Torque Converter Lock-up

Thanks for that - yes diesel 3L. What about fuel economy - it's supposed to improve too isn't it?

Thanks John
I'll check it all out

I have had a torque converter lock up kit for over 5 years. It stays on all the time. Mind you this is on a Pajero which may have a different box to the Prado and different transmission ECU configuration. I also have one in my 2018 Triton. Wouldn't tow without them. Done over 100,000klms towing 2 tonne camper. Including the very hilly terrain around the Atherton Tablelands. I never turn the unit off. You certainly can use the unit for towing up hills. Another benefit of the unit is that you can lock out 5th gear if you want to stop it hunting between gears. Some units also have programming that you can set up to suit your driving...very handy and easy to do.It makes the tranny run so much cooler. I have the one from MM 4X4 and I know he has sold hundreds and no issues. People who tow without one of these and with no Scangauge or Ultragauge have absolutely no idea how hot their transmission gets. Plenty of stuffed transmissions from over heating.Every person I know that has one fitted swears by the unit. The inventor/manufacturer of the unit is on the Pajero forum and is one smart cookie as well as very helpful with any questions.The MM4X4 unit is a very sophisticated unit that talks to the ECU and is unlike many of the older lock up kits that have been around. Those rubbishing the unit obviously have never used one and are simply relying on assumptions.

QLD camper
WELL SAID.
I see the kits as being similar to people who heavily modify their vehicles and THINK they are TOUGH, When in fact they are less reliable and breakdown. Look at wreckers and repair shops for proof.
They are shocked when the steering tie rods of their vehicle get bent, purely because the wide wheels stressed them past their ability. I must NOT mention wheel bearing life right now!

The lock up kits result in some changes and as mentioned, they also repair the failures for profit. WIN WIN.
I agree, if it was a good idea it would have been engineered into the vehicle features and performance.

Hi Qldcamper,

Toyota actually updated the cpu for the transmission in the facelift model 200 series, from MY2016 I think. It basically does the same thing as a lockup kit, and they did not change or update the actual transmission. Of course this was on the 200 Series, and not the Prado.
Macca.

"Don't you hate it when your reply disappears when you hit the send button."

If you use either Firefox or Edge browsers, then install an addon called "Textarea Cache" to the browser. Textarea Cache stores what you have typed into the larger forum reply text areas in forums so you can recover it when you have some sort of crash in the forum. (It does not copy your text from smaller areas like password and personal detail fields.)

It has saved me many times in situations like you have just suffered.

Leigh W

I mostly agree with your statement, but the auto is capable of withstanding high torque loads as the torque converter at or near stall can deliver around double the engine torque output, via it's internal design of torque multiplication, so auto OK there!
It is totally a different issue to have the TC lockup clutch NOT transmit torque values past a certain amount. WHY? Because the factory DID TEST the TC lockup clutch and it can only handle a small amount of torque before Destruction Slippage occurs. Once it happens, the clutch is TOAST.

I have rebuilt Nissan autos where their clutches in the auto slipped for a short time, the owner detected it by being aware. BUT the internal clutches in some packs were burnt blue with heat. A piddly little TC clutch designed to just hold a cruise attitude with be short lived if stressed.
I hope those who have a lock up system fitted are REALLY AWARE people.

Thanks for that Roy. My Prado is a 2013 also and I have a trans cooler fitted. As you mention though I have no idea about the temperatures. Might be a place to start looking. As for why I was asking - I guess I had looked at a couple the websites about them. I know the manual for the Prado says only tow in S4 but it's tempting sometime on a straight level stretch to use 5th but then the slightest change makes it go hunting between 4th and 5th. I wondered whether the lock up kit would help this.

