Steering gear leak?

[acoen]

1994 740IL, 160k miles

It appears that I have a leak near the point where the steering shaft enters the steering gear, just above the servotronic controller (or appears to be coming from there as there is a dust cover, maybe coming from above). From what have seen here is that is very rare to have a leak there. This leak is pretty bad, leaking a 1/2 liter per day. If it is the steering gear are there kits available? Second question do the servotronic controllers leak and if they do, do they have an oring or gasket. I'm going to check it again this weekend, maybe an upper hose gave way, imposing as a steering gear leak. It is definitely dry near and around the reservoir and pump...Any thoughts or guideance would be appreciated.

Aaron

[shogun]

For the 740 steering gear there are no repair kits, I have them for the ZF steering gear boxes for the 735 and 750, but not for the 740. But I cannot imagine that there is such a big leak on the box itself, it is most probably from steering hoses, banjo bolts on steering hoses on the steering box, or from the servotronic controller seal.

[acoen]

Shogun,

Thank you for the valuable input, I will check it out the upper hoses and servotronic controller again...I'm thinking the servotronic seal is leaking, that was always my first thought when I discovered the location of the leak. Is there a specific O-Ring material I should use for that seal. At least it will be an easy fix, if it turns out to be so simple. I will post my results. I work for a company that has a fabrication shop that manufactures hydraulic hoses, if the hoses are bad, they could always rebuild them for me...

[shogun]

ther servotronic unit under the steering gear on my 750 has 4 bolts. 2 bolts hold the unit to the steering box, the 2 other shorter ones hold the unit together, so just losen 2 of them.
As for the O-Rings I assume your hydraulic shop has the right stuff on stock. Maybe you post the dimensions of these 2 o-rings then for the records, as these are not available from the dealer.
You can see the 2 O-Rings as well as the bolts on my website below under fixes>>steering, and then scroll down. There you can also see the location of the bolts, left side from the plug and across are the 2 which hold the unit together, and the other 2 holes are the long bolts which hold the unit on the steering.
Heads are also different.
M4 bolts, 42 mm bolt, with M4 standard thread, threaded portion is 15 mm long
Fitting torx I just checked is 2.5 S2
also called 2.5MM HEX 10PK 25MM BIT S2
1/4" drine titanium coated s2 steel 25mm hex bits
Here is a good pic of the unit and bolts and o-rings
http://www.fcpeuro.com/products/bmw-...em-32411134770
http://s16.postimage.org/e6v3f64p1/32411134770_ZF.jpg

[acoen]

Thank you so much Shogun,

This is the exact information I need. I have never owned or worked on a BMW before, this is my first. I purchased it from my neighbor knowing it had a few little problems, biggest of all being the power steering leak. Everything on the top side of the system is dry and clean. Now that I see how the servotronic system goes together, I recall seeing fluid ozing around the base of the solenoid. I first thought this was fluid leaking from the steering shaft leaking down around the sevrotronic. I will replace the orings, check banjo fittings and report my findings this weekend. I also may have overfilled the power steering system contributing to my leak. I filled the reservoir to the base of the screen...Would this cause a leak or seepage? Again thank you...Some of the best automotive resources I have seen have been here

[shogun]

this is the official version of LAD oil level
http://www.bimmerboard.com/members/q...0Reservoir.jpg
with engine OFF.

But I usually have it below the strainer with engine running, because if the LAD regulating valve on the rear axle is not 100% at zero in parked position, fluid will flow overnight or when long time parked from the rear axle to the Pentosin container thru the return line and the container could overflow.

Usual suspects are the o-rings at the servotronic solenoid, the crimped parts of the hoses, the outlet connections below the Pentosin container, broken banjo bolts (when tightened too much), the copper washers on the banjo bolts.
And sometimes the housing of the steering box itself, I just resealed my steering gear box with a repair kit I have for the 735 and 750 box.

[acoen]

Shogun,

Thank you, the information you provide is priceless. Again thank you, I will post my findings. I should know something this weekend.

[shogun]

here are a lot of pics of an empty 750 engine room where they changed the engine, does not matter that the engine is an M70, but here you can see details where all the lines go for the steering, LAD and also the heater valves hoses, heater valves etc.
Excellent pics, I suggest to download the pics, very good for future wrenching
http://www.louv.tv/cars/750/engine/

[acoen]

Hi Shogun, for some reason the link is not working?

[shogun]

try again, for me it works http://www.louv.tv/cars/750/engine/

[acoen]

try again, for me it works http://www.louv.tv/cars/750/engine/

Shogun,

I closely inspected the location of the leak yesterday morning. The leak is coming from the steering input shaft. The servotronic and hoses dont seem to be leaking at all. I placed my hand above the leak and it is clean and dry. Very clean, hoses seem to be holding together. It is a steady leak a drip/drop every 3-5 minutes, faster if it is warmed up. I recently purchased the car knowing it had a few problems, the previous owner used power steering fluid not the CHF11S.....The system has now been flushed with the correct fluid, but the leak has become worse. I don't want to put too much into the car as it is not worth that much, but it is in pretty good shape. My problem is that it looks like a huge undertaking to get the steering gear out to replace the seal. Is there any step by step procedures in removing the steering gear? Can I get the input shaft seal? In a last ditch effort are there any stopleak additives that are compatible with CHF11S? Wish it was better news....Thank you Shogun, just needing some advice on this one.

