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Garage => Mechanicals => Topic started by: oscar on 10 March 2010, 01:56 AM

Title: Power steering reseal
Post by: oscar on 10 March 2010, 01:56 AM
Trying my best at the moment following a few threads and the following link of a 126 box rebuild which a few others have posted up before
http://www.davidpetryk.net/Mercedes/Steering.htm

but I'm at a standstill.  I've got the pitman/pinion shaft out.  Then I started winding the steering shaft a little then extracted the rack.  On inspection of the casing I find a steel ball inside sitting in the left over ATF.

Shown in the pic now sitting in that spanner, it's about 7-8mm diameter but I'm not sure if it's come out of the ball cage or is supposed to sit in that dimpled bit on the rack piston part to the left of the ball cage.  If it goes there then that means I'm missing a ball since I only found one yet there's another dimple on the reverse side.

I'm hoping it's one of the recirculating balls and if it is, how do I get it back in?  I wasn't planning on pulling that section apart.

(http://img535.imageshack.us/img535/4426/imgp6739medium.jpg) (http://img535.imageshack.us/i/imgp6739medium.jpg/)
Title: Re: Power steering reseal
Post by: koan on 10 March 2010, 02:37 AM
The ball has come out of the ball nut, there are 24 of them (I think). No other loose balls in there.

koan
Title: Re: Power steering reseal
Post by: oscar on 10 March 2010, 02:53 AM
Definintely only one ball.  By "ball nut", do you mean it has to go back in the "U" shaped thing and if so can it be worked back in through the worm shaft without having to undo anything else?

As far as I could tell it seems the leak was occuring through the steering shaft spline.  Without the proper four pronged large socket I'm having a bit of difficulty taking that end cap off to get to the shaft seals but will get there eventually.

One other thing, I've got the the circlip off the valve section but can't seem to get the cap out.  Do I just lever this thing out pictured below or does it screw out?

(http://img710.imageshack.us/img710/6625/imgp6741medium.jpg) (http://img710.imageshack.us/i/imgp6741medium.jpg/)
Title: Re: Power steering reseal
Post by: koan on 10 March 2010, 03:23 AM
The ball can only have come out of the ball nut, the square bit with the "U" shaped guides, it would have fallen out when you unscrewed the worm shaft. Should be a lot more balls somewhere.

Getting the balls back in requires one half of the "U" guide to be removed and the balls dropped in one a a time as the worm shaft is turned.

Should use the the proper tool, a C-spanner or a hook-wrench but I used a brass drift and a heavy hammer to crack the four-slot nut free then a pair of circlip pliers undo the middle piece.

The cover on the spool valve just pulls or prises out.

koan
Title: Re: Power steering reseal
Post by: s class on 10 March 2010, 03:34 AM
It is my belief that the recirculating unit should have a total of 24 balls - but it is just my belief, I've never seen anything in a manual about it - and have seen several that I'm certain had only 23, and one with 25  ???  The units that had only 23 balls may have been previously 'overhauled' - and I'm guessing 1 was lost at that time. 

It is tricky to get the balls in - good luck!
Title: Re: Power steering reseal
Post by: oscar on 10 March 2010, 03:54 AM
Awsome, thanks fellas. 8)

I think I may have undone the steering shaft too much at first but not completely, hence only one ball fell out. 

The good news is that I wound down the worm enough to see other balls emerge, popped the ball in and screwed the worm back up and it joined the rest of the crew.  It was a bit more involved than that and required a bit of jiggling but no big drama.  With doubt over how many balls there should be I'm kind of tempted now to see how many balls there really are.  But, judging by the bash marks on the four slotted nut on the steering shaft I'm guessing this box has been opened before.  To be honest I always thought for a high mileage car the steering was surprisingly fantastic.  Clearly it's been replaced or rebuilt at some stage but there's no guarantee that the ball count is as per ex factory.  I'm dead certain though that I haven't lost any more.

Also conquered that four slotted nut by placing that rack part back in the box with a couple of bolts to hold it there, put my weight on the box, then large pipe wrench on the nut was hit with a mid sized sledge hammer once only and that was enough.  Would've used a vise if I had one, but it's broken from doing something similar a while back.

Oh and got that valve cap out ok in the end.  Needed a lot of prodding and levering from all sides but it slid out eventually.
Title: Re: Power steering reseal
Post by: goldacre on 11 March 2010, 01:02 AM
I take my hat off to you Oscar on doing this job in house  :-*

I had a good hard look at my leaking steering box and surrounding paraphernalia then looked at my shabby tool box collection (Holden Torana beginnings) and farmed it off to AutoMac.

