Our Community is 940,000 Strong. Join Us.


Jimmy Lockup Clutch Vibrates


dmcdlrn
11-03-2007, 08:34 AM
I bought my 97 Jimmy a few months back for a winter car and only drove it a few times up till now. I noticed about a week after I bought it that the tranny fluid was a bit burned. I quickly drained fluid, replaced the filter and added lucas. I have noticed (even prior to that) that my lockup clutch seems to function properly, but when I come to a small incline where just a touch more power is needed, not enough to release, it will vibrate. Sometimes this is fairly violent. After much scratching of my head I concluded that it has to be the lockup as it will cease immediately when I just barely tap the brake with my left foot, and only happens when the clutch is engaged. I assume that it is slipping, so I figure three possible problems: worn surfaces(does have a tow package), bad solenoid, clogged line.

The question is, is there any way of telling if it is the solenoid, clogged lines, or is it just plain the surfaces and requires a new TC? Should I get a flush, or drain it again and replace the filter again in hopes that it is clogged again from all the extra sludge it's pulling? It seems to run fine otherwise. Shifts are fairly smooth and it seems responsive. It did seem a bit hesitant when it was really cold the other day.

Any help would be greatly appreciated. I got a steal on the truck and I love it, but I would rather not drop the money to put a rebuilt (especially in the winter when my other car is up) if I could just swap a solenoid.

97 automatic 4.3 4x4

MT-2500
11-03-2007, 09:29 AM
Lucas is not the best additive for a TCC shudder.
Lube-Gard (red bottle) is one of the best TCC shudder additives.

The lockup solenoid is controled by a TCC-PWM duty cycle solenoid.
You need a transmission capable scanner to check it out.
Any codes? if so post back code no.

Engine running and sensor problems can also cause a tcc shudder.

Also the 97 is a bad year on ign switches.
That causes a lot of transmission and engine electrical problems.

Can you feel any shudder when it is locking up?

dmcdlrn
11-03-2007, 09:45 AM
Thanks for the reply! I have been so "upset" about this... very very frustrating with basically no documentation anywhere. I'm a fairly good mechanic without being a mechanic, but I just can't find docs to educate myself about this specific tranny.

I'm not throwing codes. I had the SES light come on once about 3 months ago, and before I took it to be scanned it went out. At that time I wasn't noticing the problem as much with the TCC so I didn't know any better. It came on again a couple days ago on my way to work, but went out before I arrived. That night I took it to autozone and after basically begging them, the guy scanned it and said no codes. He mumbled something about a pending failure or something, but said there was no further information.

Should I add the red bottle stuff? I don't think I have any more room, I would have to drain.

Drivability wise... the truck acceleratres just fine. I feel it shift (slightly rough last night when it was really cold) but usually fairly smooth. Once I get to cruising around 50 I sometimes will feel a very very slight shift like feeling and I'll see the tach drop and careful playing with the gas prooves 0 slippage on the tranny. Release is responsive and smooth as well. I have done some driving with it locked and tapping the brake with my left foot and it releases very smoothly and keeps going.

Basically it seems to shudder only when under "heavy" torque while engagued... such as a small hill big enough to take a bit more gas, but small enough to not downshift. Oh, also if I give it more gas when it starts shuttering, usually it will quiet down... this is why I lean towards lacking lockup pressure... more pressure applies when more pressure exist in tranny? I'm just not familiar with how it transfers hydraulic presser from the bottom end to a spinning TC with only a shaft going into it... I have only owned standards till this. Is there room for a throw out bearing type of thing?

Again, Thanks for replies!! I will take it to a tranny shop to get the transmission read if necessary. Basically if I could limp it through the winter (no towing, and frankly, I could dissable the lockup as far as I'm concerned... I usually go 45 - 50 all the way to work which is where the problem arrises) then next summer I can put a rebuilt in myself while I have my summer car back and it's warm out.

