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robertobaggio20
10-18-2009, 12:23 AM
Hi everyone,

I've run into some weird difficulties with my car. Mine's an 1991 E34 525i, 24 valves. I just changed the auto trans oil to Dexron III (4 litres were changed), together with a new gasket and filter. Following this, i've encountered the following problems :

1. Sometimes, at very low gear, the engine revs with no response from the car. Then it catches and moves.

2. Shifts between 1-2, 2-3 and 3-4 have become more 'noticeable' although still basically smooth. This is during normal driving. It used to be totally smooth and the only way i'd know that gear shifts are taking place would be via the sound of the engine and by the way the rpm meter would suddenly change. However, gear shifts are still smooth when i'm driving the car fast.

3. When i drive the car for the first time that day, my lower gears seem to catch abit and go with a jerk when i'm accelerating. This behaviour disappears after some driving time, as if something that was cold has now become hot and is no longer causing a problem. This did not exist before the oil change.

3. An odd problem has occured which my mech says is due to the gbox. When i do a hard brake from 70kmh down to zero, the car stops as it should, and then fails to move for a couple of seconds after i've release the brake pedal. And then, it begins to move.

4. Recently, i changed some of my brake hoses, serviced my front callipers, and changed my brake pads as well. Brakes were bleeded several times following the problem described in #3 above.

5. My car has ABS brakes. Furthermore, there would be a slight knock when shifting from neutral to both D and R, but apart from that, nothing. Finally, there was a green disc marked "lifetime oil" on the bottom of my gearbox. I was recommeded ZF oil (mine is a ZF 5 speed gbox) but i decided to use Castrol Dexron III instead to function as a low end flush of the gbox ; I wanted to change to ZF oil 2 months later. The oil that was removed from my gbox was darker in colour but was considered to be in good condition by my mechanic. The transmission had been changed around 2 years ago by the previous owner (the previous trans had gone bust).

I need help ! Dunno what is causing the problem, and am wondering if i screwed things up by changing the oil and am not sure how to fix it. The old oil has been discarded.

Please help me understand what is going on. I don't want to waste time and money going on a wild goose chase. My gbox was such a smooth thing (overall) and now its screwed up. Has anyone here come across a similar problem?


Thank you.


Baggs

Tourburgring
10-18-2009, 10:55 AM
The 5-Speed Auto Transmission is not standard for a '91 525i, so somebody must have changed it for a later tranny at some point. The later 5-speed transmissions from the E34 540i did use a special "lifetime" transmission fluid that was supposed to last the life of the vehicle. Personaly I don't really believe in leaving transmission fluid in for 'life' especially if the vehicle has high mileages.

For these later transmissions it is critical to use the correct fluid and I don't think Castrol Dexron III meets the spec. If it is a A5S-560Z transmission the Bentley manual states that Dexron must not be used in this transmission and recommends only the BMW spec ATF semi-synthetic (Shell LA-2634).

Find out what model of transmission you have and if it is an A5S-560Z I would immediately fully drain the fluid (including the torque converter) and change the filter then refill with the correct fluid. Hopefully the Dexron III hasn't caused any permanent damage.

CarDriver
10-18-2009, 02:07 PM
+1 !!!

What he said!!!!!!!!!!

woodnthings8
10-18-2009, 04:53 PM
It also sounds like you may not have serviced the trans with the correct amount of fluid. 4 liters just doesn't sound like enough when you drop the pan. Did you service it with it running and up to temp? Have you checked the level since you originally changed the fluid? Even though it is not what BMW recommended, transmission fluid is transmission fluid and while it may not be good for your transmission to run DEX III over the correct stuff it should still react relatively similar. I would drain and flush the trans with the correct fluid and then verify it is correctly serviced. From most of what you describe it sounds like a fluid level issue.

gtopaul
10-18-2009, 06:47 PM
It also sounds like you may not have serviced the trans with the correct amount of fluid. 4 liters just doesn't sound like enough when you drop the pan. Did you service it with it running and up to temp? Have you checked the level since you originally changed the fluid? Even though it is not what BMW recommended, transmission fluid is transmission fluid and while it may not be good for your transmission to run DEX III over the correct stuff it should still react relatively similar. I would drain and flush the trans with the correct fluid and then verify it is correctly serviced. From most of what you describe it sounds like a fluid level issue.

I agree. Low on fluid. Don't drive until you fix it.

robertobaggio20
10-18-2009, 08:09 PM
Hi guys,

Thanks alot for the valuable comments. I spoke to my mechanic. This is what he said :

1. New oil filled up - about 3.5 litres. Old oil removed about the same quantity too.

2. The new oil was red in colour (castrol dex 3), he wondered why i did not use oil that was white in colour but changed it anyway as i had brought the can to him. Official oil recommended was ZF 71141, part number 328 but i had used Castrol Dex 3 for a low level flush to see if it fixed knocking problem (please see earlier post).

