A buddy of mine is wanting to sell me his 2004 Suburban Z71 5.3 4wd with 210K miles for $2000. A check engine light is on and says knock sensor, and there is a small bit of rust on the rear bumper but not bad. He uses it 6 days a week for his job and it stays on the road, he does road calls for internet etc. He is selling because it gets 14mpg. and wants something that gets better gas mileage. I on the other hand have been looking for something with decent power that will tow a trailer or car hauler from time to time. I know very little about 5.3 motors and their power/reliability etc. Is this a good deal? Are these motors good for higher mileage?
2004 Suburban Z71
- Thread starter krismoriah72
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The rear axle assembly is 1 year old. Trans is probably original.
Likely will need a trans before long, they can be short lived--but the 4L60 should be cheap to replace. Install a trans cooler either way. Engine should be fine. The rest of it, as long as it's not too badly rusted (the bumper is a common rust area), shouldn't be bad for your anticipated light usage.
Find out what gearing it has--should be on the glovebox door or on the build sheet. 3.42's might be on the weak side, 3.73 would be better.
Find out what gearing it has--should be on the glovebox door or on the build sheet. 3.42's might be on the weak side, 3.73 would be better.
I have an 07 silverado i just rolled 410,000kms on it. All original engine and drive line! I did my knock sensors its ez. Its a very common issue on these engines. Water gets in and the rear one rusts badly.
3.42 was for the Tahoe.
Went through the Suburban decision process awhile back when I picked one up. A few thoughts off the top of my head...
-Suitability for towing really just depends on what you find acceptable; some guys are cool pulling cars with four-banger S-10's, while others need a modified turbo diesel.
-OEM gearing is pretty poor for heavier towing. With Z71 tire size, and the 4L60/10-bolt combo, you'll be lugging the thing down the road in OD, which is absolutely brutal on that transmission architecture. With only four (widely spaced) gears to play with, you'll have a big jump down the third/direct.
-The 4L60 is fine for light usage, in lighter trucks. Put it behind the 5.3L, in the largest vehicle, and start pulling...they don't last a long time. Good thing is though that they're available everywhere in junkyards, and/or there are several different outfits that specialize in rebuilding them to a better spec.
-Suspension (coil-spring rear, light spring rates, p-metric tires, etc.) is set up for ride comfort. This is great for riding around empty, though.
-2004 was the first year for hydroboost brakes on the half-tons. This is a great feature!
-G80 rear locker is really helpful for off-roading/snow/etc.
Other issues are common to the GMT-800 platform (like the knock sensors), and well understood.
Went through the Suburban decision process awhile back when I picked one up. A few thoughts off the top of my head...
-Suitability for towing really just depends on what you find acceptable; some guys are cool pulling cars with four-banger S-10's, while others need a modified turbo diesel.
-OEM gearing is pretty poor for heavier towing. With Z71 tire size, and the 4L60/10-bolt combo, you'll be lugging the thing down the road in OD, which is absolutely brutal on that transmission architecture. With only four (widely spaced) gears to play with, you'll have a big jump down the third/direct.
-The 4L60 is fine for light usage, in lighter trucks. Put it behind the 5.3L, in the largest vehicle, and start pulling...they don't last a long time. Good thing is though that they're available everywhere in junkyards, and/or there are several different outfits that specialize in rebuilding them to a better spec.
-Suspension (coil-spring rear, light spring rates, p-metric tires, etc.) is set up for ride comfort. This is great for riding around empty, though.
-2004 was the first year for hydroboost brakes on the half-tons. This is a great feature!
-G80 rear locker is really helpful for off-roading/snow/etc.
Other issues are common to the GMT-800 platform (like the knock sensors), and well understood.
Can't speak from particular knowledge on the GMT400 platform's chassis, etc., but the 5.3L is as good an engine as there is in its segment. The 4L60, on the other hand, just isn't strong enough to hold up through hundreds of thousands of miles under "normal" use.
Nick1994
$100 site donor 2024
I'd buy it in a heartbeat.
