[purohitanuj]

Originally Posted by 4x4addict

Most Torque Converter AT's are solid and bullet proof including the 6-Speed ASIN units that come in the latest MUX, Fortuner, etc. The 6-Speed ASIN also comes with a drain plug and filler.

No just drain plug but complexity as well. For example, the Asin ones have 4-5 shift solenoids and 3-4 variable pressure solenoids.

I got my 6 speed AT valvebody serviced due to stuck solenoids, which was due to Mahindra not flushing ATF in any of the service schedule.
Mahindra asked me 4L for full AT box replacement. I got serviced under 30K.

Round ones are variable pressure solenoids. Long ones are sift solenoids.


Opened up valve body with scary one way valve bearings open and ready to fall.



As Mahindra does not provide child parts, the stuck solenoid opened up for further investigation.



Cleaned and assembled valve body ready to go back into transmission.



My point is the simpler the gearbox, the less chance of it to fail. Mine got stuck at 1.10Lakh km. Many would not even touch half the kms so they would be fine. But in my case, I see reliability as paramount.

On other hand, the Suzuki has only 4 shift solenoids.



P.s. Will be writing a full thread on AT service. Keep an eye if you are interested. It will have all technical details like timing diagram of solenoids.

[4x4addict]

Originally Posted by purohitanuj

I got my 6 speed AT valvebody serviced due to stuck solenoids,

Which Mahindra are you talking about?

Are you suggesting that the Automatics offered by Isuzu/Toyota/Mitusbishi in the MUX/V-Cross/Fortuner/Prado/Hi-Lux/Montero/PS etc are prone to trouble?

[purohitanuj]

Originally Posted by 4x4addict

Which Mahindra are you talking about?

Are you suggesting that the Automatics offered by Izuzu/Toyota/Mitusbishi in the MUX/V-Cross/Fortuner/Prado/Hi-Lux/Montero/PS etc are prone to trouble?

I am talking about DSI International gearbox 6 speed AT in Mahindra Scorpio S10 in my case but I say in general. Yes all automatics are prone to trouble if not maintained; which all Indian manufacturers are known to do - i.e. not maintain in service schedule. These are marketed as Sealed For Life.

[4x4addict]

Originally Posted by purohitanuj

I am talking about DSI International gearbox 6 speed AT in Mahindra Scorpio S10 in my case

Oh, yes. DSI went bankrupt and got bought out by Geely Automotive. ASIN is generally a very reliable transmission.

Originally Posted by purohitanuj

Yes all automatics are prone to trouble if not maintained; which all Indian manufacturers are known to do - i.e. not maintain in service schedule. These are marketed as Sealed For Life.

I thought the discussion started about using a 4-Speed AT in the Jimny. Not sure where you are going with this any more.

Anyway, all I can say is 5 Speed is more efficient that 4-Speed. 6-Speed is more efficient that 5-Speed. And you can get very reliable transmissions in 5 and 6 Speed. I don't think reliability is an excuse to offer 4-Speed any more.

[s4ch]

Originally Posted by purohitanuj

I am talking about DSI International gearbox 6 speed AT in Mahindra Scorpio S10 in my case but I say in general. Yes all automatics are prone to trouble if not maintained; which all Indian manufacturers are known to do - i.e. not maintain in service schedule. These are marketed as Sealed For Life.

OFF TOPIC:

I think you'll find that the Scorpio S10 AT gearbox has an ATF change mentioned in the Scorpio S10 service manual for the 60k service. I have the same car and completed this fluid change. Gearshifts are super smooth now, was always smooth but even better after the change.

Most TC gearboxes are pretty reliable if maintained with on time ATF changes, don't expect the Jimny 4 speed TC to be any different.

Excited about this launch and if considerably cheaper than the the Thar then this will be my second car in an SUV only garage (currently have a Scorpio S10 Automatic).

[purohitanuj]

Originally Posted by s4ch

I think you'll find that the Scorpio S10 AT gearbox has an ATF change mentioned in the Scorpio S10 service manual for the 60k service. I have the same car and completed this fluid change. Gearshifts are super smooth now, was always smooth but even better after the change.

Most TC gearboxes are pretty reliable if maintained with on time ATF changes, don't expect the Jimny 4 speed TC to be any different.

Excited about this launch and if considerably cheaper than the the Thar then this will be my second car in an SUV only garage (currently have a Scorpio S10 Automatic).

Generally AT boxes contain 10L of ATF, from which, approximately 50% is in the Torque Converter, cooler lines and the cooler itself.
When the ATF is changed, only the slump pan is removed which is like replacing 50% old ATF with new. Flushing is different process in which almost all ATF is replaced.
In this case, Mahindra does “change” at 60K. Ideally, they should change at 30K and flush at 60K.
Also I am not sure about the new “sealed for life” AT boxes. I think they don't have maintenance requirements as per vehicle maintenance schedule.

