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Chevrolet Blazer GMC Jimmy Transmission Problems

I just bought my blazer and transmission is leaking. After purchase of blazer guy tells me it was a non op. What should I check for first , how should I approach.


  • repairdogrepairdog Posts: 948
    86 Blazer don't know what you mean exactly - it works or doesn't? Sounds like it just leaks - if so look at the level on the dip stick, check the vent on top for the tube and cap, vac modulator on the side has a diaphram and vac line up to the engine, pan seal, rear seal, and front seal (that one will see fluid dripping out the bellhousing up front - requires trans be pulled to fix).
  • blaze4x4blaze4x4 Posts: 29
    (2001 Blazer 102,200 miles) Well, I replaced the rear driveshaft U-joints (at the rear axle, two of the cups had rust inside), but I still have a harmonic vibration that seems to cycle. For whatever reason, this morning on my way to work, it started out REAL bad. As thing warmed up , it subsided, but was still there. Any history of a torque convertor going to pot on these Blazers. As bad as it was this morning, I gotta a feeling I'll soon know whats causing this, something is going to let go!
  • repairdogrepairdog Posts: 948
    Could be the rear pinion bearing, transmission, or actual driveshaft out of balance. I always get mine spin balanced when replacing both U joints - they tack weld a small weigh on it. Looks like a 4wd and that output is thru the transfer case so they do have problems. If an LT with Autotrac the fluid is special blue synthetic called Autotrak II at dealer and its to quiet cluch pack chatter in the transfer case. Did this problem start and then you changed the u joints as a first shot? Is vibration speed related and seat of the pants or steering wheel shack? Could be tires if worst when cold. Had out of round rear disc/drum and they caused a hopping shack over 60mph.
  • thanks for the advice i do appreciate it. ;)
  • blaze4x4blaze4x4 Posts: 29
    I don't use the E brake at all. Last brake job, put new rotors on all four corners... seems like an out of round drum section of the rear rotor would have shown up then. The vibration was there prior to replacing joints. It is an Autotrac (4 button selector... 2Hi, 4Hi, 4Lo, Auto4wd). You don't suppose that as bad as the rear U joint was that it took out the pinion bearing (currently 102,300 mi.)? The vibration is always there, just some times worse than others. Most noticeable at speeds of 55 plus mph. Was on the expressway last weekend, and like to rattle my teeth out.I had the trans flushed, filter replaced at dealer ~22,000 miles ago. Vibration in the seat of the pants. I didn't replace front shaft u joints. I was told that until vehicle is in four wheel drive, shaft doesn't spin, is that true?
  • repairdogrepairdog Posts: 948
    I have one of these exact Blazers and they are known (sorry) for some vibration problems. Often nearly impossible to find/fix:
    1. If not done already, change that front u-joint also and balance the driveshaft.
    2. Have your tires force balanced that is computer read and it shows out of spec tires and heavy spots - 1 in 10 tires are often so far off they should not be used and sees bent rims/heavy spots in them too.
    3. Check the trans mount and engine mounts for separation.
    4. Put the Blazer rear end on jack stands and drums/disc on with at least 2 lug nuts, with a helper start and put in drive and you watch the rotating drum/disc and see it perfectly round and no oval - mine were - new ones are usually cheap China junk and I've had several bad ones recently as I've done 4 complete brake jobs in the last year on mine.
    5. Check the rear calipers slides - bet you did not grease the pins in the brackets and they hang up and eat the inside of the rotor and drag. Also hope you put rebuild calipers on those rears cause they are a cheap single pison one that cocks in the bore and hangs often too.
    6. Flush the transfer case and add the blue GM Autotak II syn fluid, and then drive 100 miles, reflush and add 2 new quarts - GM bulletin on this.
    7. Have you replaced the lower ball joints - #1 weak spot, and looked at all steering jonts and greased all of them.

