98 C/K 4X4 Automatic Tranny Problem

[1998_CHEVY_4x4]

when pulling any small or big trailer with this truck, the tranny hits really hard when going into a higher gear. tranny does not hit hard for the first few miles
it does take a few miles before this starts to happen. this only occurs when towing a trailer.
when i turn off the truck and wait for a few minutes the tranny works fine for a few miles then the hard shifting begins again.
the farther i go on the freeway with a trailer, the harder the tranny hits when going up a gear.

the last time i was towing a 6x8 trailer with a dirt bike, tranny fluid went every where. truck still shifted, just oil every where. truck now smells of burnt fluid.
put tranny fluid back in and now there is no leaking (not towing anything). truck runs and shifts good. truck has started to make a low wobble noise lately also.

felt a really bad vibration in a turn the other day, vibration also happened when shifting into gear after the turn, this vibration has only happened once.

this truck has a 1500 motor

anyway, hoping some may know what is going on with this tranny.
will answer any question you may have.

nice site, looking forward to chatting with you all.

[j cAT]

hard shifting is because the PCM knows tranny is slipping .. on shutdown it all resets.

so why is this happening when towing only ??? this maybe due to you operating in OD when towing. never use OD use 3rd gear . this prevents over heating and then slippage.

the tranny fluid to use must be dexron VI. this is now the GM approved fluid. GM does not use this spec anymore in any vehicle. also will not do any warranty coverage if this dexron III is used. many tranny shops still use this damaging fluid .

I would drop pan replace filter, clean up the mess in the pan install dexron VI and add a tranny cooler in front of the ac condenser. that should do it.

[1998_CHEVY_4x4]

thanks for the info j cAT.
we kinda thought electronics were involved do to the tranny not hard shifting after a restart. just did not know for sure.

with the leak and smell of burnt fluid, i wanted to change tranny oil/filter.
still do not know where the fluid came from.

really wondering about how much damage was caused by this. so i will be taking the truck to a shop to check things out.

thanks again for the info. i will definitely not tow with the truck in OD.
will also look into putting a tranny cooler in.

[j cAT]

what happened which is quite common is the tranny fluid boiled and bubbled out the tranny vent IMO....

pan drop filter change then do the fluid exchange method at the radiator tranny fluid line.takes 12 qts to do. this will remove the bad fluid engine on in neutral . as 1 qt comes out you add 1 qt in the dip stick bore.

dexron III turns to acid when over heated so only use dexron VI ....

since you tow add the tranny cooler when you do the fluid exchange method since that line will be disconnected .. easy to install a tranny cooler on these trucks save your transmission.

[1998_CHEVY_4x4]

started looking at coolers today, they are some what cheap, will put one in.

OD seems to be getting worse, even without towing. OD hit hard once today, i put it in third, ran good.
i drove in 3rd today, seemed fine.

looks like i will be getting a fluid change very soon. do not want acid in the tranny.

still worried about the noise this thing is making. noise is getting bad when in OD, not so bad in 3rd.
this noise started before the fluid burned up.

thanks again for the advise

[j cAT]

could be the torque converter got some tranny particles in it with the over heating . fluid change may help it or it may be damaged . hard to say until it is serviced .

when checking the fluid use a white cloth see if it has particles .. use a magnifier.

[1998_CHEVY_4x4]

going to service soon, will look for particles. have not had time to work on it, cause of work. have not been driven the truck either.

will probably take it to a mechanic. thinking it would only cost about 100.00 to get flush done. this way the flush will get done correctly.

thanks again for the info j cAT
i will keep you updated

[Schurkey]

Good luck with having a "professional" do it right. They're likely to flush the FLUID and never drop the pan to change the filter. It has been my experience that the guy doing the flush is the newest, most-junior member of the service team.

"I" would never put expensive fluid into a transmission that had the potential for needing an overhaul, especially when the trans wasn't spec'd for the expensive fluid in the first place. In my driveway, that'd get Dex/Merc (Dexron III substitute) until I knew for sure that the trans didn't need to come out for rebuilding.

