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Comments
"Mine has the locking diff and doe not do it."
I'm not suggesting that all vehicles with a locking differential will have this problem. Mine never did until about 3 months ago (after about 24K miles).
You said:
"It behaves just like a normal open diff until there is enough speed difference (about 200 rpm) between the two rear wheels to engage the locking mechanism."
Right, but clearly, the thing is a mechanical device that needs to react to slippage in some way to lock up. There must be some sort of clutch type mechanism in there and I am suggesting that might have something to do with it.
You said:
"and if you are going over 20 mph it won't engage anyway. ":
Right, but what does that have to do with a "stutter/clunk" that occurs while stopped?
anybody who's had the obnoxious clacking/ticking that sounds like a bad lifter should definitely try changing oil! I've had the noise since the dealer performed my first complimentary oil change and switching to 10W30 Mobil1 only made matters worse. Switched to 5W30 semi-synthetic and the noise has all but subsided within about a week of the change. (Apparently these engines HATE 10W30 oil even in the heat of summer....I'm thinking the dealer used 10W30 and not 5W30 on my first change).
For my first oil change on my '02 Envoy, I noticed on the receipt that the dealer used 10W30 engine oil, so I asked about it, and he said that's what GM recommends the dealers use in all the Envoys in this area (North Texas.) I called 2-3 other dealers around here and was told the same thing. I don't know why they don't use the 5W30 like the oil cap states. I have a feeling it's because it's cheaper for them to buy 10W30 in bulk. So that's what the dealer has been putting in for subsequent oil changes, too. Maybe it's because of the southern climate here.
'Right, but clearly, the thing is a mechanical device that needs to react to slippage in some way to lock up. There must be some sort of clutch type mechanism in there and I am suggesting that might have something to do with it.'
That mechanical device in the locking mechanism works from the >200 rpm difference in axle speeds to engage. Otherwise it is not engaged.
You said:
"and if you are going over 20 mph it won't engage anyway. ":
'Right, but what does that have to do with a "stutter/clunk" that occurs while stopped?'
Several times I have read it described as happening after coasting down to a stop from highway speed, or certainly from a >20 mph speed, and then getting the stutter-clunk. It would not be engaged from 1) highway or >20 mph speeds and 2)not be engaged unless the rear wheels were spinning 200 rpm or more differential speed, like one stopped, and the other spinning. Even if you locked the diff starting off from a stop, as soon as you get over 20 mph it will disengage.
Just don't see how anything in a locking differential could store up enough energy to cause a stutter-clunk to be felt through the drive train and vehicle after a stop.
The main difference between the two is the viscosity when cold. When cold the 5W-30 will flow like a cold 5 weight oil, the 10W-30 like a cold 10 weight oil, and when hot, both like hot 30 weight oil.
I noticed when I put in 10W-30 the cold engine noise was slightly reduced. So I use 10W-30 for my spring and summer oil changes, 5W-30 for the winter change. Same brand.
If people who do not have locking differential also have this "disease" then I will shut up about it possibly being the cause.
BTW, is CLUNK even a word?
Frank
Yes. As a noun: A heavy dull sound (as made by impact of heavy objects)
And, as a verb: Make or move along with a sound as of a horse's hooves striking the ground
tidester, host
Other than the shudder and some very minor valvetrain noise, which I've noticed in every overhead cam engine I've owned, no real complaints and very happy after nearly two years of ownership. Admittedly, I've massaged the vehicle a bit with CAI, JetChip and K&N Filter as well as a Denali grill, bug shield, weatherflectors, rear step hitch, mud flaps & rear wing.
Anybody have experience with side tubes? Will they block the debris which the flaps miss or do I need to go with running boards? (Those black tubes look so much nicer on a white truck).
Thanks,
Ray
No one seems to be mentioning the driveshaft yoke
binding. As you stop, the rearend raises up and the yoke slides in and out. If it's binding, it probably slips the other direction under acceleration. It may just do it at a rest. Seems to me this is a common problem with pickup trucks.
GAM
Checking tire pressure on a spare vs checking pressure as the tire supports the truck. I would expect that a spare with 30# of air will gauge higher once mounted on the truck.
Sort of like a balloon that gets squeezed. The pressure rises in another section and forces the ballon to extend.
"Yes. As a noun: A heavy dull sound (as made by impact of heavy objects)"
Tidester, you can be the keeper of the "New Sounds of GM" dictionary. Heres a new one we can put beside clunk. What should we call the sound your forehead makes rapidly tooting the horn after trying to describe the clunk problem to the dealer?
tidester, host
The posting references the slip yokes and I pretty much can guarantee that if the triplets have a slip yoke on them (to which I am sure that they do), this is the problem at hand! My 1999 Jeep Grand Cherokee Limited V-8 did the EXACT same thing as what we are experiencing. Mine in addition to a multitude of other JGC owners had experienced the same issues at hand.
