Transmission Flare / missed shift / slipping (2 Viewers)

[anhizer]

Hi all,
I have been experiencing a weird transmission issue on my 98 land cruiser over the last year or so. It only happens when the truck is cold during moderate/hard acceleration (getting onto the freeway). Taking my foot off the gas seems to let it shift, it really only happens when I'm accelerating up to cruising speed. I was hoping it would improve on its own, but it also hasn't gotten any worse over time. I was able to take a video of the shift problem:


I took the truck to a local shop and they inspected the fluid and said it was fine. To me it looks old (not bright red, not burnt, maybe a dark red/hints of brown?). It is at the proper fill level per the tech manual (hot/level/ran thru gears/measured in park while running).

The shop reached out to a transmission repair guy who recommended putting some lucas ATF additive; i tried this and this did not seem to help (video is post adding lucas goop). I didn't hope for much but figured it wouldn't hurt the situation too much.

As this is such a infrequent occurrence I'm not super concerned, but I'm hoping to start off-roading the truck a bit and wanted to make sure everything was good before I get myself stuck somewhere remote.

I followed the tech inspection procedure and verified the throttle position sensor is working properly (used techstream and also verified resistance).

Next thing im going to try is draining the ATF and refilling with fresh stuff; not sure if this will help but it wont hurt.

Anything else i should look at? Any thoughts on how major a concern this is?

Thanks!

 

[RoaringFork]

Drain it, pull the pan, and inspect... with an intermittent problem, I doubt you’ll see the cause, but a good inspection is where to start. Check the filter, check the shift solenoid connections and wiring... replace filter, replace gasket, install pan, fill trans...

If problem persists, I would guess slow/sticking solenoid or trash in the valve body...

Good luck, and happy new year!

 

[anhizer]

Yeah, sounds like a good idea. What do you look for on the solenoid? I looked online and other then verifying the connection is there anything to inspect? Is it worth while to throw some new solenoids in there?

Also, forgot to mention but the shop basically said the only thing they would/could do is throw a reman transmission in there. Given your response this seems a bit extreme for a solution...

If the solenoids are bad that seems like an easy enough of a fix; if the valve body is gunked up how bad a job is that to fix?

Thanks!

 

[RoaringFork]

Yes, verify connections... loose terminals, or the wiring has come loose and can shift around while driving...

You can ohm out the solenoids, but given your symptom, they’re probably electrically fine. You can’t really mechanically test them for proper flow on the bench...

As far as replacing them... you could throw a whole set in there but I would check cost before considering that...

The valve body is also pricey but should come with solenoids...

Putting a trans in the truck will certainly fix your problem, but how much more is that than a valve body??

A flare between shifts would not indicate a failed transmission, it indicates the shift isn’t happening fast enough... all controlled by valve body and solenoids...

Maybe someone who has dealt first hand with this problem can give some resolution. I would start with a trans service and inspection and go from there. Price out the other parts in the mean time.... don’t forget the trans pan gasket!!

 

[anhizer]

I actually had purchased a filter/gasket kit a while back (and ATF fluid) with then intent of doing the drain & inspect but never got around to it. I took it to the shop for some other maintenance and had them evaluate the trans.

The shop did give me a fairly reasonable price on a OEM reman trans (3k installed + tax). Looking at the cost of solenoids if i need all 4(?) its 1K from rock auto. I don't see a valve body assembly so Im assuming you have to rebuild that. There appear to be some smaller ones that are cheaper... auto transmissions are some black magic to me lol.

Thanks for the reply!

 

[RoaringFork]

The service manual should have a shift solenoid chart... it will describe which solenoid(s) are on and which are off for each gear... you can narrow down how many solenoids you might need. If only 1 or 2 that will bring your cost way down...

I would say the valve body is a dealer only part. They are complex enough aftermarket companies stay away... be prepared for $$$

$3k is a reasonable price for a reman trans installed...

personally I would just deal with an intermittent shift flare and wait for the trans to die completely before throwing $3k at it. I could buy another 80 for that...

But first things first, you have the needed parts for step 1...

 

[gatormark91]

Do a full drain and refill (not just a pan drain) before you do anything else or replace parts. Fluid can look good, but the additives can be gone. New fluid will clean deposits out over a week or two of driving. Do NOT do a power flush, just a replacement using the PS cooler hose method. New fluid can fix a lot of shifting issues if the problem is just deposits or a blocked up solenoid and not an actual failure.

