All deep and meaningful on auto transmissions.

BX Tech talk
AlanS
BXpert
BXpert
Posts: 841
Joined: Mon May 16, 2005 9:53 pm
Location: Queensland, Australia

All deep and meaningful on auto transmissions.

Post by AlanS » Sat Jul 02, 2005 10:38 am

Posted elsewhere but here goes anyway for future reference.


This week I've had my first opportunity to take a decent look at and become a little educated on the ZF auto in these cars.
It has always been said that the ZF auto was considered "bomb proof" in the CX yet in the lighter BX it has had all kinds on things said against it; granted not the same box, but rarely does a manufacturer go from a quality product to a crappy one and then persist with the crappy one and it gets used on further models still bearing the crappy reputation.
I have heard it said on many an occasion that a BX auto "might" last 120,000 klms, so you have to ask, why?
I'll go back to the start.
Friend of the family is looking for a car and has a soft spot for my BX. We search high and low looking at cars everywhere but most were neglected, abused or sold, so in desperation I spot a car in Sydney but it's an auto. It has low klms, she's not that happy with an auto but she decides to give it a go, so buys it.
Happy for a while, but is sceptical of getting anybody to service it near where she lives (with good reason I might ad) and seems nervous about driving it even thiough it only had 80 K klms on it.
Eventually she brings it up here to me to take for a run and do whatever needs doing to it.
When I drive it, I'm firstly somewhat impressed at how it gets off the mark; none of the slipping and roaring I am used to with autos. Changes are fair, if anything a bit jumpy in the lower gears but when it goes into 4th, it seems to fall back momentarily in speed, almost as if something is half seizing. This can't be right.
I check the ATF; it's black. To drain, I find there's two drain plugs both that take an allen key about 5mm. One is set higher in the sump than the other and a look at the ZF manual shows the tp one holds about 1 litre that is splash fed to it. I check the service records and see it had 1 litre of Dexron3 put in it when it was serviced in Sydney prior to her taking delivery. I also note that the insides of the drain plug are partially stripped and vice grips or stilsons have been applied to the lower plug but can't determine if it was removed or not. I remember that Dexron3 came out long after the BX was on the market, so I decide to play it safe and ring a friend who owns a small oil & lubricants company and ask the question as to what it should have in it. He comes back with a different fluid. "Not Dexron3 then?" I comment to which he gasps in horror and tells me under no circumstances should Dexron 3 be used in these transmissions. When I ask why, he tells me that the Dexron3 contains additives and extra friction enhancers that makes this fluid incompatable to the set up in these ZF boxes and they should be run on ATF type D2 fluid which is not an expensive ATF.
Further reading of the ZF manual tells me that the transmission should run at 100 degrees, yet this car had an opened thermostat that only allows the gauge to reach around the 60/65 mark, the original one specifies opening at 82 degrees, so I also replaced that too.
The result has been, that by removing both drain plugs, I managed to get 2.7 litres of the old ATF out and replaced by the proper stuff and the increase in temp due to replacing the thermostat has the box working at around its optimum operating temp, so now all changes are smooth, there is no drag back on changes and overall the car is much more responsive and pleasant to drive.
The point is that this car was serviced by a well known repairer who obviously is of the opinion (as I've heard expressed by other repairers in the past) that Dexron3 is the latest of the Dexron fluids and supercedes the others; this is incorrect and according to the oil guy can destroy the internals. Couple this to a box operating below optimum temperature making it think that it's driving the first few miles of the day all day, and little wonder the autos have been blowing up.
In the past, we have seen on a number of occasions, Dexron 3 being put into C-matics which then causes them to not change cleanly and to also get slow in the synchros and even had some use it in manual gearboxes as they used to back when Total Fluide T was readily available. It is obvious that these guys aren't checking the technical specs before blindly dumping this stuff into them; I wonder how many transmissions these problems and actions have killed?
Perhaps we had a bomb proof auto all along. It just couldn't stand being poisoned.
A final piece of info from the man at the oil company was that the D2 is an "oil" based fluid whereas the Dex3 is "Ethylene glycol base, loaded with a variety of additives" so ask yourself; would you run Coolant in the sump of your engine? Because basically that's what they've been putting into these autos. They don't create a problem that have been designed to be run in Dex3 (Note I said "designed to be run" on Dex3 not the other way around. Dex3 was originally a fluid made for heavy industrial machinery such as coal cutters where slippin was an issue and the friction enhancers prevented this slipping whilst still acting as a kind of lubricant. The boxes used in BXs and Xantias were never designed to work with Dex3; therein lies the crux of the story.