cheers

Happy Ex.
That is all very good, BUT you have revealed the reality of it. IF the fluid is becoming black or discoloured when it shouldn't really get like that, especially on a short time period. Any heating which you detected above normal TC action has to be the poor little clutch friction heating. Immediate action has to happen then.
But, if it has ever happened, the clutch is buggered anyway.
The whole idea of the ecu controlling it is So There Is Never Any Abnormal slip, because it knows it will happen and not OPENS to prevent damage from slip.
Your reply has Concreted the case AGAINST having one fitted.
Yes, tc action, will and does, generate a lot of heat but having a cooler (preferably in the hottest line, ie, exit line, (gets rid of the most heat quantity so the engine cooling system doesn't cop it)
Even If a kit has it locked, excessive torque will destroy the TC lockup clutch pretty soon, as your fluid indicates. That clutch must NEVER SLIP OR BE SLIPPED UNDER LOAD. It's purpose is to lock and unlock and not be slipped.

Hi Roy,
You said the oil was black and reaching temps of 150 Deg. C. Before you fitted the cooler and Locking kit, So the car was as the manufacturer intended when it was doing this. so I can't see how that concretes the case against fitting a locking kit.
What temperatures was the transmission reaching after fitting the cooler and what temperatures does it reach after fitting the lockup kit? And have you had the oil checked after fitting the locker?
Are you glad you fitted a Lock up kit and would you fit one again?
A couple of friends sing the praises of lockup kits and it was the first mod they did when they updated their vehicles. I haven't been convinced to fit one but find the people that have them love them and I'm yet to find someone say they wish they had never fitted one.
I believe a scangauge or similar is a must.

Tonysmc
There is , to me a few anomalies in the reply.
First up, most people DO NOT REALIZE, the temp recorded and displayed via a scan gauge is ONLY the temp RETURNING TO THE AUTO, and definitely NOT the temp of the much hotter fluid leaving actually leaving the torque converter. If the pan/sensor temp said 150C that is AFTER it has been cooled by some means. Therefore the fluid will have been fairly COOKED and likely to turn a different colour. If that happens it also begins to lose it's lube ability and frictional qualities for clutches.
With a lock up mod you don't ever know IF and WHEN the poor little clutch is slipping and cooking itself. THEREFORE, Don't look at the road, ALWAYS/CONSTANTLY LOOK AT REVS to try and detect TC Lock clutch SLIP. Good luck!
That said, the enormous heating of the fluid is trying to be cooled by, a conventional heat exchanger if not prior cooler is there to get rid of heat by using the highest differential of temp levels, oil to air, to maximize the best rate of heat dissipation.
Under towing conditions greater heat is generated if TC normal slippage is happening. Engine KW's go into heating the fluid through "work" done on the fluid.. All entirely normal. What people are trying to achieve is: using a lockup clutch to cancel out that heat value, BUT it is operating under conditions where the clutch cannot accept the torque loading and slips and heats, and burns, and is destroyed. That is why the manufacturer spent millions of $ testing and doing research and programming an ECU to detect the engine torque loading at any speed and disconnect the Lock UP clutch so it is still serviceable.
People towing in adverse conditions, without a trans cooler, are relying on the engine cooling system, WHICH MUST COOL THE ENGINE TOO, to dissipate ALL HEAT SOURCES
through the radiator water. If it becomes too much and engine is fried, then the auto is not any help to you. Cool it first to SAVE ENGINE.

Friends singing praises may not be technically minded and living on borrowed time. I wonder what tune it is?
Everything runs fairly close to failure, but if the threshold isn't exceeded then reliability happens.
Years ago, a VERY SMART person I know of, thought he could hold brakes and try and stall the converter in a 351 Fraud. System was already normal hot and about 20 seconds of full power and no motion, the TC simply cooked the fluid to rubbish. Rebuild!

You do realise RMD that an Ultragauge can measure the pan and the hotter pipe in an automatic transmission. Pipe is where the tranny fluid is hottest.

Quote.."People towing in adverse conditions, without a trans cooler, are relying on the engine cooling system, WHICH MUST COOL THE ENGINE TOO, to dissipate ALL HEAT SOURCES
through the radiator water. If it becomes too much and engine is fried, then the auto is not any help to you. Cool it first to SAVE ENGINE."
This exactly where the lockup kit is working at its best. I,ve experimented quite a bit over the years with the kits on my cars and as I said...I wouldn't tow without them or an Ultragauge. You can poo-poo them all you want but like thousands of other users, I,ll stick with em. Between my cars and my travel mate we have nearly a quarter of a million klms put on our vehicles using the lock up kit and not one issue.