 

[looking4lc]

as mentioned above, first, do a Full flush, test it. if it fixes it, great otherwise, i am 80% sure its solenoid. i have dealt with kinda similar issue and used solenoids fixed the issue.

i know there is a way to check if solenoid is not functioning (Youtube) otherwise, 4 solenoids will run close to 400$ (just checked them on eBay.

i would do the steps above if i were you. Good Luck and please update us

cheers

 

[2001LC]

I've liked BG products for a long time. If available in your area you may try one of there additives for flushing & conditioning. I'd then flush with 12 qts of M1 MV full synthetic ATF. Run for 5K miles and see how it does.

But before doing this, here's one more consideration. IDK what controls this or if applicable to all years. But it was once pointed-out here in mud that our transmission will not up shift to higher range until at operating temp (warmed up). You may want to explore this and what controls are involved as a next step.

 

[looking4lc]

Speaking of additive, Lubegard is very well-known for fixing these issues, you want to try it. its promising

 

[anhizer]

Quick update - I pulled the pan today and did an inspection; everything looked OK connection wise. The pan seem fairly dirty; the magnets were covered in sludge as well as the bottom of the pan. No large pieces, everything looked very fine and black.

On the test drive it seemed to shift okay but it the problem usually only happens when its cold.

Question on the fluid levels: I was reading an older thread and it stated that the trans temp needed to be in the 97-115f range for the 'Hot' level; i cant tell if this is only for the WS fluid or the Dex/Merc too. I verified the levels at 115f and around 140f (service manual says to check at 158-176). At 115 it was low, at 140 it was in the middle of the hot marks. The TSB that was linked only seemed to apply to WS ATF only based on the year range... what temp should i check it at?

 

[2001LC]

I'd bring that level up a bit, peg that high mark is best. On your 98 drive until engine at normal operating temp, shift through all gears and check on level ground, engine running. Bring to top mark. If you switch to a synthetic like M1 AFT, its performance will be better in all temps.

I've used Mobil 1 ATF for years in the 98-02 transmissions, they love it!

Note: That filter/pick up screen pictured should be replaced if pulled out, because of the gaskets on top side.

 

[anhizer]

Thanks for the tip- thats the procedure i used to check the level. It was just shy of the top mark; ill verify levels after a longer drive and make sure its full. I put a new filter in and switched to a full synthetic- valvoline maxlife (The local shop didnt have any Mobil1.)

 

[2001LC]

Full flush of 12 qts of max life, should do just fine. Synthetic runs cooler, so does not expand as much. For that reason I too drive a bit longer, and harder before checking..

 

[Eicca]

For what it’s worth:

How’s your charging system?

My Lexus transmission throws all kinds of fits if the voltage isn’t totally kosher. Last winter someone at a shop didn’t tighten my negative battery cable. I found out after panicking thinking my tranny was about to crap the bed. Slipping on takeoff, flaring shifts, etc etc etc. Somehow I came across a few forum posts where guys replaced batteries/alternators and that fixed their trans issues. Tightened my negative terminal and she’s been fine ever since.

Unlikely to fix your problem, but at least worth a shot.

 

[anhizer]

wha really? Thats super weird. tbh its never given me any issues; the battery is older but it starts up right away.

 

[Eicca]

wha really? Thats super weird. tbh its never given me any issues; the battery is older but it starts up right away.

Computers really hate being starved for voltage.

 

[anhizer]

Another brief update- drove the truck to work today and experienced the shift issue again. Ill keep driving it for a few hundred miles and give the fluid some time to hopefully loosen up whatever is stuck. On another note- Now that im hyper aware of the transmission shifting i managed to get it to miss a shift while warm. I suspect that the shifting problem hasn't got any worse I just never put it in the right condition to occur. The problem only seems to happen under hard acceleration, regardless of temperature.

 

[DreddIsDead]

any updates on what was causing it?

 

[anhizer]

No real updates; i haven't noticed it recently but i also have been driving it less frequently and learned to change my acceleration patterns (i let off when i think it should shift). That being said I have not observed the issue recently so perhaps the fluid flush fixed the issue. In any event it didnt hurt.