You will be $795 better off than i was  :(

G

PS how much was the re seal kit????
Title: Re: Power steering reseal
Post by: s class on 11 March 2010, 02:40 AM
Quote from: goldacre on 11 March 2010, 01:02 AM
You will be $795 better off than i was  :(

:o  :o  :o

For that price I hope they rebuilt, machined/ rehardened and rechromed the teeth of the sector shaft.

A reseal kit is about ZAR250 here - which is somewhere around A$37.
Title: Re: Power steering reseal
Post by: oscar on 11 March 2010, 03:36 AM
Damn, $795.  Seal kit cost me $16.91US in Sept 08 which I see now they cost $20.23 USD https://www.autohausaz.com/search/product.aspx?sid=hddi3i2izskvek55tabuipax&partnumber=1074600061

You gotta adopt the w116 DIYer motto goldacre.  Fix it or f*#@ it trying.  8)
If you don't succeed, then you go spend the big $ on a guaranteed part.  The discovery process in trying and potential saving outweighs the cost of paying a pro plus the part you couldn't fix.  If you do succeed, it's a good excuse to buy good tools with the savings.  I basically had nothing 5yrs ago apart from cheap spanners and screw drivers.

This was my first reseal and although it seems daunting at first, after a while the parts look simple when you visualise what goes where.   And that link for the w126 box is almost identical to ours.   I started taking pics and realised soon that it wasn't worth the effort when that link is good enough for a first timer or pro.  It just doesn't deal with the worm and balls but I didn't plan on going that far either. 

From the time I jacked the car up till the time I closed the box up was about 12hrs with quite a few breaks.  It still needs a thinners wash prior to painting and bolts torqued for bearing caps.  Still waiting on new tie rods and damper before I'm on the road again but fingers crossed there'll be no more leaks.
Title: Re: Power steering reseal
Post by: s class on 11 March 2010, 03:48 AM
Oscar I've resealed several MB boxes now and all have been leak free since.  The only trick to watch for is the locking nut that secures the sector shaft adjustment on top of the steering box - the nut is usually not included in the rebuild kit, but should be replaced as it has an integral rubbery seal ring on its back side.  Even with a new one of these nuts, I had leaks initially, and I was surprised at just how tight I had to torque this nut to prevent leaks.  Fortunately, I did all this learning on the 280SE, which has good access to the top of the box when its in the car.  On a V-8, you want to get it right first time. 
Title: Re: Power steering reseal
Post by: robertd on 11 March 2010, 04:37 AM
Good on you Oscar,

I,m with you, I've just had to redo a job that was done by a qualified mechanic for a roadworthy on the 280S I've recently acquired.

I find that most times mechanics don't take the time to get it just right, instead they bang away with the attitude " she will be right mate".

The job entailed unsticking a front brake caliper, I had to take it back three times with no satisfaction.

I've since discovered that he had incorrectly installed the heat shield on the inside of the piston causing the brake pads to be pinched to one side making a real mess of it.

Fun and games

Rob
Title: Re: Power steering reseal
Post by: oscar on 11 March 2010, 10:09 AM
sclass thanks for that tip about the locking nut.  I tried for ages to get it to take the thread again and ended up shaving a bit of that nyloc or rubber with a stanley knife.  I didn't realise the importance of that seal until now.  It's the only thing stopping oil coming out of that hole.   

Your'e dead right about the V8s too.   It's one thing I love about the m110 with more space to swing spanners.

So I'll have to source a new lock nut and I don't reckon they'll have one at the local engineering shop.  I tried to get a replacement pitman arm nut and despite the huge range of nyloc nuts they had, they didn't stock halfnuts nor were any of the same pitch size.

Rob that would've been annoying, got a couple of those stories too.   As much as we'd all like to find a bit more time to work on our cars we're not under pressure to get one job out of the way to get another car up the hoist before knock off time. It's a luxury for DIY to be able to sort things out even if it takes a few hours here and there over a few weeks.  So long as there's another means of transport of course.  I couldn't survive as a mechanic, I just couldn't work quick enough.
Title: Re: Power steering reseal
Post by: Big_Richard on 13 March 2010, 06:57 PM
modern cars are quick and easy for mechanics to keep turning over - its the 30 year old cars we play with that always have hidden surprises waiting to turn a 5 minute job in to a 6 month nightmare ;)
Title: Re: Power steering reseal
Post by: oscar on 16 March 2010, 06:29 AM
Right now I'm thinking spending money on a professionally resealed unit might have been worth it.  My first attempt at a reseal has failed miserably.