Thank you Tonysmc and others for your positive/affirming comments.
I have reread several times RMD's reply to my experiences and no matter how I looked at it I could not see how he came to those conclusions from what I had said.
This is all getting too crazy now to bother replying to at all, however for your benefit, and for Suitcase and anyone else who is interested I will willingly answer your questions.
Yes the overheating and discoloured fluid was when vehicle was stock standard.
Now the TC will still reach similar high temperatures if for some reason it has not locked on long hills when towing. A bit of an adjustment to the driving style will have it lock and the temperature will rapidly fall to safe limits. I now have an alarm set at100 deg. so I take action to get the TC locked long before it reaches anything like 150 deg. I have no doubt it would still reach that temperature if left unlocked though as I find the add on oil cooler probably reduces the pan temperature a few degrees but has little effect on the TC temp. Of course I am not quoting controlled environment tests here, just casual observations of the gauge which will never be conclusive.
Once the TC locks the temperature will quickly match the pan temperature which would suggest to me that there is no clutch slippage at all. Pan temp. is usually in the 80s range somewhere and the motor is in the low 90s when towing. As RMD points out it is better value keeping one's eyes on the road so I mostly rely on the alarms to alert me of a pending problem.
Yes I would definitely fit these again. My opinion is that while four cylinder vehicles have manufacturer tow ratings that are fantastically high, I do not believe most are capable of sustaining those towing limits without several modifications. Most of these vehicles will perform very well on the highway or around town when not loaded or even moderately loaded. However if towing anywhere near their rated limits will need some special attention somewhere.
I like the MM 4x4 unit as it has some very sophisticated features. Personally I subscribe to the simple is best approach in a lot of things but we are dealing with a sophisticated motor and transmission here so I feel the sophisticated features in this unit are not only justified but probably necessary. I leave it turned on all the time weather towing or not. It just quietly does its thing in the background without any fuss at all.
I also like the UltraGuage because you can monitor up to six or eight things per screen and with multiple screens available. Not sure why you would want to do that but you can. The feature I find very useful though, is the ability to set alarms (audible and/or visual) for anything you want.
Simply put, my view is that if towing 2t plus with any four cylinder diesel/auto you definitely need to monitor your temperatures. You will then probably quickly realise you need a torque converter lockup kit as well.
I have no doubt that some others will have a different view on this however one can not make any intelligent comment or decision if they are not monitoring their engine and transmission temperatures to know what is actually happening.
Roy G.

BIGFISH
I never said they didn't work!
Your mention of reply to where I said the maximum heat value is being produced you need a cooler, Your reply said"This exactly where the lockup kit is working at its best."
That is nonsense, as it is at, or near maximum engine torque where the OE system would NEVER have it in lockup. That is why the OE system UNLOCKS it under those conditions so the clutch ISN'T fried.
On flat cruise with minimal torque loading, I know you can "crib a bit" and have the clutch locked more than the maker intended.
My concern is for those who aren't able to detect or realize they are making the clutch slip and therefore closer to failure.
If you can use one without frying the clutch, contrary to what you said above about using it when under high torque situation you described, Then keep doing it!

Here is some interesting reading I found:

"The torque convertor is never locked up 100%, there is always some slippage allowed, this is to prevent hydraulic pulses at a constant frequency damaging the stator and turbine vanes. The hydraulic pressure is varied by the dampner control valve which is operated by the dampner solenoid, which is controlled by the AT ECU. The variable control process is as known as PWM (Pulse Width Modulation). The AT ECU uses engine rpm, vehicle speed, input and output shaft speeds, accelerator position, gear set engaged and ATF temperature inputs to decide when it is appropriate to lock, partially lock or unlock the torque convertor. The AT ECU programming is very complex and this is why any aftermarket modification to alter the locking and unlocking of the torque convertor must work with the AT ECU and only enable TC lockup to occur when it is mechanically safe to do so."

