high transmission sump temperature?

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high transmission sump temperature?

April 11, 2014, 02:01:19 am

For my first five years with this coach, I never had this happen.

But for the past year, ever since I started towing the MDX, I get about five minutes of annunciator beeping commencing about a minute after reaching the bottom of the Grapevine and getting off the retarder. No idiot lights and all gauges normal except transmission temp just slightly elevated.

What's up?

Re: high transmission sump temperature?

Reply #1 – April 11, 2014, 08:44:16 pm

Not sure what's tougher Grapevine or headed North down the valley into Derango.

If your are using the Allison ATF it does a better job of helping out the transmission when one gets stressed (HOT) using the retarder. I'd suggest dropping a gear or two, slow down a touch and enjoy the view to avoid overheating. pc

Re: high transmission sump temperature?

Reply #2 – April 11, 2014, 09:07:12 pm

Boring note I know but with usinf Amsoil Torque Drive in Allison I never get hot and I fly up the Grapevine no big deal. Been up and down it many times.
Believe it.
JohnH

Re: high transmission sump temperature?

Reply #3 – April 11, 2014, 09:19:28 pm

Agree on the synthetic transmission fluid allowing me to not have to worry about having to constantly adjust the retarder (though I have a fairly lightweight 34' coach).

The last trip I took with the older fluid had the transmission temp light/buzzer going off constantly when descending in the Rockies. Since changing over to synthetic, I have no issues at all over the same areas of the Rockies.

Re: high transmission sump temperature?

Reply #4 – April 11, 2014, 09:28:13 pm

Slow down a bit going up and your Silverleaf helps a lot there too. On the down side ride, gear down another gear or even two and then the retarder does not work as hard either. I have run long grades up and down all over the country. Eisenhower grad into and out of Denver in the middle of the summer is tough. Less air to pull across the radiator at altitude and the heat of the day and then pushing up and then down. Synthetic lowered temps on the same road at the same time of year over 20 degrees.

Re: high transmission sump temperature?

Reply #5 – April 11, 2014, 10:02:44 pm

I did use lower gears and slowing down a tad, but made no difference. I like the idea of synthetic and will give that a try next service. I knew it was more tolerant of high temperatures, but didn't know it helps keep temperatures down. Good to know.

What are my options in synthetic atf?

Re: high transmission sump temperature?

Reply #6 – April 11, 2014, 10:33:15 pm

With the Allison, their Transynd would certainly be at the top of the list.

And to reduce transmission temperature while producing the same braking HP, down arrow to a lower gear to raise engine RPM. This along with a lower retarder setting will both produce less heat AND the faster-turning water pump will help dissipate the heat produced.

Re: high transmission sump temperature?

Reply #7 – April 11, 2014, 10:40:39 pm

Quote from: wolfe10 – April 11, 2014, 10:33:15 pm

With the Allison, their Transynd would certainly be at the top of the list.

Tom's 2003 should have come OEM with Transynd as well, per a Foretravel Service Bulletin

From Barry's site:

Transynd Fluid change interval

Re: high transmission sump temperature?

Reply #8 – April 11, 2014, 10:43:24 pm

I did try downshifting to no avail. I will give Transynd a go when I get back home.

Re: high transmission sump temperature?

Reply #9 – April 11, 2014, 10:51:50 pm

I have gone down hills in 2nd gear before with the retarder. It was a long steep downhill and it did not overheat. I know that there are always differences but it was lower then it would be in 4th or 5th gear.

Re: high transmission sump temperature?

Reply #10 – April 11, 2014, 10:56:31 pm

Coach had \Transynd in and I changed it, like it better now.
JohnH

Re: high transmission sump temperature?

Reply #11 – April 12, 2014, 10:34:10 am

I've read that Transynd won't cause a transmission to run cooler but will allow the transmission to better tolerate high temps.
jor

Re: high transmission sump temperature?

Reply #12 – April 12, 2014, 11:33:09 am

There is downshifting and then there is downshifting. For maximum engine braking you should be 10% above engine red line. So if your engine's governed max speed under power in 2500rpm, you can go to 2750rpm while going down at zero accelerator.

Re: high transmission sump temperature?

Reply #13 – April 12, 2014, 01:08:45 pm

Is the concensus that transmission temp is the cause of my beeping? It doesn't start until a minute after I stop using the retarder at the bottom of the grade but am still coasting and doesn't go away until after a few minutes with normal throttle. Downshifting and retarder still work normally during the beeping but don't make it stop.

Re: high transmission sump temperature?