Alan S
By the time you're old enough to know it all, you can't remember why you were learning.

tom
Citroen Sorceror
Posts: 1239
Joined: Fri May 20, 2005 8:51 pm
Location: straddling the channel

Post by tom » Sat Jul 02, 2005 5:16 pm

ALan! I always run coolant in my sump; we call it oil over here. That being said, 150, 000 miles is not excessive for an autobox. Most of the fluid stays in the torque converter though so you will need to repeat this process a few times.

Mr B
Northern Moderator
Northern Moderator
Posts: 710
Joined: Mon May 16, 2005 12:32 pm
Location: On a sofa, up the road from Marty!

Post by Mr B » Sat Jul 02, 2005 6:29 pm

As usual Alan, a very informative piece. That Dex3 sounds like wierd stuff, "oily antifreeze"!

AlanS
BXpert
BXpert
Posts: 841
Joined: Mon May 16, 2005 9:53 pm
Location: Queensland, Australia

Post by AlanS » Sat Jul 02, 2005 11:02 pm

It seems to have opened a Pandora's box over here as it is commonly accepted that if a transmission on a BX or XM lasts 120K klms (70,000 miles) it has lasted about "average" mileage.
One with say 200,000 klms is particularly long living and above that, "evil forces are at work" :twisted:
I could never get my head around it, but now it seems that most of the service guys have been working under this false impression of compatability; nobody bothered until now, to question the oil or the reason they were all blowing up. It was a case of just referring to the transmission as being "shit" and then charging on average $4500 upwards for a rebuild. :shock:
I know of one car that had only about 120K klms on it when it supposedly blew and I can relate this and at least 3 other autos back to the same "specialist" all of which have blown at a low mileage; gotta be more than coincidence.
When you put "Dexron3" into the 'Mobil Oils' site search, you freak out when you see what it was made for;

http://www.mobil.com/Australia-English/ ... id_424.asp

it definitely wasn't motor cars nor their transmissions by my way of reading it, in fact, it doesn't even come up as Dexron3, it turns up in some coded part number for use in in heavy industrial machinery.
In fact directly from their applications chart comes this:
# Suitable for commercial transmission applications requiring Type A (Suffix A), Dexron and Type F fluids. Do not use in passenger car automatic transmissions
so obviously transmissions designed for it to be used in which I know do exist, are far removed from the types we have in the BX, Xantia and XM.
I wondered why my contact both freaked out when I mentioned it and kept scowling everytime he used its name.:cry: :cry:

Alan S
By the time you're old enough to know it all, you can't remember why you were learning.

AlanS
BXpert
BXpert
Posts: 841
Joined: Mon May 16, 2005 9:53 pm
Location: Queensland, Australia

Post by AlanS » Mon Jul 04, 2005 12:55 am

Can somebody over there do a check and find what fluid they are using in the BX and Xantia auto transmissions for me outof academic interest please?

I won't go into it here at present, but it seems that there seems to be a common misconception over here about the properties of certain types of ATF that is obviously keeping auto transmission repairers living in a manner to which they have grown accustomed. :roll:


Alan S :twisted:
By the time you're old enough to know it all, you can't remember why you were learning.

Geoffrey Gould
BXpert
BXpert
Posts: 545
Joined: Sat Jun 25, 2005 7:26 pm
Location: Bristol.UK.

Auto boxes.

Post by Geoffrey Gould » Mon Jul 04, 2005 3:03 pm

Hello Allan s Have been reading your article on auto boxes with great interest having had a BX box or 2 very suddenly die quite comprehensivly. Also an XM with 3 speeds. Funny one that bought by someone that thought that it was a 3 speed box. (no 4th. gear.)
In a way had been told that D3 was OK for the boxes, I cant go into details, names etc. by some one connected with Citroen, I'm still pursewing that one. It does explain a lot as regards why a 70,000 mile box expired.
Used D3 in large comercial stuff for a long time with no trouble and was told by supplier that "D3 was a greatly uprated D2 spec ATF, better temperature and wear,oxydisation properties etc. etc. ) It was implied that it could be used in place of D2 WITHOUT ANY PROBLEM.
I think that a most sincere Thank you is due to you for looking at this problem.
Cheers
Geoff.
PS.
Nothing compared with your weather but it has suddenly gone very dark. thunder etc. rain bouncing 6" off the road and hailstones from a bright day in about 5 minutes.