Auto Tranny Problems

[84renegade]

Hey everyone, just moved to San Diego from NY a couple months ago. Man it is great out here, but what happened to the Jeep wave??? No one does it!

Anywho, to the problem. My fiance has a 97 TJ auto tranny 4cyl engine. It seems as though when she first starts the Jeep and puts it in drive or reverse and steps on the gas, it doesn't go into gear. The engine will rev for a few seconds and then finally pop into drive and go. It seems as though it only happens when she first starts the Jeep and continues intermitently for about a minute. A year or so ago, her tranny was leaking a bit, so I changed the fluid and added Lucas Tranny Fluid to try and seal the seals. Any idea what may be wrong and how I can fix it? Thanks for the help.

[OhioYJ]

Just taking a wild guess, and note my knowledge of automatic transmissions is somewhat limited. I'd say something is sticking in the valve body, either a shift solenoid or governor, maybe a fluid change, or flush might help.

Lucas makes some really good stuff, but should only be used in certain situations, that Lucas stuff is pretty thick stuff, and your Jeep is relatively new to need something thick, at least in my opinion.

[disturbed 1]

Have you checked the fluid level? What kind of fluid did you use when you changed it? ATF+3 or ATF+4 is what Mopar transmissions need. Other trans fluids are a no-no in newer Mopar transmissions. I personally wouldn't have used the Lucas, but that's just me. :cool:

[Knuckelhead]

and did you change the filter when you changed the fluid? A clogged filter can act like that...

[84renegade]

I used the Lucas stuff because the transmission seals were leaking and that is supposed to help stop the leaks. The fluid level is fine, but I've noticed that sometimes it is airated, can that have something to do with it? And if so, why does it happen. Yes, I did change the filter when I changed the fluid.

[OhioYJ]

What do you mean airated? Like bubbly or foamy?

Like I said Lucas makes some awesome stuff, and I use quite a bit of it, but unless that thing has a ton of miles, that Lucas may be a little thick for a newer transmission, and could be clogging things.

[disturbed 1]

Bubbles mean it's getting churned up---classic symptom of being overfilled. It's better to be lower (not terribly though) on trans fluid than to be overfilled.

One other thing to check is the checkvalve in the cooler line. When it goes bad it can cause the delayed shift into drive problem-I think, I don't have my FSM at the moment.

[84renegade]

Thanks for the reply's guys. I think I'll change the fluid again and just use the recommended fluid and see how bad it leaks and go from there. Does anyone know approximately how much it costs to have the tranny seals replaced and is it something the home mechanic can do?

[Knuckelhead]

[QUOTE]Originally posted by disturbed 1:
[QB] Bubbles mean it's getting churned up---classic symptom of being overfilled. It's better to be lower on trans fluid than to be overfilled.

One other thing to check is the checkvalve in the cooler line. When it goes bad it can cause the delayed shift into
drive problem-I think, I don't have my FSM at the moment. QUOTE]

What he said...

[b1pig]

like disturbed1 said....

Having just went through turmoil with my ZJ's 42RE, I have a pretty positive clue what it is. There should be an anti-drainback valve in one of the cooler lines. The spring may have failed, or the rubber plug deteriorated.

Here's how I know.
The people that rebuilt my tranny told me to remove the valve. They said it restricts flow, and it was an "update" that they did, which would be putting a less restrictive valve inside the tranny. They were full of ****, because, now... after being parked overnight, the Jeep would not go into gear for a few seconds.

They way I figured it out?
The 42RE (and probably yours, too) doesn't pump fluid in park. After it has been parked all night, fire it. toss it DIRECTLY into neutral. Give it a second... and then tap it into either drive or reverse. If it goes right into gear like it's the middle of the day, then it is the anti-drainback valve that is faulty.

No need of a rebuild... and it will do no damage alone.

Hope that helps. ;) :D

[disturbed 1]

Originally posted by 84renegade:
Does anyone know approximately how much it costs to have the tranny seals replaced and is it something the home mechanic can do? Where's it leaking from? To replace the internal seals you'd have to pull the trans out. If you're familiar with dropping the trans and taking it apart, yes it's something you can do in the driveway. If not, bend over because a shop will charge you at least a grand to do it.

If it's just leaking from the trans pan, put a new gasket on (the rubber/plastic one from Jeep is the best) and make sure the pan rails are flat....if the bolts were tightened too much they will bend the rails and that'll cause leaks. Just tighten the bolts a little past snug.

[Knuckelhead]

[QUOTE]Originally posted by b1pig:
There should be an anti-drainback valve in one of the cooler lines. The spring may have failed, or the rubber plug deteriorated.QUOTE]

Yep, the valve was an add on by OEM to correct that problem. ;)

[jdstj]

I'm no expert but I think there is a Technical Service Bulletin (TSB) for that exact problem. Just do a search for TSB and with a little digging you will find it. For anyone who cares TSB's are one step before a recall. It is mainly for mechanics for ease of use when finding a problem.

[disturbed 1]

FYI-the checkvalve can't be rebuilt/serviced----it must be replaced as a whole assy. It'll be on one of the cooler lines, kind of near the radiator-you can't miss it.

[StealthTJ]

Originally posted by disturbed 1:
FYI-the checkvalve can't be rebuilt/serviced----it must be replaced as a whole assy. It'll be on one of the cooler lines, kind of near the radiator-you can't miss it.We always *remove* those check valves in any Jeep trannies that we rebuild.
They fail too often and can often fail "shut", not allowing fluid to flow well and burn up the tranny.
We've seen a few like that.
We remove the "check valve" and replace the manual valve (in the valve body) with an aftermarket one that allows fluid to be pumped while in park.
Works great.

Sounds like what you are experiencing is torque converter drain from a fault check valve.
Try, when 1st starting it up, putting it in neutral for a couple of seconds before shifting into reverse or drive. That that solves the problem, then it's torque converter drain back and that's caused by a failed check valve (most of the time).


Fred

[84renegade]

Here's an update on the tranny situation. I replaced both tranny cooler lines because they were deteriorating and one of them got a pithole leak. The tranny is still reving, whether I do the thing with neutral or not. I believe it only happens when the car is at a stop and then she tries to accelerate. It may also happen between 1st and second gears. Could it be that the bands need adjustment or replacement? I'm not too familiar with these and how they work.

One other thing. When she is at a stop light, in the first 5-10 minutes of driving, her RPM's will drop to 300 or so and then jump up to the regular idle (~700rpm I believe). When it does this, the Jeep will actually jump. Any ideas??

[StealthTJ]

Originally posted by 84renegade:
Here's an update on the tranny situation. I replaced both tranny cooler lines because they were deteriorating and one of them got a pithole leak. The tranny is still reving, whether I do the thing with neutral or not. I believe it only happens when the car is at a stop and then she tries to accelerate. It may also happen between 1st and second gears. Could it be that the bands need adjustment or replacement? I'm not too familiar with these and how they work.

One other thing. When she is at a stop light, in the first 5-10 minutes of driving, her RPM's will drop to 300 or so and then jump up to the regular idle (~700rpm I believe). When it does this, the Jeep will actually jump. Any ideas?? Probably two separate problems.
Anyway, sounds like it's time to pull it and disassemble it and see what's pooched.


Fred