MT-2500
11-03-2007, 10:23 AM
Yes a bottle of Lube-Gard red may help.
They are small bottle and should not overfill it.
The check engine light may be a clue to the problem.
A good scanner will store code present or in history.
Try to get the code and post back.

The lockup on yours is applied in steps of 1-10 by a modulated signal.
or 10% steps up to a 100% apply.
In the lower percentage range the clutch will slip just like letting out slow on a standard transmission clutch.
Or can shudder or grab just like a bad standard transmission clutch.
The Lube-Gard additive may help the clutch friction shudder.
If that is the actual problem.

Another problem on shudder can be caused by bad fluid or using the multi-purpose or one fluid fit all fluids.

Your transmission calls for dexron 111 that has been discontinued to Dexron 6.
Which is a synthetic blend.
That may help but I am a little slow on changing a older transmission over to the synthetic stuff.
Check around and see if any place has the old dexron 111 left or some of the older dexron/mercon ATF fluid.
Carquest has a good stock of the Dexron/Mercon stuff.

If you can get the code post back the code no.
Good luck
MT

DelCoch
11-04-2007, 12:24 PM
I had the same problem on my '95 with a shudder when pulling a small hill at highway speed, which would cause the SES light to come on momentarily. I had the tranny flushed with a machine and no more problems.

old_master
11-04-2007, 01:51 PM
....I had the tranny flushed with a machine and no more problems.

You are one of the lucky few. Flush is NOT recommended under ANY circumstances.

dmcdlrn
11-04-2007, 02:29 PM
You are one of the lucky few. Flush is NOT recommended under ANY circumstances.

So I have heard... thus I am steering clear. My buddy who works at a shop said to do the filter and replace the fluid, drive it for a while, then do it again, but not to flush it.

I may take it to a tranny shop up the street from work this week to have them run codes on it. Depending on what goes on there, I may do another filter, put the special fluid and the red stuff at the same time.

old_master
11-04-2007, 05:47 PM
Good idea! Get that Lucas out of it, change the fluid and filter, add a bottle of the Lube Gard MT spoke of, drive it and see if the SES light goes off on it's own. FYI, Dexron III is now obsolete. It has been replaced by Dexron VI fluid.

DelCoch
11-05-2007, 02:51 AM
You are one of the lucky few. Flush is NOT recommended under ANY circumstances.
May I ask, what is the reasoning behind that?

dmcdlrn
11-05-2007, 12:54 PM
I'm no mechanic as mentioned earlier... but there is a ton of controversy about the to flush or not to flush issue. I have heard from reliable resources that it has a high chance of blowing the crap off of seals and other components in doing so, removing the "glue" that is holding the aging tranny together.

Again, I may have no clue what I'm talking about.

old_master
11-05-2007, 03:55 PM
Some shops do what’s called a “fluid exchange”, (the lazy mans way of servicing an automatic transmission). The transmission cooler lines are attached to a machine that pumps in new fluid and captures the old fluid that is displaced as it leaves the return line. A fluid exchange is like changing engine oil and not the filter, not a good idea. A fluid exchange is less likely to cause damage to the transmission, but does nothing for a dirty filter.

A transmission flush on the other hand, is a far more risky procedure. A transmission flush is designed to loosen particles using a powered pulsating action. Sometimes a special solvent is added to aid in loosening contaminants and particles. The loosened particles can then become lodged in other passages and/or in the valve body. Another common occurrence is the pulsating action can rip the filter material loose from the filter frame allowing particles already trapped in the filter to travel throughout the transmission. Some transmission flush machines have the capability to reverse flush. The fluid is forced through the passages and the filter in the opposite direction. This pushes out everything the filter has already trapped, and then sends it through the entire transmission. Again, this procedure does not involve replacing the filter.

There are flush machines that can safely flush the transmission and torque converter. The oil pan, gasket, filter, and valve body are removed during the process. It’s not the typical $80 job you get at the “Quick Oil Change” places.

