Torque Converter Question

[ErinMorrigan]

I bought a 2014 RAV4 AWD with 99K miles last summer. It has 117K now. It’s been a total dream, but about a month ago, I noticed a very brief sensation/sound almost like going over a rumble strip, but only about 25% as hard/loud, and only for 1-2 seconds. It only happened once or twice, so I blew it off, but it’s gotten much more frequent.

Following a lot of Googling, I became aware of an issue with torque converter shudder in the 2013-2015 models, and from reading tons of other peoples’ experiences, I suspect this is the issue. As I said, it’s a faint rumble (I would not call it a shudder, at least not yet) which occurs usually between 35-45mph and 1500-1750 RPMS, usually when gently accelerating. Transmission is totally smooth and unremarkable otherwise. Of course, I am outside the extended warranty for this issue, as confirmed by my local Toyoya dealership/service dept as well as when I called Toyota directly.

I have an appt for Toyota to diagnose it on Tuesday next week. If it is indeed the torque converter, I will most likely have my mechanic deal with it as I have had nothing but bad experiences at the dealership. I honestly don’t even trust them to diagnose it, but my mechanic (who I dearly love) doesn’t have the equipment, so off I go. My mechanic did test drive it on Monday incidentally, as well as putting it up on the lift and looking for other issues that could cause this (none found). They were able to replicate the rumble, but also got it to keep rumbling at 45mph, which has never happened; it's only ever been 1-2 seconds for me. They did find 3 of my tires are unbalanced, so I have an appt to deal with that Monday. They don't suspect that is causing the rumble and are the ones who said to take it to Toyota to check the torque converter.

Anyway, I have been unable to get clear answers to a few questions:

1. What actually happens when/if a torque converter fails?
2. If it is indeed going, is my whole transmission/engine at risk? The service rep at Toyota said he had never seen a failed torque converter cause transmission failure, but the internet strongly disagrees.
3. Can I still drive it, or am I potentially causing other damage? My garage says “ if it’s going, it’s going”, and if it’s just this one part that’s going, I’m okay with waiting until I can save the $ to replace it vs throwing it on a VISA or a loan, but not if it’s gonna cause a domino effect.
4. Is there any realistic solution aside from spending $3K to replace it (if indeed this is the issue?)
5. Could this actually be due to a software issue (I've read that also, that it was never the torque converter itself, but rather software that needed to be updated.)
6. I have seen so many posts about Lubeguard Instant Shudder Fix product. They say it is diagnostic, meaning if you install it and it works, you had a fluid problem. If it doesn’t, it’s a mechanical problem. Is there any harm in trying this? (Some reviewers said it made their problem way worse, but it seems like maybe that just means they had a mechanical problem to begin with, and it would have gotten worse anyway?)
7. If I do add that product and it works, is that it? Or would it mean that I should have the fluid drained and replaced, and maybe magnets added to the pan (forgive me if I’m not saying this right - just a girl who’s read too much!)

Basically I want to know, if you were me, what would you do? Please and thank you, and Happy Thanksgiving!

[Mjolinor]

Not Toyota specific, just knowledge form a lot of years mending auto boxes and such things. I am assuming it to be a standard auto box and not some sort of CVT.

I would stop using it and replace the oil and the filter in the gearbox and cross your fingers. With auto boxes any fault can cause complete failure if ignored. You need to look carefully and smell at the oil that comes out. If it smells burnt, has any sort of grains in there then something is burnt. If something is burnt then it will not last long even if you do change the oil and filter.

The sort of shuddering you describe does sound like a slipping clutch. More modern (<30 years old) gearboxes have a clutch in the torque converter that lock up under instruction from the engine / gearbox management when there is not a lot of demand from the throttle. This is to make them economical as the torque converter is removed from having any slip once the lock up clutch is on. Different vehicles lock up differently but most commonly it will not try to lock in first or second, maybe not third and some only lock up in top gear.

Presumably the gearbox can be put into manual mode. Try that and see if you can tie the noise down to a particular gear or all gears or whatever.

In the long run it matters not, if you have a clutch slipping then the gearbox will need overhauling. The best indicator is the state of the oil in the gearbox. Burnt oil is easy to identify.

All of the above is not Toyota specific and there may be specifics related to your car that I know nowt about.

 

[flash22]

I would start with a fluid and filter change also do the transfer box and front and rear diffs if it's never been done it's well overdue, the transfer box chain can suffer from wear if the fluid isn't changed, also be aware that AWD cars need a fully matching set of tyres or at least matching tyres per axle

I take it you're in the US, It's a traditional auto U760E or F

 

PS. this is a UK based forum, NA cars can vary greatly compared to the European market