[1998_CHEVY_4x4]

went to have a flush, they said they do not replace filter. did not do the fluid change.
now just looking to get a inspection and so on.

thanks for the reply Schurkey

[j cAT]

Originally Posted by 1998_CHEVY_4x4

went to have a flush, they said they do not replace filter. did not do the fluid change.
now just looking to get a inspection and so on.

thanks for the reply Schurkey

remember I said pan drop filter replace and the fluid exchange ..
you never do a flush which means a machine is hooked up then they do not drop pan because that takes more time and this is a damaging service. the fluid exchange after the pan drop filter replacing/cleaning is what you need since the fluid got cooked. .

you must use dexron VI since that is NOW the approved GM fluid. do not use dexron III ....

[j cAT]

Originally Posted by 1998_CHEVY_4x4

went to have a flush, they said they do not replace filter. did not do the fluid change.
now just looking to get a inspection and so on.

thanks for the reply Schurkey

The flush gets all the crap to get flowing around and then damages the torque converter.. this method is OK on some vehicles manufactured but NOT GM vehicles esp.... a 4L60 tranny....clutch material is very high on these so no force fluid activity is allowed ..

on trucks like yours some put a tranny filter in line with the cooler. this filter has a magnet in it. many that have had issues with shifting due to being old have found this filter to work very good.. back when GM made Saturn vehicles they did come with this filter from factory .. fluid lasted much longer...

[1998_CHEVY_4x4]

i thought the flush came with a filter/fluid change.
thought they would flushed the tranny then, put in new filter and fluid.
maybe going to a quick oil change place, was a bad idea!

just taking my chances with a shop, hoping sat.
its to cold and this thing needs some kind of adjustment or something. vibrating is getting worse.

thanks again j cAT.

[777stickman]

My opinion is that you really need a new tranny! Fluid & filter changes or fluid transfusions most likely will not cure your tranny issues.

Good Luck to you.

[Schurkey]

Originally Posted by 1998_CHEVY_4x4

i thought the flush came with a filter/fluid change.
thought they would flushed the tranny then, put in new filter and fluid.
maybe going to a quick oil change place, was a bad idea!

Quick-Change artists are often crooks. Spiffy Lube can K-M-A.

I drop the pan, remove (and inspect) the bulk of the "crap" and debris. Seeing the debris, I have a feeling for the general condition of the transmission--metal pieces are never good, large chunks of burnt friction material are never good, but fine grey powder--in reasonable amounts--is pretty normal. I replace the filter which is going to be contaminated with crap and debris, reinstall the pan having gotten rid of ~5 quarts of contaminated fluid, and THEN flush the rest of the contaminated fluid out knowing that when I'm done, nothing but clean fluid has been put into the pan; so extremely little contaminated fluid remains in the transmission--only the residual oil that was in the geartrain and bushings, trapped in the clutch drums or in some of the transmission fluid circuits--ounces, not quarts.

Flushing then dropping the pan means that the new fluid comes in contact with all the debris at the bottom of the pan; and when you drop the pan, you're dropping the new fluid which then has to be replaced with more new fluid.

I'll say it again--no way in hell do I pay for synthetic Dexron VI when the transmission came from GM set-up for inexpensive Dexron III; and the transmission may be terminally wounded anyway so it would all be wasted when the trans comes out for rebuilding.

AFTER the transmission has been overhauled...I could see installing Dex VI.

In truth, I'm fairly satisfied with Dex/Merc (Dexron III substitute) as I've never had a single transmission problem I can blame on "defective acidic fluid". None of my vehicles are newer than 2003; so all of them came factory-filled with Dex III. Again, if I ever buy a newer vehicle, I suppose I'll have to stock-up on the newer fluid.

[j cAT]

what some have done with a contaminated tranny is they used dexron III as a flush fluid to remove the antifreeze that got to the tranny from bad radiator . then after all the bad fluid came out [much cheaper flush fluid] they installed the dexron VI..........