3. He says oil was changed from the torque convertor too.

4. The oil pan was relatively clean when he dropped it, changed the filter and gasket.

5. The engine was switched off when the oil change too place.

6. All this was done 2 weeks ago. Fluid level has not been checked since. There is no dipstick on this gearbox.


It is quite clear that something is wrong. These are my questions :

a. How should the oil change be done on this gearbox ? Its a ZF 5 speed and you're right i could have been upgraded when it was changed 2 years back.

b. Can I use this ZF oil or do i use the Shell oil ?

c. Since the oil filter is just 2 weeks old (and the previous oil was relatively clean in my mechanic's view), can i reuse the filter and the gasket after cleaning out the filter to remove as much of the dexron 3 as possible ?

d. Do these problems have anything at all to do with my ABS braking issues (please see my first post).

Would greatly appreciate your advice, and thanks for all the help, i clearly screwed things up here, i just hope i've not caused permanent damage.



rgds,
Baggs

gtopaul
10-19-2009, 07:16 AM
You can't change the oil in the torque convertor without dropping the transmission and removing it. The only other way is to have it power flushed, which is the only way I would have done it anyway, which gets all the old fluid out. The car has to be running in order for the fluid level to be checked. This requires removing the plug in the side of the trans, while it's running, and putting in the new fluid until it starts to run out of the hole. Then it's full. Better take the car to someone that knows what they're doing.

robertobaggio20
10-19-2009, 08:04 AM
Thank you Paul for your good comment. I'm learning more and more about this with each reply.

I just spoke to a mech who has around 20+ years of experience with cars, including older BMs such as mine. He says the following :

1. Dexron 3 is fine for my car. He has changed it in other cars with no problems.

2. Different types of gbox oils can mix together in the gbox. It will not lead to any problems because of this.

3. The symptoms i'm experiencing are due to insufficient transmission fluid. He has asked me to top up with 2 addition litres of Dexron3, with the engine running etc.

What do you guys think ?

ross1
10-19-2009, 08:07 AM
Underfilled

woodnthings8
10-19-2009, 09:24 AM
What do you guys think ?

What I said earlier!!!
It also sounds like you may not have serviced the trans with the correct amount of fluid. 4 liters just doesn't sound like enough when you drop the pan. Did you service it with it running and up to temp? Have you checked the level since you originally changed the fluid? Even though it is not what BMW recommended, transmission fluid is transmission fluid and while it may not be good for your transmission to run DEX III over the correct stuff it should still react relatively similar. I would drain and flush the trans with the correct fluid and then verify it is correctly serviced. From most of what you describe it sounds like a fluid level issue.

robertobaggio20
10-19-2009, 04:27 PM
Thanks woodnthng8. I'm going to top up an additional 2 litres of Dexron3 in a few hours. I'll report the results back here later in the day. Wish me luck !

robertobaggio20
10-19-2009, 04:31 PM
I have another question. Is there a cheap way to flush the gearbox? If i need to use new semi synthetic oil to flush my gearbox, it will cost me a bomb....i might need 17 litres apparently, inclusive of the new oil for myself (9 litres). This semi sythetic ZF oil is like 4 times more costly than Dexron3, and is a total waste if all i'm going to be doing is merely flushing it through the gearbox after first draining out the existing oil and then throwing this away ! There must be a cheaper way to do it...maybe a substitute fluid that does the trick of clearing out the old oil, does not react adversely with new semi-synthetic oil, and is really cheap. Has anyone here tried any substitute?

woodnthings8
10-19-2009, 05:47 PM
Fluid pumps from the front of the transmission through the cooler then back to the rear of the transmission, You should be able to disconnect the aft line and run the engine, as you put fluid into the pan it will pump out through the cooler return line. You can take it to a shop with a power flush machine and it will all happen automatically. It will still cost you for the fluid, but it will waste less.

robertobaggio20
10-22-2009, 07:36 AM
Hi Everyone !

Problem solved ! I've got my mech to top up 2 litres (that's how we say it in malaysia :), 2 litres = 2 quarts) into my gearbox with my engine running. It overflowed at that point. After that, the obvious shifting from 2-3, 3-4 and 4-5 disappeared. The obvious shift from 1-2 remained there, but now i remember that it was always there (any idea how to fix this?).

An update on the braking problem that i had with my car (please see my first post above). The top up of transmission fluid fixed this. I found out why as i was trawling the net for info. Please see : http://www.pelicanparts.com/bmw/techarticles/E36-Tranny_Fluid_Auto/E36-Tranny_Fluid_Auto.htm

Basically, during a hard brake, all the trans fluid would rush to the front of the gbox, and would leave the gears at the rear without fluid. During the time it takes fluid to flow back, the gearbox would not function....this is how it is designed. Too little gbox fluid leaves too little fluid in the back of the gearbox during a hard brake.

I want to thank all of you here for your expert and spot on advice about how to fix this problem. I had been very worried about what could be wrong. My car's warranty disappeared long ago, and repairs can be very costly.* Thanks guys !

Baggs

* now i seem to have a problem with my air con compressor. After some time, there is an odd throbbing sound coming from the engine bay. It disappears where i switch off the air con. Does not always reappear after i switch the a/c back on, but shows up later. Has been the case for the past 2 days. I wonder if this is a fixable problem for the air con, or do i have to replace something?