Need transmission advice

[mike.germann]

Hey guys. First off, I gotta say that i LOVE my SD. DEFINITELY some of the best looking trucks on the road. I wouldn't trade it for anything. However, it seems like all I've done since I had it...is put money into it. Specifically, the transmission. And I'm a little down about it. I'm wanting to make my transmission run as efficiently as possible, and like everyone else, make it last as long as possible.

After the recent trans-rebuild during a 4,000 mile road trip, my trans was spiking. Up to about 240* (YIKES, i know) After investigating, I found out that my trans cooler wasn't changed.

I realize that oil breaks down at high temps. And that I probably shortened the life life of my transmission, without knowing. NOW I'm very conscious and very concerned about the health of my transmission, especially since my wallet suffers more than I do...

Almost every time I get in the truck, I'm thinking about the transmission. Seems like there's WAY too many variables that break down transmissions, and I guess I'm always concerned that I'm hurting my trans.
(dropping $3000 in the trans rebuild made me very concerned to keep it healthy, I just don't really know the best way to do so...)


I was told to change my trans cooler. I just bought a Tru-Cool MAX trans cooler from DieselSite. Paid $128 for it, and should get it sometimes this week. A cheaper alternative to buying the 6.0L cooler, even though that's what I really want.


https://www.dieselsite.com/index.asp?PageAction=VIEWPROD&ProdID=205

I have another cooler (a cheap one from Advanced Auto) that's rated for vehicles towing more than 10,000 pounds. Even though I don't do any towing, I wanted all the cooling I could get and I plan to install both of these coolers in series to help keep temps low. Any advice on the install?

I'd also like to use Royal Purple ATF because I hear it's the best, if I can afford to (i have an ATS deep pan)...$$. Where's the cheapest place to get this?

I assume I need to change my trans filter, too. Anyone have any recommendations of what brand or store/website to get this?

Also, any maintenance advice for 4r100 transmissions? I'd rather do preventative maintenance than drop thousands of dollars to fix it. AGAIN.

PS. Any advice helps. I refer back to these forums DAILY, and definitely appreciate the support.

After reading dozens of horror story forums and from practically killing my trans in just a few months of owning this truck, it's humbling knowing that all I know is that I know almost nothing at all.

PLEASE HELP.

 

[WD40]

Mike, sorry to hear about your transmission and the fact that the person who rebuilt it didn't do a full job by replacing the cooler and making sure it was working right before it left his or her shop. That being said it to late for you to do anything about that now.
So if I were you I would change the ATF and make sure you get it all out and put all new fluid in and RP is a good one from what I have heard. Brians Truck Shop only uses Schaeffer's in everything he rebuilds.
So I know that it's good and has a longer life than some of the others out there.

I see you are running big tires and that puts a lot of stress on your transmission and other parts of your truck. It would be better to have a V/10 or a 6.0 cooler on your truck, but you have all ready spent the money on the new one's, hope it works out for you, and yes I would put them in line after you get the new fluid in.
Good luck and hope this helps some.
Doug

 

[JLDickmon]

or even that aftermarket cooler piggybacked on what's already there..

but I agree..
you have a lot of stress going INTO the trans with your setup, and a lot of stress on the backside with the 38's..

and about the best you can do is keep the fluid clean and cool...

 

[BJS]

I have another cooler (a cheap one from Advanced Auto) that's rated for vehicles towing more than 10,000 pounds. Even though I don't do any towing, I wanted all the cooling I could get and I plan to install both of these coolers in series to help keep temps low. Any advice on the install?

I would highly advise against installing them in series. The problem comes in that there can be too much of a restriction on the flow making the transmission work to pump the fluid through the coolers. With the one you just ordered and put it in series with the oil-water cooler in the radiator you'll have plenty of cooling, if you're still spiking high temps you have a trans problem even with your newly rebuilt transmission.

 

[mike.germann]

This may be a dumb question, but if were looking at the front end of the truck, which one of these coolers is the oil-water cooler in the radiator?

Another question: if that's correct, how do people run an auxiliary cooler and not have problems with fluid flow?

Ps. I think I forgot to mention that I'm taking my stock 7.3 cooler out, replacing it with the cheaper Advanced Auto cooler, and then use the Tru-Cool MAX cooler as my auxiliary.

Is that a better setup? Or still too much resistance to fluid flow?

 

[BJS]

your oil water cooler is in the radiator. the trans line will go from the trans to the radiator then out to the oil to air cooler. The trans has the power to put the two in line just not to many more The oil to water cooler is basically a tube going through the tank in the radiator but it helps if you're moving slowly or don't have fans on the oil to air coolers.

If memory serves me right the early '99 trucks were the only ones that came from the factory without the oil to water cooler in the radiator but I might be mistaken and it could be all '99 trucks.

 

[mp18d]

I have this theory...

when I bought my pickup, it had 45,000mi on it. Box stock. At about 140,000 I flushed the trans and noted fluid coming out the rear port of the transmission, meaning the cooler bypass was plugged. Never did notice any signs of overheating with the stock trans temp gauge. Changed out the bypass and added Dieselsites cooler.
At about 200,000 put an aftermarket temp gauge on it. Ran around 140-160 even with a big load behind, pulling up the passes here in the Sierras as well as out of canyons with livestock. Still no change in the factory gauge.

Now at 225,000 I have noticed that the trans temp is running about 160-180 up to 190-200 in traffic (if I go to Sacramento or Reno where there is traffic) I drove up the backside of Donner Summit, an old 2 lane road winding, bypassing I-80. It's steep, and slow what with the cyclists and all. Temps jumped up to 210-220 but as soon as I hit the freeway they went back down to 140-160. Still no movement in the factory gauge.

I believe the cooler bypass is plugged again, will change it out 2morrow with a new flush.

I think the cooler bypass routinely plugs somewhere around the 100,000mi mark, give or take but folks never know it cause there is no change in temps according to the factory POS gauge. The damage is done to the fluid and thence to the tranny. My pickup is not hotrodded at all but often times works very hard. I have no signs of any trans problems, the thing has (knock on wood) never been touched other than the 1 flush and new cooler bypass....
My theory is the plugged cooler bypass leads to problems we haven't been aware of.

My .02 and worth about what ya paid for it!


Mike

 

[JRJ04]

I wasnt aware of the bypass causing overheating issues... My understanding was that it aided in warmup...anyone care to chime in?

 

[mike.germann]

Thanks for the info, mp18d! Good info.

I understand how high temps kill the fluid, and later kill the trans.

This is pretty shocking, but during my 4,000 mile road trip after my rebuild, temp guage climbed to 250*. (really bad, I know). Ambient temperature was 100* or so. I was told the it was just the gauge giving a false reading and that I shouldn't be worried, but when I used a thermal gun to test it, it was only 4* off...meaning my trans really WAS that hot.

I need to change my fluid, asap. Need to make time for it.

I was thinking maybe I need to have the transmission taken out and inspected to ensure everything is intact, seals, etc,.

 

[BJS]

I wasnt aware of the bypass causing overheating issues... My understanding was that it aided in warmup...anyone care to chime in?

to the best of my knowledge there are no thermal sensitive (thermostat like) items in the bypass only a pressure sensitive spring. IE when pressure is too high it bypasses indicating a plugged cooler stack. This keeps the rubber lines from rupturing or disconnecting when the cooler is plugged or other obstructions are seen such as a kinked cooler line. However a spring that sees pressure cycles will eventually wear out.