Chevy Silverado/GMC Sierra's w 8100/Allison

obyone

http://www.helminc.com/helm/Result.asp?Style=&Mfg=GMC&Make=CHV&Model=SILV&Year=2001&Category=1

ryanbab

Hey i know you or matt posted it but could you look and see what the shock bolts should be torqued to?

Thanks

noobie1

So Oby, where do you get the part numbers? Don't they have CD's for purchase where you can look them up?

-David

obyone

Not sure on that. All I know is that it isn't in the manual. The CD's may have the part numbers. You would have to check with Helms on that one.

Ryan

70 lb ft

4964me1

Are these the only manuals available? A few years back a relative of mine got me a full set of manuals for my Cutlass. I THINK they came from GM. The set included:

Body by Fisher manual

Chassis service manual

Electrical troubleshooting manual (had schematics for EVERYTHING; VERY helpful)

All were for that model year only.

Maybe they do things differently now, but I'll look into it and let you guys know.

obyone

But these are the only ones I know of that have the factory approval.

mbwhitley

Where do you go to get an oil analysis done?

That's something I'd like to be able to get every other year or so.

ryanbab

http://www.blackstone-labs.com/

$18.50 for the test

I have the kit but didnt use it. Ill probably do it this spring.

Took about 7-10 days to get the kit

obyone

Ordered mine on or around the 8th. Haven't received anything yet.

ryanbab

ordered mine same time as you actually i ordered mine the 9th. Got it last wed the 19th. 10 days

It helps that i live in the same state as this company (indiana)

Maybe yours is on a boat??? I bet if you lived in the continental 48 you would have had it by now

obyone

Alaska is connected the last time I checked. Being on that continental part. How did they ship yours? USPS? If so, then I don't think mine's coming by boat. If it is, I need to find another company cause I don't need the results sent back to me by boat. Where did you say this company is from? Indiana? figures......lmao

ryanbab

Mine came by USMail

yep us indiana people must be slow. You know it has to get through all them corn fields before it makes it outta state

Ryan

owenm2

Anyone bought/used the Hypertech programmer for the 8.1 yet?

http://www.hypertech-inc.com/

1i2cu

Just found out my 2001 GMC Sierra 2500HD EXT/C with 8.1 and Allison plus a whole lot of goodies is ONLY worth 24,000.00. I waited longer to get it then I've owned the thing. Thats life in the big city I guess.

LOL, Get a fwe bucks and spend it !

loyalgmcguy

At 8,000 miles my 8.1 Allison is using 1 quart every 1,200 to 1,500 miles, better than some report but still an irritant. Question: I use 10-30 Valvoline but am considering a switch to Mobile One synthetic. Has anyone switched to synthetic and did it help oil consumption? Second question: I have not changed the filter or the fluid on my Allison but my towing has been limited. Do I need to: 1) Do nothing yet; 2) Change the filter only; or 3) Change filter and fluid. My dealer says do nothing.

4x4man

My truck only seems to use about a 1/2 qt in about 2,000 miles or so, only have 4,300 miles right now so not much to report on that.. I switched to Mobil 1 at my last oil change, 3k, and is down about 1/4 qt right now, so not bad! I have towed my boat, only 3K or so, and haven't used any extra oil but the boat is nothing to hold the truck back if you know what I mean.

On the tranny, I would change the filter. The Allison owners manual states we are required to change the external filter at 5,000 miles. Funny how GM has left this important piece of information out...

http://www.allisontransmission.com/documents/product/publications/pubs/OM3063EN.pdf

I included the link to the pdf file for the owners manual for the allison tranny, something GM should have included with the owners manual for the truck...oh well, just my opinion.

Bob

cowboyjohn1

I recently got back from a 4400 mile trip with my 8.1, Allison. I used 1 quart of Mobil 1 on the trip and I did not drive it easy. I am happy with it.
cowboyjohn

eric2001

Well, to date, I have burned 1/2 quart since last oil change (1700 miles) and did not seem to burn any before first change @ 800 miles. I have not done any towing yet, but snow is on its way, and the sleds will be out back.

Bob: mine goes in on Thursday for the cold start knock, I was told this is normal, but I asked the service man to document it, he said he would. He told me about the service bulletin they released a couple weeks ago on this, but I still want them to document it. Will file with BBB on Friday for the extended warranty if all goes well.

