89 Suburban Transmission Problems

Looks like the transmission problems have finallky caugh up with me. bought the burb at 140,000 miles, changed the trans fluid and 10,000 miles later having problems. Fixed rear seal to transfer case just recently and so tranny might have been run low on fluid prior to purchase.

Symptoms: Work ok in low, reverse works. Won't shift to second.

Prior posts discuss driving not in overdrive might help.

Haven't brought it to the mechanic yet, but suspect the worst. Somewhere there was a discussion of buying a remanufactured transmission instead of rebuilding local. Last transmission I rebuilt didn't last a year so am hesitant on that. Any thoughts?

Brought it in to one mech, estimate is $1,500 with one year warrentee to replace with a rebuilt

Estimate from another was $1,385 with a two year warentee.

Found the following site for cost of a rebuilt at $854 w/o installation. Giving some thought to installing it my self with help of mechanic friend.

http://www.certifiedtransmissions.com/default.htm

If you plan on keeping it for a few more years get a GM factory rebuilt.
While this is not the most inexpensive way to go, it has less worries in my opinion.
When the trans went in my 90 Suburban, I put a GM rebuilt in, it has any upgrades that my have been done, plus it comes with a 3yr 50,000 mile warranty, any problems anywhere in the country while at home or traveling just go to a GM facility and get repairs under warranty.

:2cents:

GM does not provide factory rebuilds for an 89 any more.

CAlled one junkyard and they had one from a vehicle with 212,000 miles on it and wanted $495. Not likely to be sold to me.

Found a 1988 parts vehicle with 65,000 miles on a remanufactured tranny for $500. Transmission was remanufactured by a company in Fort Dodge, IA. Transmission had cooler and filter on it but was used to haul race cars.

Any thoughts on filters for transmissions.?

Well, folks the latest update. Friend who works at transmission shop said the cable between the throttle body and modulator sometimes gets stuck. He spent about 20 minutes unsticking it and I took it for a test drive.....shifts smoothly now.

WHATEVER automatic trans source you use, be sure to have the new unit filled with Redline D4 ATF. This stuff is as much a step above Mobil 1 as Mobil 1 is above regular ATF. It has oil-like lubricating qualities that keep your bearings from fragging. Most failures are not clutches or valves, but shrapnel from bearings.

By the way, my friend Dick Guldstrand puts this ATF in all the automatic "Vettes he builds, with 500-700 hp!

At about ten bucks a quart, you can pay now or pay (a LOT) later.

Well, folks the latest update. Friend who works at transmission shop said the cable between the throttle body and modulator sometimes gets stuck. He spent about 20 minutes unsticking it and I took it for a test drive.....shifts smoothly now.


Hello. My 88 suburban just started doing the same thing. Do you know where the modulator is that you mention, and by chance how he managed to unstick it?

Thanks for your time.

I have a 97 that was used to pull a trailer (in OD) Yea I know not a good thing I had some fluid blow by and a code for shift modulator come on. I flushed and changed the filter and drove back home. The problem is the warning light will come on nad the burban will shift hard from 1st to 2nd then it will shift great again. The shop wanted to rebuild the valve body (cheap 600 dollars) LOL the cable between the throttle body and modulator may help me, Did he remove to clean or can anyone help.
later all

Hello. My 88 suburban just started doing the same thing. Do you know where the modulator is that you mention, and by chance how he managed to unstick it?

Thanks for your time.


There is a cable that runs from the transmission to the throttle body. He disconnected at the throttle body and pulled it and released it by hand the full travel of the cable several times.


The theory was that sometimes "junk" collects on the cable and causes the cable to stick.

This worked fine for a few weeks and then symptoms came back. I then put some seafoam trans treatment in it, ran it a few days and changed the fluid.


Been three months now with out any shifting problems.

Down the road I plan on using the auto rx http://auto-rx.net/ as a treatment if it continues to work well. It appears the seafoam is more of a "shock treatment" and the auto rx is a longterm cleaner.

Best of luck. I found a junker with a recently remanufactured trans for $500 so have that in reserve.