GM 6.0L Q's

Caver Dave

Caver Dave

Just holdin' it down here in BFV
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Joined
Mar 10, 2005
Location
Hooterville (24171)
While it may be a few months before any action is taken, I'm looking at a "new" towrig. The 2500 Sub does fine (5.7/4L80E), but is a stripper (crank windows, no A/C, etc) and would like something with more "amenities" ("what a drag it is growing old..." ;) )

Since I do NOT need a Pstroke/DMax/Cummins, I started looking at gassers in the 2500/3500HD line. Taters 8.1L is a HOSS, but MPGs are a bit low for "around town" & anything but towing (pretty low for that too! :D ). The only other option is the 6.0L

For those of you with 6.0's any likes or dislikes with the engine?

Are there any known "bad" years/block ID's, gotcha's, must haves/must do's to increase reliability/longevity?

Anyone running a tune (ride along or mail order) that can comment on MPG or power gains for their 6.0L?
 
The only thing to stay away from would be one of the early ones with cast iron heads instead of aluminum. Otuerwise, they're all pretty great. All of them got 317 heads, except the early ones like I mentioned.

If you get one, you'll probably have to do a rear cover seal and rear main seal eventually, unless it's already been done. It seems to be more prevalent on the 6.0. Just fixed mine about 3 weeks ago. Easy and cheap, just gotta pull the trans.

I'd definitely rune a tune. The stock ones leave a lot to be desired! I bought HP Tuners and an NGK AFX wideband and I data log my info and email it to my tuner, then he will make any adjustments and email me back and revised tune file. I have a healthy cam and a few other things, so it was a necessity. For your needs, a decent intake, maybe some exhaust, and electric fans if you'd like. That should serve you well and free up some power you already had. A good tune will wrap it all up and really wake that 6.0 up.

I've been getting about 14mpg and have been running a hair rich. I'm on 35s with 4.10s. Not bad.
 
First, thanks for the info!

Croatan_Kid said:
The only thing to stay away from would be one of the early ones with cast iron heads instead of aluminum. Otuerwise, they're all pretty great. All of them got 317 heads, except the early ones like I mentioned.
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Can you define "early ones" or break that down into year models? What's the downside of the CI heads vs AL... other than weight?
Also, do all the HP/TQ numbers stay the same across the various models (1500/2500/3500) and year models?
Also, what R&P ratios were available std/opt. in the 2500s? IIRC, tater's 8.1 truck has 3.92s?

Croatan_Kid said:
Easy and cheap, just gotta pull the trans.
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Uh, "easy" and "gotta pull the trans" don't equate brother! :D
 
I had a 2000 model with 6.0, cast iron heads, and it was a good truck. Got 13mpg or less no matter what though. Now Blaze has it.
 
I have a 6.0 in my 2004 Yukon XL, has 135k on the clock and has so far been a good motor. I average 12-13 MPGs in the city, 16 on the highway.

Slight thread jack - How many miles do you all have on your 6.0s? I am just trying to guage a good life expectancy for mine before it starts to give me trouble.
 
Caver Dave said:
First, thanks for the info!



Can you define "early ones" or break that down into year models? What's the downside of the CI heads vs AL... other than weight?
Also, do all the HP/TQ numbers stay the same across the various models (1500/2500/3500) and year models?
Also, what R&P ratios were available std/opt. in the 2500s? IIRC, tater's 8.1 truck has 3.92s?



Uh, "easy" and "gotta pull the trans" don't equate brother! :D
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99-2000 1500HD and 2500 NON HD had the LQ4 6.0s with Iron Heads. (2500HDs and 3500s didn't come out until 2001, at which time they swapped to aluminum heads as well) There is nothing wrong with them other than weight, they flow identical to the Aluminum 317 heads, they are just HEAVY. If you were building a performance motor the heat dissipation difference between iron/aluminum would make a difference, but for a DD/tow rig, it makes no difference. And it is an easy swap to the newer 317s (or preferably 243s to bump compression up a tad, avoid the earlier ls1 241s though, they flow worse than the truck heads) The only other difference is the crank snout being longer on 99-00 (same as Gen I/II smallblocks) but that is only an issue when it comes to engine swaps and mating to transmissions. The other LS style engines use a shorter crank snout that bolts right up to the flywheel for the T56 6 speed, and newer 4l60E trans. The 5speed manuals used a thicker flywheel to make up the diff, and the 4l80e used a flywheel spacer to make it the same length as the old school smallblock setup.

All LQ4s were the same power ratings until the body style change, standard R&P is 4.10 in 2500HDs. 1500HD and 2500 could be 3.73 or 4.10. Your buddy's 8.1 would have been 3.73. With a simple tune, the 300HP LQ4 can surpass the 345HP rated LQ9 6.0 that came in the Esky/SS etc, they are severely detuned from the factory. (Although the LQ9 has flat tops for higher comp, and a few other small changes, rods etc and they are very receptive to tuning as well)


As far as MPG, when mine was stockish, with 285s, 4.10s, and EFILive, I would do a best of 16mpg on long trips (keeping it below 65 or so, doesn't like to wind out with the 4.10s), highway 70mph and above would knock it down to 14-15mpg, city driving in Raleigh was 12-13mpg, towing a 36ft 5th wheel through the mountains for a weekend I average 11mpg, normal day to day was 14-15mpg.

