To do or not to do?

[johnny--2k]

With 189K miles on my new to me Z71, I don't know what has or has not been done by the 1 previous owner in terms of general maintenance, so I'd like to know your thoughts on what I should or shouldn't do.

The main one that I'd be hesitant to do is a trans flush... since it runs fine, I don't want to start causing problems. The diff fluid was one I was not sure on though. If it has never been done, and I change it, do I run the risk of causing more harm than good?

Then there is the question of the water pump/t-stat. What's the avg life on these? Any symptoms to look for that it's beginning to fail?

The rest of the basic maintenance will be done as they come along like plugs/wires, power steering fluid flush, and fresh brake fluid when I get around to putting on the new brakes I have sitting in my kitchen .

Anything else I should look for in terms of general maintenance?

 

[swathdiver]

What color is the transmission fluid? Do you have access to a Tech2?

 

[johnny--2k]

Honestly not sure, haven't checked it, and no access myself to a Tech2

 

[swathdiver]

Well, I would change all the fluids save for the transmission unless you can determine that the transmission fluid had been changed before. If it is brown I probably would not do it. If red or some red it is likely that it had been properly maintained and you should be ok in changing it. It's a real pain to drop the pan on my GMT932, is it any easier with the 800s?

The Tech2 can read the transmission oil life on the GMT900s, not sure if the 800s have this feature. My fluid was turning brown and my Tech2 said it had 35% of life left. I changed it all anyway and reset the transmission oil life to 100%.

At 189K, it's probable that many maintenance items and repairs have already been done over the years but we also know that clean fluids prolong the life of those components. Check for grease fittings on your steering gear and lube your yoke and u-joints too if possible.

 

[johnny--2k]

Gotcha! I'll check it this weekend, and see what I can find out. Thanks!

 

[HiHoeSilver]

With 189K miles on my new to me Z71, I don't know what has or has not been done by the 1 previous owner in terms of general maintenance, so I'd like to know your thoughts on what I should or shouldn't do.

The main one that I'd be hesitant to do is a trans flush... since it runs fine, I don't want to start causing problems. The diff fluid was one I was not sure on though. If it has never been done, and I change it, do I run the risk of causing more harm than good?

Then there is the question of the water pump/t-stat. What's the avg life on these? Any symptoms to look for that it's beginning to fail?

The rest of the basic maintenance will be done as they come along like plugs/wires, power steering fluid flush, and fresh brake fluid when I get around to putting on the new brakes I have sitting in my kitchen .

Anything else I should look for in terms of general maintenance?

There are a number of methods to "change" the trans fluid in varying degrees. The one thing you definitely want to avoid is a full on flush. You can drop the pan, change the filter /gasket, and just put that 5 qts in as new. You could even put a pan with a drain plug (if you don't already have one) and do those 5 qts at a time as you feel like it. Or you can use the cooler line method to pump it out under its own power... Many success stories this way. This is also a good way to empty the pan without taking a bath if you want to put a new gasket in.

Agree with @swathdiver on lubing stuff. Any squeaks or creaks? How's the ride feel?

 

[johnny--2k]

No real squeaks or creaks, and overall rides great. Only slight clunk/rattle I get is in the front over bumps, and I can feel it in the steering wheel. I do know the intermediate steering shaft has been replaced a couple of times, so I'm sure it's going bad again...

I'm guessing overall it probably could use new bushings all around, but ball joints are good, front hubs are brand new as are tires.

As far s the trans, since it shifts fine and is not slipping at all, I am leaning towards just not touching it at this point assuming the fluid looks decent.

 

[ivin74]

With 189K miles on my new to me Z71, I don't know what has or has not been done by the 1 previous owner in terms of general maintenance, so I'd like to know your thoughts on what I should or shouldn't do.

The main one that I'd be hesitant to do is a trans flush... since it runs fine, I don't want to start causing problems. The diff fluid was one I was not sure on though. If it has never been done, and I change it, do I run the risk of causing more harm than good?

Then there is the question of the water pump/t-stat. What's the avg life on these? Any symptoms to look for that it's beginning to fail?

The rest of the basic maintenance will be done as they come along like plugs/wires, power steering fluid flush, and fresh brake fluid when I get around to putting on the new brakes I have sitting in my kitchen .

Anything else I should look for in terms of general maintenance?

You problaby are going to need to change the gaskets listed below since these rigs are know to leak oil from there. I have done all these gaskets on my yukon and sierra.

Valve cover gaskets
Oil pan gasket
Valley pan gasket
Rear main seal

 

[Rocket Man]

I would not change any of those gaskets unless you have oil leaks, especially the rear main seal since you have to pull the transmission to replace it.

 

[Chubbs]

No real squeaks or creaks, and overall rides great. Only slight clunk/rattle I get is in the front over bumps, and I can feel it in the steering wheel. I do know the intermediate steering shaft has been replaced a couple of times, so I'm sure it's going bad again...

I'm guessing overall it probably could use new bushings all around, but ball joints are good, front hubs are brand new as are tires.

As far s the trans, since it shifts fine and is not slipping at all, I am leaning towards just not touching it at this point assuming the fluid looks decent.

I recently started get a "CLUNK" what feels like the front. Its pretty serious going over humps where the suspension can drop out or really get a cycle in. I checked the front end over several times and what I found is the bushings that secure the torsion bar crossmember to the main chasis are really degraded. You may or may not have the same thing happening with your truck but I think its going to become a common occurrence. Their is a great R&R thread under the 'technical' subforum of these NBS trucks. You will want to see the write-up first so that you know what to look for. Even if the bushing hasn't fully come apart, any cracks or deterioration calls for a replacement.

http://www.tahoeyukonforum.com/threads/torsion-bar-crossmember-bushing-replacement.95499/

I purchased a set on eBay pretty cheap.