Engine/Transmission (1994 - 1998) Cold shoulders

[TWafer]

I know this topic has been discussed before but I still can’t decide what to do. I live in upstate NY where it’s cold in the winter, often well below zero. I drive about 10 miles each way to work which is just enough to barely get the truck warm. Even on a longer drive you never got an overabundance of heat in the cab.

I replaced the original thermostat hoping that it would help. I got one from NAPA and hate it. :{ It fluctuates much worse than the original. 50 degrees or more. I know that fluctuation is supposed to be “normal”.

From what I've read there is supposed to be a “new” 180-degree thermostat that’s supposed to help with the fluctuations but in reality keeps the temp around 160. That seems pretty cool to me.

The newer 24 valve models have a 190-degree thermostat installed. If I put one of these in my 95 12 valve what could I expect. Wide variations at a higher average temp? I hear they are expensive and don’t want to throw money away if it won’t help me. Any other recommendations/

Thanks

Tim

 

[Mundgyver]

Why not do like the 18 wheelers do and cover your radiator with a fabric, zipper adjustable cover. I have a set of shields for my grill that I install if I am going over to Idaho or up into Montana that work very well for me. Try blocking off half of your radiator or do it incrementaly and see where that takes you. You might find a sweet spot.

 

[bgilbert]

Well first off Napa t-stats are known JUNK. Only use Cummins stats. Yes there is a new updated Cummins 180* stat that doesn't fluctuate. I have one, it doesn't fluctuate, but only runs 165-170* tops. I'm like you, I'd like to have one run at 180* all the time, it would give warmer heat. Plenty of t-stat pn's on the search. Do you use your block heater before work? Use it and try what Mundgyver suggested. If it remains that cold for such a long time, how bout removing your fan? Plus with such a short to and from trip to work, it wouldn't overheat. Beyond that, 10mi to and from isn't gonna be enough to give you heat. Might try a gasser.

 

[NHouse]

Aside from the fluctuation of the gauge being annoying, I don't think a thermostat is your problem. If I were you I would remove the fan, try a cold front, and definately plug in the truck at night. I have left mine plugged it for days at a time before, it won't hurt anything and it starts and runs so much better after being plugged in all night. If for some reason you can't plug it in, I would consider an Espar since it gets so cold where you live.



In 15-20 degree temps, mine is starting to blow warm air before I get out of the neighborhood if I plug it in all night.



Nick

 

[Jschafer]

I have ran mine in the winter without a fan with no problem with non working driveing, I run a timmer on my plug so that it heats for 3 hrs before i start the truck, if I let it warm up say 10 min I will have heat real quick.

Also could try a 12v ceramic heater in the cab.

 

[TWafer]

I have tried most of the above suggestions. I do have a timer I plug it into if its down below 10 degrees or so. I also have a fitted zippered bra for the hood and have blocked the radiator completely with cardboard before as well. I never found any of that helped to any great extent though. I think you could run with the radiator blocked nearly year round and not overheat. I have never tried removing the fan however. It’s never failed to start for me even if I forget to plug it in and its well below zero.

When its down below –10 it just never seems to get really comfortable in the cab no matter how far you drive it. When the temp gets up to the top of its fluctuating range its nice, but it only stays there a very short time and then plummets and there’s a noticeable drop in the air temperature coming out of the heater.

I just wondered how the 190 thermostat would behave in a 12 valve. It apparently works well in the never models.

I love the diesel other than this problem. I have considered one of the Espar heaters but damn they’re expensive.

Tim

 

[Mundgyver]

What about the routing of your heater water lines. I know on my 2001, I have one line that pulls off the top of the head at the # 6 cylinder and the other goes to the front near the thermostat. I don't know what your routing would be, but maybe you would benifit from just rerouting where you pull the hot water from on the block and where it is returned. I say this because even when I am in -20 weather and just started, I can feel warm air with in about 1 1/2 minutes after start up. Not hot, but I can feel it starting to warm.

 

[McCRam]

I think that the 24v tstat is different than the 12v. I would definately get a cummins tstat. I went through napa checker and carquest before I learned that lesson.

 

[Howard Durand]

How about the heating system itself. Is there good flow through the core. Even at 160* you should be getting warm air all the time.

I may be wrong but I think the AC runs when the defroster is on. Might want to pull the relay for that and see if that makes a difference.

 

[mjoppie]

i got it!! build a pole barn, run floor heat in it and keep it in there at 70* all winter . lol



i am having similar troubles as you are, but mine only takes about and hour to warm up , and the heat never gets very hot at all. takes the truck running all day to get the inside hot on a cold day. lets hear the results of that thermostat you use. anybody got the cummins p/n for the updated 180*? i was thinking about changing the heater core until i read the last issue of tdr, then said i would live with cold heat.





matt

 

[ABorchard]

The trick for quick heat is to use the recirc position on the heater control after plugging in. You will have warm right away that only gets warmer. All the other HVAC positions bring cold outside air into the cab though the heater core. Besides making the interior cold this prolongs engine warm up since in essence the heater core is a full flow mini-radiator. When it's really cold, like 25 below, I've seen my coolant temp drop to the bottom from normal almost instantly from switching between recirc and one of the positions that draw in outside air.

