It's so cold..........

oiler · February 06, 2008, 11:01:14 PM

A bit O/T but interesting for Crosley and guys with new GM's
With the -40C weather last week a interesting problem cropped up with 06-08 GM Duramaxes
Last Tuesday 3 08's were towed in with inop. trans.
Wed saw 4 more towed to our dealer and we now have a total of 18 inmovable trucks.
Some dealers have had upwards of 40-50 come in.
Seems a "smart" engineer decided to toy with the programming of the new Dmaxes
The owner is able to engage a high idle on the truck in cold weather via steering wheel controls to help with a faster warmup
GM decided to engage the torque converter clutch on high idle and stall out the torque converter thus making heat and transfering the heat through the trans cooler to the rad.
As it turns out he new dexron is gelling at -40 and plugging the cooler thus smoking the torque converter and damaging the pump and input shafts
repair estimates are $5600 per truck vs $3800 for a reman trans.
problem is theres none available and it looks like a 5-6 week wait for trans parts and the same for a reman to show up
Can you say POed customers?
Jeff

chimp koose · February 07, 2008, 12:47:47 AM

Isnt it amazing what a little technology can do for the average guy?

UGLY OLDS · February 07, 2008, 06:13:40 PM

Jeff...Do they have a bulletin out on this yet :?: :?:
Thanks... Bob..

jaybee · February 07, 2008, 06:50:15 PM

As usual all it takes is just one more variable than the engineer condidered during design.

Crosley.In.AZ · February 07, 2008, 10:51:59 PM

interesting... are block heaters used in these applications?

I would think the diesel fuel would not like the extreme cold temps

junkyardjeff · February 10, 2008, 08:02:28 PM

I always thought when its that cold they left them running all the time.

oiler · February 10, 2008, 08:26:04 PM

No there isn't a bulletin as of yet but I see one coming
The Dmaxes are actually very good in extreme cold and they all have block heaters.
I've started them up in -35C on the lot without being plugged in and they actually start quite good
They use pilot injection so that a very small spray at hi pressure (40 thousand PSI) is injected on cold start and that makes it very easy to light off the diesel
Thats the reason a Dmax will not rattle and bang on startup like the Fords and Dodges
The trans problem has only happened when the guys have left them running all night.
Come out in the morning and the truck is warm but no trans left.
Too bad too cause up till now the Allison has had a bulletproof reputation.
Jeff

Crosley.In.AZ · February 10, 2008, 10:14:53 PM

interesting... the trucks run / idle all night and the trans fluid still gels up?

:?

Fat Cat · February 10, 2008, 10:47:48 PM

Why aren't they using Transynd in the Allison's? All the big allisons I work on have Transynd in them.

oiler · February 10, 2008, 11:20:12 PM

Apparently the Transynd has a pour point of -46 whereas the Dexron is -45
Not a big enough difference to justify the extra cost (according to GM)
You should see this fluid when it comes out of the lower cooler line
It's got the consistency of Jello
The upper cooler line and the trans will have clean normal dexron in it
The torque is blue as is the stator support and the oil pump is normally split in half from the heat buildup.
Jeff

wayne petty · February 11, 2008, 08:24:56 PM

wow sounds like its time for a thermal /pressure bypass mounted close to the tranny for extreme cold weather climates... i do understand that somebody is going to figure out a reflash for the ecm to correct this...

i am thinking about places that might have that have cryogenic temps on a regular basis...

either that or in those areas.. thermal insulation on the return line from the radiator..

just another stupid thought from wayne....

oiler · February 11, 2008, 09:49:39 PM

stupid thought,I don't think so.
Apparently GM has always known about the gelling it just wasn't an issue until they started building up the extreme heat with the pulsing of the TCC and the clutches.
The reprogram was released Sat. so every diesel will have to come in for it.
I've now got 28 Allisons on order so it should be a busy March
Good thing I went off flat rate
Jeff

wayne petty · February 11, 2008, 11:43:10 PM

another stupid question....

what about the crankshaft thrust bearing surface?

since the converters and the input shafts/front pumps were damaged... any chance of a thrust bearing failure problem???

just a thought....i dont know who hard it is to drop a few pans to see...or if gm thinks this is a good idea...with all the torque to yeald fastners possably involved... if any on a diesel....