As far as life expectancy, mine had 135k when I sold it, I never had any issues with the truck other than normal wear items, fuel pump at 70k, and water pump just started to drip while I had it for sale (pointed it out to new owner). Never had any other leaks, my brother's 03 6.0 had roughly 350k on it, ran great, no leaks, no smoke etc.
 
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Yeah...what he said :D
 
I had a 03 6.0 xcab5 speed and love it. It was a blast to drive and wast bad on gas for what it is. I sol it to. Buddy when we bought our house. Now i have a early 07 reg cab 6.0 work truck model and I love it also. Not as fun to drive as the 5 spd though. I average about 14 mpgs. I was considering selling it to get rid of a payment, but decided its to good of a truck to sell. Like all others have said, in stock form they feel like there held back. I plan to get a mall order tune exhaust and intake so mine can stretch its legs a little. if I ever get a different truck, it will be another 6.0
 
Mine has a little lifter tick, my fault for not putting in new lifters when I built it. Oh well....

I put 243 heads on it, as GC said earlier. It makes damn good power and a LOT of torque. LS based motors are freakin awesome!
 
ive got an 02 4wd excab 2500hd. It gets the job done. Fuel mileage is 8-10 loaded and 12-16 empty. Id love to have a good tune done to it but ive just not justified spending the cash on it. It only gets drove about 4k miles a year.
 
3 years so far with a 6.0 normal output 2010 2500HD. It's no barn-burner but gets the job done just fine. 12-13 mpg all the time. I have had one or two tanks up near 15, the engine seems really sensitive to whether it's running E10 or straight gasoline. I always get the better mileage on straight gas. Mine is a CC LB with 3.73s and 2wd. I used to get better mileage out of my '06 Dodge CC LB 2wd Hemi and a little better performance, although the engine was more "peaky". 14-15mpg out of that truck normally.
 
I only spent 100 bucks on my actual tune. I email data logs to my tuner and he will mail me a revision. I've gotten 6 so far, same price. If any of yall were closer, I could help you out. Of course, I bought HP Tuners and, recently, a wideband....so I have a lot of cash invested, but it's worth it to me. I've got another truck to build and I'll need it then too.

I did have a different guy do the tune on my 4.8 and with him I mailed the ECM and a list of mods, he tuned it, and mailed it back. That one ran 275 with free lifetime updates. It was just a pain having to mail it to Texas with a 4 day turn around.

Forgot to mention, I got about 12 hauling a ex cab 4x4 Silverado home from Durham. Not too shabby.


I've seen several 2500HD 6.0 trucks for sale lately and for great prices. Usually from 4000-8000 bucks. Do you want a 4x4 or does it matter to you? Ex cab? Crew cab?
 
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There was a period during manufacturing that a run of 6.0's had a knock that was hard to trace. I think I even read a little about it on here. I was looking into a used truck at the time and it came up. I never followed through with it though. Can't find it now...:rolleyes:
 
R Q said:
I've not done any research on it myself but look into "6.0 knock"
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Caver Dave said:
Come awn bro.... you got to give a little more than that! :usa:
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R Q said:
There was a period during manufacturing that a run of 6.0's had a knock that was hard to trace. I think I even read a little about it on here. I was looking into a used truck at the time and it came up. I never followed through with it though. Can't find it now...:rolleyes:
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It's not a Knock, it's piston slap, and while not ideal, it does not point to an issue. It is not limited to 6.0s, but rather all LS based engines for a period of time. (and even a few other platforms) It is the result of a poor design of shorter skirted pistons and looser tolerances, but does not effect the performance or longevity of the engine. I have torn down 100k+ LS motors with piston slap, and have perfect crosshatching still on the cylinder walls.
 
I had an 01 5.3 that had the piston slap from new.
Put a set of lifters in it at 140k and snapped a rod at 185k.


Cant attribute either of those to the piston slap issue and really 185k, poorly maintained and regularly abused miles...ill take it.
 
BigClay said:
Slight thread jack - How many miles do you all have on your 6.0s? I am just trying to guage a good life expectancy for mine before it starts to give me trouble.
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Mine was at 248k miles and still ran great, smooth and quiet.
 
Caver Dave said:
Hey brother! Need to hookup some time to let me "check yourtruck"!

Howyudoin?:D
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sounds good....been doing great busy as ever! Trying to slow down a bit to get back into the offroad scene again! If you want send me a contact number and next time im traveling through winston in my hd ill give you a shout.
 
I have a 2001 2500 With the 6.0 . It knocks loud for about 3 min than it is fine. Not ideal but has been doing it for as long as I have had it 4 years. It would probly hurt resale but I don,t care I am going to run her to the end. Does not use oil at 150K
now. Good power likes to rev. I pull about 7,500. I get 11 around town. 14 highway and 8 to 10 towing depending on
how much mountain driving. Like said above Tuning really wakes these motors up.
 
Anyone know if a 01 6.0 with 270k on engine with rebuilt 4l80 is worth 2500? How much would a man be looking on a 6.0 if complete catastrophic failure were to happen?? Appreciate it in advance! Slowly gettin back into the 4x4 game!
 
270k miles on a 6.0? It's worth about $400 if it works ok. Not sure what a rebuilt trams would be worth but I'm guessing nowhere near $2100
 
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