229k on 2003 XL Denali maintenance tips?

[StickerShockPDX]

I bought this Denali at a public auction. I thought it would go for twice as much as I paid for it so I didn't preview this one as much as I would normally have. The only things I have found wrong on it are the seatback power control knobs are broken on both front seats, one of the clips that holds the flap? to make a flat cargo area is broken on the mid buckets, the liftgate struts are shot, and the load leveling is not functioning.

If I can find the parts at my local yard I am sure I can fix the interior stuff and I've ordered the liftgate struts. I don't have the cash right now to delve into the Autoride or whatever it's called on the Denali.

What I am concerned about is keeping it going for another 70-100k miles.

I've spent hours on the forum reading up on things. I had a 2000 Suburban a couple years ago so I'm fairly familiar with these trucks. Because I don't know the history of the maintenance I will surely start out with plugs/wires, oil change, check all under body fluids, etc.

I managed a Jiffy Lube for a few years in the 90's and have seen some transmission fluid filter changes go bad because they had never been done on high mileage vehicles. I've checked the fluid on my Denali and it smells pretty clean/new. Anyone have experience changing the fluid/filter on a high mileage Yukon? Should I just leave it be until rebuild/replace time? It does seem to hold the gear too long shifting around 25-30 mph. I'm not sure what gear that's in but it holds up to 3000 rpm v shifting in the mid 2000's on other gears.

Also, I have a bottle and a half of Seafoam left from another car, any thoughts on running it through and chances of too much carbon hitting my oil pump?

Any other cheap maintenance items or things to look out for?

 

[JBTJ]

Transmission fluid and filter should always be changed no matter how old it is. Unless you like to replace transmissions for the fun of it. The key is to how you replace the ATF. Doing a flush is a bad thing IF it hasn't been done on a regular basis. The safest way it to use the transmission's pump to pump the old fluid out and replace with new ATF. I installed an external filter as shown in this thread and makes the process much faster and cleaner
. http://www.tahoeyukonforum.com/forum/showthread.php?t=61672&page=2
First you should drop the pan and replace the filter, then top off with 4 quarts of fresh ATF. Then I simply disconnect the input line at the external filter and stick the hose into a milk jug marked off in 1 quart increments. Start the engine and allow it to fill the jug to the 4 quart line. Turn engine off and dispose of old ATF. Pour 4 more quarts of fresh ATF down the dipstick tube and repeat the process until fresh clean ATF comes out. Around 12 quarts should. Since I installed the external filter I no longer need to replace the internal filter. So transmission service is easy and super-fast to do.

 

[StickerShockPDX]

The way we did the trans at JL at first was just drop the pan and change the filter. Later we got a T-Tech machine which did basically what you are talking about. It hooked up to the trans cooler lines. We ran the vehicle and as the vehicle's own pump pushed fluid towards the cooler the fluid would go to the T-Tech. You filled the machine with new fluid and as the old came in it had a plunger that kept the new and old separate and using the power of the vehicle's pump pushed the new fluid in. Very clean and no extreme flushing like I would guess a 'flush' does.

Even with the T-Tech because there is so much detergent in the new fluid it would 'clean' up so much gunk that people would experience bad results if it hadn't been done for over 50k or so. I want to avoid this so I am unsure if I should even try. I like the external filter mod. Maybe I'll drop the pan once and use your external filter mod to keep it cleaner.

Anyone else have thoughts on replacing what might be very old trans fluid?

 

[Sasquatch]

I used to be a mechanic and in my experience it`s never good to change very old transmission fluid. If it`s brown and stinks i would just leave it alone. We had customers have us do a fluid change even though we advised against it and sometimes the car wouldn`t even make it off the lift and we would have to have it rebuilt.

Your fluid is red and it doesn`t smell bad so i would probably go ahead and change it.

I changed my fluid they way jbtj explained and it works great. I went with Dex vi fluid.

