Transmission shift problem

[Andrew]

Good day everyone,

I am experiencing an odd problem with my '99 740i ZF-HP24.

It performs flawlessly on the open road however once I have driven around in town for a while it does the following and I am going to quote from a post submitted by a boardmember as the problem is identical to mine:

I've got a 740iA w/sport pkg. - runs fine most of the time, but after the car gets a good workout (one hour our more) the transmission goes haywire... insists on keeping the car in too low a gear (eg., 3rd at freeway speeds) and stays there even as the car slows down until it "unsticks" with a big clunk. If I put it into manual shift mode, and try to bump it to a different gear, the indicator shows the new gear, then pops back to the gear it is stuck in with no actual shift taking place. In the city, typically it gets stuck in 2nd... on the freeway, in 3rd. No warning lights come on, no messages displayed. Anyone else seen this kind of problem?Any solutions


Once you are back on the open road it remains in 4th gear at about 100mph and eventually after about 20 miles it changes into 5th and thereafter behaves normally - the problem can be repeated. I have scanned the transmission for fault codes, tryed disconnecting the battery to no avail.

Any Ideas?

[Don]

Andrew,
I had a similar problem with my 97 740il. Mine also stuck in 2nd and 3rd gear however a quick bump in manual mode seemed to do the trick after a few seconds delay. I was forewarned by my previous mechanic that this would likely happen at around 120K and that the only fix was a costly new trans. My car did not start having problems until about 140K. Upon my first time to my current mechanic (a sharp certified Porsche Master Mechanic) for a different repair on the car, he asked if I wanted him to fix my shifting problem also. I told him what my previous mechanic told me and he said I guess that’s why he’s your “previous” mechanic and we both laughed. He said he has fixed this on countless 7’s just by draining the trans (servicing the trans). Anyway, he changed the fluid in mine and it took about 2 weeks before it started working correctly I guess the new fluid had to dissolve the crud left by the old fluid. I’m at 175K now and have had no further problems. I drive the car very …spirited and use sport mode quite often. Good luck!

Don

[Andrew]

Hi, thanks for your insight - its uncanny about the milage - you were spot on, my car has around 135,000 miles and still has the original fluid. I was reluctant to change it at this time since other members experienced problems thereafter, but I have nothing to lose at this point. I will have to make sure that I use corrcet fluid and filter.

Can anybody refresh my memory with regards as to the correct filter for ZF HP-24 and the correct fluid?

Thanks

Andrew

[jon-h]

I suggest a trip to the e38.org web site for detailed information. Briefly, the only filter recommended is the OEM filter - there have been performance-related problems attributed to aftermarket filters. As to fluid, a lot has changed since the car was new and Esso was the only option. Many manufactures now state their fluid meets the BMW spec. The most commonly available may be the Valvoline ATF V-Max, but read the info and decide for yourself.

[claudio512]

I have an OEM MAF... if interested contact me by email.



"Keep Right, Pass Left. It's the Law."

[Wonder]

I have the same exact problem on my 2000 740i sport. I think the problem is the Oil Cooler aka Heat Exchanger. Here are some earlier post on this problem.

http://www.[Oops!].com/forums/posts/457270

http://www.realoem.com/bmw/showparts.do?model=GF83&mospid=47528&btnr=17_0162&hg=17&fg=05

[Wonder]

[Andrew]

Thanks everyone for your assistance - I believe that the oil cooler could well be responsible for these symptoms, make you wonder why - does it become blocked with sludge?

It makes sense that the transmission is trying to cool itself by avoiding changing gears (which creates heat) - strange that there are no codes though.

Nevertheless I will scource a cooler and then proceed with changing the filter and the oil - I will let you know if this solves the problem.

Once again thanks for the insight

Andrew