Community Forums

JonathonM · 05-21-2023, 05:49 PM

Just finished my first trip in (new to us) 2007 Hurricane 34B. Its a W20 chassis with allison 6-speed.
On a long uphill stretch in central AZ (HWY-87), the "trans temp high warning" came on.
Trans had just shifted from 4 to 3. I was in 3rd gear at about 3300rpm. Ambient temp of 90deg. Trans temp is unknown. Coolant temp was 210 (185 T-stat installed).
I was not towing but both water and fuel tanks were full as well as typical load for a weekend of camping (nothing heavy but still notable).

I pulled over at the next exit (2-3 miles), stopped, put the trans in neutral and put the rpms at about 1200 to cool the engine and trans fluid down. Engine quickly cooled to 185 and the trans warning disappeared after 10ish minutes. I continued and no warning the remainder of the trip.

My chassis does NOT have an auxillary trans cooler - only the cooler inside of the radiator. Many of my future trips will be into or out of Phoenix in the summer in 100deg+ temps while towing 4klbs. Therefore I would like to install an auxillary trans cooler after the radiator. Trans temp gauge is also being installed.

My questions are these:
1. At what temperature does the trans temp warning light turn on?
2. Has anyone installed an auxillary trans cooler?
3. Is there a "factory" trans cooler for the W20/22/24 chassis?
4. Is there a packaged/engineered auxillary trans cooler system that requires very little frankenstein installation?

donr103 · 05-21-2023, 08:53 PM

Many of us have gone to dedicated trans temp gauge.. like... scan gauge.. or extra gauge.. glowshift.com.. 1st you need to assess the trans oil in transmission.. how old is it... color.. smell.. when was filter changed? See derale.com.. don't push it so hard.. monitor temp and drive as fast with out overheating... remember you are driving a basic Chevy pickup with a house on it..push it too hard.. you could burn it up.. also.. Google transmission oil temps vs trans life.. and make your own informed opinion.. I added an extra derale.com cooler to mine.. and put in lower thermostat.. in engine.. but you decide how far you want to go...
Good luck and keep us posted

dsrtrider300 · 05-21-2023, 09:26 PM

I had the same problem with my 07 W24 with Allison 6pd 2100 trans, There is a Workhorse bulletin about adding an Aux. trans cooler. I did that and added a trans temp guage on dash. Call Brazels and talk to Jon i believe thats where I got the bulletin for the upgrade.

yeloduster · 05-22-2023, 06:39 AM

I had a similar experience when climbing Wolf Creek Pass. In researching transmission cooling I discovered this method of cooling your transmission. Click HERE.

Aluminum is a very good conductor of heat. Notice the large fins that are immersed in the transmission fluid and the corresponding large fins that are exposed to the air flow under the vehicle. It has a port for an analogue temperature gauge sensor so you can directly monitor the sump temperature.

One of my reasons for selecting this way of cooling was I didn't need to cut transmission lines to install an auxiliary cooler, I didn't have to find a location to mount and then mount the cooler and I didn't have to route wiring in case it was fan cooled.

Since installation I've never seen transmission temperature above 200° F. It works REALLY well.

Easy installation and uses the standard Allison deep pan internal filter. If your Allison was hot enough to send the message you should change the fluid. See the Allison Forum for details about doing that and the current recommended transmission fluid.

JonathonM · 05-22-2023, 06:54 AM

Don,
Thanks for the information. Glowshift trans temp gauge is on its way. MH has 16k miles on it. I bought it at 15.5k in Feb. The fluid was low and moderately dark. I changed the filter and drained/filled the fluid in the pan with Transynd. Color now is nearly red. Does not smell burnt. Smells like trans fluid should.
I also run a 185 T-stat.

Dsrtrider,
Thanks, Ill give them a call today.

Yeloduster,
Given the condition of the fluid, do you think it still needs to be changed?
I hadnt considered a deep pan. I think I'll consider it now. Which do you think cools more effectively, the PPE pan or an aux cooler?

Also, does anyone know the type, thread and size of the fittings on the trans cooler hoses?