 

[JBTJ]

The way we did the trans at JL at first was just drop the pan and change the filter. Later we got a T-Tech machine which did basically what you are talking about. It hooked up to the trans cooler lines. We ran the vehicle and as the vehicle's own pump pushed fluid towards the cooler the fluid would go to the T-Tech. You filled the machine with new fluid and as the old came in it had a plunger that kept the new and old separate and using the power of the vehicle's pump pushed the new fluid in. Very clean and no extreme flushing like I would guess a 'flush' does.

Even with the T-Tech because there is so much detergent in the new fluid it would 'clean' up so much gunk that people would experience bad results if it hadn't been done for over 50k or so. I want to avoid this so I am unsure if I should even try. I like the external filter mod. Maybe I'll drop the pan once and use your external filter mod to keep it cleaner.

Anyone else have thoughts on replacing what might be very old trans fluid?

That is the reason you do not want to use that process. You already know what could happen, so why even try? Do it the way I posted and you will be fine. I have used that process on many vehicles over the years and not once had a problem from it.

 

[StickerShockPDX]

It does smell clean and looks red. The way you've done it is basically the same as the t-tech. There is no external power going to it at all. If we were busy we'd pull it out to get another car in the bay.

Using the machine just made it easier. The old came out and instead of going back through the cooler it pushed the plunger which pushed the new in. All from the car's own power.

Here is a commercial for the t-tech. It's pretty dry but it shows how it works. Seems to me it's the same as what you are doing.

I've done 80-90 pan drops and 50+ t-tech services, so I do know 'bad' trans fluid smell/texture. The fluid in my truck smells and feel fine, I just want to KNOW when everything was done, by doing myself. I don't want to break anything.

 

[JBTJ]

I think this is the biggest problem you mentioned "Even with the T-Tech because there is so much detergent in the new fluid it would 'clean' up so much gunk that people would experience bad results " Even though the fluid looks and smells clean the detergent can still dislodge clutch material and deposit it in places that could do harm. I would not use the machine.

 

[StickerShockPDX]

I haven't worked there for 17 years so I don't have access to the machine anyhow. I'm concerned about changing all the fluid rather than just what comes from a pan drop. Using your method also changes nearly all the fluid and would cause the same troubles. Even pan drops on very old fluid has caused problems that I want to avoid.

 

[JBTJ]

I haven't worked there for 17 years so I don't have access to the machine anyhow. I'm concerned about changing all the fluid rather than just what comes from a pan drop. Using your method also changes nearly all the fluid and would cause the same troubles. Even pan drops on very old fluid has caused problems that I want to avoid.

You seem to keep forgetting about the detergents those machines use, that is a problem in itself.

No, my method will not cause any problems, and it does change ALL the fluid. Many folks have done it with great results. I have not heard of one instance where this method has ruined any transmission. Then again, I've only been doing it on JEEPS and other trucks for nearly 35 years. I learned it from my dad who was a mechanic for over 50 years.

 

[StickerShockPDX]

I'm not forgetting anything. I know how the machine works. Sorry if my description of the T-tech wasn't clear. The machine we used ONLY uses the trans fluid. It does not use any external fluid or detergents. You pump the cylinder with new ATF and when the car pumps fluid towards the cooler it goes through the machine and pushes the cylinder which in turn pushes new fluid into the cooler. No extra detergents, no extra fluids.

I'm glad you've had good results with your method. The T-tech does exactly what you are doing. Old out. New in. No external power. No extra detergents. The machine just makes your way closer to idiot proof by connecting right to the cooler lines and using the car's own pump.

I used to be a mechanic and in my experience it`s never good to change very old transmission fluid. If it`s brown and stinks i would just leave it alone. We had customers have us do a fluid change even though we advised against it and sometimes the car wouldn`t even make it off the lift and we would have to have it rebuilt.

Like Sasquatch, we had people with old smelly dirty ATF insist on pan drops and just changing that relatively small amount of fluid caused more problems than it fixed.

---------- Post added at 05:51 PM ---------- Previous post was at 05:45 PM ----------

Because the fluid is a good red and smells/feels clean, I am going to at least drop the pan and replace the filter while doing your external filter mod. I will also do the maintenance from one of Jay's posts with the new accumulator pistons, boost valve, separator plate, and PWM delete valve. Hopefully this will all lead to a longer trans life.