I also read an interesting aspect raised on another forum and was that the transmission oil pump is located in the torque converter, locking the converter at the wrong time can result in low oil pressure in the transmission and this can result in band slipage and premature failure of bands. The other aspect raised often is having the torque converter locked during gear changes imposes more load on the bands during gear changes.

Hi Peter
Thanks for your reply.
It is comforting for you and other Pajero owners to know you have a transmission that apparently does not suffer from the issues discussed in this thread. However this is little comfort or of benefit to Suitcase or in fact most drivers of other vehicles.
I am not suggesting that your 'specialist' is wrong but as another poster already suggested, these comments and advice usually come from the same people that stand to make money if their advice proves incorrect. The reality is that it is you and I, the vehicle owners, who will have to shell out when something goes wrong, not to mention the inconvenience this may cause.
I cannot comment on the Auto Manual Mode that the Pajero apparently has as I have never driven an auto Pajero. I do know that the Prado in question does not have that mode so again small comfort there. The Prado 'S' mode does not make the auto operate like a manual.
I can also say again, from personal experience that an add on transmission cooler does not overcome the overheating problem and in fact has no to minimal affect on TC temperature and will reduce the pan temperature a little which is not the problem. The Prado also has a dedicated oil cooling section on the one edge of the radiator but it is the heat generated within an unlocked TC that is the issue and I believe should be avoided if possible rather than trying to cool the already cooked oil from an unlocked TC.
Yes the high TC temperature is a spike that will dissipate quickly as you say, however once the temperature rises on say an uphill climb, it will stay that way until conditions change and the TC is able to lock, however long that takes.
I am strongly recommending that if you tow with a four cylinder diesel auto (Pajero or other) than fit an OBD gauge and monitor your engine, TC and transmission pan temperatures. You can then adjust your driving style accordingly or even decide to fit a TC lockup kit if you deem it necessary. Or alternately choose to ignore the 150 deg. being generated by the slipping TC, your choice your car and your money.
Happy traveling
Roy G.

I tow with my Pajero in manual mode and follow the manufacturer's instructions to tow in 4th gear. I drop into auto going through towns as my model will change down in manual mode but not up if you stop at a round about for instance. If I forget to go back to manual mode and 4th gear once back on the highway it is immediately obvious in the transmission temps (pan and pipe). The only time I saw the temperature go up was on the Oxley Hwy between Port Macquarie and Walcha when it got to about 120degC and no amount of changing down could lock the transmission. Normal highway driving see pipe temperatures of about 72degC. I have opted not to fit a lock up kit just keep an eye on the temperature.

Happy Ex
If your auto still gets hot with a cooler fitted, it is either far to small for the job AND/OR it has been placed in the return line to AUTO, a situation where all the EXTREMELY hot fluid is first DUMPED into the radiator water, which just happens to be nearly boiling because of the engine load. That means, during the short transit time through the system, you WILL BE GETTING almost uncooled fluid returning to the auto. NOT WISE!
That is why thinking people fit such a suitable cooler into the HOTTEST line exiting the auto, where the maximum HEAT DIFFERENTIAL is happening between the fluid and outside air temp range is greatest. Think thermodynamics!
That way you get RID OF FAR MORE UNWANTED HEAT from the fluid and you are not then taxing the normal auto and engine cooling anywhere near as much.

Had both manual and auto's, auto make life much more pleasant in stop start traffic and off road.

Second benefit is an auto lasts for ever if you look after it whereas a manual trnsmission you will most likely be replacing a clutch or two. Will be interesting to see how long the new DCT transmission last.

I think VW have stopped fitting DCTs to their vehicles. We scrapped an otherwise perfectly serviceable MY05 2L TDI sedan because a minor rear seal leak contaminated the dual clutch. About $5-7K to repair.