Flyer15015 · 05-22-2023, 10:43 AM

OP,
I added a PPE deep Tx pan and an oversized filter to my Allison 1000 and it has provision for a temp gage so we added that also. I rewired the 2 pancake fans up front to a 3 way toggle switch and I turn them on at the base of any long pull.
Going over Monarch pass (11+k') we run 2800 RPM in first gear for about 5 miles and the Tx never goes over 195, which my local shop says is fine.

All this pulling an 8K# enclosed car hauler.

Mike in Colorado

JonathonM · 05-22-2023, 11:15 AM

[QUOTE=Flyer15015;6506850]OP,
I added a PPE deep Tx pan and an oversized filter to my Allison 1000 and it has provision for a temp gage so we added that also. I rewired the 2 pancake fans up front to a 3 way toggle switch and I turn them on at the base of any long pull.
Going over Monarch pass (11+k') we run 2800 RPM in first gear for about 5 miles and the Tx never goes over 195, which my local shop says is fine.

Thanks Mike,

Unfortunately mine didnt come with electric fans. Can you post a picture of your electric fan setup?
I have two 12" fans that I planned on using to cool the rear of the engine but haven't installed them yet - might have to repurpose them...

My concern with the deep pan is that while it may be sufficient for most Colorado and monarch pass ambient temps, it may not be enough for 110+ that we regularly experience here in Phoenix. Most shops around here simply put on the biggest cooler/fan that doesn't significantly decrease fluid flow or pressure. If that doesn't work, they add a finned pan such as the one you describe.

Im just wondering if there some combination of "factory" hoses and coolers that will "bolt on"...

JonathonM · 05-22-2023, 11:16 AM

Quote:

Originally Posted by Flyer15015

OP,
I added a PPE deep Tx pan and an oversized filter to my Allison 1000 and it has provision for a temp gage so we added that also. I rewired the 2 pancake fans up front to a 3 way toggle switch and I turn them on at the base of any long pull.
Going over Monarch pass (11+k') we run 2800 RPM in first gear for about 5 miles and the Tx never goes over 195, which my local shop says is fine.

Thanks Mike,

Unfortunately mine didnt come with electric fans. Can you post a picture of your electric fan setup?
I have two 12" fans that I planned on using to cool the rear of the engine but haven't installed them yet - might have to repurpose them...

My concern with the deep pan is that while it may be sufficient for most Colorado and monarch pass ambient temps, it may not be enough for 110+ that we regularly experience here in Phoenix. Most shops around here simply put on the biggest cooler/fan that doesn't significantly decrease fluid flow or pressure. If that doesn't work, they add a finned pan such as the one you describe.

Im just wondering if there some combination of "factory" hoses and coolers that will "bolt on"...

Flyer15015 · 05-22-2023, 11:33 AM

If yours does not have the 2 pancake fans in front of the AC radiator, you can certainly add them and wire them up to a toggle switch.
Summit Racing and Amazon has a bunch to choose from.
Since the Tx is cooled by the radiator, moving more air thru there is always a good idea.

Mike in Colorado

jacwjames · 05-22-2023, 11:49 AM

I have a Allison 3000 in my coach. I started having higher transmission temps after my radiator was replaces and I suspect the company didn't size the internal tranny cooler correctly. I was in Phoenix in 2021 and got stuck in stop go traffic and tranny temps went to +230F. Did not give a warm fuzzy feeling. Also had higher temps when I'm backing into my garage, also got to ~230F. This had never happened before the radiator change.

So I added a Derale auxillary cooler that had the fan and use a 140F switch to turn it on. Tranny temps now stay 170-180.

Last week I took the rig for a drive and backed into the garage, temp went to 178F. I let the rig idle and monitored the temp and the Derale cooler, took ~10 minutes to drop the temp to 140 and the fan shut off.

