more advise
The coolant should not be boiling of the system is secure and the radiator cap is operating properly. The purpose of the cap is to allow the system to pressurize, preventing boiling at typical operating temps (that can get above 212F around the cylinders).
Have you pressure tested the system with a UV sensitive dye added to look for leaks?
Do you have bubbles coming out of the fluid at the radiator fill hole with the cap off?
By the way, if you have the latter symmptom it’s time to do a pressure leakdown test on the cylinders. Typically those bubbles are being blown into the water jacket from a cylinder when compression and combustion happens…and they get there through a headgasket breech.
i havent used the UV dye auto zone tried to get me to buy it i assumed they wanted more money guess i was ignorant on that one.and no sir i dont have any bubbles in the fluid with the cap off.
i greatly appreciate the help sounds to me like theres not much els to do after the motor flush but try the UV dye and if it leaks i guess im out of the game on that hit
oh one more question (i am 19 that mite explain it if i am annoying with the consecutive comments) if i do have a head gasket breech would u recommend a liquid sealant like blue devil or steel seal whats the positive and negative effects with products like those?
No apology necessary. We’re here to help.
The only fix for a headgasket breech, IF it turns out that you have one, is to replace the headgasket. This is major work, But doable with a good repair manual for guidance, willingnes to invest in some tools, and awareness of your limits. By “limits”, I mean the a professional that does rebuilds will have the equipment, expertise, and knowledge to assess and rework (if necessary) the heads better than you can at home.
But without a leakdown test, you don;t know if you have a headgasket breech. Never start removing major parts until you’ve done the testing first. That’s a good way to get in too deep and never solve the problem.
hey mountain bike thank you for your time and advise but come to find out auto zone just sold me the wrong thermostat i put the one from napa in and it looked just like the one that came out the first time auto zone told me that when i bought their thermostat that they may have changed the design just changed but anyway i put the one napa in and it runs fine no overheating thank you again for for your time 
The overheating problem might be caused from a defective fan clutch. http://www.rockauto.com/catalog/moreinfo.php?pk=815240&cc=1314573
Tester
Hooray! Thanks for the update.
FWIW I too have had that happen to me.
I replace my thermostats every 5 or 6 years, as preventive maintenance. Well, it was time and the car was running fine. NO OVERHEATING.
Well, after installing the new thermostat, it started overheating, and what’s more, the new thermostat seal was badly leaking.
I went back to the store and demanded an exchange. They swore up and down that I must have screwed something up, my thermostat housing is warped, my car is overheating because it’s an old POS, etc.
They finally relented and gave me another one, although they clearly thought I was off my rocker.
Guess what?
No more overheating.
No more leaks.
I really hate to even ask, but could the thermostat be in backwards?
Check ignition timing and if it is off greatly, the timing chain may have slipped and is therefore worn out. You may want to plug a code reader in and see what comes up when you run the engine.
Wouldn’t my engine run rough if timing was off? Not always.
Hey guys, at 11:47 OP posted that the car was fixed. Apparently the parts store gave them the wrong thermostat. After putting in the correct part, all is well again.
@oldtimer11 on all of the vehicles I’ve worked on, it’s physically impossible to put the thermostat in backwards.
But I wouldn’t doubt it if there’s some vehicle out there in which it would be possible to put the thermostat in backwards . . .
Yes, many cars today have locating notches so the thermostat only fits one way, it is a good thing too because in the old days many were installed upside down. Ask me how I know!