GMC Envoy questions

[Tornado Red]

My sister and brother-in-law just bought a 2004 Envoy with the 4.2-liter I6. I think it has about 40k miles.

I haven't said anything critical, though it seems to me they bought one huge gas-guzzling PIA. Is there anything they can do, or should do, or anything I can advise them to do, that will make their Envoy-owning experience as good as it can be? Best oil, best OCI, best transmission maintenance, best brake and suspension parts, best cooling system checks, etc. And of course how to get the best fuel economy, considering 15 mpg is typical.

My guess is they plan to keep this truck for ten years or longer, assuming they can afford paying for fuel. Your ideas?

 

[mrsilv04]

What's a PIA? I know what a POS is, but am not sure about a PIA.

 

[Quest]

PIA = pain in da aaarsh..

Q.

 

[andyd]

Oh, you mean PITA

 

[andyd]

Quote:

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Oh, you mean PITA

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Im an I6 fan but wonder how GM has managed to screw them them up. They used to make some pretty good 'uns 40 yrs ago.

 

[XS650]

The two biggest things they can do, other than keeping it running properly, is to keep the tires a few psi above door sticker pressure and drive smoothly so as to avoid using the brakes or gearing down unnecessarily. Every time you step on the brakes you are converting the kinetic energy you paid for with expensive gasoline into useless heat at the brakes.

The factory probably recommends 5W-30. Don't go any thicker.

 

[Tornado Red]

Quote:

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The two biggest things they can do, other than keeping it running properly, is to keep the tires a few psi above door sticker pressure and drive smoothly so as to avoid using the brakes or gearing down unnecessarily. Every time you step on the brakes you are converting the kinetic energy you paid for with expensive gasoline into useless heat at the brakes.

The factory probably recommends 5W-30. Don't go any thicker.

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Good to know. I've got 10 gallons of Delvac 5w40 I was thinking of contributing (it's got a 7-quart capacity, I think). Maybe I'll keep the Delvac and find something else that will work better in that engine. But what?

 

[XS650]

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Good to know. I've got 10 gallons of Delvac 5w40 I was thinking of contributing (it's got a 7-quart capacity, I think). Maybe I'll keep the Delvac and find something else that will work better in that engine. But what?

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M1 5W-30 is good enough for it's frisky cousin, the Z06 Corvette. Just get an oil that meets manufacturers spec or better and use it with reasonable change intervals. If it has an OCI indicator, use it. If the OCI indicator is set for conventional oil and you use a decent synthetic, your engine will be happy and you will be running 6000 miles or more between changes.

 

[Merkava_4]

The main thing that will save you fuel is to coast in between red lights. You can do that easily with an automatic transmission. If the speed limit is 45MPH, I'll accelerate up to that speed and then completely let off the gas and coast the rest of the way to the red light. I've even passed some people up while I'm coasting.

 

[The Critic]

Change out the differential(s) with your favorite 75W90 synthetic oil. This will help the fuel economy, very, very slightly.

Also flush the transmission with DEXRON-VI. This is currently the best fluid for GM automatics on the market today, at least for the ones that take Dexron-III.

 

[MrCritical]

Change the fuel filter, use Top Tier fuels, and takeoff at a leisurely pace. That is a heavy vehicle with a lot of wind drag.

 

[CBDFrontier06]

I hope they have better luck than my co-worker. She has a fully loaded 04 and it seems to always be in the shop for some wierd problem, mainly electrical stuff. It's eaten 3 batteries (all of which have dumped their contents down inside the engine compartment when they fail) and they can't seem to figure out why it keeps doing the same thing over and over. Every time it happens, she's away from home. Apparently it has enough power to unlock the doors, she gets in, sticks the key in the ignition, uses what juice is left to try and start the engine and when that fails, it won't let her remove the key from the ignition. It has some sort of electrical interlock in the ignition switch, so she's been forced all 3 times to leave her car in various places with the key in the ignition. Granted, it's not in any danger of being driven away by a thief, but that's just idiotic.

Other problems have included windshield wipers that work when they want to (and they usually don't want to when it rains) and I believe she's replaced an A/C compressor. Thankfully she opted for the extended warranty which apparently included a loaner and other perks.