I haven't checked, but if this forum holds archives dating back to 1999, you can search the JGC forum for "Slip Yoke" and you will find the exact same problem as what we are describing..
Just my two cents..
Thanks!
IExplore2000
Here's a suggestion for you to which I would like to gainer support from the group.
Since there has been numerous issues about this forum becoming a playground for complaints, I propose the following:
* Similar to the Honda Accord forum (and many others), I suggest that you FREEZE this topic of discussion and create two new ones! You could possibly create the following:
1) 2002+ Chevy Trailblazer, GMC Envoy, Oldsmobile Bravada Problems (maybe include Buick Ranier, Isuzu Ascendor)
2) 2002+ Chevrolet Trailblazer, GMC Envoy, Oldsmobile Bravada (maybe include Isuzu Ascendor and Buick Ranier)
I honestly believe that this will help to keep the topics of discussion more focused to everyone's liking so that if they are 100% problem free with their vehicle, they can simply focus on posting messages to the "rants and raves" side of the forum (and vice-versa for those who have experienced "perpetual woes.")?
In my opinion, I think that this is a very "active" forum and that's wonderful. Heck.. we are already nearing 14 THOUSAND postings people!!. However, there needs to be some sort of separation to help keep the topics more "focused" and to help keep the general audience happy. For example, I've been considering the new Honda Accord Coupe as a second car and found it QUITE pleasant to venture over to that particular forum and spend time reading the good and the bad... more so, educating myself in an unbiased way! Perhaps the "happy" forum can focus on more pleasant items such as: modifications, upgrades, accolades, "how to's (i.e. changing a light bulb)," etc. The "problems" forum can continue working collaboratively/effectively as we all do so well to help resolve/get answers to the problems at hand?
Just food for thought... All those who agree TYPE EYE! :-)
Thanks!
IExplore2000
OH.. and let's not forget.. to keep things clean and searchable, delete those discussion threads that were created and contain less than 10 postings!!
;-)
Iexplore/Gam2 -
Slip yoke explanation seems to fit pretty well, but in my case I can pull up to a light and while I am sitting there, I feel this very light thump effect. Further, it sometimes repeats maybe two or three more times if I just sit there. The repititions even seem to be regularly spaced apart. These effects were what made me think something might be going on in the rear axle. It seems to me that friction release in the yoke would happen just once and it would be all over. But again, in my case, the effects are very mild. Many people probably wouldn't notice it.
All in favor indicate with AYE and opposed with NAY! I thought I just heard Iexplore volunteer to keep count? :-)
tidester, host
Does anyone with this problem notice if the RPM is briefly dropping below the normal 600 when this happens?
BTW speaking of words, "studder" is not a valid word, "stutter" is. As per Dictionary.com anyway. "Clunk" is also valid word.
But most makes/models have a general board and a problems/solutions board. They grow in size, but the Discussion Search function makes it easy enough to find specific problem threads.
Anyone interesed in the new version of DOD? "On a 15-minute drive, the TrailBlazer V-8 switched between four and eight cylinders more than 40 times without hesitation." USA Today
Steve, Host
RPMS do NOT fluctuate when stutter occurs.
Clunk felt from undercarriage when stopped at intersection.
Steps to reproduce: Truck must be cold. Start truck and drive short distance (<.25 miles) to a stop sign or intersection. Wait at intersection for ~1 min. You will feel a clunk or series of clunks from the lower rear of the truck. Feels like the car behind you didn’t stop in time and tapped your bumper! Could be some sort of binding problem in the rear differential or other mechanical connection. After driving a few minuets and stopping again, the problem does not reoccur. However, the next time the truck is cold, the same thing will happen. Could it be a lubrication issue in some part that occurs after truck sits awhile?
The service tech said: Normal Behavior.
I have given up on this on and just live with it. I'm out of warrentee now anyway, so I can't go complain about every little thing anymore. Barring a recall fix, I don't see this going away.
I'll have to say the 2004 drives a lot different than the 2002..stiffer sway bars, etc. Got 4WD, Silverstone with medium gray interior (LOOKS GOOD!), black wall tires, Bright Alum. wheels, leather, sun roof, DIC, running boards, 3.73 rear end, locking diff. ALL the GOODIES.
Obviously, if a previous thread only has 4 or 5 postings and seems to be inactive, ARCHIVE it and steer discussion to the new threads. I think that this will help to clear the waters for those searching for active threads. OR.. as Tidester mentioned, keep this one going and start a new thread for "problems and solutions."
BUT.. IMOP I somehow feel that it would be better to just archive this thread (along with others) and create two new ones. This will allow us to start fresh so that new comers can clearly choose a thread to surf without getting a "skewed" vision that the triplets are nothing but trouble.
Just my two cents!