-Eric

loyalgmcguy

Thanks guys for the advice. Mobile One seems to be a preferred alternative. One of the other discussions regarding synthetics seems to suggest that the cold start knocks some are experiencing are somehow related to, or made worse by, synthetic lubricants. Any comments?

4x4man

I heard the exact oposite...I heard there was a chance the cold start knock could be quieted or stopped by using synthetic oils. Oh well, didn't work for me.

Eric
Got a buddy that works for Goodyear, he seems to think the knock is really a lean ping due to carbon build-up on the pistons, not the pistons or lower rod bearings as suggested. I am still confused on what the problem really is, but a good point none the less, if it was the pistons expanding and contracting, why did it take 2400 miles to show its ugly face, it should've been doing this since day one. He stated the poor quality of fuels has a lot to do with the problem. Something about graphite in the fuels or something like that.
Anyway I am going to try a couple of tanks with BG-44K and see if the noise goes away or not. Still have another 1,600 miles or so before I can do an oil analysis to check out the motor.
Good luck at the dealer, I sure can't find a reputable one here!
Bob

obyone

or is it lack of graphite in the fuels? I remember when gas was called leaded versus the unleaded version we have to use now. Something about air pollution if I remember correctly. The cold knock on startup is identical to what used to happen to the fords. And THEY called it piston slap.

quadrunner500

...using 10W30?

Curious about Ed Bozarth Chevrolet. My bad opinion of them came from the sales floor, not service department. Service was actually fairly helpful few years back when I had question about my '94 Z28, service guy was nice, spent some time with me looking up some data for me in shop manuals.

Burt Chevrolet service department won't win many awards either for pampering their customers. And they too can wear that "what are you talking about?" look of denial. But at least, they are no-nonsense, have reliable shuttle service, no appointments, 1st come 1st serve, in by 7:00 am, usually out by 5:00 pm same day.

edwardt1

Because of current interest rates I'm
considering trading my 2000 1500 GMC
SLT Z71 EXT for a 2002 2500 HD Crew
cab. I will be doing very little, if any towing.
Which engine do current owners
recommend?

Thanks,

Edward

4x4man

I don't know much about fuels, or quality of them but thought I would throw it out there to see what kind of opinions it would get as I just don't know anymore and wanted to know if this was the next theory that was pulled from someone's [non-permissible content removed].....

By the way I agree with the above stating Ford had the same problem (well do we really know??) and it was called piston slap. But again if this is piston slap, why didn't it do this on DAY 1?? What changed so dramatically in 2,400 miles to make this all of the sudden start making this noise?? When did the Furd engines start their magical dance, anyone know by chance??

Bob

4x4man

My boss stated he likes Burt Chevrolet's service, maybe I'll give them a call and see if they have a clue. You haven't by chance heard anything or had any experience with Len Lyall Chevrolet service have you??
I just want to make sure I leave my truck with capable hands.. If I find that the service manager and or tech(s) I talk to try to butter me up or give me the standard BS about this and try to sweep it under the rug I will leave, which is what happened at Bozo's. I guess that is 1 for GM, zero for me.

Bob

4x4man

Well if you aren't going to be towing, that would rule out the 8.1L for need....but want is another story!! The 8.1L/Alli is a powerful combination that will put a smile on your face everytime you push the go baby pedal. I have heard many people comment that the 6.0L is perfect for them, so it must be a great motor also. I did not test drive a 6.0L so I cannot give any impressions. There seems to only be about 2-4mpg difference between the 6.0L and the 8.1L, but don't forget about the Allison price tag...
Test drive both and see what you think. If you don't care for the extra power and really won't be towing or hauling, stick with the 6.0L and save a little bit of money.

I went with the 8.1L because, well first I thought I would be able to avoid the cold start knock that has plauged some of the other motors, second I was tired of buying a new toy that my current truck couldn't handle and then have to eat the difference with a larger down payment to get into a new truck. Did this twice...no more!!!
We plan on getting either a 5er or slide on (keep going back and forth every day) in a year or two and so we bought for that in mind. These trucks are getting very expensive and some day I would like to have a truck I can call MINE, not a joint venture with the banks!!
Sorry for the book, just wanted to throw out a few opinions for you...