    Thats a quick shot at some of the things to look at.
  • blaze4x4blaze4x4 Posts: 29
    Looks like I have my work cutout for me. Although I didn't replace the rear calipers, I did remove the slides, wire wheeled the clean (yes, they'd been hanging up!) and greased (heavily). Earlier this spring, had upper and lower ball joints replaced, along with the idler arm and front end alignment, just before having the intake gaskets and thermostat replaced. Tires AND wheels are new (will have rebalanced). Thanks for all the suggestions. I'll pick away at them one at a time and let you know what I find.
  • I changed transmission fluid added a stops leak oil as well.I do have a knock that almost sounds like a diesel motor.It is not the motor, motor is strong. I was thinking possibly transfer case,drive line or axle.Am I close?
  • repairdogrepairdog Posts: 948
    86 Blazer so 2.8L V6 motor? Is the sound always there even when not moving (in park)- if so rules out drivetrain.
    Any smog pump on it? Vac hoses rotted out or leaks? Exhaust leaks, flange gasket, muffler. Need more info on the when/where/etc for noise. Crawl around and listen and post some specific clues for me.
  • The sound appears to be coming just center of the motor itself.Sound remains when waiting at a light but as i accelarate it stops brief moment .I will get underneath tomorrow to see where pin point is.Thanks
  • The Blazer did come with street tires not 4WD and they are small.I never even stop to think the tires could be main starting point as for the vibration.
  • I have a 97 blazer. About 2 months ago it started jumping out of high gear on the highway. Since then i have had the transmission rebuilt. Now It still jumps out of high gear, But if i stop and turn off the engine for a few minutes then restart it. High gear works again. sometimes for a short time sometimes longer. But it always works again, at least for a short time after i restart it. Any thoughts? All i seem to be getting is the run around and no straight answers.
  • I am not a trans expert but there are solenoids that control the shifts and are you sure its dropping out of 4th or is the converter unlocking - feels like a shift?
    Any good trans shop can test these so.... maybe time to change shops. Keep trying.
  • My 2000 Jimmy slt 4.3L auto shifts really abruptly when its hot usually after I've been sitting in stop and go traffic (which happens too often I'm in Southern California) sometimes it shifts so hard it chirps the tire normally I might mind that but I feel like its going to self destruct anyone else have this issue?
  • #1 is get the filter changed in the trans and that replaces about 5 qts of the fluid. Valoline Max has high mileage fluid that I use. This may solve the problem. If it does not (it has on 2 of mine) then GM has a bulletin on the TCC bore wear that contains the TCC isolator and regulator valves fixed by dropping the pan and Not a full rebuild. Find a good trans shop and ask questions - normally all trans built after 15 Jan 99 have these updated so look at your production date on the door sticker.
  • In my 01 blazer the 4wd electronic controller switch changes on its own, it gets stuck in 4wd low and won't change manually back to 2wd. Is there some kind of electronic control in the transmission that would cause this or is it a bad switch? Has anybody else seen this before? There is also an electronic problem with the gauges, the tach does not work, the gas gauge will fluxuate from empty to full to empty etc, this may not be connected but I thought I should mention it just in case.
  • Look at the 4wd problem answers posted but if this is in 4Lo that means the encoder motor is engaging - hope not when moving - so is it in 4Lo? Check the wiring on the side of the transfer case and see if it is cut/ripped/nicked - seen that and causes that type problem. Also a sensor on the transfer that tells the TCCM (computer in the cab pass side kick panel) low/high gear status. Front axle has to couple too. Again after the wires are fixed, disconnect the battery for 30 minutes and see if the TCCM reboots/resets.
  • When I disconnected the dashboard switch it brought it into 2wd, I'm pretty sure its just a bad switch, I'm gonna try replacing that to start off.
  • I have a 2000 Sonoma with 50k miles that the trans wont sift in Drive. When in Drive at a stop it will not go into gear. but whrn I manually shift into 1st or 2nd it will engage, then while driving I can manually shift into 3rd then Drive and it will move thru the gears. when coming to a stop (in Drive ) it will not down shift into 1st. I again have to manually shft into 1st or 2nd to move. Do you have any idea what the problem may be