I cannot tell what/if anything the knock sensors are causing the truck to do other than set the light. I have ridden in the truck several times and seems to run fine...is it causing bad gas mileage or something that i cannot notice?
On the 4L60 issue since i may be getting it pretty cheap, would u upgrade to a 4L65? If i go the reman route i dont think they cost much more. Yes i agree 4L60s are pretty easy to get ahold of. Last time I priced a used one was $550. My local garage will install for $350 so im in good shape as far as keeping costs down.
He said the Z71 came with a trans cooler..not sure but it does have one on it.
On the 4L60 issue since i may be getting it pretty cheap, would u upgrade to a 4L65? If i go the reman route i dont think they cost much more. Yes i agree 4L60s are pretty easy to get ahold of. Last time I priced a used one was $550. My local garage will install for $350 so im in good shape as far as keeping costs down.
He said the Z71 came with a trans cooler..not sure but it does have one on it.
Nick1994
$100 site donor 2024
14 mpg sounds right for a Suburban.
A family member has an 05' Tahoe that gets 16-16.5 mpg in almost all highway. It gets 25k miles a year. Runs like a clock, just thirsty.
A family member has an 05' Tahoe that gets 16-16.5 mpg in almost all highway. It gets 25k miles a year. Runs like a clock, just thirsty.
I would put my own code reader on it before buying it. It the knock sensor is bad, it may pull timing back, that would hurt power and economy. 14 around town is about right though. and 18-20 hwy. Figure that you will need a trans soon and price that replacement out.
Last edited:
Originally Posted By: Nick1994
A family member has an 05' Tahoe that gets 16-16.5 mpg in almost all highway.
Then she's either driving 85 MPH everywhere, or really needs a tuneup.
Originally Posted By: spasm3
It the knock sensor is bad, it may pull timing back, that would hurt power and economy.
Correct. When functioning correctly, they'll push to the ragged edge of timing; doesn't take much in the way of carbon buildup and minimum octane to start pulling back dramatically. With them not functioning at all, power/economy are down.
A family member has an 05' Tahoe that gets 16-16.5 mpg in almost all highway.
Then she's either driving 85 MPH everywhere, or really needs a tuneup.
Originally Posted By: spasm3
It the knock sensor is bad, it may pull timing back, that would hurt power and economy.
Correct. When functioning correctly, they'll push to the ragged edge of timing; doesn't take much in the way of carbon buildup and minimum octane to start pulling back dramatically. With them not functioning at all, power/economy are down.
Nick1994
$100 site donor 2024
Originally Posted By: Ramblejam
Originally Posted By: Nick1994
A family member has an 05' Tahoe that gets 16-16.5 mpg in almost all highway.
Then she's either driving 85 MPH everywhere, or really needs a tuneup.
Originally Posted By: spasm3
It the knock sensor is bad, it may pull timing back, that would hurt power and economy.
Correct. When functioning correctly, they'll push to the ragged edge of timing; doesn't take much in the way of carbon buildup and minimum octane to start pulling back dramatically. With them not functioning at all, power/economy are down.
It's got 140k miles. It has had a tuneup before, it's taken care of real well. They bought it 1 year old.
I've driven it on a couple road trips this year, just what it gets. Not driving like an old lady but not quite race car status either.
Originally Posted By: Nick1994
A family member has an 05' Tahoe that gets 16-16.5 mpg in almost all highway.
Then she's either driving 85 MPH everywhere, or really needs a tuneup.
Originally Posted By: spasm3
It the knock sensor is bad, it may pull timing back, that would hurt power and economy.
Correct. When functioning correctly, they'll push to the ragged edge of timing; doesn't take much in the way of carbon buildup and minimum octane to start pulling back dramatically. With them not functioning at all, power/economy are down.
It's got 140k miles. It has had a tuneup before, it's taken care of real well. They bought it 1 year old.
I've driven it on a couple road trips this year, just what it gets. Not driving like an old lady but not quite race car status either.
Originally Posted By: Nick1994
I've driven it on a couple road trips this year, just what it gets. Not driving like an old lady but not quite race car status either.
Monitor knock retard on trips and see what it's doing; pushing 20 MPG isn't overly difficult with these.
