4WD inspection/maintenance

Discussion in 'Shop Talk' started by swamp man, Jun 17, 2006.

  1. swamp man

    swamp man Well-Known Member

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    I'm fairly handy when it comes to working on automibiles,but I have never owned a 4WD,and I know very little about them.Anyhow,I'm considering buying a '97 Z71.I've looked it over pretty thouroughly,compression checks out(it has high miles),plugs look good-all the rugular stuff I check out before buying a used truck.I do know that the 4WD works,but is there anything I should look for to be confident that it isn't on it's last leg?Any tests I can perform?
    Also,when I purchase used vehicles,I go through them with a fresh tune up,fresh fluids and filters,etc.If I buy this truck(and if the 4WD checks out,I will),what type of maintenance/adjustments would yall recommend?
    Thanks
     
  2. Beeman

    Beeman Well-Known Member

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    The first question I ask people is do you need a 4wd? If you do that's fine, if you don't it's nice to have but is harder on gas and has more moving parts but is better on resale.
    The 4wd system on those trucks are very reliable. Be sure to physically check to be sure it engages 4wd as ther are 2 engagements that must be made, the transfer case must engage and also the frt. axle has to engage. The indicator light that shows the picture of all 4 wheels engaged will verify the frt. axle engagement. Also be sure it disengages OK. Leaks at the frt. differential where the axle goes in are common so frt. diff fluid level is important.
    Coolant leaks are the biggest problems encountered on those models. The corners of the intake manifold leak and if not repaired early I have seen the gasket deteriorate enough to leak oil into the crankcase of the engine. Water pump leakage is another common problem.

    Changing fluids is always a good thing. I would definetly get rid of the red dexcool antifreeze if it's still in there. Be very careful to use the correct fluids for the application as the use of the wrong fluid can be expensive.
     

  3. swamp man

    swamp man Well-Known Member

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    Thanks,Beeeman.I wasn't shopping for a 4WD,and to say I "need" one might be a stretch,but I'm liking the Idea.I have a coupla' camping spots and fishing holes that I have to hike into,but could easily get to with a 4WD.I like to play in the mud,but It's always been with baja bugs.
    About that intake manifold leak-Is this problem because of faulty gaskets,improper fit,or what?If I buy this thing(and it looks like I will),I'd like to remedy this problem before it starts.I am a bit of a hot rod nut,so the heads will probably get a little work,and everything upstairs from there will likely get replaced with aftermarket stuff.
     
  4. dirty

    dirty Well-Known Member

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    you may want to look into an oil sample test. i think between that and a compression test you'd have as much piece of mind as a person can get. there are probably a bunch of places that do oil samples. the only one i've used is 'blackstone laboratories'. it's a real simple deal. they send you the contianer for free. so you don't have to pay until you send in the sample.
     
  5. Beeman

    Beeman Well-Known Member

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    GM used Dex-Cool antifreeze(red) which had a tendency to destroy much in it's path when any air was in the system with it. This is part of the coolant problems in those years. In 96 Chevy changed their fuel injection and their heads to a desigm that uses 8 bolts to hold the intake to the heads instead of the older 12 bolt design. They also changed the intake gasket design to a plastic gasket with a captured silicon seal around the ports which sealed at low torque. The original design gaskets leaked and then when people replaced them they didn't follow proper procedures and torques and the problems snowballed from there.
     
  6. tiogacounty

    tiogacounty Well-Known Member

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    The coolant leak involves several issues. First the design is suspect because GM is dedicated to installing the intake with a robot, which created design issues that greatly compromised the longevity of the gasket. Second, Dexcool is garbage and gets immediately removed from any used GM I buy. Third, if the gasket is not changed by a meticuliously clean mechanic there is going to be problems. The gasket needs to be scraped very carefully to avoid getting debris in the block. Blown engines a few months after a gasket swap are fairly common. I had a Chevy 1/2 4X4 from the late 90s and wasn't real impressed. It needed the gasket and a trans. before it hit 85 thousand. This truck was lightly used and extremely well maintained. Overall, it was a very comfortable truck that ran well, but the repairs were unacceptable. Dropping thousands in a four year old truck doesn't cut it in my book.