    thanks Mark
  • I have a 1997 4wd Blazer that is stuck in third gear. It will shift into park and reverse fine. Vehicle has only 32500 miles on it, but has been sitting for about the past 2 years til recently. I have put approximately 1000 miles on it with no problems til now. Any ideas? Thanks
  • Pull the codes and see what they are. Check the adjustment on the shifter cable on the side of the trans.
  • Pull codes from trans. Have filter replaced and pan cleaned - long time to sit. 97 (only) have a known ignition switch (name but actually the ign module in the column) that can cause many problems with many componenets.
  • gotta 99 blazer 2 door 4wd 4.3l The transmission knocks when stopped in drive but does not knock in neutral or park, whats going on?
  • You sure it really is the trans and not some engine part as thats when the rpms drop as the converter loads up. Check fluid and if you have never changed, as most, do the trans filter and fluid thats first and see whats in the trans pan. Then as a helper puts it in drive with foot on brake and e-brake on look under the hood and see if he AC compressor or alternator is dragging. Shut off and look under hood again at the belt and AC and alt. Then if its only when you first put it in drive thats a GM trait due to clearance in the rear diff, or u-joints if worn out, or transfer case.
  • ok ill try changing the fluid, gottanother one for ya, when turning at low speeds right wheel makes one loud pop every once in a while??
  • Lower ball joints are the #1 reason - jack it up and grease them and uppers and the other zerks on all the linkage and have to remove the front plastic skid plate to get to the idle arm front one - like 10 or so total. If that doesn't do it look at the CV axles are the boots ripped and any grease coming out. Then the hubs, brakes, or the classic hood shifting at the hinge bolts - yes GM added a spring washer to each side to fix so carefully place a rag in between the fender and hood and close (do not bend anything and see if thats it.
  • 99 blazer 2 wheel drive, never had a transmission problem until the intake manifold gasket leak was repaired. Immediately after repair transmission will not shift properly. Goes in and out of gears at will during all speeds. Occasionally wont start. We checked fluid level everything is okay. Not sure what was done to make this happen all of a sudden when I have NEVER had a trans problem. Any suggestions!! I am scared I am going to mess up my transmission. When I am on the highway I have to lift my foot off the gas in order for it shift gears. Also when I shift gears , it shifts real hard.
  • Probably they did not connect a sensor properly after the intake done so all lines and connectors need to be rechecked. Shop should do it that did the intake. Could be a vac line leak also. When was the trans filter last changed (every 50k)? 4L60E trans do have some known hard shift conditions due to dirty fluid and a TCC solenoid problem but often a filter change fixes. Finally any SES light on and codes?
  • I have a 1997 Chevy Blazer. Got it for a steal! Truck has 138,000 miles on it and was a highway driven vehicle I bought from a friend who I trust when he tells me he had no issues with it. soon after I purchased it the fuel level gauge stop working. I replaced the level sensor with a genuine GM part and the gauge works but bounces when I turn on the turn signals? First problem :(

    We towed my boat to and back from Canada with no issues other than the bouncing fuel level gauge and since then have driven the vehicle for approximately 5K miles. My wife broke the hazard switch and the heater core started leaking a little, no real problem that I can not deal with. Now the vehicle intermittantly stalls while driving just like someone turned it off however the electrical power remains? Most of the time after it stalls it starts right back but sometimes lately it is difficult to start. I really do not even know where to start? The fuel pump sounds normally at ignition start. I am confused please help?
  • repairdogrepairdog Posts: 948
    Again, see all the posts on the known 97 only problem ignition switch (the connector and wiring acually) in the column - not key/tumbler - so do that first. May solve all problems.
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