Reply #14 – April 12, 2014, 01:57:07 pm

Quote from: jor – April 12, 2014, 10:34:10 am

I've read that Transynd won't cause a transmission to run cooler but will allow the transmission to better tolerate high temps.
jor

I read the same thing but I did see cooler temps on a hotter day on the same route.

Re: high transmission sump temperature?

Reply #15 – April 12, 2014, 03:57:45 pm

Tom,go to the member list and look up Gary Omel, go to show posts and look for post 101, it has good info on hi trans temps.

Re: high transmission sump temperature?

Reply #16 – April 12, 2014, 04:13:20 pm

Quote from: John S – April 12, 2014, 01:57:07 pm

I read the same thing but I did see cooler temps on a hotter day on the same route.

I couldn't tell if my old transmission fluid was just degrading and not able to transfer/remove the heat or if the synthetic was just far superior in transferring heat, but the end result was a much cooler transmission reading and no beeping coming from the dash.

Re: high transmission sump temperature?

Reply #17 – April 12, 2014, 09:42:38 pm

Quote from: Bill Willett – April 12, 2014, 03:57:45 pm

Tom,go to the member list and look up Gary Omel, go to show posts and look for post 101, it has good info on hi trans temps.

Sure hope that's not the case.

Re: high transmission sump temperature?

Reply #18 – April 12, 2014, 09:46:40 pm

Come Monday I'll find out if it still has Transynd and when last changed.

I'll all is well, I'm guessing the heat from the retarder is dissipated just fine as long as the transmission is downshifted and i have added cooling, but when i reach the bof the m

Re: high transmission sump temperature?

Reply #19 – April 12, 2014, 11:51:55 pm

Tom , I don't write very much but feel this time ,my thoughts might help. Whether you have Transynd or not is not going to "fix" your problem. It sounds like you have run the grape vine several times without problems and now,, you have a beeper and a panel light, long after the hill. Something has changed.
I believe I was told that Allison has three temperature probes. One or more of them is seeing hot oil and it is not being routed to the cooler.
When in retard function , there is a spool valve that blocks all transmission sump oil from the cooler. Only the oil in the retarder goes to the cooler and returns directly the the retarder. On the 2000 and older coaches , an aggressive down hill with full retard will show high heat on the trans mission gauge within seconds because that probe is right at the retarder outlet and,, the system is only using a small percentage of the total trans oil. When retard is off,, the valve shifts and the hot oil mixes with the sump oil and the temp drops rapidly.
I "believe" that in the early 2000's ( 2001,2002'2003 ) that transmission dash gauge was hooked to a different probe so the later coaches won't show the fast gauge reaction. Retard feature pros and cons When properly programmed,,the Silverleaf will.
You have hot oil somewhere due to valve body routeing and / or poor cooling circulation due to blocked cooler, low lube pressure, internal leakage, etc. This NOT problem to guess at. I highly recommend you find an Allison "factory" shop and have them hook their computer to the port ASAP. It is amazing what they can learn for $150-$200
Valley Power in Sac. has ,or had, a very sharp tech that knows retarders.
I don't compose and type very well so if you would like more info,, please call any time
Gary O 615-849-2377

Re: high transmission sump temperature?

Reply #20 – April 13, 2014, 07:55:16 pm

Had the same thing happen about a year ago. Took it to an Allison tech service. Nothing diagnosed bad on the computer. They told me it might be a bad sending unit on the transmission. They sent me one, put it in myself. No more problems.

Re: high transmission sump temperature?

Reply #21 – April 16, 2014, 01:12:42 am

We made it home without incident. The southbound Grapevine is not as steep as the northbound and has never given us problems. We downshifted to fourth and lightly used the retarder to keep the speed at 55. Transmission temperature went no higher than 215, the same as my previous northbound run.

Earlier today I used the keypad to check fluid level and fault codes, all was good. It may be nothing more than just slightly overheating it on the Northbound runs towing the MDX, but I will take it to Valley Power next week for a look-see.

Re: high transmission sump temperature?

Reply #22 – April 25, 2014, 01:43:01 am

I took the coach to Valley Power today. The service manager has been there 18 years, and thought I was confused saying I had a motorhome with a retarder. Must have been the first Foretravel to cross his driveway. At least there were lots of fire trucks there, so he knows his business.

Anyway, he found nothing wrong. The computer said all was ok, no stored faults. The transmission fluid was Transynd ( he could tell by looks and smell), and looked and smelled like new...no overheating.

So he sent me on my way. Next time I take the Grapevine northbound (soon), I will have the VMSpc telling me the retarder temperature along with the transmission temperature, so will know more if the beeping reoccurs. But it may not, as I plan to downshift to fourth instead of leaving the transmission to make the decision, so the retarder should have less work to do.

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