Lets no more divert from the main Jimny thread.

Originally Posted by 4x4addict

I thought the discussion started about using a 4-Speed AT in the Jimney. Not sure where you are going with this any more.

My simple point being the old gen AT boxes had a dip stick to check the ATF level and drain port to remove the oil. The same dip stick port was used to fill the ATF as well. This meant that one could maintain these boxes at home.
Now with new AT boxes, the dip stick is removed, which makes checking fluid a lengthy process in itself and also one cannot maintain these at home.
The drain plus has vanished leading to removal of complete oil pan to remove the ATF.
I agree lets not divert this thread further.

[Sankar]

Originally Posted by purohitanuj

I am talking about DSI International gearbox 6 speed AT in Mahindra Scorpio S10 in my case but I say in general.

Not all of them are the same except the basic principle of how it works - planetary gearsets, clutches and brakes. Component quality, design and manufacturing won't be the same. A typical Aisin will be more reliable than a DSI which is not a top tier transmission manufacturer.

Originally Posted by purohitanuj

My point is the simpler the gearbox, the less chance of it to fail. Mine got stuck at 1.10Lakh km. Many would not even touch half the kms so they would be fine. But in my case, I see reliability as paramount.

I have done 84xxxKMs on my Aisin 6 speed and there are others who have crossed the 1lac+Km without problems. Mahindra in its new Scorpio and Thar is using this very same transmission, they have ditched the DSI for good. For the XUV they are using another Aisin 6 speed transaxle.

Transmission oil change etc is not called for in the routine service for the Aisin equipped Toyotas, but can be done. But there is a fill plug, drain plug and reverse dipstick on the pan. There are several DIY videos on youtube for this specific transmission. In India it comes on Crysta, Fortuner, Vcross 1.9, MuX 1.9, Scorpio-N, new Thar; not sure if I have missed any except maybe the imports.

[Aditya]

Why it's important to change the transmission fluid of your Torque-Converter AT - Posts moved to a new thread.

[ritedhawan]

I understood the importance of changing ATF when I lost my 2007 Honda Accord 2.4L few years ago, the conventional AT in that car got damaged thanks to my being unaware of ATF replacement. The conventional AT is pretty durable and all it asks is replacing ATF as specified in the manual. If you don't do it and go for that mistaken belief which says something like 'Sealed for life' then you are asking for trouble when it comes to ATF issues.

Lesson learnt the hard way, in my current 2008 Honda Accord 2.4 L . I got the ATF replaced as per manual. Shifts became smooth. I keep an eye on the ATF level's and color. Its important to replace ATF with OEM specified ATF. Another important fact, in my car you cant simply pop the hood and pull the ATF stick to check levels or color, because that is misleading. First, on cold start, start the engine and wait for the first instance of radiator fan to turn on , then shut off the engine and wait for a few minutes. Then I can go ahead and pull the ATF level stick to check the level and color.

[Sankar]

Nice to have this forked off as a separate discussion thread.

For reliability sake another preventive maintenance that can or should be done (on the keepers) is to have an external fluid-to-air transmission fluid cooler installed bypassing the stock cooler which would be fluid-to-coolant type of cooler.

Stock transmission fluid cooler would be a small heat exchanger type similar to some engine oil coolers which is like an enclosed can with coolant and atf circulating in their respective circuits separated by thin metal walls. And on larger vehicles it would be part of the vehicle radiator. The bottom tank of the radiator would have couple of internal lines that circulate the ATF inside the radiator filled with coolant/water.

With age and mild corrosion the walls that separate the coolant from the atf would give away leading to mixing of the fluids to form what is colloquially known as the pink milkshake. When this happens its bye bye transmission and would need expensive repairs and whether a simple full flush with new atf would fix it is not clear. If the damage is not too bad probably it would work.

Anyways as the owner of a long termer or keeper (some vehicles are hard to upgrade/change from for the performance/utility/reliability combination it offers) what could be done is to bypass the coolant-to-atf heat exchanger and replace its function with an external fluid-to-air radiator style cooler in front of the engine radiator. When doing this one has to select the correctly sized transmission cooler and mount it properly close to the radiator and in the area in front of the radiator fan. Once done it will last the life of the vehicle and there will not be any concerns with atf mixing with coolant ever!

Some vehicles with "tow" package or special applications come with small fluid-to-air coolers installed in front of the radiator but these are in series to the coolant-to-fluid trans coolers. They don't bypass it.

I had an external transmission cooler installed in mine, bypassing the stock cooler inside the radiator. When it was on the temps were in check which I could compare with before and after using the scangauge. Currently its not on the vehicle since the mounting was not proper, I'm planning to get it done again.


