E34 540i premature autobox failure

Hi all,

My trusty old '93 E34 540i has an intermittent reverse selection problem. It's always had a slight delay of a couple of seconds before engaging reverse for the past 4 years I've had it. I bought it with 88k on the clock, and it's now got 135k on it. The transmission has never been touched during the life of the car, as far as I am aware.

During the past few months this delay has increased to around 3-5 seconds, and when selecting reverse to park at work on Monday, it wouldn't go into reverse initially. I revved the engine a bit (1500rpm), and reverse finally engaged with a Godawful 'thunk'. It's stilll given me reverse all this week quite normally, so I thought I'd do a little research into the problem whilst my gearbox is still intact!

Well, after trawling the internet I discovered, mostly from North American websites, that there was a potential design flaw in the valve body of the ZF 5HP30 (A5S 560Z) autobox, a 'ticking timebomb' like the early V8 Nikasil engines were.

It turns out that the valve body, which sits in the autobox sump pan, has some Checkball valves in it, and these Checkballs are made from plastic/teflon. After years of being slammed up under hydraulic pressure against the hole they are sealing, which happens every time you select a gear range (D,R,3,2,1 etc), they eventually wear down in size and either get stuck in the hole, or pushed right through a separator plate. There was also a problem with plastic manual shift valves and plastic pressure valves as well.

The reverse Checkball seems to be the main culprit, causing delays in selecting reverse, and eventually no reverse. In extreme cases you can apparently get pressure 'spikes' that overpressure the clutch drums in the epicyclic geartrains, and burst the spot welds on the reverse clutch drum, thereby rendering it scrap, and requiring a complete transmission removal and overhaul. The plastic pressure valves can sometimes 'stick', causing overpressure spikes that pop clutch drum spot welds. I believe that revving the engine causes the gearbox hydraulic pump to increase it's pumping pressure, and if not controlled properly by these 'sticking' plastic pressure valves, will overpressure the multiplate clutches, causing 'rough' gearshifts and potential burst clutch drums etc.

There was a valve body repair kit from ZF that included uprated metal components that cured all the problems, and everything I've read seems to indicate that if you catch the problem in time, all you need to do is drain the autobox, remove the sump pan, remove and overhaul the valve body, and refit it and refill the autobox with new fluid and a new filter. You could also simply fit a new uprated valve body instead.

All this can be done with the autobox still in the car, if you catch it in time. If you do the job yourself, there are some things to be aware of, the most important being the type of fluid used in this particular autobox, and method of filling the autobox after repair.

The 5-speed ZF5HP30 autobox was a sealed-for-life gearbox, filled with a unique special semi-synthetic fluid, with no underbonnet dipstick and no facility for the average owner to do anything with the autobox. It must NOT be filled with the more common red type Dexron III fluids that you can buy from any automotive shop on the high street. The correct fluid was most commonly Shell LA2634-which was specially manufactured for ZF by Shell, or in some later cases Esso LT71141, which are gold in colour, and not the usual red.

Also, the fault is not caused simply by ageing fluid and a dirty filter. If you just change the autobox fluid and filter, it does not usually cure the problem, because the damage has already occurred to the Checkballs and plastic pressure valves in the valve body.

This seems to be the main flaw with this transmission, as the 'heavy metal' part of the gearbox-the main epicyclic geartrains & multiplate clutches-are pretty tough and can do over 200,000 miles if looked after, according to reports I've read.

Needless to say, mine is now booked into my local autobox specialist next week for an examination, and a valve body overhaul, a full transmission flush, and a new filter and fluid refill. I was quoted £240 + fluid + VAT for a valve body overhaul, and another £165 + VAT for a full transmission flush and new oil. It all comes in at under £500-not cheap, but cheaper than a new autobox, and with new fluid and filter as well. In the meantime I'm using my 525i instead! The 540i still works ok, apart from the delayed reverse, but I don't want it to expire just as it's going in for preventative maintenance!

I also found out that the ZF 5HP30 autobox can cope with up to 425BHP, and handle 560NM of torque (hence the A5S 560Z designation), or 413lbf/ft in old money, so it is an exceptionally strong box for the 540i, and can cope with supercharging the engine.

This gearbox was also fitted to the E32 740i, and E31 840i, as well as the V12 E38 750i, and I believe early versions of the E39 540i and E38 740i. Later 4.4 V8 versions of these models were fitted with the ZF 5HP24 (A5S 440Z) autobox, which was not rated as strongly as the earlier ZF 5HP30 on the 4 litre V8's. The 560 and 440 designations on these autoboxes refer to the amount of torque they can handle in NM. The HP30 and HP24 parts refer to internal dimensions of gearwheel sizes/spacings, although exactly which ones I'm not sure.

None of the 6-cylinder models were affected, and neither were the 'small' 3 litre and 3.5 litre V8's. The only models affected were the 'big' V8's, the E34 540i, E32 740i, E31 840i, also E38 750i V12, and possible early E39 540i's and E38 740i's, but you'd need to check the identification plate on the side of the autobox to be certain. The colour of the autobox ident ification plate also signified which fluid it was filled with, int ehcase of the ZF 5HP30, a black plate signified Shell LA2634 oil.

