New to me 99 Suburban: 5.7 vortec repairs

unabashedpraise

Adventurer
Do these readings look normal? I've noticed the temp rarely gets above 190.
Oil pressure I'm not sure about either.



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rayra

Expedition Leader
Oil pressure on vortec motors can be quite low at idle. GM won't even call it low until it's below double digits. As long as it comes up at higher RPMs you're fine. With a high mileage motor it's going to be hard to raise it much, even with an oil pump change.
Operating temps, IIRC your earlier generation ought to also have a 195F thermostat. But there are also 180F and 175F available, listed as 'alternates'. Yours appears to have a 180F.
If you can lay hands on an OBDII scan tool (or equivalent*) you could look up the actual temperature sensor reading, instrument gauges are not always accurate. Needles get moved, stepper motor response can change. Your actual temperature might not be what is displayed. But if you deliberately put in a 195F thermostat and your gauge reads 195F, then such a possibility can be dismissed.


* I have a Panlong bluetooth OBDII reader / transmitter, which I couple with an Android tablet and the Torque app. With it I can read / display much of the vehicle sensor data. And with that I can verify my dash needles, or re-install them properly after I've had things apart to replace dash lights or stepper motors. That's in my Hey Vortec Guys topic as well.
 

unabashedpraise

Adventurer
Oil pressure on vortec motors can be quite low at idle. GM won't even call it low until it's below double digits. As long as it comes up at higher RPMs you're fine. With a high mileage motor it's going to be hard to raise it much, even with an oil pump change.
Operating temps, IIRC your earlier generation ought to also have a 195F thermostat. But there are also 180F and 175F available, listed as 'alternates'. Yours appears to have a 180F.
If you can lay hands on an OBDII scan tool (or equivalent*) you could look up the actual temperature sensor reading, instrument gauges are not always accurate. Needles get moved, stepper motor response can change. Your actual temperature might not be what is displayed. But if you deliberately put in a 195F thermostat and your gauge reads 195F, then such a possibility can be dismissed.


* I have a Panlong bluetooth OBDII reader / transmitter, which I couple with an Android tablet and the Torque app. With it I can read / display much of the vehicle sensor data. And with that I can verify my dash needles, or re-install them properly after I've had things apart to replace dash lights or stepper motors. That's in my Hey Vortec Guys topic as well.
I do have a Bluetooth obdii adapter and torque pro. Last temp reading I saw was 194 degrees. Maybe it's the way the gauge is designed. Seems too low since "normal" isn't straight up like in my zj.




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KLAKEBRONCO

Adventurer
I have a 96 Z71 pickup. Same platform and engine.
I'm gathering parts now for a 6 lug 9.5" 14 bolt rear axle swap.
As far as I'm concerned the 10 bolt is absolutely garbage and is the biggest weak point in the platform.
I'm upgrading the brakes to 99+ (2001+ Suburban/Tahoe) 6 lug disks from the 1/2 ton at the same time.

There are ways to upgrade the front to 12,13 or 14" rotors using factory parts as well. You have to up grade to 99+ knuckles/hubs. Re-ream the balljoint taper and then use newer calipers and caliper brackets as well as matching rotors


The rear axle and brakes as well as a limited slip are the top priorities to fix on this platform in my opinion
 

KLAKEBRONCO

Adventurer
What is the path forward on the rear diff? Mine is making some noise at 320k miles. 3.42 gears (I think) open diff.
See my post above.
10 bolt needs to go....I'd lean heavily towards a regear as well.....with a 32.5" tall tire I'd like to swap to a 4.10 gear
I have 3.73's now but if I had 3.42's a regear would be very high on the list
 

rayra

Expedition Leader
Meh. Great, if you want to do the work / spend the money. But the only tens failing I know of happen when people can't take their foot off the gas when their rear wheels leave the ground. Kinda like the dolts that are breaking Raptors all over YouTube. They can't take abuse. They can take a huge amount of normal use and strain. But by all means you want to rock crawl, jump ****, or otherwise lurch 6000lb+ around by its gear teeth / clutches, you should consider the upgrade.
 

unabashedpraise

Adventurer
About the only reason I can see me changing the rear axle is if something catastrophic failed.

