Clunk on stopping

rune · February 13, 2013

So I've had the truck now for about 2 1/2 months now and put a little under 10k miles on her. Now that I've been able to get her opened up and running good, and all the crap burned out of her, I've started focusing on some of the smaller things. My number one item right now is this really nice heavy clunk that occasionally occurs when stopping. Normally I would just think U-Joints but this is beyond that. This is a I come to a stop, and about 1-2 sec laters I have a big jerk forward. First time it happened I thought someone had hit me. It definitely feels like it is coming from the rear.It doesn't happen all that often, but when it does it's the same. My thoughts are that it is the locker dis-engaging, but I've got the same one in my colorado, and it's not that violent. Any clue what it is?

06 ECLB 8.1 6SPD Ally 4.10s 4X4

Also I seem to have something leaking from the front lower portion of the block. It's not the oil cooler lines. I noticed it when I was airing up the front tires. You can see it right around the skid plate location. Any suggestions?

tanked_darren · February 13, 2013

Slip yoke. Be prepared you are about to get 8 to 10 people say the same thing. Common well known issue look it up, sounds like a seal bark sometimes too.

Mine does it occasionally.

Many years of trucks have the slip yoke issue.

I don't think I've seen anyone post about an Allison having it though...

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txab · February 13, 2013

+1 slip yoke.

Leak.... get under there and start tracking it down.

StingerZ16 · February 13, 2013

i have had the same thing happen with my Duamax and Alison.

I friend with same engine/ trans set up ask me about it cause he has the same feeling.

so it sounds like this is "normal".

does it lead to any long term problems?

GMCustomerService · February 13, 2013

StingerZ16,

I am sorry to hear about your concern. Assuming that you are under warranty, I would have to recommend that you bring this to the attention of your local dealer during your next visit. Thank you.

Tricia, GM Customer Service.

HawkScot · February 13, 2013

StingerZ16,

I am sorry to hear about your concern. Being that you are under warranty, I would have to recommend that you bring this to the attention of your local dealer during your next visit. Thank you.

Tricia, GM Customer Service.

Tricia, what makes you think he is under warranty?

06 ECLB 8.1 6SPD Ally 4.10s 4X4

rune · February 13, 2013

I think it's funny she replied to Stinger, and not me....but whatever. Truck over all has 81k on it. I knew the slip yoke was an issue on the 4l80s, Never really heard about it affecting the Allison. I'll check that though. The truck was a one owner truck. The guy was meticulous on the maintenance, and I have a full copy of the service records from the dealer. He always went to the same one. My suspicion was the truck was used for a slide in camper based off of the condition of the in-bed 7 pin and no evidence of a 5th wheel. Overall though the truck runs awesome. Had it on a round-trip cross county adventure, and she just runs awesome at 75-80. Averaged about 13mpg heading east and 12 coming west. Doesn't seem to matter if your running 60 or 80. She just inhales the fuel, but that's why she is my tow rig. Almost zero oil burn. I've got close to 6k on the most recent oil change (Mobil 1), and maybe a 1/2 quart of burn. As far as the leak up front, are there any known problems other than the oil cooler hoses? Any thing specific I should be focusing on as the source? I know just about every issue with the Colorado, and how to fix it, but I'm still learning the Silverado.

dewfpo · February 13, 2013

I have an '05 8.1L w/Allison and have a dry/binding slip yoke issue as well. Years ago, GM came out with a special teflon based grease to put on the splines. Unfortunately they didn't put a zerk/grease fitting on the slip yoke like other manufacturers did, so you have to pull the rear driveshaft to grease it. This helps quite a bit but can't actually solve the issue.

DEWFPO

kurt1993 · February 27, 2013

mine does it haha i had this same post like a year ago 01 8.1 ecsb 4x4, oh and i changed all my U joints out on the rear it seemed to help the stock ones dont have greese fittings the aftermarkets do

dankapp · May 2, 2013

Just a quick question, if GM knows that this is an issue do they cover it under the 100,000 mile power train warranty? If not what can I expect price wise to have the dealer fix this? Thank you in advance.

tanked_darren · May 3, 2013

Just a quick question, if GM knows that this is an issue do they cover it under the 100,000 mile power train warranty? If not what can I expect price wise to have the dealer fix this? Thank you in advance.

Yes

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