Run hot ATF thru heater core for faster cab heat

[Dennis Garrett]

Kansas winter #6 coming up fast for me & the Red Ram. On my 45 min. trip to work I freeze my butt off for 15 minutes waiting for the heater to do it's thing. At the same time, I'm looking down at the transmission temp, and within a couple of miles, it's sitting on about 150 deg. That's about as warm as my Cummins engine ever gets, when it finally does warm up. Why hasn't someone figured out a way to route the hot ATF from the converter, into & out of the cab heater core before it goes through the trans cooler? Why do we have to heat the cab with hot antifreeze, when we have just as hot ATF much quicker? It would require some kind of change over kit with valves & a little extra hose to regulate the heat, & and when heat is not needed, route it the normal way thru the trans cooler. Those of with Auto trannys could have a cold weather advantage over the stick shift guys! I smell a business opportunity someone here for somebody.

 

[illflem]

Dennis, great idea, I can see no problem with it whatsoever. Try running fanless in the meantime, it's an easy job with excellent results.

 

[Whitmore]

What about the pressure ? how much psi is on it now and how much is on the trannie???

 

[Dennis Garrett]

I'm not sure about the pressure, but maybe volume might be a concern. When I added my spin-on filter to the hot line going into the transmission cooler, I had to add about 3' of common 3/4" transmission hose, It's held up fine for five years with plain old hose clamps. I don't think there is very much pressure going to the cooler anyway, I've pulled that hose, aimed it in a bucket, and pumped the fluid out in "N" when I change it. There's flow, but not much pressure. This might be an interesting & worthwile project if I knew more about it. Is the heater core really built that much differently than the trans cooler? Maybe we wouldn't need full flow through the core, just divert some of it?

 

[tgbol]

In the mid 80's GMC offered an air cooled Deutz diesel in their 60 and 70 series trucks. Because it was air cooled they put an engine oil cooler in the heater box and ran engine oil through it to heat the air. GMC trucks don't use a control valve they just divert more air through the heater core to regulate the heat. I think the Dodge is the same way.

 

[Diesel Freak]

I can see it now... . a ruptured heater core with ATF all over the floor of the truck

 

[Dennis Garrett]

I guess that's a point, an even worse mess than antifreeze. I had an old 84 chevy with the 6. 2 diesel. It had almost the same hydra-boost unit my Dodge does, to run the power brakes & steering. That thing was constantly leaking, allowing PowerSteering fluid to leak back along the rod to the brake pedal, and eventually soaking the carpet & pad. We finally had to replace it. This idea might require replacing the original heater core, or maybe adding a seperate one specificaly for oil with blower, behind the seat or someplace.

 

[illflem]

The return line to the AT should have the same pressure as the pan - zero. The only pressure build up would be from restrictions such as the heater core or tubing. ATF might even be easier on the system than coolant, leak not as likely. Will also give you more ATF capacity for a cooler running transmission not to mention an additional cooler. If you tie into the heater hoses at the T-stat and the AT cooler return you will only need 5 ft of hose, some couplers and clamps. Need to also make a U hose for the disconnected heater lines. May also want to flush the heater lines/core with ATF to remove all coolent. Maybe the ATF after the trans cooler is too cold? Or would you use the fluid before the trans cooler? No heater in Park. Somebody do it!!!!

 

[Evan A. Beck]

I'd avoid it... The pressures are going to be too high for the heater core. Start your truck 15 minutes before you leave for work instead. Use your block heater too!

 

[The patriot]

I dont have an auto trans in my truck, but in my last car, when the TC locked up, the temp would go down to the outside temp. After a 45 mile ride on the interstate, you could put your hand on the side of the trans, and it was cool.

Does TC lockup effect the oil temp on these?

Eric

 

[illflem]

Eric good point. The TC doesn't lock up until the ATF reaches 80°, even on a 400 mile drive entirely in OD lockup, in cold weather my AT temp never drops below 120°, but this is before the cooler.



Evan, cooling return to the trans goes to the pan = no pressure.

 

[Dennis Garrett]

Here's another idea. I think an aux. trans cooler with electric fans might just fit behind or under the passenger heat. Run the electrical under the carpet to the batteries or fuse block, and bring the transmission lines up through a couple of holes under the seat to the cooler. This way you could keep the factory heating system intact, and use the trans cooler under the seat for quick warmup, until the engine warms up enough to provide the cab heat. Someone out there might have an idea how to run the plumbing, so you could control or turn off flow to the cooler under the seat.