For more info, visit:

http://bimmer.roadfly.com/bmw/forums/e32/1481895-1.html

http://www.bimmerfest.com/forums/archive/index.php/t-188106. html

http://www.digest.net/bmw/archive/v9.msg04644.html

http://www.e38.org/zf-5hp30-service.html

http://www.bimmerboard.com/forums/posts/356031

They all say that if caught early enough, major damage later can be prevented. Ignoring the symptoms means they'll only get worse over time, and may result in the complete failure of the entire autobox.

So, nothing too serious then!

Alex

that is a very useful piece of info and as a fellow 540 owner i now know why my gear changes feel rough even after a fluid and filter change its always gone into gears ok but when driving its a big savage changing up and down the box time for me to get mine checked although i have just laid it up for a few months now  and have been reduced to a smart car (ok dont all laugh 4.0 to 600cc) but even so i will get it checked when its back out 

thanks for a good write up

RedOctober wrote: Plastic bits in a BMW drivetrain? What next, plasticine differentials & chocolate pistons  Alex

shhh dont give them any ideas

Yes, I do sometimes worry about the technical direction they sometimes follow, considering they're meant to be 'driver's cars'.

A driver needs to know which way his engine temperature is heading on a regular basis, not some dopey 'idiot light' that only comes on after the damage has been done.

A proper temperature gauge tells you the rate at which the engine temperature is rising, so you know roughly how long you've got before you absolutely must turn the engine off-vital, I think, if you're on a  crowded motorway and have to make your way across several lanes of traffic to the hard shoulder before you can switch off.

All the 'idiot light' does is tell you that you've overheated, not how fast your engine temp is rising. I often wondered why they never had oil pressure gauges too. If anything, an oil pressure gauge is even more important.

Most oil pressure switches illuminate when the pressure has dropped to around 3-7PSI. That means that you could be barrelling along at 6000rpm with a paltry 10PSI oil pressure, and the oil warning light will not be lit, so you'll think everything is ok, even though your main and big-end bearings will most probably have turned to soup, and your crankshaft will need a re-grind.

In reality, at 6000rpm, an engine needs at least 40PSI, and sometimes up to 80PSI on really high performance units. Most cars tend to give around 50-70PSI at maximum engine speeds.

I've actually spoken to some people who thought the oil pressure light was an oil LEVEL light! They waited until the oil light came on, and only then topped up the oil, after the sump had run dry, and then wondered why the engine was making 'a strange heavy knocking sound', the results of which were usually a huge bill for a new engine.

Sometimes I think we need to get 'back to basics' with vehicle instrumentation. All cars should have an oil pressure gauge, a engine temperature gauge, and a voltmeter, and all drivers should undergo a short tuition as to how to interpret the reading of these instruments, and the potential consequences of a fault in those systems. It surely can't be that difficult to implement as part of driving instruction.

Basic knowledge like that could save people thousands of pounds. All we need to do now is persuade the vehicle manufacturers to provide the necessary instrumentation.

Got to admit I'm very suprised that an engineering led company like BMW would ever dream of going down the 'idiot light' route for critical parameters of vehicle instrumentation. They've got nothing to gain, except maybe saving a few pounds on a vehicle costing many tens of thousands, and everything to lose in their reputation for engineering excellence.

Remember what happened to the mighty Mercedes Benz when their bean counters started meddling with the engineering ethos? Shoddy quality and a damaged reputation that is only now recovering from the shameful cost-cutting of the 90's.

Right, rant over I think

Alex

Hi Andrew,

Yes, my 540i is booked in to my local autobox specialist on Wednesday afternoon-I gave them a full desription of the fault, and what I found. I was somewhat alarmed when it wouldn't give me reverse last Monday when reversing into a parking space at work, not least as I was straddled across the main car park road inside our workplace, and everyone else was rolling up in droves, waiting for my lame car to move itself-hence my revving the engine to engage reverse faster, followed by the violent 'thud' as it finally enaged 

When I got home that night, reverse was ok, so I was able to reverse into the driveway ok. That's when I went on the internet for some research.

When I read about the fault in my autobox, I nearly laid an egg

Then other fault you mention about trannys failing when the engine was revved in P or N for an MOT relates to a fault that the earlier 4-speed ZF autoboxes were prone to, speciffically those built before the late '80's.

What was happening was that in P or N, a valve in the valve body was not sealing properly, and fluid was bleeding past it and slightly pressurising one of the forward multiplate clutches in the autobox, so it was neither fully engaged or fully disengaged-it was partially engaged and trying to move the vehicle forward, generating lots of heat and wear in the process.

This slippage was enough to burn out the so called 'A' pack clutch in a short space of time if the engine wss revved in P or N.

Ironically, if you left the box in R or D it was alright, as the clutch packs were fully engaged anyway in these autobox ranges. Anybody that had this fault was advised not to leave the box in P or N for any length of time and not to rev the engine in these autobox ranges. People were advised to leave the autobox in D at traffic lights, not shift to P or N.

