ronaldqs@gmail.com
Gen 3 Torque Converter
Hi Guys,

I have a small issue with my Gen 3 Auto torque converter (I think).

History:
I have a '04 3.2 SWB Auto with about 150 000km on. About 10 000km ago I had to replace the gearbox with a used one due to mechanical failure. This was after a transmission oil change at a dealer (a whole other discussion). When I had the gearbox replaced I had the torque converter overhauled. I have had no major issues since then until this past weekend.

I did a trip down to Bloem from Pretoria. I noticed that the torque converter was being a bit temperamental. It seems to be over-sensitive. Cruising at between 135 and 140Km (120 if the cops ask) the revs initially start out at about 2500Rpm. After one or two hills, the torque converter seems to give up and the revs pick up to 3100Rpm. This obviously hurts my fuel consumption but more importantly, the engine is working overtime. On the way back from Bloem yesterday morning the same scenario occurred, this time however the A/T Temp light also came on. I then pulled over and checked the transmission oil which was clean and at the correct level (indicating no major mechanical wear). I then nursed the car back to Pretoria using the manual setting and not "allowing" the torque converter to kick in by gearing down and driving up the hills in 4th etc.

My questions are:

1. Can the sensitivity of the torque converter be set?
2. Can I trick the converter into running the gearbox in top gear and at minimum revs somehow?
3. Is there perhaps a fault with my torque converter?
4. Is the torque converter issue detrimental to my transmission?

Your expert advice would be greatly appreciated :)

Also, please criticize any incorrect assumptions I have made :)
User avatar
Affiliate Member
Re: Gen 3 Torque Converter
either

the filter is clogged on the A/T transmission
or the wrong grade oil is used
or the oil is low and the wrong dipstick is used so you are getting a faulty reading
I believe the gen3 is all electronically controlled so there is no kick down cable to adjust

perhaps ask the dealer for a software flash or take another 1 or 4 gen3's for a test drive and compare behavior.
RoelfleRoux
Re: Gen 3 Torque Converter
The 2500rpm to 3100rpm jump, is that in the same gear, or do you think it changed down to 4th?

In a similar vein; when running in manual mode, did the same symptom re-occur or did the revs remain where it should?

Your initial posting makes me think that something could be wrong with the clutch. There is a little clutch in the box that "locks-up" under normal cruising load. When you go up a steep-ish hill, you will notice a small jump in revs (about 200-300rpm), this is when the clutch disengages and drive is transmitted via the torque converter. That 200-300rpm increase is the "slip" in the torque converter. Prolonged and/or excessive slip can cause a temp increase in the box.

This is just my initial thought and I really am no expert. I'm sure the experts will arrive soon enough.

Roelf
ronaldqs@gmail.com
Re: Gen 3 Torque Converter
Hi Roelf,

What you are describing is exactly what I am experiencing. The same issue occurs in manual mode. How could I have this clutch checked? Is it located in the gearbox?

Thanks,

-Ron
Skillie
Re: Gen 3 Torque Converter
Hi All

I have the same behaviour. My revvs drop back to 2100 on the other side of the hill though...

I always blamed my tyre size for this, up to now.

When I considered tyre sizes, the experts on this forum warned that a bigger size tyre could have this effect.

I am currently running 165/75R16 tyres and if I'm correct the standard is 165/70R16 tyres.

Regards,
RoelfleRoux
Re: Gen 3 Torque Converter
Ron,
I cann't offer you any more sensible advice. I have reached the limit of my knowledge.

Skillie,
I'm sure bigger tyres can have that effect. The DiD is already sitting with long gearing before fitting bigger tyres. My instinc is that if the revs increase only occasionally and for short duration, then all should be OK. That is afterall how the box is designed to operate. If the rev increase is regular and for long periods, then one is temped to think that heat could increase and that the longterm effectiveness of the gearbox oil could be jeapardised. A solution could be to engage 4th gear in tiptronic mode when you see this happening; most probably with a heavy load and a headwind or something.

This is only likely to occur in a very narrow operating window (or if locked in tiptronic). If the load gets really high, then the box will gear down.
Re: Gen 3 Torque Converter
Skillie wrote:Hi All

I have the same behaviour. My revvs drop back to 2100 on the other side of the hill though...

I always blamed my tyre size for this, up to now.

When I considered tyre sizes, the experts on this forum warned that a bigger size tyre could have this effect.

I am currently running 165/75R16 tyres and if I'm correct the standard is 165/70R16 tyres.

Regards,
I think in your case, it ise definitely the torque convert unlocking - but that is normal, especially at fairly low revs around 2100rpm. From my experience, above 2400 or say 2500rpm (cruising in 5th), the torque converter should stay locked even if you encounter a hill. If the hill is very steep, and you slow down, causeing the revs to drop to below 2400rpm, then the torque converter will unlock (and revs rise).

I believe the oversize tires will just exagerate the problem a bit (as you travel faster for the same rpm).
2008 Pajero DiDc LWB GLS
2005 Pajero DiD SWB GLS (sold)
Re: Gen 3 Torque Converter
Why does the torque converter unlock when the vehicle encounters a hill at low revs? Is this as it prepares for a gear change??
2006 Pajero GLX 3.2 DiD LWB A/T, aux battery system, roof rack, tow bar, 9000 Lumen LED Light Bar, Speedo Cruise (Bestech AutoCruise)
RoelfleRoux
Re: Gen 3 Torque Converter
The torque conv is the "normal" drive device in an autobox but results in a small power loss. The lock-up clutch is there to reduce fuel consumption and is only engaded when the load on the box is low.
Re: Gen 3 Torque Converter
RoelfleRoux wrote:The torque conv is the "normal" drive device in an autobox but results in a small power loss. The lock-up clutch is there to reduce fuel consumption and is only engaded when the load on the box is low.
That is also how I understand it... but then why does this happen - cruising at say 130km/h, with torque converter locked, if you accelerate up a hill, the torque converter stays locked. This is definitely a large load?
2008 Pajero DiDc LWB GLS
2005 Pajero DiD SWB GLS (sold)
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