[acoen]

Shogun,

I closely inspected the location of the leak yesterday morning. The leak is coming from the steering gear input shaft, the servotronic and hoses are not leaking. The hoses above the leak are good and it is dry and clean above the steering gear. The leak is a good one about a drip/drop every 3-5 minutes, quicker when warm. I recently purchased this car knowing it had a few issues. The previous owner used regular power steering fluid, I recently flushed the system and added the correct fluid CHF11S. It seems as if my leak has accelerated. I'm at a lose on what to do now. Removing the steering gear seems like a huge undertaking, especially without a rack. Do you have any suggestions? Are there any step by step removal procedures on removing the steering gear? Do you know if the Steering gear seals are available. As last ditch effort is there a stop leak that is compatible with CHF11S....Your guidance is certainly appreciated....Thank you

Aaron

[acoen]

I first want to say that I don't normally don't trust such solutions and I am still skeptical, but here it goes. It has been over a week and my power steering input shaft is leaking with the CHF11S. Leaking worse since I flushed the system. The car has no other leaks, just this one seal. Upon some findings on this site I am now trying AW32 hydraulic fluid with a hydraulic sytem stop leak....The seal conditioner I used is called Blue Devil hydraulic stop leak. I have read some good things and for the cost of about 30 bucks, I thought I would give it a try. The AW32 is light weight (yet heavier than CHF11S) and the stop leak has a consitancy more like that of brake fluid (smells like it too) and clear like water or alcohol. I placed 4 oz of stop leak for about a quart of hydraulic fluid. After warm up the leak has slowed some. I will check back later this week with my findings. Chances are that the powersteering fluid that was used in the past has dried or damaged the seal. The Blue Devil is supposed to solve this issue...I'm skeptical we shall see.

[acoen]

It is hard to believe but the leak has disappeared after 3 days of driving there are no signs of leaks. I place a pan under my car when I park to gauge how much fluid I loose. I don't know how long it will last but I have plenty of stop leak. This will give me some time to accumulate the parts to permanently fix the problem....

[pmathews]

Interesting development, please keep us posted. I have a slow leak with my power steering, and like you, the prior owner had added standard PS fluid. I have since replaced with CHF11S, but was concerned that the bad fluid had ruined my seals. The PS line replacement looks to be very difficult, there's not much room between the engine block and the shock tower, so I've been waiting to tackle this. If the stop leak really works, that would be great news. Of course, these solutions are typically designed for regular systems vs. CHF11S, but in theory, it should work. Thanks for the writeup and please keep us updated

[acoen]

Interesting development, please keep us posted. I have a slow leak with my power steering, and like you, the prior owner had added standard PS fluid. I have since replaced with CHF11S, but was concerned that the bad fluid had ruined my seals. The PS line replacement looks to be very difficult, there's not much room between the engine block and the shock tower, so I've been waiting to tackle this. If the stop leak really works, that would be great news. Of course, these solutions are typically designed for regular systems vs. CHF11S, but in theory, it should work. Thanks for the writeup and please keep us updated

I have been checking it every day and so far no leaks at all! Amazing! My system calls for CHF11S as well but after some research I found that AW32 hydraulic fluid will work, although not ideal. Using standard hydraulic fluid may upset the purest, but for nearly a 20 year old passenger car, it seems to be working well. I will keep the forum up to date.

[acoen]

UPDATE,

I has been a couple of weeks and not one drop. Seems to be holding!

[shogun]

you are not the first one using AW-32 hydraulic oil and Lucas hydraulic oil booster & stop leak, bob91750 is using it since around 2007 and he reported in 2009 that it stopped his leak too
http://www.bimmerboard.com/forums/posts/694831/

[acoen]

you are not the first one using AW-32 hydraulic oil and Lucas hydraulic oil booster & stop leak, bob91750 is using it since around 2007 and he reported in 2009 that it stopped his leak too
http://www.bimmerboard.com/forums/posts/694831/

Oh yea, I know, that is what got me thinking it may work in my application. I however use a different hydraulic stop leak, the one I used is Blue Devils hydraulic stop leak. I cannot believe how good it has worked so far. Again this may not be a permanent fix, but it did solve the problem at least for now. Thanks again for the heads up.

[sungmin82]

I've had a leak in my power steering for my 2006 330xi. Had it for almost a year now and just continued to top it off with CHF11s until someone told me about Blue Devil Power Steering Stop Leak. I poured in about 1/3 of the bottle and topped it off with my power steering fluid. I haven't had a leak for two months now.

[shogun]

My above link from 2013 does not work anymore, here recovered with the wayback machine: 12 Cylinder Engine Swap , Transplanting a 1993 BMW 850ci engine into a 1989 BMW 750iL https://web.archive.org/web/20060721...rs/750/engine/

but many pics do not work anymore, pitty