Bob

ruddster

Edward,

I wanted to add to 4x4man's comments. The main difference is the rear axle ratio options. With the 6.0L, 4.10's are the only option, whereas the 8.1/Allison has a 3.73 option. I compared mileage on my 8.1/Allison 3.73 chevy with a co-workers 6.0L/4.10 GMC, both 4x4 crew cabs, same stock tires, etc. At 70 mph, the 6.0L/4.10 combo turns @2,376 rpm versus 2,046 for the 8.1/Allison/3.73 configuration. The mileage difference is almost nill. My last tank was 13.05 mpg, under a mixture of city & hwy conditions.
So, if you call the mileage even, it comes down to the extra expense for the increase in power. The "List" price adders for the 8.1/Allison is $2,704 (using 2001 chevrolet pricing). This figure is roughly 5% more than the stock 6.0/4.10 offering, which for me was close enough to justify going with the heavier-duty drivetrain.
Sorry to be so long winded!

Jeff

4x4man

Good point on the axle gears..totally forgot about that point also.

Bob

bigsnag

Heard a 1/2 ton start-up the other day. Made a horrible knocking for a few seconds. It actually sounded different that the Ford piston slap. The Chevy sounded like rod bearings. I don't know what engine it had in it. I could tell it was a '99-up. This doesn't mean that some engines don't have piston slap or a piston slap-like noise. I seriously doubt that it is a lean condition caused by carbon build up. That would manifest itself when the engine was hot. The hotter the engine gets the worse the sound would get.

bobsquatch

Might be raising the compression and detonating. Just a thought.

4x4man

That's possible to....question, is there any other way, outside of miracle fuel injector cleaners or tearing down the motor to get rid of carbon on top of the pistons?? Is there something we could maybe spray into the combustion chamber of each cylinder through a removed spark plug that would breakup the carbon and remove it??

I am just trying to come up with anything I can try myself until I can find a dealer service department I can trust....
Thanks all,
Bob

noobie1

Carroll Shelby, creator of the legendary Shelby Cobra about horsepower: "IF MORE IS BETTER, THEN TOO MUCH IS JUST RIGHT".

-David

bobsquatch

Even if there is a product that would do that I would be leary about using it. A large amount of buildup coming loose at once could score cylinders and do other damage. Water injection is something I have heard of to reduce carbon but not sure how it is done.

mgdvhman

..Zactly!

..you can have too little....but you can't have too much...

I'd rather have more in reserve and not use it....than be wishing I could stir up more!
- Tim

tomh12

Tim's last post had to be for you, grasshopper! This reasoning can apply to many situations. Read it, learn it, live it.
LOL
Tom

mgdvhman

I get in enough trouble by myself!

haha
- Tim

bigsnag

Again, either of these conditions will be manifest when the engine is hot, NOT cold. They would also be heard as more of a ping, not a knocking like most people have described.

edwardt1

Thanks for all the responses to
my question about engine choices.
I have not had the opportunity
to test drive a truck with the 8.1.
I hope to drive one this week.
I will let you know which engine
I choose.

Edward

loyalgmcguy

One of our local auto shops is promoting a reprogramming service he claims will add 25% more power to the 8.1. I have always stayed clear of such modifications but am curious if anyone has tried this on their 8.1 and with what results.

ryanbab

ask them to do a dyno and prove their results

Im guessing its to good to be true

mlempire

I own a 00 6.0 and a 01 8.1 chevy 2500's 01 is HD.
with 2000 load i climbed a long and nasty grade at 80mph and still climbing when i backed off my 6.0 wimps out at about 70 mph . fuel use is a bummer with the 8.1 though. 13 -14 with the 6.0 and 10- 11 with 8.1

mlempire

engine dies at freeway speeds and on excel... let it sit for 30 min..starts and runs for 30 to 300 miles and then repeats problem... allison slips and wanders for gear selection while coasting at a stop sign and then excell to highway speed....
steering now loose and rattles.. the list goes on

4x4man

Outside of the cold start knock, my 8.1L/Alli is flawless, shifts are crisp, power and acceleration are unbelievable. A proper running setup will make you very happy when pushing the go baby pedal, at any speed or in any situation.

