Extra Transmission Cooler?

[Mike330R]

I have a Perma-Cool trans cooler w/ a fan on it. I was going to install it on my 1500 but ordered a Dmax.
I am wondering if I should put it on the new truck once it gets here. I use the truck in hot conditions (desert during the summer) and feel it may be needed.

Would it be overkill or is overkill on keeping a tranny cooler a good thing?
Is there such thing as to cold of a transmission?

Thanks for any info.

[77TransAm]

One thing to watch out for is the flow capacity of the cooler - if the cooler is sized for the smaller 3/8" lines that the trans used in the 1500 truck, you may cause a flow restriction in the 1/2" ID lines used with the Allison. If that is the case you'll be worse off than if you had left it alone. Speaking of leaving it alone, we never had trouble in the desert southwest even on the hottest summer days. With the improvements made in the '04 transmissions, things will be even better. I'd vote for leaving the trans cooling system stock.

[Kennedy]

I've seen trans temps around 200-210

[Buck]

I would just put on the Allison deep pan and call it a day ;) . That is what I did and haven't seen temps over 200

[Mike330R]

Thanks for the info. I am pretty sure it is the 3/8 lines.

I will leave it alone and sell this unit.

[David Proske]

Buck,
What are you doing towing 10K with juice in level 4??

[Buck]

I don't see what the problem is with it. EGT's always stay in check, never over 1350

[Mike330R]

Mike L.
What is the name of your shop? I'd like to contact you about more info on this.
Can you send me you number? mike330r@sandbros.com

Thanks!

[jimmer]

Hellow Mike L I have a 04 ally trans what can i do to raise the pressure in 4th & 5th I dont think keeping the trans a little cooler will help keep alive or will it

[Kennedy]

Originally posted by Mike L.:
The new '04 trans has big time issues. Pressure drops by 50% in 4th and 5th gear. We are looking at the problem now. As far as deep pan; get real. 3 extra quarts and an aluminum pan won't do squat for hot fluid coming out of the converter. My '04 Ally heats up fast in stop and go traffic, empty. I see the same thing with my customers trucks. Seems when the air flow stops so does the cooling in the Ally. Two coolers in parallel might be the answer. Deep, good looking pans are a cosmetic bandaid that make you feel good looking at it and showing it off, not much more. I agree on the pans. I run the deep TIN pan on mine. Extra capacity doesn't hurt.

Your statement about airflow stopping goes to my suggestion of a thermostatic electric fan on the OE cooler. A second cooler will do little if no airflow is present...

[Mike330R]

Maybe I could remove the fan from the perma-cool unit and install it on the OEM cooler?
How large is the OEM cooler?

[Lone Eagle]

MikeL, you need to do a little home work if you are going to be a self proclaimed Allison expert on this forum. Any time you increase the oil capacity 10-15% you improve the cooling. The bigger pan adds additional air cooling also. Our trucks came with a short pan for clearance. Allison recommends the deep pan. Two coolers in parallel won't do squat. The majority of the oil will take the path of least resistance unless you want to install a high dollar flow divider.They need to be in series. Later! Frank ;)

[Kennedy]

Move more air across the factory cooler, especially when stopped...

[Lone Eagle]

You should have read a few of my post before bad mouthing Mike. I am a retired Millwright and line mechanic. I specialized in hydraulic troubleshooting. All my experience with coolers was hands on. I started installing after market trans coolers in the early 60s. I am Vietnam vet so needless to say I didn't vote for Clinton. Nothing I posted is incorrect. Now ain't you sorry you read something that wasn't there? Later! Frank

[Lone Eagle]

John, didn't one of the members post about mounting a fan for the cooler? It has been quite awhile ago. The only time mine has gone to 210 was in a lot of stop and go. I haven't had a problem towing my trailer even in July and August. Later! Frank

[SoCalDMAX]

OK.

Here's my take: in 34,000mi of driving, including probably 8,000 towing over the mtns on Hwy 8, I've never gone over 200 or 210, and the higher temps were attained in stop and go unloaded. I have an Allison deep pan and maybe 75% Transynd.

There are a few statements I disagree with or need to understand better.

1. Several members have tried (IIRC) Amsoil and Mobil 1 and experienced clutch slippage with extra power. They switched to Dexron III or Transynd and stopped experiencing slippage at those same elevated power levels. This lead them (and me) to believe there are friction modifiers or similar in Dexron III/Transynd; and other fluids might have too much lubricity for the Allison.

2. I don't understand how a stacked plate cooler can have flow issues. The cross sectional area of even a 24 plate version appears to exceed the flow rate through the fittings at either end of any cooler. It would far exceed a single tube type cooler. BTW, the factory cooler is a stacked plate. If the real issue is fluid viscosity/temp/flow rate then parallel coolers would help.

3. Although I agree with Lone Eagle that parallel coolers of unequal flow rate (restriction) will have differing amounts of fluid, it doesn't seem to be a problem to me. Example: a 24 plate stacked cooler in parallel with an additional 48 plate cooler. The 48 will get more of the fluid (not twice as much, since I think the fittings would be equal size and add some of the restriction) but let's say 60% goes there and 40% goes to the 24 plate... it's all good since the 48 has 66% of the new total surface area, the 24 has 33% and the new total is 150% more than the original setup.

4. IMHO, the Allison deep (tin) pan does help somewhat. Not only does it extend further into the airflow beneath the truck, it also holds 5 extra qts, not 3. The added capacity can only help for fluid longevity, and physics dictates that a larger amount of fluid changes temp slower, all else being equal. What is the original cap? 12qts? With 17qts, one has a little more warning that things are heating up. One might get out of the stop and go traffic before the larger cap. system overheats. My only anecdotal support is I've never felt that mine ever got warm enough to even consider extra coolers. The same pricipal applies to the Mag-Hytek diff cover:(finned aluminum) and doubles diff fluid cap. to 8 qts vice 4. Or the Duramax itself, thus 10qts of oil is better than 5qts.