Today I took all the balls out, 24 of them, because the worm would bind in one direction.  I found that the last ball I put in last time was one turn above the rest and wasn't going into the ball nut.  I managed to feed them all in through the end of the worm gear making sure they all disappeared and once all in I could turn the steering shaft from lock to lock without any binding.  

Once I did that I gave it a clean and applied magic black spray and made it look new.  Refitted the box and aligned the steering shaft to centre.  Put the lines on and the last picture shows the result.  Big leak out of the pitman shaft seal.  Prior to removal the leak was in the steering shaft seal.  Somehow I've damaged the pitman seal I think when hammering it in with a socket though I thought I was careful.  I might enquire locally if I can get the seal by itself and try again but in the short term I'm just going to swap out the 280's box with this one to get the car on the road again.

Last week before disassembly,
(http://img7.imageshack.us/img7/2236/imgp6723medium.jpg) (http://img7.imageshack.us/i/imgp6723medium.jpg/)

After reseal  and magic black paint
(http://img30.imageshack.us/img30/8981/imgp6751medium.jpg) (http://img30.imageshack.us/i/imgp6751medium.jpg/)

Reseal fail at idle.
(http://img683.imageshack.us/img683/8091/imgp6755medium.jpg) (http://img683.imageshack.us/i/imgp6755medium.jpg/)
Title: Re: Power steering reseal
Post by: s class on 16 March 2010, 07:06 AM
Don't give up Oscar - I know that this kind of 'learning the hard way' is backbreaking.  But its usually worth it in the end.  Those main lip seals are all available individually from MB. 

When you pull off the sector shaft cover again, examine the shaft and seal first before just digging out the seal, to try and see if there is an obvious reason for the leak. 
Title: Re: Power steering reseal
Post by: TJ 450 on 16 March 2010, 07:21 AM
I'm with s class... I went through the same process with the 6.9's transmission. After MT's assistance with the incorrectly assembled servo, the tranny still had to be pulled apart again...

The satisfaction is well worth it in the end.

Tim
Title: Re: Power steering reseal
Post by: koan on 16 March 2010, 07:41 AM
Annoying when that happens.

I've got spare blue seals here if you want them oscar, but the reason for that is I was told they aren't very good and to use standard black seals.

koan
Title: Re: Power steering reseal
Post by: oscar on 16 March 2010, 08:39 AM
Thanks fellas.  It's amazing how quicker you get at removal and refitting when this kind of thing happens. ::) Though still annoying, I don't think years ago I would've had the patience.  I saw this leak and I think I just said "Damn!".  Nah, I'm sure I said the "F" word too, but ya get on with it.

I agree it will be worth soldiering on.  Especially now that I'm confident I've found the cause, ie hitting the seal in with a socket too small which has bent the lips downwards so only the outer lip is contacting the shaft.  The inner lip that would hold the pressure in isn't doing anything. 

I did what you suggested sclass and could see the error once the shaft was out.  Ended up taking the seal out too and although it's intact, it's no use now.  I'd take a photo but imagine a cross-section of the seal looking like this below.  Normal on the left, rooted on the right.

Shocking drawing I know, plus it's not that pronounced but I'm sure you lot will get the gist of my error. 

Thanks for the offer koan. Closest MB stockist is two hours away so I'll see how I go locally and if nothing, I might just go for a drive to get it and some other supplies from Wagga, then maybe pull an all-nighter tomorrow. I should buy a press too. 8) Failing that  I may be in touch.

(http://img692.imageshack.us/img692/9716/sealfailure.jpg) (http://img692.imageshack.us/i/sealfailure.jpg/)

Title: Re: Power steering reseal
Post by: oscar on 16 March 2010, 07:06 PM
Any thoughts on using single lip seals as opposed to the double lip?  Have your alternate seals been double or single lip koan? I assume the the second lip is like a dust seal and helps the reverse side of the inner lip to be lubed but none of the shops here had them. I might just coat the reverse side of the seal with some rubber grease as a protective measure.

Here's what I've got, two seals, one's got a metal outer case but I think I'll use the one without.
(http://img682.imageshack.us/img682/6453/imgp6759medium.jpg) (http://img682.imageshack.us/i/imgp6759medium.jpg/)
(http://img706.imageshack.us/img706/2073/imgp6760medium.jpg) (http://img706.imageshack.us/i/imgp6760medium.jpg/)
Title: Re: Power steering reseal
Post by: TJ 450 on 16 March 2010, 07:35 PM
The outer lip is for protection. The standard procedure is to pack it with grease... I just used GP grease for the transmission and crankshaft seals.

IMO, the single lip may be an issue, because the steering box is positioned so that it cops a fair bit of dirt.