All the winter front, cardboard and fanless do is keep the coolant temp up after it's warm, none will speed the warm up, running cool is just a fact of life for diesels.

 

[JoshPeters]

Well Gentlemen... . SMorneau and I had this conversation going to or from Muncie last year. His truck will NEVER get heat up here in the IceBox of the Nation. My truck... I have heat in 5 miles. The ONLY difference we found... ... . Automatic vs Manual. I think the heat transfer at the Oil to water cooler is what does it. The guys in this post that are complaining of lack of heat... . are manual trucks. The Auto guys are offering ideas. I don't have an answer as to how to fix your heat issue. An Espar heater comes to mind as an option, but that is expensive. Good luck!



Josh

 

[bgilbert]

I'll add, after I changed my heater core, Napa unit, which was alot bigger than the original, it gave MUCH better heat. Even during the summer, with no air moving, all heat/ac controls off, I can feel the heat passing through the core from the air vents. Thats when I put a water shutoff valve inline. Looks like if you live in such a cold climate, best to just remove the fan during those cold times, plug in, and partially cover up the radiator. I'd get ahold of Cummins and find out if they have a 190* 12valve t-stat. They put this motor in plenty of different apps, so one has to exist.

 

[TWafer]

Hmmm. A little more history here first. I have owned the truck since day one and its never produced comfortable heat so I don’t think the heater core is an issue. It is a manual transmission though.

Also I ordered it without air conditioning so I don’t have any of those controls.

I've lived with the poor heat for 10 years now and guess I can continue to do so but was just searching for some miracle cure. Apparently it just bugs me when I get to work and everybody else is toasty warm in their vehicles and my windshield hasn’t defrosted yet. At times some of the other guys had other brands of diesels and seemed to have adequate heat as well. They convinced me to replace the thermostat because they thought it was defective. :-laf

I took it to Saskatchewan a couple years ago on a hunting trip where it was 20 to 40 below zero for a week. My brother complained the whole time about the lousy heat in the truck. :-{} It was cool in the cab even driving it all day.

I want to replace the lousy NAPA thermostat at any rate and can live with it as it was before but just wondering since I’m changing it anyway, if a 190-degree thermostat would benefit me at all or even fit for that matter.

On a side note I did just put up a 40 x 80-foot pole barn this past fall and winter (Supposed to have been done long before winter :{ ) but no heat in the floor. Still it was nice to park it inside for part of the winter. :-laf

Tim

 

[mjoppie]

lets get that floor heat in!!



ok my trucks a auto and still has crapy heat just like tim is explaining. on a cool morning (40*) it takes about 60 miles to warm up before i turn the control knob to a cooler setting.



matt

 

[Mundgyver]

Just for curosity how are your water lines to the heater routed Where to you pick you water off at and where does it return. Could this be a flow issue with the design? How much flow do you get through the lines,1 gallon, 2, 3, 4, 5 gallons a minute?? The radiator can be cold, but darn it, the heads and block will be warm and if the hoses are located at the pic and return points that have no flow, then cold it will be, but if you have good flow, you should be warm. So what is the routing please and how much flow/pressure is there

 

[Mundgyver]

Just for curosity how are your water lines to the heater routed Where to you pick your water off at and where does it return. Could this be a flow issue with the design? How much flow do you get through the lines,1 gallon, 2, 3, 4, 5 gallons a minute?? The radiator can be cold, but darn it, the heads and block will be warm and if the hoses are located at the pic and return points that have no flow, then cold it will be, but if you have good flow, you should be warm. So what is the routing please and how much flow/pressure is there

 

[ABorchard]

Tim are you saying your truck doesn't have a recirc position, the one with a cab picture with a u-turning arrow though it?

I'm pretty sure it does. Try it, you'll like it.

 

[TWafer]

Tim are you saying your truck doesn't have a recirc position, the one with a cab picture with a u-turning arrow though it?

I'm pretty sure it does. Try it, you'll like it.

As far as I can tell, No, I don’t. :{

As you can see even in March the heat is turned up all the way. :-laf (It is snowing out however)

See picture below. (I hope)

 

[TWafer]

Hoses

Some interesting points being brought up here. For some reason I’ve never even considered problems with the heater core or hoses. They are as they came from the factory except for a tee fitting I installed to flush the system. I didn’t do this till a couple years ago however and don’t see as it made any difference. Here is a picture of the lines. One hooks into the top of the head and the other to an elbow at the lower radiator hose. I couldn’t get the camera in there for a picture. I assume this is standard. Sound right?

How can I do a flow rate check? I assume they have some way to measure this at a garage?

I'll add, after I changed my heater core, Napa unit, which was alot bigger than the original, it gave MUCH better heat. Even during the summer, with no air moving, all heat/ac controls off, I can feel the heat passing through the core from the air vents.

A bigger heater core!! Now that sounds interesting! Any part # or anything to ID this? Your post slipped in there while I was writing and I didn't notice it before.



Ill add that below 10 degrees I never have to turn the heat down no matter how long you drive it. Doesn’t matter if the radiator is blocked or not. Above 20 degrees to about 45 you would have to drive 50 plus miles before thinking about turning the dial down. The problem then is with the fluctuating temps, especially with the NAPA thermostat you will want it right up again as soon as the thermostat opens and the temp drops like a stone.



Tim