 

[JTK]

I'm a former GM T360 chassis, atlas 4.2L owner (2005 Trailblazer LS 4x4). They are very nice riding, handling and a super comfortable truck. The turning radius is amazing on them. Like XS650 says, keep the tires aired up slightly more than the door jamb specs. IIRC, I kept mine around 32-34psig all the way around. The 4.2L is a super smooth engine and is fairly easy to work on. I ran the spec'd 5w-30 in mine, but have heard of owners running 5w-20 up to 40wt's without issue. Your BIL will want to drain & fill the font & rear diffs, do a pan drop & fluid change on that 4L60E, drain/fill the PS fluid and I'd swap out the Auto-trak II in the transfer case as well. The bodies and interiors are awful in terms of fit/finish/quality and the more options on them, the more troublesome they are. The front axle (4x4's) has some funky components as well. Sealed, grease-filled bearing housings, etc. No matter what they do, they will be lucky to get what the sticker says, 15-20mpg. Having owned one, I would not buy one again.

Joel

 

[Ed_T]

We had a Chev Trailblazer 2003 which was a bag of worms. Electrical gremlins, a shifter interlock that would intermittangly fail (love that stranded feeling), current surges through the dash causing the gauges to go nutty (even the dealer's tech saw that one!), axle grinding, axle whistle, failed radiator cooling fan switch (that pushed mpg down to about 10), ate a battery, lying dealer svc dept: ("your tranmission fluid is dirty"-this is a 'sealed' trans and they had NOT inspected the fluid - scumbags), poor body integrity and interior fit.
Finally at 50k miles we had had enough and traded it in at a considerable 'loss' for a well-reknowned 'foreign' make, which has been bulletproof for the last 103k miles.

I wish them good luck with this ill-starred design.

 

[alanu]

do the trailblazers have the same brake system as the Colorados??

If so what a disgusting piece of engineering. Not suprised coming form Chev. 3hrs to do a brake job for the fronts. You must remove the hub (typically siezed in the spindle) and remove the rotor from the backside. Back brakes are another reinvention of the round wheel. Absolutely stupid engineering which is not innovative but cash cows.

 

[JTK]

Ed, did the dealer tell you that 4L60E was sealed? They are not. There is no drain plug on the pan, but they do have an ATF dipstick.

The Colorado/Canyon chassis is a completely different chassis designation. The GM T360 is shared only by:

Trailblazer
Envoy
Rainier
Isuzu Ascender
Saab 9-7x

Lots of people mistakenly associate this chassis/engine with Isuzu. It's 100% GM, nothing to do with 'zu.

Joel

 

[Ed_T]

JTK my recall on the trans was no owner-accessible under-hood dipstick. Also I recall the trans fluid interval was 100k miles.

It did have a kinda neato air filter setup which indicated when to change it.

Some other post on this board indicated that until a 2006 manufacturing change, there is likely great difficulty in pulling the spark plug paks, because of the PI$$-poor screw-into-the-head design for the pak tie-downs (my technical descriptions). Another fine example of GM 'sweating the details'.

With F, GM, and Chrysler off my lists, I sleep better not anticipating the next sure-to-happen headache.

To round out the story, a co-worker has had since new a GMC Envoy with the six cyl, and during their 60k miles so far it has been faultless, except for a brake squeak appearing at 55k. It took them 1/2 doz. repairs attempts and a verbal threat to the dealership owner to write GM about shoddy service, and an ensuing discussion with the dealership owner, to finally pierce the service dept's wall of "If we don't think its broken, it isn't. You're just a customer."

The co-worker has sworn off GM as well.

 

[Ed_T]

Sorry that is a 2004 GMC Envoy.

 

[Travis99LS1]

thats funny, my neighbor just hit 215K miles on his..Has only changed the trans fluid once..never touched the diff. and uses pennzoil 5w30...and changes it whenever the OLM gets to 0%..which is usually like 7-8K miles

 

[JTK]

Ed, all GM T360 do have an ATF dipstick. I don't know of any application where a 4L60E is sealed. It's on the exhaust manifold side, back tucked near the firewall. I did that coil hold-down bolt write-up awhile back. Those can catch you off guard on the 2002-2005 4.2L's 2006+'s are different from the head up. On the pre 2006's, if you remove and never-seize those bolts early, you'll never have a problem. The other problem spot on the 2004+ 4.2's is the air injection reaction system (blows filtered air into the cat). The check valve on the exhaust manifold is the weak spot that can hang & fill the (electric) air blower with exhaust condensation and wreck the whole $$$ system. IMO, with some tweaks and attention to detail, this could have been a great truck for GM. In reality though, if you are in the market for this type of vehicle, a used T360 can be a major bargain. FWIW, I bought my 2005 used in '06 for $17900. I drove is for ~15mo and got a trade-in allowance of $13500 for it towards the new Cobalt.

Joel