Thanks,
IExplore2000
ALL IN FAVOR.. TYPE: EYE! And yes I will keep count! :-)
On the topic of possible additional forums, lets keep what we have now. If you have something to say, say it here. That way, we can all read the good, the bad, and the indifferent. I don't mind reading about mud flaps and lift kits even though I have no interest in either.
Frank
Exactly what the tech told me: Normal Behavior
re: 13348 of 13354 STEERING "rubbing noise?" by tripicchio
Yep, I've noticed this too and the tech reported doing the same. However....it's still there. Feels, like you said, a "rubbing" or resistance in the steering column.
Frank
Most folks have no problem offering a solution to a post if they're already there browsing that forum, but you can't expect people to go out of their way. I don't see myself ever waking up and thinking "Gee, I'm going to go out and solve some random people's triplet problems today."
As far as the little discussions, they should auto archive on their own after a few weeks of inactivity. We try to catch most of them when they start and redirect the posters to a more active board too, but some slip by.
Steve, Host
Nay- I'm not interested in checking several different boards to see what is new or what other people are experiencing - whether it is good, bad or whatever.
Calling around today including my dealer, I find that Jiffy Lube is the only place where they said they could but 14 qts of Amsoil into their equipment and use it to purge out the stock fluid.
Pep boys also offered the power flush but said they had no way to use my oil as their system is preload with a specified fluid.
Anyone think that J Lube really can do what they claim?
I really want to use the Amsoil but dropping the pan alone might get only 40% of the oil.
Even if J can do as they say, what % of the remaining oil really would be new vs dumping the new oil at $9 per Qt???
As far as interest in Displacement on Demand, I guess I will never get a chance to buy a short wheelbase Trailblazer with a regular V8. IMO the 8% gain in mpg that GM claims for the DOD system isn't worth the mechanical-electrical complexity, potential for long term reliablity issues and high service costs. Should be interesting anyway, to see if GM has managed to make it work after a 20+ year hiatus.
If everyone's happy with this one thread then I am happy... BUT.. the next time someone whines and cries that we are "complaining too much" on this thread, then we need to gang up and infiltrate the PC with some sort of virus preventing them from accessing this site!
I am kidding... but not really... ;-)
Also, in response to tblazed's comments on adding a new triplet DOD thread... probably not a good idea.. Seems as if everyone wants to see this thread hit the 20K postings mark, so the YAY'ers probably suggest that we keep it here?
My two cents..
Thanks!
IExplore2000
I wholeheartedly agree! Look at who is having the most problems on this board. It's the ones with all the gizmos!
The fact that it was a failure 20 years ago doesn't mean it can't succeed now.
From a GM web page article: "With two valves per cylinder, only two actuators per cylinder are needed".
"The solenoid control valve assembly contains electronic control valves or solenoids that direct the feeding or withdrawal of high pressure oil to the lifters in a sequenced manner. Engine oil flows to the solenoids from oil passages in the cylinder block and (based on the position of the solenoid valve) either activates the valve lifter (enabling normal V-8 valvetrain operation) or deactivates the lifter (disabling the valvetrain), allowing the engine to operate in 4-cylinder mode."
Lots of things should be successful now that aren't. I hope it will work for GM this time. Certainly they have had plenty of R&D time to work out the bugs. But I don't think I want to be one of the guinea pigs to find out. Time will tell.
It was suggested that I have the pan dropped and after draining the oil, a hole would be tapped into the torque converter to drain its oil. Cooler lines would be opened to allow that fluid to drain.
Mechanic said this would drain 95% of the old fluid.
I am not sure I like the idea of drilling and tapping the torque converter.
Anyone have this done??
If I ever lost the tranny, my guess is altering the TC would invalidate any warrantee I might have
Frank
I can't imagine that you are getting only the old out while pumping it through to the cooler lines.
Should I plan on actually using some extra Amsoil with the intent of draining say 15 quarts from a 13 qt system?
I asked about whether doing this would affect crankshaft balance. Their reply was that when you drill out the converter you are removing metal. Putting the plug in replaces the metal. Sure, there are probably small differences in weight, but apparently not enough to matter. Also, the converter is thick enough (as I recall from ~25 years ago, it was about 1/4 inch or so) that threading it is not a problem.
Now, I am no professional mechanic, and take no responsibility if you wish to do this. I can only tell you that I have done it and didn't have any problems.
I know places charge a fortune to change transmission fluid, but just how often do you plan on doing that? I've got 54,000 miles and haven't even thought about changing the fluid.
I'll do it at 100,000 and then again at 200,000. If it goes out after that, I don't care so much.
My S-10 uses a PF52, TB a PF58. I have one of each here. The PF52 has a different size threaded hole (5/8") vs. the PF58 (3/4") that screws onto the engine. PF52 will not fit on a 4.2 I6.