tranny maintenance - negelected

Here is my experience with 1997 Thaoe at 136K miles. Manual says light duty change AFT - never. Severe duty- 100K.

So at 100K it pulled the pan, cleaned it, and replaced filter. Only 1/2 of the fluid comes out and the drain plug on the torque converter was hard to find. So I replaced half of the fluid.

At 135K the torque convertor went out. Fluid was dark brown. The shop pulled the 4L60E apart and it was in surprisingly good shape although a couple clutch disc and bad forward gear needed replacement.

Recommendation: I would now have changed the ATF when I got the vehilce at 36K and REPLACED the pan with one having a DRAIN PLUG.

Then I would drain the pan and replace the fluid every 3rd oil change.

I did something like this on a Range Rover with a ZF 4-speed (it had drain plug) and sold it at 176K to a friend who is still running it today, probably now 187K.

Pan without a drain plug is a real mess. With a plug... just refresh fluid at oil change and it's painless.

Almost forgot - I have heard so many stories about good trannys having problems after a full, machine flush at a shop I would avoid that if you high miles already. Use this technique with more frequent changes to clean up the neglect slowly.

My 97 has about the same milage as you.

If it were me, I would change the fluid and filter every 40k when towing regularly and 60k if not towing at all. My Hayes manual doesnt even show any tranny maintenance up to 60k.

I bought my Tahoe with 129k and the fluid looked perfect and smells fine, but if I start towing more, I will be changing it soon.

swp5767,

Maybe the previous owner just had the tranny rebuilt :)

Got records ?

I'd have agree with the first two assessments. Despite what the owner's manual and service manuals might advise, I change transmission fluid frequently. I try to maintain a 30K mile interval, and usually skip the filter change on alternate drainings. I also make a habit of installing an oil drain plug in every pan I pull, whether or not it is mine.

Many transmissions are now getting drain plugs from the factory, but many more still aren't. For about $4 in parts an a little labor, the next trans oil change becomes a lot easier.

http://72.19.213.157/files/TransPlug.jpg

http://72.19.213.157/files/TransPlug4L60E.jpg

For about two bucks and change you can get a standard ½-20 drain plug and sealing washer (Dorman/Motormite P/N 65245) and for about another 20¢ you can get a mating ½-20 jamb nut. Locate a suitable place to install the plug. Verify that there is at least 3/4 inch of depth or clearance inside and above the pan so that the extra length of plug inside the pan presents no interference. If your location is near the drain pan magnet, remove the magnet so that heat does not weaken it. Drill a ½" hole in your chosen location, remove the washer from the oil drain plug, and assemble the plug and nut through the pan to hold the nut securely in position. Apply three good tack welds (or braze) to alternate flats on the jamb nut. Clean up the interior of the pan from any flux and weld spatter, remove the plug, and install the sealing washer and plug once the pan has cooled. Bolt the pan back on and try to re-use the factory pan gasket, since most of them are vastly superior (in several ways) to the cork/compound replacements provided in filter kits. Even if the plug is not in the lowest part of the pan, you'll be able to drain the majority of the oil and make the job a lot easier - You can actually look forward to the next trans oil change.

http://72.19.213.157/files/TransPlugNut.jpg

I actually "cheat" and only drain the pan via the plug, then install the plug and refill as necessary every other change. The pickup filter and magnet in the pan is usually not contaminated sufficiently in 30,000 miles to warrant pulling the pan for a full service. It still changes about 2/5ths of the oil and drains any heavy contaminants, and is about 400% better than what the service manuals recommend.

I bought my Tahoe from a dealer and have no records. I doubt they would do any trans maintenance.