 

[illflem]

Dennis, I feel if you are going to go though that much hassle and expense you would be better off buying a 12 volt electric heater. I've seen many, they are around $50. Still into the ATF though the heater core idea though and have asked Bill K what his feelings are, waiting for reply.

 

[lgibson]

12volt heat

On my Isuzu PUP diesel, I just use a good quality 12 volt heater with a good blower motor. The truck is up in Alaska and the engine never warms up even with the fan off and the radiator completely wrapped, and a heat blanket covering the underside of the engine. So I just use the 12 volt power. I can remember the brand name by maybe someone knows a good one. That Isuzu starts every time and has never failed to start and idle. And has always ran perfectly in over 200,000 miles.

My CTD I use a remote starter and start it 15 to 20 mins. before I go anywhere. It is still cold when I first get in it, but warms up fast once I drive it down the street.

This is in extreme cold so it will work for you on the outside.

 

[Evan A. Beck]

illflem, there is pressure (not sure how much) in the lines... I have seen them blow off before. Makes for a herendous mess. Disconnect one while the truck in is gear, and you'll see.

 

[Jeff H]

Insall it more like a helper

Just leave the heater core as it is. Use your oil cooler. Just box in the oil cooler. Then duct it in to the intake of your blower for your cab heat. Something on that order any way.

Ya it is a cold ride. But I just put up with it.

 

[fest3er]

Originally posted by Dennis Garrett

Kansas winter #6 coming up fast for me & the Red Ram. On my 45 min. trip to work I freeze my butt off for 15 minutes waiting for the heater to do it's thing. ...

You can do a few things to shorten the heat-up time. First, use the block heater, turning it on 2-3 hours before you start the engine. Next, after you start the engine, pset the parking brake and put it in gear, and use a throttle stick to run the Rpm up to about 1100 for 2 or 3 minutes. Lastly, use a piece of cardboard or 1/8" closed cell packing foam to block 60-70% of the radiator, at least leaving the P/S and trans coolers uncovered. I found I could get some heat after 5 minutes when I was in No. IL when the temp was 0F or so, and was getting good heat after 10 minutes or so.



As to the TC not locking up, mine has *always* locked up in D and OD as soon as I got up to lockable speed, even without a pre-warmup. Go figure!



Fest3er

 

[Dennis Garrett]

I tried a 12 volt heater a couple of years ago, it was a joke for the cu. ft. of the Ram cab. I've tried taking the fan off, not much better. I always put cardboard over the radiator except for the transmission cooler when it's cold, even changed the t-stat. Problem is, after about 2 miles, I'm on the highway, & once I'm out there doing 75 or so, at 0 deg. it's even harder to get it warm up. Idling 15 min before I drive it? No, still really doesn't warm up if stone cold, & I don't have time for that anyway. I do plug it in at home, & that helps, but when I leave work in the middle of a Jan. night & it hasn't been plugged in or started for 24 hrs, I just have to live in it for 15 minutes until the heater does anything. It's been like this since it was new. The more I think about it, I think a blower equiped transmission cooler mounted under or behind the pass. seat might be the answer. I'll need to shop around & find the right fit, and then dream up some kind of plumbing system that works. Might even solder the connections inside, to avoid leakage/seepage. Also got to figure out how to wire it & where to mount a switch. It's starting to sound like work, but it might be the answer!

 

[illflem]

Dennis, just in case you haven't figured it out, if you run the heater on Recirc it will warm the cab much faster.

 

[HC]

When you consider how much more surface area a radiator has than a typical transmission cooler, you have to believe that the engine creates a lot more waste heat than the transmission. I suspect that if you tried to tap the transmission heat, there might not be enough to go around, and even if you do get enough cab heat you might end up running your transmission at cooler temps than you really should. Putting it another way, just because the cigarette lighter warms up really fast, doesn't mean it can replace a 1500 watt space heater. I could be completely wrong, but, it's something to consider before spending too much money, especially given there are some "proven" alternatives.



I orginally wanted an ESPAR heater, which I think is the best solution for really cold climates, but since I live in the South I ended up getting an exhaust brake instead. It can be used to speed warm-up in the winter, and I get the daily benefit of having the brake 365 days a year. It's also cheaper and simpler, so I think that will translate in to less chance of problems on down the road. JOMO



12V heaters:

http://www.4x4store.com/Steel-H/index.html

http://www.therm-tech.com/

These require about 25 amps, so you'd probably have to run a fat wire, not just use the lighter plug in. Also, they only put out about 1100 BTU - so thats about 1/4 to 1/5 of a typical room space heater, and less than 1/10 of the heat an ESPAR puts out. But remember, the ESPAR heat is not immediate; you would want to set the timer to come on about an hour before you leave for work.