Bob

2500hd

Time for my first oil change and was wondering what types of oil you guys are running in your 8.1's. I have around 650 miles and the dealer told me to change it at 700 miles . When can I change to synthetic oil and at what mileage is the engine considered to be fully broken in? I have always done my own oil changes in the past but I am worried about voiding the warranty . Should I just take it in?
2500hd

ruddster

I changed oil at 500,(Mobil "dino" 10-30), at 1500 (Mobil 10-30 synthetic blend) and at 3000 (Mobil 5-30 synthetic). I would like to use a better filter than the AC PF 454, like the AC Ultraguard Gold, but none seem to be available for the 8.1. For your warranty concerns, just keep the receipts for the oil & filter, and of course record date & mileage at change.
We here in Nevada just got our first frost this morning, 24 degrees. I expected the start-up to be a little more noisy, but the "knock" was barely audible. I don't know if the synthetic oil is making any difference, but I don't seem to hear the start-up noise as bad now. (Could also be my hearing is going now, like my hair & waistline!!!)
So far, have 3,800 miles on truck. Very slight, intermittant start-up "knock", tranny works great, mileage around 13+, no abnormal oil consumption, no other problems, just a great truck.
The only "issue" is the light spring on the gas pedal. Had the truck loaded with wood & had a hard time keeping even pressure on the pedal because of the rough road & the light spring tension. Anyone else had the same experience??

cowboyjohn1

I agree with 4x4man on the 8.1/Allison. Only I do not have a cold startup knock. Great engine/trans combination.

I would be interested in what loyalgmcguy learns about reprogramming for 25% more power. Although I really don't know why cause at stock it will do everything I ask it to. I guess I just like a lot of power.
cowboyjohn

scrutinizer

Howdy folks, been reading some of the posts about the 8.1/Allison combo. My '01 is going in for a new tranny next week. It's got a rattle and it's been shiftin' funny. At 1st I thought it may just be me getting used to it. At around 40ish, just chuggin' along, there's a sound that resembles a spray paint can being shaken up underneath. It took some time to hear it over the whine. I guess they all whine some don't they? When heading into a hill towing my tractor in regular mode, I pushed in the tow mode button and it upshifted! (the exact oppisite of what I expected)I lost some rpm, and had to stomp on it to downshift. Anyway, the boys in service tell me that GM doesn't want them doing anymore than changing filters and fluid. If there's a problem, they want the tranny back and they send a new one. Anyone hear this same thing? It's o.k. with me, I'd rather have that than some hacker inside it with a pair of vice grips! Motor knocks like everone elses. So did the 6.0L that I totaled! Plenty of power though. Anyone know about the headers that Gibson makes? How about a hypertech reprogrammer for this combo? My 1st post here, so bear with me if it's goofy! Thanks for any responses. Happy truckin'

4x4man

I changed my oil at 750 miles or so with dino oil (5w-30) and then at 3k I changed to Mobil 1 synthetic with the PF454 oil filter. Keep your receipts and log your mileage and they cannot void your warranty for performing your own maintanance. I agree with Ruddster that I would like to use a better filter, I wrote an email to Mobil 1, they just told me to call their 800 number for more help, and I haven't done it yet. Mobil's webstore hasn't been updated with our trucks, so you can't do a search for an oil filter. I did read that Purolator has a filter available for the 8.1, L15313, on their website, but haven't looked to see if anyone carries it around here, Only choices were Fram, Champion and the AC Delco PF454 from the dealer when I did my 3k oil change.
Do it yourself, not only to save money, but to make sure it is done CORRECTLY.

Bob

4x4man

I can only answer one of your questions and that is yes the Allison does whine, that is just a charactorist of the tranny.
The only problem I had with the tranny was when coming to a stop it would feel like someone bumped into me after I stopped. I read on another board that it was common that the trans was still learning and that it helped if you manually shifted down the gears to help it learn faster. As I came to a stop I did this a few times and it is smooth as can be, no more bumping when coming to a stop.

I don't have any noises that sound like a spray paint can being shaken at speed, so I have no clue as to what that could be. Have the dealer check it out, maybe it is not the tranny but something else.
Let us know what happens.

Bob

richcolo

If you were in 2nd, 3rd or 4th gear and under load when you punched the T/H button, It probably locked the torque converter up, resulting in an RPM drop. I bet that would feel a lot like an upshift, and would be surprising. T/H keeps the converter clutch locked up in 2nd through 5th, to keep trans temps down, as well as changing the shift schedule. When not in T/H the converter only locks in 5th. The point is, I think that is how it is supposed to work, and not a problem, even though it came as a surprise. I'll also bet when you did stomp it and get it to downshift, that the RPM went quite a bit higher than it had been before you punched the button.

Can't help you with the rattle, except to say some time spent underneath with wrenches looking for anything loose might be well spent.