I haven't towed with my burb, nor had it loaded down. Are these brakes that bad? I haven't noticed any issues.


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KLAKEBRONCO

Adventurer
Meh. Great, if you want to do the work / spend the money. But the only tens failing I know of happen when people can't take their foot off the gas when their rear wheels leave the ground. Kinda like the dolts that are breaking Raptors all over YouTube. They can't take abuse. They can take a huge amount of normal use and strain. But by all means you want to rock crawl, jump ****, or otherwise lurch 6000lb+ around by its gear teeth / clutches, you should consider the upgrade.

Go to a pick n pull yard and take note how many 10 bolts are missing or the covers off and spiders or axle shafts are missing
While you're at it note how many of those are stock trucks

Something catastrophic will fail.
And btw the 9.5 14 bolt is a direct bolt in that was actually available on some 1/2 ton trucks
 

rayra

Expedition Leader
whatever man. You've taken the wrong lesson from your anecdotal experience and rote repetition of lore. The parts are pulled because those 10 bolts (and the vehicles they are in) have been on the road for so very long. I've been driving and wheeling them for over 30yrs, mostly in CA deserts, approaching 750k miles combined across four vehicles. I'll say it again, it's the abuse they are subjected to, not anything inherently wrong in their design. Try to pop / lurch a 5000-lb rig up a bench or boulder crawl, play on a jeep trail, sure, you might bust it. But it will be your own fault.
You want to do that kind of wheelin' get a lighter vehicle or a tougher axle. Hell that's how Dana axles got famous.
 

unabashedpraise

Adventurer
Changing driver's window regulator tomorrow. However, spider injectors on hold. My 5 month old may need another surgery next week. We found out Monday, and figured I don't need the extra stress.

What do you think of this? I was going to replace the cancer ridden rear panel, but this looks MUCH better. Think it will help departure angle much?


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unabashedpraise

Adventurer
just a little

/lol


best wishes for your baby.
Thanks. Found out that she is doing better than they thought, follow up in six weeks.





Right now I'm replacing light bulbs in the instrument cluster. Abs, brake, and another one won't light up, even with bulbs that I verified in other positions.


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unabashedpraise

Adventurer
Trying to get a plan together for future mods and repairs. Any suggestions?

I should preface this by stating my goals for this thing. Mainly will be a family vehicle. Would like to get as much off road capability out of it as possible. I knows it's not a goat. My zj would probably run rings around it. But the zj isn't big enough! So the types of trips we would take wouldn't be rock crawling style. More like camping along easier mountain passes or desert roads like white rim road. Whichever this thing could handle. I'm not looking to drop this off ledges or tackle black bear pass. What areas would you suggest?



Aftermarket/stock wheels-
-I really like some of the newer-ish Chevy wheels. Did they keep the same backspacing for all their 6 lug wheels?

Increasing overall ground clearance-
-I'd like to go with 33" tires (or bigger!), to increase ground clearance. To do that (33"), I've read that some people have rubbing issues on stock, some don't. Some people crank the torsion bars, but I'd rather not mess with jacking the suspension up. So I was going to look into a 2" body lift, but I'm not sure it's needed, or that I want to mess with it. Gaps, rear heat and ac lines, bumper relocations, etc all being issues I may not want to deal with. Decisions, decisions...

Increase approach angel-
-trim/remove valance?

Increase departure angle-
-Man that bohemoth of a gas tank hangs really low! If I do a body lift, I want to look into raising it. If I don't body lift, I guess I'll have to fab a giant skid?
-Also want to cut rear quarter panels and add a rear bumper. Problem is that tank hangs so low, not sure it will help that much. I want the bumper to be tucked up, similar to this, with a hitch added to it.


-Looking to lift the rear end up a bit. I like a small raked stance, and right now it's a hair lower than the front. Add a leaf? New springs? Not looking to add blocks. This is also holding up replacing the shocks.








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KLAKEBRONCO

Adventurer
I don't follow. You don't want to replace the 10 bolt but you do want to add modifications that will stress it more than stock use isn't in a way that will stress it MUCH more than stock when it's already marginal when is d as intended as stock
 
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