Automatic transmission loss of drive issue. (1 Viewer)

[Urtwob]

Hi Guys.

I would like to hear from anyone who has had a similar experience as I have had Re my automatic transmission.

When I drive the cruiser onto a very steep gradient the drive train seems to lose drive momentarily.
For perhaps a second or so and then it gradually gains full drive again.

If you didn’t use foot brake the vehicle would definitely have time to start rolling backwards.

It does not matter what gear, ie Drive, or 2nd or L. And indeed it doesn’t matter if you are in Low range.

There is slightly more oil in transmission just now as I did think perhaps the transmission was getting momentarily starved of oil.

In my opinion it is to do with the torque converter, it feels like by elevations the front of the vehicle sharply upwards, it’s like as if there is perhaps an air-lock inside the converter, an air-lock that does not affect driving when on the level but only becomes disruptive when the vehicle is steeply off-level.

I have not taken sump off yet to clean the oil filter. My reason for not doing so is that I have been advised that it is not necessary and perhaps not a great idea.

On my previous LC100 I achieved over 500k miles and I never took of the sump.

Not because I didn’t want to, but because I had serious difficulty with every bolt being seized. I eventually broke one and I quit at that point. Some time afterwards a reputable experienced mechanic told me that in his opinion if the oil was not dark “burnt” and no obvious impurities his Experience was that there was nothing to be gained.

Anyway, I can’t say who’s right or wrong, I’m just sharing my experience.

Back to Topic,

Has anyone experienced anything like this ?
I would really appreciate any and all feedback please.

Thank you.

URTWOB

 

[OEMGUY0720]

Based on your description, from my experience it sounds like the torque converter is shot -assuming the ATF is still good.

 

[jsloden]

I haven't experienced this before but it wouldn't hurt to change the fluid first. Have you checked to see if it's at the proper level?

 

[Urtwob]

I haven't experienced this before but it wouldn't hurt to change the fluid first. Have you checked to see if it's at the proper level?

Yes fluid is just slightly above its proper level as I was suspicious it may need a little more.

Fluid is is a good clean healthy state.

What I forgot to say in my initial post was that this problem Has been going on for over 2 years now.
The unbelievable thing is this is a working Cruisrr. Every week it is hauling 2.5 to 3 ton loads of soil or aggregate.
The cruiser is more than capable for the job with the transmission as it is.

It is only when you drive up a very steep incline that I experience this loss of drive.
It’s just momentarily lost and then it picks up the drive again and goes on up the steep incline.

I hope I’m explaining this properly guys.

Thank you.

 

[Urtwob]

Based on your description, from my experience it sounds like the torque converter is shot -assuming the ATF is still good.

Hi #OEMGUY0720
Apologies for not responding to your post earlier, this is a copy of another response I made.

Yes fluid is just slightly above its proper level as I was suspicious it may need a little more.

Fluid is is a good clean healthy state.

What I forgot to say in my initial post was that this problem Has been going on for over 2 years now, and has not deteriorated at all.
The unbelievable thing is this is a working Cruiser, Every week it is hauling 2.5 to 3 ton loads of soil or aggregate, sometimes 2 maybe 4 loads daily.
The cruiser is more than capable for the job with the transmission as it is.

This problem only ever arises when you drive up a very steep incline, only doing this I experience this loss of drive.
It’s just momentarily lost and then it picks up the drive again and goes on up the steep incline.

I hope I’m explaining reasonably clearly.
When it first did this, 2 years ago I was certain it was the torque on its way out.
But here we are 2 years later same torque and cruiser is actually doing very well considering how hard it actually works
Each week.

Cheers and thanks my friend.

 

[OEMGUY0720]

Got you. Yep all LCs drive train is really over engineered and can sustain a lot of beating and still function. That’s why this vehicle is UN’s top choice of transport.

It could be anything from the torque converter to the disks itself sliding, and unfortunately the only way to confirm if it’s the culprit is by pulling the tranny down and doing a thorough inspection. You can also do a full drain and fill of the ATF, once and for all rule that out. And while at it, pull the trans pan down, replace the gasket (inexpensive) inspect for any tell tale indicators like big/small sediments or possibly (hopefully not) fragments of anything. Also, after doing this procedure I would strongly suggest hooking up an OBD2 scanner so you can monitor your AT pan temperatures real-time so you can see for yourself if it’s hitting 200°F temps (bad) on the pan.

This is what I use btw to keep an eye on critical temperature areas of concern on the truck. Heat is any equipment’s #1 enemy, and the fluids keep the temperature down.

 

[Urtwob]

Got you. Yep all LCs drive train is really over engineered and can sustain a lot of beating and still function. That’s why this vehicle is UN’s top choice of transport.

It could be anything from the torque converter to the disks itself sliding, and unfortunately the only way to confirm if it’s the culprit is by pulling the tranny down and doing a thorough inspection. You can also do a full drain and fill of the ATF, once and for all rule that out. And while at it, pull the trans pan down, replace the gasket (inexpensive) inspect for any tell tale indicators like big/small sediments or possibly (hopefully not) fragments of anything. Also, after doing this procedure I would strongly suggest hooking up an OBD2 scanner so you can monitor your AT pan temperatures real-time so you can see for yourself if it’s hitting 200°F temps (bad) on the pan.View attachment 2994767
This is what I use btw to keep an eye on critical temperature areas of concern on the truck. Heat is any equipment’s #1 enemy, and the fluids keep the temperature down.

Thank you #OEMGUY0720

Really good comments/ suggestions.
I will think these over tonight my friend.

Really like the temp monitoring system you have installed.

Cheers.

 

[3_puppies]

does the issue happen when the trans is down shifting?
what I'm thinking is maybe on a hard downshift it is causing the issue.
do the engine RPM's increase during the issue?