hi i have a 01 ram with 360 and can only get it to heat up too 160 put new heater core in and fan clutch and temp senor and water pump and 8 new thermostats all 195 and flushed the system 10 plus times and samething top hose it hot and heater core hoses are hot and bottom is is cold to the touch and the rad cap is cold to the touch dont know what to do anymore any help is great thanks

 

8 t-stats. that must be a record.

160 is about where it runs with stuck-open tstat. can you test one of them in a pan of hot water on the stove. use a cooking thermometer that won't blow out at 220*. you want to see the t-stat remain closed until about 180-190 and then crack open. turn the stove down and hold about 195 (almost boiling but not quite) and see the tstat come wide open. then take it off the heat and slowly add some ice cubes and watch it close back up.


on a truck running at 180-195 the lower radiator hose should be warm, say about 120-140 depending on outside temp. on a truck running at 160, it will be pretty cold, say 90-100ish.

i've always like the stant brand superstats. well built with lots of material and in my opinion a lot better than the $5 versions. more expensive at $15ish.

 

rollin down the road it only hits 140 and idling it hits 160 and boiled the thermostats before putting them in and they open and close like they should i get heat in the cab no problem i kept changing thermostats thinking they where stuck open but didnt help

 

so if the tstat opens/closes properly, but the gauge says its cold - the next test is to challenge the temp gauge and verify the actual coolant temp in the top radiator hose.

if your top radiator hose measures 195, then you have a problem with the temp sensor or wiring problem or gauge. you can easily test the top hose with an infrared temp gun. or tape the wife's cooking thermometer to the bottom of the hose.

on your 01 you can do a gauge sweep test. while holding in odometer trip button, turn ignition to on and keep the button depressed for several seconds. the truck will do a cluster test, including sweeping all gauges to something like 1/4, then 1/2, then full.

your 01 has a single temp sensor in the top of the intake manifold i think on passenger side front. not the IAT sensor in the air plenum, but the coolant temp. make sure you changed the right one.

 

Behind alternator.

 

i did the gauge test and everything worked and i have used a temp gun to check and plug my laptop in the obd port to get temp reading going down the road put new temp sending unit in today and didnt help

 

what does the infrared temp gun say?
what does the obd/laptop say ?
what does the dash gauge say?

 

gauge says bout 140ish and laptop says 150 and temp gun 155

 

so they all agree, and they all read low.

i was under the impression that the temp gun on the top hose was 195 and that only the gauge and/or the OBD was falsely reading low. sorry.

i read that you've already replaced 8 t-stats, but - its the job of the t-stat to remain full closed so the engine will heat up to 195. the t-stat is all mechanical, so there's no electronic mystery. I also read that you did a stove top hot water test to verify that one or more of those t-stats opens and closes properly around 195.

so - what could possibly cause this?
where are you? north pole? is it -30 there?
could all 8 t-stat be the wrong fit, allowing coolant to pass
could the t-stat housing be jacked up, allowing coolant to pass
could the t-stat seat be jacked up, causing it to not seat and seal, allowing coolant to pass?

i might try this experiment. from a cold start, and with an assistant. disconnect top radiator hose from radiator and start the truck. with t-stat closed you should get either no flow, or just a little dribble of flow... if you get a steady flow of coolant, your t-stat is leaking.