We got to take the truck to the mountains for the first time yesterday. It performed well in the climb out of Denver better then any of our other trucks had. We took a narrow dirt road out of a small town going over another pass. During this climb the tranny temp climbed to about 200. At this point we noticed a whine/noise that sounds just like the "cold whine" that the manual discribes. This noise contined for the rest of the day even when the temp dropped to about 150. Also the tranny did not seem to cool off much even when we started down and it was not working hard. The noise was not there today when we drove the truck after giving it a normal warm up.

Is this a normal noise that we should hear when we work the tranny?

Should the tranny have cooled off as we drove during the day?

My concern is that we are going to haul a trailer this summer and is this something we should have looked at or is it "normal". We have not had a diesel before and not pulled a trailer so these types of things worry us.


Thanks for the help.

Barkeep

Does the noise seem to change pitch at all with engine/vehicle speed? Can you make it go away or change by changing gears? Is it there at idle also? In park?

Does the noise seem to change pitch at all with engine/vehicle speed? Can you make it go away or change by changing gears? Is it there at idle also? In park?

The noise got louder as the transmittion approached a shift point. After shift it droped off a bit then came back for the next shift point. In overdrive it was not as noticible but still there. When we manually geared down (on the downgrades) the noise was there at each shift point both 3rd and 2nd.

The noise was not there in idle or park.

We did notice the noise again this evening but it was the "cold transmission" noise that is always there when you don't let it warm up enough as we did not in this case. It went away this evening as soon as the truck warmed up.

I hope this helps.

Thanks for the reply.

Barkeep

So the noise seems to be related to trans speed, not engine speed or vehicle speed? Oh wait, you said it lowers after shift points? Maybe it could be engine related......Hmmmm

My wife and I were just talking, and think we might have first heard the noise on the freeway up the mountain out of town. We were toward the top a 6% grade that took us about 20 minutes to climb. She was passing and wanted to see how the truck would pass and pull the hill at the same time (she put her foot in it (she says like the NHRA <grin>)). As we passed the Ford I heard what I thought was a scream. I thought it was the Ford but maybe it was our truck. We noticed the sound for sure when we started up the dirt road at a 9% grade 30 minutes to climb. It continued for the rest of the trip.

She was doing about 65 mph and finshed the pass at 80. She says that she was really impressed with how well it accelerated and passed on the hill. We just hope we did not hurt it.

As I said, we have not heard the same sound today except for when the truck was driven without warm up and it went away in about 5 minutes driving to church.

Hope this helps and thanks again,

Barkeep.

Could it be the engine cooling fan kicking in on the hill? It would also make the same noise as the engine gets up to its normal operating temp...http://www.dieselplace.com/forum/smileys/Embarrased.gif

I wonder if it is not the same powersteering noise i am getting. I hear my noise during upshifts and downshifts. Noise comes in after i have been on hyway at higher speeds for a while. Noise goes away after truck sits over night and won't come back till next hyway trip.


mike

Cooling fan makes sense.. You have a weird p/s noise dont you Mike, havent really followd your thread...

Eric


there are a few of us here with my powersteering noise. One of our members had a new pump installed at the dealer to solve it.

Mike:

Thanks for the input. I will have to check with my wife and see if she noticed anything with the steering.

Sounds like we will just have to take another trip up into the mountins and check it out http://www.dieselplace.com/forum/smileys/Clap.gif . It might be a week or so but I will let you know if it comes back.

We had not heard this noise on any other trips and we have done many hours at freeway speeds.

No one answered about the tranny temp not dropping. Is it normal that once you get it warmed up to 200 it just stays there until it is off for a while? I know it's not high but I thought that once we got down to the flat land it should have cooled off again. We drove for over an hour and did not see much of a change.

Thanks for the help,

i would bet its the fan clutch.. that's how i would describe it.

Hey guys..


First post.. Good to be here :)


Well I ride a full sized bus every day (shutle to the parking lot).


I noticed that this thing ALSO WHINES THE SAME WAY but the difference is it whines ALL the time!When Turning & Accelerating, the whine is especially loud. Also, the whine is definitely related to the transmission speed.


Best of all.. I heard that noise about a year ago and its been running 5 days a week almost continuously since.


It does a 1.4 mile trip with LOTS of stop lights and much time in 2and 3rd gear.


The drivers dont know anything but every time I ride it, it gets me curious.


ram

I drive the mountains everyday (30-40mph type roads, 5 to 10% grades). Just started hearing the 200deg WHINE on hot days, after a bit of a climb. Sounds like transmission slip, but the RPM's don't go up, and no loss of power, but the tranny makes a racing sound, and its LOUD. The WHINE goes away when the tranny cools a little. Also, using tow mode seems help keep me from hitting the magic temp threshold... I'm convinced this is temp related tranny noise. And I do get the same sound when she's cold...


I am definitely looking into this some more...


I read something, somewhere about a mode the tranny uses to help cool itself down, can't remember where I read that... any thoughts?

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<A name=232></A>attached a bit From the Allison Q/A on GM stuff... So - if the torque converter clutch does not apply (what does this mean?), that just raises the RPM's a bit, right (slips)? Would it make a racing sound? If high temperature was causing the TCC to "not engage", what would happen?


Anyway thought it might explain the sound when cold. The Cool Down mode I remembered is also mentioned at Allison, and is only a shift profile engaged at 250deg...





Q. Shift Delay - Why does my transmission seem to "hang" or delay upshifts when cold? (Diesel powered trucks only)</A></TD></TR>
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<TD width="95%">A. On diesel powered trucks, the Allison transmission has a feature to shorten engine / cab warm-up times. This feature is called Heater Performance Mode. This feature raises part throttle upshift points (2-3, 3-4, 4-5) to increase engine speed when cold weather conditions are detected. In addition, the torque converter clutch (TCC) will not apply below a transmission sump temperature of 31°C/88°F. This also aids in warming the cab more quickly. Under these conditions, it is normal to experience upshifts that seem to "hang" or be delayed.</TD></TR></T></TABLE>