Allision getting warm

Ok, it just started this morning driving to work. Noticed the temps steadily climbing up to close to the 200 mark which is way out of norm for my truck. I read earlier posts on this and I haven't throwing any codes yet. Heard a strange squeak or high pitch sound for just a brief second or so and wasn't quite sure if it was me or not. From what I gathered reading the older post that the converter can warm things up with no codes. So I'm heading over to my buddies transmission shop to see what he can find in the morning. Any other ideas or direction that will help out? Thanks!!

Depending on conditions I expect the average Allison 5 speed to run approx. 100°f over ambient.

Thanks John. It was just in normal morning commute traffic and has never been this high in those conditions since I bought the truck new. Maybe in the dead of the FL summer, in stop and go traffic, it would climb up but not this high. The truck is at the shop now so we'll see what he comes back with.

Stop-n-go city traffic during the hottest months of summer is one of those conditions when the transmission will run closer to engine coolant temperature. It's due to an unlocked torque converter and frequent stops where you're holding the truck still, but the transmission is in drive. It's just due to friction, and is likely normal.

Running in Tow/Haul mode can help, but it might be necessary only while towing at slow speeds.

Thanks for the reply MP. I understand and running in tow/haul mode in that traffic definitely keeps things a litter cooler. Been doing it for years down here. What is happening right now is not normal. I know the temp don't seem extreme right now ( +20 according to John's 100 degree above ambient temp) but something is going on. I've owed this truck from new and know her like the back of my hand. Also, engine temp is holding normal at about 180, which the two always ran neck to neck.

Ok, brought the truck back tonight. They couldn't replicate the conditions on the short trips with the scanner so I'll run it on Monday and swing in after the drive back home. He's thinking maybe a faulty sensor but it still doesn't explain the noise I heard.

I should have mentioned that whenever a transmission problem appears, the usual best first plan-of-action is to do a service (fluid & filter). This allows you to look at fluid quality and level.

Secondarily, as the years tick by, the various coolers slowly lose their efficiency due to an accumulation of bugs and debris. Give them a good look.

MP

Thanks MP. The thing is the transmission was just serviced two months ago. Full fluid change and new filters. Nothing was suspect at that time. We're looking into a flow issue now. I noticed today that while in normal stop and go she'd climb up to the 200 mark but while at highway speed she'd drop back down to normal temps.

As for your second point, everything is pretty much brand new (5 years old) after replacing everything after my accident.

Quote:

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Originally Posted by oneton

... I noticed today that while in normal stop and go she'd climb up to the 200 mark but while at highway speed she'd drop back down to normal temps.

As for your second point, everything is pretty much brand new (5 years old) after replacing everything after my accident.

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What was the ambient temperature? Was the truck towing a trailer? Was the fan-clutch engaging (could you hear the fan roar?) stoplight to stoplight?

MP, no load, just a half empty gang box in the back. Temps yesterday was around 90 degrees. Clutch was just replaced with a brand new unit about two months ago as well. It was one of the last used pieces I bought after my accident that I been wanting to change out. But I have noticed that this one doesn't roar like my original but the engine temp are holding with no fluctuation.

The later model (and OEM replacement) fan clutch is much less aggressive than your original. Apparently, the noise of an engine trying to cool itself was offensive to someone, so they made it less offensive (read: less aggressive, less cooling). Although it may not have an (immediately evident) appearance of less engine cooling performance, the tranny may. You may see a correlation in engine temp once it is exposed to greater climate temps and load. This is a predictable outcome where I live (when an LB7 original fan clutch is replaced), where summer temps frequently approach that of hell. Phoenix (appropriately named) is routinely only about 5-10F higher than we see, for comparison.

The "new" fan clutches seem to engage much softer, and never seem to fully engage. Mine is original (fingers crossed) and roars to beat the band. Others I travel with who have similar trucks with later clutches routinely run much hotter than mine under similar conditions, often 100F+ with near GCWR loads over 6%+ grades. I've seen mine get over 230/230F (ECT/tranny) only once, but the ambient temp was 119F, and after about 5 miles of 6%+. It hurts to have to kill the A/C when it's that hot outside.

I seem to remember John (Kennedy) talking about some fan clutches he sold being very effective. I'm thinking he said they engaged early and solid.
I'm getting old though, I may be imagining this......
Dave

I'll check out Kennedy's site and look DD! Thanks!

Now check this out...last two days I had over 700 lbs in the back and the Allison never got over 150-160. This is driving me mental! lol

Hey guys, just an update on this issue. While doing an oil change a couple of weekends ago I noticed some fluid spray on the underside of the bed from the transfer case. Pulled the plugged and checked the fluid level. Yep, pretty much bone dry. So now I know what the dry bearing noise was. It took almost 2 quarts to fill her up. It's been two weeks now and I have yet to see the 200 mark again. Actually she barely reaching engine temps now. I'm happy now....lol

Uh-oh!

Better get that one under control. I have a friend (an infrequent TDP visitor) who called me yesterday. He was (is) stranded in North Dakota (like somewhere in Egypt) with a blown transfer case on his 2004 2500HD. It dumped the ATF slowly over time, and his best guess is he's been driving it for at least a month, completely dry. As soon as he told me his situation, I knew exactly what it was. Pump-Rub-Hole. He got a replacement TC this afternoon, but is still installing, I think. Anyway, better find out where that fluid went! It doesn't just evaporate.

Oh I know Dmax. Two rub holes in two cases, second one was supposed to have the case saver installed. *rolling my eyes* This one is leaking at the rear yoke. We'll be addressing that next week. Just not sure if it's the yoke or the seal or both. May opt for a undersize seal if the yoke is worn down, if it's too bad I'll spring for a new yoke.

Oneton,
Do a DP search and look for one of my old posts about my TC leak. I have posted it twice. There is a weep hole on the back of the yoke and my truck leaked there. It is an easy fix if you have the same problem that I did.

Good luck
John

Thanks John, I'll look it up.

Oneton,

I hope this helps, I just pulled it off of an old post.

I have posted this before, you can do a search for tail shaft leak. My 2006 was leaking in the same area as your 2001 is. I suspect that your front u-joint is dry (no T case fluid on it) and the rear of the T case is also dry. The only thing that gets wet is the floor of the cab. There is a flat plug in the back of the T case/drive shaft yoke in front of the u-joint with a small weep hole in it. My truck was leaking around the seam of the flat plug. It only leaked when in motion and never left any fluid on the U-joint right next to it. I cleaned the yoke and plug with brake parts cleaner, sand paper and a toothbrush size wire brush. After it was clean I sealed it with JB weld quick dry and it hasn't leaked a drop in more than 100k miles. Additionally, I did seal the weep hole with JB weld even though the leak was at the seam and I also covered the entire area with clear silicon gasket sealer.

You will need to remove the drive shaft to try this fix but you will not leak much fluid. A quick trip to Walmart and $10.00 will get everything you will need. If you try this fix please post the results. If the dealer replaces the seal again and the rear T case bushing I would be surprised if the leak stopped without replacing the yoke.
Good luck
John

Thanks John, that was the post I found when I went looking for it. I appreciate it.