donr103 · 05-22-2023, 03:49 PM

Imho. You can get more heat removal with large external cooler with a fan.. they are simple to install.. what I do is cut hard trans line with copper tube cutter and slide on 2 or 4 small hose clamps and just slide rubber hose to cooler over hard trans line.. takes no time at all.. ofcouse you need to install cooler 1st.. and although it takes no time,... it's trying to figure out where you like it.. so it only takes 30mins to install.. but trying to position it where it pleases you.. can take time.. all common hand tools.. then if you want a switch for fan..
Then.. and I mean in my opinion.. there is age old question.. do you plum cooler before radiator or after radiator.. everyone will have opinion all over the place..
One thing I can tell you is I have never seen an automatic transmission burn up because it was ran too cold.. but I don't do work in Alaska or Canada.. so I try to run as cool as possible.. so back to age old question.. before radiator or after radiator..?
I don't like to put all that heat into my radiator.. but I want coldest oil running to trans.. so.. what will you do? Plum before or after ?.
I already had one factory plum before radiator.. so I added one after.. on return line..
Tell us what you do... I might think of 2 coolers.. one before and one after.. just an idea.. settling on this question is what will take you more time..
Imho.. use tube and fin style of cooler.. instead of plate and fin..
I just can't believe yours has no external cooler.. it's over 10 ton.. but any way to save a buck.. by the way.. does your engine have an oil cooler on it?
Good luck and keep us posted

JonathonM · 05-22-2023, 05:10 PM

Quote:

Originally Posted by donr103

does your engine have an oil cooler on it?

Oddly enough, it does.

I think the trans cooler may have been an option on the "lighter" W20 chassis. The original owner vacationed mostly in costal and northern Cal so they probably thought they didn't "need" one.

The direction of heat transfer between fluids and air is all relative to the trans fluid out temp. If the goal is to optimize cooling of trans fluid when its temp is higher than the coolant temp (200ish+), the best way to do this is to put the trans cooler after the radiator.

donr103 · 05-22-2023, 07:17 PM

I see your point.. but here is where I am at.. your radiator is 18yrs old and so is trans.. the trans is pumping a lot of btu's into the radiator.. now imho the penny pincher's at the factory.. put just enough size radiator to berly get unit out of warranty.. maybe 36 months.. way past that.. I look at it like this. Trans is a big heat pump and pushed under heavy load.. pumps out big heat. Right into the same system that is already cooling engine and engine oil.. I am not trying to convince you one way or the other.. members posted here radiator job can run 2 or 3 grand.. just saying.. and that is if you can find one.. think of how much heat that radiator is handling..
One thing to check.. is the area between condenser and radiator.. members posted here.. dirt and crud build up there and cuts heat transfer from radiator.. you tube KEVIN CAUDELL.. and you will see what I mean.. you can't see it.. without loosening condenser.. he uses hot water and special tool to flush out Hugh amounts of crud.. and they post similar symptoms that you are having.. just some stuff to consider..
Good luck and keep us posted .. oh.. check fan clutch after cleaning..

bigb56 · 05-22-2023, 07:33 PM

Quote:

Originally Posted by donr103

Imho. You can get more heat removal with large external cooler with a fan.. they are simple to install.. what I do is cut hard trans line with copper tube cutter and slide on 2 or 4 small hose clamps and just slide rubber hose to cooler over hard trans line.. takes no time at all.. ofcouse you need to install cooler 1st.. and although it takes no time,... it's trying to figure out where you like it.. so it only takes 30mins to install.. but trying to position it where it pleases you.. can take time.. all common hand tools.. then if you want a switch for fan..
Then.. and I mean in my opinion.. there is age old question.. do you plum cooler before radiator or after radiator.. everyone will have opinion all over the place..
One thing I can tell you is I have never seen an automatic transmission burn up because it was ran too cold.. but I don't do work in Alaska or Canada.. so I try to run as cool as possible.. so back to age old question.. before radiator or after radiator..?
I don't like to put all that heat into my radiator.. but I want coldest oil running to trans.. so.. what will you do? Plum before or after ?.
I already had one factory plum before radiator.. so I added one after.. on return line..
Tell us what you do... I might think of 2 coolers.. one before and one after.. just an idea.. settling on this question is what will take you more time..
Imho.. use tube and fin style of cooler.. instead of plate and fin..
I just can't believe yours has no external cooler.. it's over 10 ton.. but any way to save a buck.. by the way.. does your engine have an oil cooler on it?
Good luck and keep us posted

I always put aux trans coolers on my stuff. Common practice is to cool the fluid after the radiator and that's how I did all of mine but like you, I also thought it would be good to cool it down some before the radiator. But on the other hand, if climbing a grade and the coolant gets up in temp it will add heat to the trans fluid so having the cooler after the radiator would take that temp back down. I also thought about 2 coolers but a transmission engineer on a truck forum I belong to recommends against that. Maybe he will stop by on this thread as I know he is a member here as well.