My old E28 535i had this fault. I noticed that if you had the handbrake off, and the autobox was in Neutral, revving the engine slightly made the back of the car dip, as the clutch partially engaged and tried to move the car forward.

I read that autobox multiplate clutches should be either fully 'on' or fully 'off'. They are not designed to 'slip' like the clutch in a manual transmission can. If they are only partially engaged, then they slip and burn out rapidly, requiring major autobox overhaul.

That's also one of the reasons low autobox fluid level can cause damage-there's not enough fluid to provide enough pressure to clamp the multiplate clutches together firmly, and again they slip and burn out.

In the 4-speed ZF autobox case, the cure was once again to overhaul the valve body with metal replacement parts. As you say, it was not only BMW that used these ZF autoboxes.

My '95' E34 525i had the plastic impeller water pump failure-no warning, no other symptoms, just a temp gauge climbing rapidly to the red zone. Fitted a metal impeller pump and it's been fine since.

I wouldn't have spotted that temp rise with an 'idiot light', which is why I lament BMW's decision to go down that silly instrumentation route. Green for 'You can drive me ok today', Red for 'take me to the dealer for repair-SCHNELL!!!'

No warnings, nothing-just a glowing red light between the driver and thousands of pounds of repairs.

Still, at least the 540i should be hopefully sorted by the weekend. I thought about doing the job myself, but after seeing all that was involved, I didn't fancy the idea of rolling around under the car on a damp, cold driveway in winter with dark nights, wind, rain, and a sump pan 1 foot from the driveway surface dripping hot transmission oil onto my face

Not quite a scrupulously clean environment for repairing an autobox, methinks

I'll post my findings at the weekend when I get the car back.

Alex

Hi Chaz,

The place I'm booked into is on the Wirral, in Wallasey (opposite Liverpool). It's called Robbs Garage-they have a website at: http://www.robbsgarage.co.uk

They're an autobox specialist primarily, but also do Air-Con too.

I opted for the valve body rebuild, and a full transmission flush. The fluid itself is not cheap, and not readily available off the shelf. I saw it priced at $160 for a 5 litre can from an American BMW dealer-about £16 a litre in UK money. The 540i autobox takes 5.5 litres of fluid, and a grand total of 13.1 litres if you also include the torque converter in a full transmission flush.

Cheap it is not! And you MUST NOT use Dexron III or any of the tradition 'red' autobox fluids-it may ruin the autobox. Also, there are electrical solenoids in the autobox valve body, which sit in the sump pan and are immersed in the hydraulic fluid.

I've heard of people using the wrong hydraulic fluid in this autobox, and it's stripped the insulation off the electrical wires on the solenoids when the fluid has warmed up fully!

You can change the fluid yourself-there's a drain plug on the side of the autobox. Refill is messy though. The refill plug sits at the top of a raised portion of the autobox sump pan. The idea being that when the refill plug is removed, the oil will spill out over the refill plug hole and dribble out of the hole onto your face if it's too high.

The official procedure for refilling the ZF 5HP30 autobox on the E34 540i is to make sure the transmission temperature is between 30-50 degrees C before doing anything else.

Make sure the drain plug on the side of the autobox is in place and tight. Then, using a hand pump with a short piece of plastic pipe at the end (or a HUGE syinge!!!), draw up the oil into the pump.

Then you have to remove the autobox refill plug from it's recessed position inside the raised part of the sump pan, insert the plastic pipe from the hand pump into the hole where the refill plug was, and inject fluid into the autobox.

You have to keep doing this until the sump pan fills up to the level of the top of the refill plug hole, and starts to dribble out of the hole onto your face

Then you have to put the refill plug back in, and start the engine. Then you have to run the autobox through all the positions from P-R-N-D-4-3-2. Then you must select 'manual' or 'winter' mode, and run the selector lever through the 4-3-2 positions several times.

At each position you must pause for 3 seconds before moving the selector lever to the next position. This is to ensure all the fluid passages in the valve body and autobox are fully primed with fluid.

The level in the autobox sump will have dropped considerably during this procedure, so you have to remove the refill plug once again, and add more fluid until it dribbles out of the hole again. You must leave the engine idling during this final fill procedure.

Then you refit the refill plug, and job done!

As you can see, hugely inconvenient, very messy, and you also have to make sure the vehicle is sitting exactly level too, so no driving up ramps, or raising one part of the vehicle on axle stands etc. You need a proper vehicle ramp to do the job correctly, or a pit.

It's a far cry from the good old days of the 4-speed ZF autoboxes, reaching under the car to remove the drain plug, and then refilling from under the bonnet down the dipstick hole, and checking the level with a simple dipstick, using easily available Dexron III from the high street auto shops etc.

Ahh, the good old days

Alex

Glad you got it fixed Alex.

We should be getting tranny's serviced every 5 years/50,000 miles sort of mark and certainly don't believe the sealed for life nonsense.

Some of these autoboxes will be a timebomb.  After 10-15 years the parts will be wearing and if the autobox is fixed to a bag of nails car, the autobox failure will write the car off.

Andrew