For normal preventive maintenance, changing the fluid, filter, and pan gasket is the safest way to service an automatic transmission. Most automatic transmissions require the removal of the oil pan to replace the filter. The “Quick Oil Change” places generally will not remove the oil pan and replace the filter for “liability reasons”, but yet they’ll do a flush in a heartbeat…go figure.

DelCoch
11-06-2007, 10:36 PM
Some shops do what’s called a “fluid exchange”, (the lazy mans way of servicing an automatic transmission). The transmission cooler lines are attached to a machine that pumps in new fluid and captures the old fluid . . .

A transmission flush on the other hand, . . is designed to loosen particles using a powered pulsating action. . .
A fluid exchange is what I had done. The cost was around 120 bucks. Hope I didn't give anyone the wrong idea.

Thanks for the info Old Master.

blazes9395
11-06-2007, 11:24 PM
Thats why it is important to service your transmission on a regular basis. You remove the wear particles and replenish the oil's ability to protect your transmission. Leaving fluid to long in service will diminish its protective ability, it will have to much wear material in it, which will further accelerate wear in the transmission.

This "build up" what every one is talking about is like sand paper on the valve body. The valve body is made of aluminum. Many apply valves, valve bushings in the valve body are also aluminum. Build-up material within a transmission comes from the wear of moving parts. In a transmission these are clutch packs, brass/copper bushings, bearings, and sprockets/shafts, which are usually hardened steel. As all these materials make their way through the transmission, they get into the valve body wearing the soft aluminum down. High pressure valves within the valve body wear out even faster as a result of the wear material travelling within the oil. As the bores/valves have larger clearences because of the sanding motion, the older oil has the abilty to seal the larger bores/valve because of the material within the oil making it thicker and giving it the ability to seal and allow it to function normally for the most part.

Now at this point, if you go ahead and flush and clean the transmission, you now, like others have mentioned, put even more build up in the oil which can carry this material through the transmssion clog screens (EPC motor to think of one). When the flush is complete, new oil is installed, the oil is clean, and it does not carry all the wear material the old oil did. The new oil cannot effectively seal worn out valves/bores causing them to either not functin properly or at all. Apply pressures get low, slippage occurs on the clutches, because they cannot fully engage as a result of the worn out valve body usually, and you end up burning out your transmission.

Thats why many say you don't flush or replace the oil on a transmission thats not seen regular servicing.


Transmissions are truely a great piece of engineering. If you have ever seen the insides of one, you'll know what I mean. If they are serviced regularly, they will and do last a very long, long time.

I also agree, Lube Gard get my vote too! I use it all the time.

dmcdlrn
11-14-2007, 09:28 PM
Well, thanks everybody for making this a super useful thread! I think Auto trannys are all too mysterious. I have worked on manuals some as that is all I have had, but this auto is new to me. I understand the concept, but just have no basis for some of the workings.

I ended up taking the truck to have it scanned. The shop took it for a ride and said that the lock up was in fact slipping and they recommended having the TC replaced given the age, mileage ect. I decided after talking with them nothing was going to solve the issue other then repair, so I had them rebuild my transmission while it was out. After it was done he said that I was lucky. He showed me a part... can't remember what he called it, but it was some form of fluid gear for 1st 2nd and reverse or something like that, and the teeth on it were so cheewed that there was barely any left. He said that it could have blown at any time and any hard driving would have certainly killed it. I think he was right looking at those teeth.

He said my lockup actually wasn't bad at all, but the valve was leaking causing it to not engauge properly. He said this could have been done by pulling the valve body without pulling the tranny, but it wouldn't have fixed the other issue. He also remarked that for obviously being the original tranny and having 230k on it, it was in amazing shape and now that it's rebuilt it will last the rest of it's life. I also have a shiney new warrantee to boot.

Add your comment to this topic!