I'm interested to find out what the issue is with the '04 tranny's. I don't understand why they would have changed something that was working so well.

Regards, Steve

[Lone Eagle]

A lot of good points Steve. I worked on a lot of systems that we needed to add another cooler/heat exchanger and in cases heating coils. Some of these were series and some were parallel. All the parallel systems were a pain to get equal flow through even if they used the exact same cooler. We always had to use metering valves and temp gauges to get them to do equal work. There is no easy way to add an extra cooler, weather parallel or seriesed. Over cooling is a serious problem as Mike stated but I have never seen one blow up. I have seen several large vehicles blow the filters off. That relieved the pressure in a hurry and made for a two day cleanup. I was surprised to find out how little oil our system holds. I am sure GM & Allison did a lot of engineering to come up with this volume. Too much capacity and the trans would be running too cool in mild to cold weather. Not enough and the trans is toast. As I said: Mine works great 99% of the time so I will leave well enough alone. Later! Frank

[a bear]

Lone Eagle said

Mine works great 99% of the time so I will leave well enough alone. Later! Frank
Exactly ! :D

[Lone Eagle]

a bear, I should have said that first and forgot the rest. Later! Frank :D

[Kennedy]

Originally posted by Lone Eagle:
John, didn't one of the members post about mounting a fan for the cooler? It has been quite awhile ago. The only time mine has gone to 210 was in a lot of stop and go. I haven't had a problem towing my trailer even in July and August. Later! Frank Yeah, a guy from TX I believe. I KNOW who it was, just cannot grasp the handle at the moment...

[jbplock]

Originally posted by kennedy:
</font><blockquote>quote:</font><hr />Originally posted by Lone Eagle:
John, didn't one of the members post about mounting a fan for the cooler?... Later! Frank Yeah, a guy from TX I believe. I KNOW who it was, just cannot grasp the handle at the moment... </font>[/QUOTE]IIRC Chris (chuntag95) added a second cooler with a fan...

[a bear]

It was Chris who was doing the mods. He does a lot of inter city stop and go driving and was seeing temps higher than most here. IIRC he often saw temps near 230 degrees. Not sure how the mods. turned out though. Haven't heard from him in a while. Hope nothing bad happened.

Where you at Chris? :confused:

[chuntag95]

Thanks to the guy who told me about this thread. I've been building bunk beds for the kids for the last month straight.
Back to the topic. I put a fan on the OEM tranny cooler. I found that in stop n go, it just didn't cut it. I tried temp controlled and switched without much luck. After talking to Allison's engineering department, the issue is idle flow rates are too low. In 04, a change was made to bump the idle flow up to stop the heat build up in that situation. (It is not a retrofit that can be done on 01-03 as I asked.) The way to solve heat transfer with low flow is remove more heat. I put a larger stacked plate racing cooler in place of my OEM. The tubes are huge and it is very little resistance change, if any. I had to make custom brackets and modify the lines. I can still change back to oem as I got some special quick connect fittings made for our application. They are the Jiffy-Tite to AN-12, which does not exist, except for the 8 I have (only 2 on my truck). Now, this winter, the temps have been slower to warm up, but have gotten up to 130-140. It improve that, just put on the grill cover. I have a Lund plastic that is 6 pieces and I just leave one of the center ones on. :D . The summer performance (Dallas desert of concrete) was great. Never got over around 175. I was hitting 220 almost daily. Now, according to Allison engineering, that's not a problem and you have to get to 240-260 to start an issue. I am to conservative to run that close to the limit. Synthetic fluid will also live much better at those temps as well. That is the normal failure, the fluid cooks and stops doing it's job. Since 90% of all failures are heat related (all tranny's, not Allison specific) I wanted to remove that possibility.

Sorry for the slow response.
Chris

[Lone Eagle]

Chris, how clod is winter down there? Later! Frank

[chuntag95]

We only see low 20's down here. On occation, we might hit high teens. There was only the winter of 89 that I remember sigle digits for any period of time. 7 days about killed me as I was working outside at the time.

If you are in an area that sees really hot and really cold, you can contact me and I will send you some of the quick connects I had made for an AN-12 fitting on an aftermarket tranny cooler (10x13 or so). I only have 3 sets, but should someone want one, I'd be happy to share. What's nice is I could return to the stock cooler if needed and it wouldn't take too much time. I did cut the lines to make everything fit better, but I can put back in the removed parts.

I thought about having a second set of lines made to fit the aftermarket cooler, but the connections and routing of the lines looked like more of a pain than I wanted to deal with to leave the stocks in one piece. I'll buy another set of lines if I need to, but I'm less than 2k from warranty going out on the tranny anyway. My dealer knows I mess with stuff anyway. They found my Mega when I had the priming pump and pressure gauge on it. (I had a battery leak and didn't take the time to pull anything.)

Oh, the thought about second lines was to put in some splices or QD fittings so I had one set that fit with one cooler and another set that fit with the other. I could swap back and forth from the summer or winter cooler as required in about 5 minutes. After watching the performance over this winter, I am getting high enough temperatures to not have to worry about it(~130-140).

[jjackson]

chuntag95 (Chris), would you mind sending me the specs on the larger tranny cooler you installed. I pull a 33Ft/13K 5th wheel. I live in Florida but travel through the country. I have hit 210, but I'm a little concerned that when I'm in some serious mountains I'll be pushing the limit.

Any info you can provide would be appreciated. My email address is in my sig.

Thanks, John