PS: I think this thread should be merged with this one below
https://www.team-bhp.com/forum/techn...ed-life-2.html (Why you should periodically change your Automatic Transmission Fluid (even if "sealed for life"))

[Jeroen]

Thanks for sharing this, look forward to further updates.

Just a few more thoughts on this topic. There are a number of cars out there where the manufacturer claims the transmission is “sealed for life”.

There are also typically the transmission where you won’t find a dip stick! Unfortunately, those manufacturers don’t tell you how many years/how many kilometers a typical transmission life is. It is usually sufficient for the first and second owner not to worry about. But all transmission will need maintenance.

My Jaguar XJR has one of these “sealed for life” transmissions. There is not an official Jaguar dealer who will change/flush your tranny!.

Luckily there are some excellent specialist who jump into this. For these sort of jobs I have been visiting a company here in the Netherlands. They also organise a “technical day” every year for their customers. The owner, Raymond is a a truly gifted diagnostician on anything automotive.

One of the things he specialises in is overhauling and flushing of these high end transmission. Have a look here where he takes apart the complete transmission during one of these technical days as we watch him do it!

https://www.team-bhp.com/forum/diy-d...ml#post4180547

As mentioned there is a considerable difference between flushing and just changing the tranny fluid. Flushing when done properly needs a special machine and special cleaning fluids circulated through the tranny and parts, before new transmission fluid is put in. It’s a lengthy process, but more or less fully automated. The machine does it all, extracts the old fluid, circulates the cleaning fluid, extracts the cleaning fluid, applies fresh fluid etc.

Your car owner manual will show whether is transmission change is required or not, how often and how much fluid you will require. Which is usually a lot less than the total amount in the system as you can not get most of it out. Effectively you more or less drain the oil pan only.

I did this not to long ago on my Jeep Cherokee:

https://www.team-bhp.com/forum/diy-d...ml#post5307431

A couple more points:

It makes good practice to use the manual gear selector now and then as well. When you keep your transmission in D, some of the solenoids and some of the tiny fluid channels in the brain/mechatronic don't get used. By driving in each gear for 20-30 seconds now and then, you will ensure that the fluid circulates everywhere and the solenoids get activated and don’t get stuck.

On nearly all cars with a dipstick for the fluid level of the tranny the procedure to check fluid level is with the transmission fluid at normal operating temperatures and prior to checking the level, you need to, with the brakes on, cycle through all gears, including reverse. If you don’t you might get an erroneous reading, which is usually too low. Overfilling your transmission can cause serious problems! So make sure you understand the procedure involved in checking the fluid level.

Jeroen

[4x4addict]

Originally Posted by purohitanuj

My simple point being the old gen AT boxes had a dip stick to check the ATF level and drain port to remove the oil.

All ASIN 5-Speeds and 6-Speeds have a drain plug, filler plug. I serviced my Montero AT myself. Yes, the dipstick has been deleted but I don't see that as big deal because AT fluid like your power steering fluid is not something that requires periodic top up.

I do agree with your point regarding the sealed for life. When Mercedes launched their 5-Speed Automatic, I had bought an ML320 with the "sealed for life" 5-Speed AT. When I closed 100K miles (160K kms), I took it to the Merc Dealer and he said it was sealed and transmission has to be dropped to change fluid and they don't recommend it. But, I put my foot down and made them do it.

[Jeroen]

This is the sort of machine workshops should be using to flush a transmission. Similar machines are used to flush engines too.

Again, a tranny or engine flush, should include a specific cleaning cycle with a very specific cleaning fluid. What I often see is that mechanics just flush the transmission (or engine) with some extra ATF / oil. That is already better than just draining the fluid/oil. But it doesn’t get rid of any of contaminant that are stuck inside the unit. For that you need to flush it with a special cleaning fluid.

https://www.youtube.com/watch?v=OirBwnrO5jQ

https://www.youtube.com/watch?v=_hxvDm5D9Ck

Jeroen

[attrip2008]

Any thoughts on the ATF change schedule for Hyundai 6 speed ATs? I have a Creta petrol AT (2018). I have been told a few times by the SA that these are sealed for life which I very much doubt. I have done ~25K so far due to low running but want to keep an eye out on the schedule.

I believe the same transmission is offered in Tucson and Tata Harrier/Safari. So, the idea about maintenance will help a bunch of folks. Thanks.

[busydrive]

Good thread. Will keep an eye on it. Wanted to add a similar example - Hexa service schedule says AT boxes are sealed for life. However there are many in the forum who have changed AT oil in between 60-80K KM even though service centres usually say it's not required. I haven't done it yet as it's still new.