Thinking of Buying a 91-99 OBS Tahoe/Suburban? Look Here

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Donnie Yukonie

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Admin has seen Fit to Create a Catch all thread for the countless "looking to buy" threads that go unanswered because lets face it some are repetitive. Hopefully people will read through this sticky and have all or most of their questions/concerns answered. Some of this may be biased and if it is please let me know and Ill Edit it out . Also if any of you veterans have anything to add Please post it below and I will add it at a later time . Any newbies may also post questions here that have not been answered . I will add Content as it becomes available or as I come up with it .

Fun Facts:
GMT400 Platform : Includes the Silverado,Sierra,Blazer(Full size)Tahoe,Yukon,and both the suburban in GMC and Chevy models sold between the years of 1988-2000
While each model has a manufacture specific code I.E A 1995 Tahoe would technically be a GMT420 designation. (see chart below for more info) But in reality all these trucks/SUVs are in the same family and most parts are interchangeable as they share the same style body panels, motors, trans, frames ect... Obviously there will be differences between models.

Specific destinations


Platforms and designations codes
GMT400/480 1988–2000 Chevrolet C/K
1988–2000 GMC C/K
GMT410 1992–1999 Chevrolet Suburban
GMT415 1992–1994 Chevrolet Blazer (Full Size) later rebadged Tahoe in 1995
GMT420 1995–2000 Chevrolet Tahoe
GMT425 1992–1999 GMC Suburban
GMT430 1992–2000 GMC Yukon
GMT435 1999–2000 Caddilac Escalade

Guide to model upgrades and specifications
1992 -GMC called their GMT400 the Yukon While Chevrolet Continued to Use the Blazer name until 1995 2 door models
1994- 4 door Models available
1995- the trucks received updated interiors and Grills
1996- Push button 4wd was added (no Auto option) DRL Option and Vortec Series motors added to the lineup
1997-Last production year for the 2 door Yukon
1998 -Auto selection was added along with another Interior update
1999- Denali Option Became available with a Updated interior and other goodies
2000- Limited Package AKA "SS" Which Really shared no real performance gains Just a dressed up ground effects and Wheels with Special interior.

Engine Options
4.3 liter TBI Pre 1996- (should never be found in tahoe/yukon/suburbans)
5.7 liter TBI Pre 1996-
5.7 liter Vortec 1996+
6.5 TD and non TD Diesels 2500-3500 trucks (also rarely available in a 2 door 1500)
7.4 liter Gas TBI and Vortec motors. (unsure of year specific vehicles. commonly used in 2500 suburbans and trucks)

Rear axle options
-10 bolt (most common axle used in the 1500 applications. most common gear options ranged from 3.42-3.73 with an optional G80 locker)
-14 bolt Semi Float (found in some "heavy half tons or 2500s)
-14 bolt Full Floater (Found in all 3500s)

**** Gear codes****
GT4-3.73s
GU6-3.42
Z85- Towing package
Z71- ( note before the actual Z71 Tahoe made its debut a lot of models came equipped with this package which offers skid plates and bilstien shocks from the factory

Few things to remember :
If you are buying a OBS truck there are some things to remember .This thread is for 92-99 Model year trucks With some 2000s included as Limiteds or Classics before the Model swap to the NBS trucks .

You are buying a USED vehicle being as Old as these SUVs are there will be problems I will just hi-light some trouble areas most of us have had as a common issue with the platform. but in the end your likely buying a truck with over 100k thats 10-15 years old so common sense should kick in about here telling you that the vehicle will likely need some TLC.

Issues that shouldn't affect sale but will probably already be a Obvious (COSMETICS):

--Front Leather driver seats : these were prone to Cracking/ripping on the left lumbar section This issue is very common.
Replacements seat cushions and leather can be found at the sweatshop for replacement .

Paint chipping Above Front door windows and hood : There is year specifics to this (earlier models) and it was a GM defect SOME not all trucks had this issue , Ive mostly seen it on white and tan trucks but this doesn't mean every color is safe.

Rusted Rocker : <<<<THIS Plagues these platforms more common in Colder climates Up north where the use of heavy salt is present. LMC truck sells replacements Just be aware of how bad it actually is You might be replacing more than just the rocker . (It should be noted that the doors can be affected as well at the bottom seam underneath the rubber door seal.)

Broken Interior Door handles : Ive replaced mine 3-4 times in the time I've owned my truck they weren't built to sturdy . they are cheap to replace and easy to do yourself if your mechanically inclined at all . I think Autozone even carrys them and I want to say they run maybe 15 bucks max.

Sagging Doors : On these old trucks Its not uncommon for the Front doors to sag quite a bit , so much so that they end up causing issues closing,opening because they lean on the latch . the fix is rather simple but does require some time and 2 people or if your really awesome Ive seen it done with a jack .

