running cool.

[ahale2772]

So ive got cronic cool water tems in my truck. and ive done a bit of chasing on the problem.

lately 170* is as hot as she gets, and thats not even hot enough to keep the darn cab warm.

Ive replaced my t-stat with a brandy new cummins 180* unit. flushed out the air pockets out of my system by taking one of the coolant elbows on the front of the head off, and filling that till it leaks.

my radiator is in good shape, no leaks on the whole system. and the water tem guage seems to work well, when I flog the truck, it will come up to 190 or so when it really gets hot, but olny for a second, then it drops back to 170

I took my fan off this weekend and i'm running around with it off the truck, before that I removed the shroud and found no improvement.

at idle, with the fan off, it will hover just under 200* but never get much hotter than that. with the fan on, it will cool down even more to about 150*

the Weather around my parts is not even chilly yet, its been about 50* for the last few weeks. hoping i dont freeze my goodem's off when its gets cold out and the truck stays even colder than 170

any advice? should I try to block off part of the radiator?

[ellis93]

Your heater core isn't just stopped up is it?

[ahale2772]

it blows warm air at 170*, and if I beat on the truck, with the heater on full blast, it blows hot air. but then the temp comes back down and it blows lukewarm again

[ellis93]

Some gas burners(ferds) I work on have restrictors in the cores return to slow the flow down. You could try that, core would be slow to heat but once to temp it should stay hot. If the truck would hold 160 that should be enough heat to cook the air to a nice temp.

[cougar]

My 91 is cold blooded too. The winter front helps, but below zero is just COLD

[Mark Nixon]

Why doesn't anyone run a 195* thermostat?
Personally, the '91 flatbed has no problems with running too cold in any weather.
I have a new heater core and radiator in it, it always seems to run kind'a warm (by the gauge) in the summer, but it's not a whole lot cooler (by the gauge) in the winter and no problems with heating up the cab when it's cold.

Even with 1 pane of the slider broken out all this time.

Mark.

[ahale2772]

i might go 195 mark, im guessing the reason mine hangs at 170 is because i dont have my temp sender mounted right by the t-stat, its probably just about 180 there, allowing enought water to pass and regulate the system.

I was thinking because my heater dosnt work so well that the engine is probably not getting hot enought....maybe I just need to look at my heater core.

are they a BI**H to get to?

[Mark Nixon]

Do a backflush on the heater core until it runs clear and note the amount of garbage that comes out.
Backflush FIRST, then go the normal direction until it's clear again.

The heater core isn't the nicest task to undertake, but it's definitely achievable without removing the dash or windshield, just takes patience.

As far as the temp sender, they are usually located on the driver's side, at the back of the head, which will usually cause the gauge to fluctuate.
Why Dodge/Cummins put it back there, I have no clue, because it's damned inaccurate.

Mark.

[Tsbourne09]

Mine runs cool also with a new cummins 180* thermostat. i have narrowed my lack of heat problem down to the heater core being stopped up. Gunna blow it out thursday. It is almost blocked 100% and does not blow hot air at ALL and its getting cold out! I would like to install an aftermarket temp gauge that gives a good and acurate reading with numbers insted of lines but not sure how/where to set it up.

Aint it funny how its bad when it runs hot and it sucks when its to cold...

[ahale2772]

yeah, Ive got all the heat i need in the summer, darn thing wont shut off then

i'll flush mine out this weekend

[dazedandconfused]

Glad im not the only one who has the luke warm heat issue.

[Mark Nixon]

Glad im not the only one who has the luke warm heat issue.

Must be a "Misery Loves Company" kinda' thing?

Mark.

[dazedandconfused]

Yeah I guess. I cleaned everything when I put the heater box in so I think I'm gonna change the thermostat next.

[ellis93]

Why don't you fellers try a restrictor in the cores return hose. It'll slow the water down and cause the heater core to get hotter. You don't have to close it up much, take a brass pipe bushing and put it in the line. I'd try a 3/8ths to 1/8 bushing and a hose clamp on the out side of the hose to hold it in position. If your engine temp stays at like 160 then that should really be plenty of heat to cook the air to at least 80 or 90 degrees. I'd say that would feel right nice one a 17degree day.

[m880cummins]

Some engines just run too efficient. I wouldn't really worry about it. I don't even have a fan on mine and it runs consistent 180* temps year round. In the summer if I sit at a stoplight for a long period of time it goes up to 200*. I have had a water pump go out and loose most of my water and it spiked past 250* and still ran fine. I didn't let it run long though. Just long enough to get it home. You just can't kill these trucks. Mine never got above 165* with a fan but I took it off because the clutch was shot and was tired of the noise the fan made at full speed.