I've driven it on a couple road trips this year, just what it gets. Not driving like an old lady but not quite race car status either.
Monitor knock retard on trips and see what it's doing; pushing 20 MPG isn't overly difficult with these.
Nick1994
$100 site donor 2024
Originally Posted By: Ramblejam
Originally Posted By: Nick1994
I've driven it on a couple road trips this year, just what it gets. Not driving like an old lady but not quite race car status either.
Monitor knock retard on trips and see what it's doing; pushing 20 MPG isn't overly difficult with these.
How do you monitor knock retard?
They drive pretty nice. Very comfortable. It's been a pretty decent car too.
Here's a picture I took after waxing it a few months ago.
Originally Posted By: Nick1994
I've driven it on a couple road trips this year, just what it gets. Not driving like an old lady but not quite race car status either.
Monitor knock retard on trips and see what it's doing; pushing 20 MPG isn't overly difficult with these.
How do you monitor knock retard?
They drive pretty nice. Very comfortable. It's been a pretty decent car too.
Here's a picture I took after waxing it a few months ago.
Excellent job on the wax! Especially in that configuration (2WD, front air-dam in place, highway tread), 20 MPG should be easy.
Have an Android phone/tablet? Download the Torque app, and get a cheap wi/fi or bluetooth OBD2 adapter from Amazon. $25, all in.
Have an Android phone/tablet? Download the Torque app, and get a cheap wi/fi or bluetooth OBD2 adapter from Amazon. $25, all in.
Originally Posted By: Alex_V
Can't speak from particular knowledge on the GMT400 platform's chassis, etc., but the 5.3L is as good an engine as there is in its segment. The 4L60, on the other hand, just isn't strong enough to hold up through hundreds of thousands of miles under "normal" use.
Ive used my 07 silverado for the last 15 months to tow a 16ft enclosed trailer to deliver autobody parts. Ave around 450kms per day. I now have 410,000kms on it and not one single issue. I by passed radiator and installed an aftermarket trans cool and a fan. Put in amsoil tourque drive fluid and it run like new.
Can't speak from particular knowledge on the GMT400 platform's chassis, etc., but the 5.3L is as good an engine as there is in its segment. The 4L60, on the other hand, just isn't strong enough to hold up through hundreds of thousands of miles under "normal" use.
Ive used my 07 silverado for the last 15 months to tow a 16ft enclosed trailer to deliver autobody parts. Ave around 450kms per day. I now have 410,000kms on it and not one single issue. I by passed radiator and installed an aftermarket trans cool and a fan. Put in amsoil tourque drive fluid and it run like new.
Nick1994
$100 site donor 2024
Originally Posted By: Ramblejam
Excellent job on the wax! Especially in that configuration (2WD, front air-dam in place, highway tread), 20 MPG should be easy.
Have an Android phone/tablet? Download the Torque app, and get a cheap wi/fi or bluetooth OBD2 adapter from Amazon. $25, all in.
It's actually 4wd. It had problems earlier this year and it turns out it was low on front diff fluid. A shop filled it up and it's been fine. No leaks, have no idea how it could be low.
Excellent job on the wax! Especially in that configuration (2WD, front air-dam in place, highway tread), 20 MPG should be easy.
Have an Android phone/tablet? Download the Torque app, and get a cheap wi/fi or bluetooth OBD2 adapter from Amazon. $25, all in.
It's actually 4wd. It had problems earlier this year and it turns out it was low on front diff fluid. A shop filled it up and it's been fine. No leaks, have no idea how it could be low.
4WD
$50 site donor 2024
Had the same rig in a Yukon - traded at 107k with zero repairs outside of brake pads & tires ...
Towed an 18' bay boat very well ...
Many 5.3's have gone 300k-400k+ ...
BIL has 390k on 5.3 motor and original 4L60e - no issues - but he is a 30k ATF type ...
Towed an 18' bay boat very well ...
Many 5.3's have gone 300k-400k+ ...
BIL has 390k on 5.3 motor and original 4L60e - no issues - but he is a 30k ATF type ...
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