Factory CD slave Player : This may or may not be a issue for you Most Of the factory slave units are already dead and have been replaced . If your lucky enough to find one in working order , you might want to count on it going out in the near future

Cracking Dashes :
The trucks are getting to the age now where in hot climates the dashes may be cracked around the column or defrost vents. I haven't noticed these issues as badly on the pre 1995 models but it could happen




Here are some very common things to Look out for Upon Inspecting and test driving

Wiper Motor : This was a hit or miss for some but common enough It should be mentioned Some were intermittent while others just quit working . the most common point of failure was in the motor I do believe Something to do with the circuit board burning up (no risk or report of fire(s) )

Burnt out Tail light circuit board : another faulty design in these trucks were the Taillight circuit boards , to my knowledge the OEM ones weren't a issue but the aftermarket replacements don't hold up to well TBH I replace one every year or 2

Intake Gaskets 96+ (Vortec Motors ONLY) On the Vortec motors A huge issue was the Intake gaskets leaking . This is a pretty serious issue if left alone as water/Coolant will eventually mix in with Oil and you will be replacing a motor before long . If you don't know what to look for here are some tips : Coolant smell with no visible leaks around the Radiator or hoses, Wet spots (sweat) in between the Intake and Valve covers . and a Milky consistency in the oil.
Problem: Factory these trucks came with Plastic/rubber intake gaskets which over time melt and start to leak
Fix : Updated part number--- (Fel-Pro MS98000T) which uses metal Intake gaskets to prevent the same issue


Transfer Case Pump wear Issue: To my knowledge (correct me if Im wrong guys) the NP246 Tcase AkA Autotrak Cases were the only ones affected , for the new guys that means Push button 4wd with "Auto 4wd" selection available or 4 buttons .
Problem - The actual Pump which is mechanical and Spins and is supposed to Float within the walls when the truck is traveling down the road . the pump ends up rubbing into the walls of the Case itself . The case is made from Magnisum but for what ever reason GM decided to use Aluminum for the Pump housing. what ends up happening is the pump having been made of a stronger material (steel) wins the rubbing contest and wears the pump housing right through the case leaving small cracks,Pin holes. this intern lets all the fluid out and destroys the transfer case .
Fix : you can either buy a Kit that Beefs up the housing or buy a New *Updated* Transfer case .

Trucks equipped with 4L60E Transmissions : Ive never had this particular issue but read a few more times than no that there is an issue with one of the servo valves in the 4l60E transmissions failing . most people Ive come across swap it with a Corvette servo for Fix.

"Driveline Clunk"
You may notice a "clunking" noise coming from the back of the truck. This is usually the cause of the slip yoke not being properly lubed. The main issue with this is that I've lubed mine countless times only for the clunk to return within a few weeks. as long as it isn't completely dry and you have no other play in the u-joints or backlash in the axle it will be fine.





CONCLUSION:

Please remember you are buying a 15 year old truck with 100k or more miles on it. Its bound to have issues. There will probably be things not listed here that are wrong with the vehicle. that doesn't mean its a common issue. it just means its old. We only list the common issues most of us have encountered. The plus side is these trucks are relatively easy to work on. they make good projects and still prove to be reliable with the right preventive maintenance. and to be honest are fairly cheap to restore.


MUCH MORE TO BE ADDED THIS WEEKEND!!!!
 
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Gzes

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Sagging doors. Bushings where the door pins go tend to get old and sag. Replacement door pins are inexpensive and not bad to replace
 
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Donnie Yukonie

Donnie Yukonie

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Sagging doors. Bushings where the door pins go tend to get old and sag. Replacement door pins are inexpensive and not bad to replace

That one slipped my mind thanks man! I have a lot to add so keep any and all ideas coming
 

BirchyBoy

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How about the transfer case pinhole issue? Might be expensive enough to make someone avoid one.
 
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Donnie Yukonie

Donnie Yukonie

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How about the transfer case pinhole issue? Might be expensive enough to make someone avoid one.

Yes the TCase Pump wearing through the housing is a great one !

---------- Post added at 10:05 AM ---------- Previous post was at 10:02 AM ----------

Ill Add that none of this Is proof read yet sorry for so many Grammar Errors LMFAO "sweatshop"
 

Y2KpewterZ

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Intake gaskets on 96+, rust on inside of doors on the lower seam (which is often covered by the piece of rubber)
 
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Donnie Yukonie

Donnie Yukonie

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I added Some of your suggestions Ill add some more tonight I have a few things to add but keep them coming guys
 
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Donnie Yukonie

Donnie Yukonie

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Stickied and moved Ill proof read it later along with anymore suggestions
 

Y2KpewterZ

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Problems with spider injection.. update with revised units. Crazy gas gauge needle bouncing around (i remember seeing a fix/how to thread on gmt400.com i believe,) G80 aka gov-bomb for any serious off roaders..

Important codes to look for on glove box;
GT4: 3:73s
GU6: 3:42s
Z85: Upgraded towing provisions
Z71: off road package (other then the obvious badging and such on 2000 models, Ive seen 2-doors with this RPO with no badges)
 

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