Tim
Title: Re: Power steering reseal
Post by: koan on 17 March 2010, 12:37 AM
Agree with TJ450 on the double lip seal and grease.

Offer of blue seal is still there, I'll be going to the local bearing place this week, I can pick up a another seal of the black type if you have trouble locally.

Ken
Title: Re: Power steering reseal
Post by: oscar on 17 March 2010, 04:34 AM
If you don't mind koan that would be great and I'll keep it for the next seal attempt.

As it is now, I ended up putting the seal on the right in and smothered it with rubber grease.  So far so good.  Put the new tie rods and damper in.  With all the movement of the lines to the box I also had to replace part of the return line and the old supply line just before the box.  The return line had been seeping for ages but the supply line hasn't flexed in who knows how long and it developed many cracks.

The new hoses work great, though the downside is the new return line is red, no one had black. The supply line is just ugly compared to the original sleek hose and fittings.  The steel line from the box to the hose had only one nut and when undone had this huge nose screwed into the hose end.  I liked it but the shop didn't have anything like it.  They ended up cutting the end off and making and soldering adaptors to fit.  The advantage of the setup now is that you can just replace the hose when it leaks rather than take the hole lot off the box like what was needed to replace it.  Though when it does wear out I'd like to get something that looked more original, not a mix of imperial and metric adaptors.

Got it all fitted, went back and forth in the driveway, lock to lock trying to get any air out of the system. There was a bit of a groan returning from full lock but the alignment is way way out.  I reckon it's just the tyres scrubbing the ground with massive toe out and at crawl speed.  Went for a quick drive around the block and it feels good, no groans when doing u-turns.   The toe out feels obvious though, hopefully an alignment tomorrow will  shore things up.

Last thing, I've got a cap or guard around the pitman nut.  Hadn't seen it on any other car but it's always been on the 350.  They supposed to be there?  Although it's painted black it was just gal sheet or thin pipe as you can't see a join but it goes on the shaft after the pitman arm and before the nyloc nut.

Pitman nut gaurd
(http://img260.imageshack.us/img260/7584/imgp6763medium.jpg) (http://img260.imageshack.us/i/imgp6763medium.jpg/)

Old supply line
(http://img715.imageshack.us/img715/7558/imgp6756medium.jpg) (http://img715.imageshack.us/i/imgp6756medium.jpg/)

Box end of the flex supply line with steel  line to the box removed
(http://img191.imageshack.us/img191/7035/imgp6757medium.jpg) (http://img191.imageshack.us/i/imgp6757medium.jpg/)

The replacement flex supply line
(http://img39.imageshack.us/img39/3018/imgp6761medium.jpg) (http://img39.imageshack.us/i/imgp6761medium.jpg/)

Not quite original, ugly yet functional
(http://img638.imageshack.us/img638/5332/imgp6762medium.jpg) (http://img638.imageshack.us/i/imgp6762medium.jpg/)
Title: Re: Power steering reseal
Post by: s class on 17 March 2010, 12:58 PM
Oscar, I have seen a few steering boxes with that cover/guard around the pitman arm nut.  In the case of steering boxes that don't have it, I assume its because they get discarded during rebuilds/re-seals - and after 35 years there aren't many steering boxes around that haven't had some sort of intervention. 

I can only presume the function of the cover/guard is to act as a heat shield to protect the nylon part of the nylock nut.  So perhaps certain models were equipped with this, and others not, depending on the proximity to the exhaust?
Title: Re: Power steering reseal
Post by: koan on 17 March 2010, 02:12 PM
Quote from: s class
I can only presume the function of the cover/guard is to act as a heat shield to protect the nylon part of the nylock nut.  So perhaps certain models were equipped with this, and others not, depending on the proximity to the exhaust?

From memory I think the manual says only certain models have the heat shield.

koan
Title: Re: Power steering reseal
Post by: oscar on 17 March 2010, 09:23 PM
Never thought of it being a heat shield but it has to be.  Too thin to be a guard and it makes sense that it would only be on models where the exhaust is closest.  It doesn't surprise me either that some have probably been discarded.

Report back from the wheel alignment.  Dropped it off at the local Bob Jane T-mart who usually do our tyres etc.  I get a phonecall from the bloke who did the alignment who said he was amazed how good the steering was compared to other old mercs they get through the shop that need up to a quarter turn of the wheel before the car changes direction.  Let me at em I thought.   :D I would guess that most have neglected bushes and joints and a box that could do with some adjustment.  It reminds me of povo when I first got it.  Box wasn't too bad but the car would fall from left to right, was good around corners and with decent camber in the roads it would track ok but otherwise it was hard to keep in a straight line.   Yet it was driven like that for a few years by a Uni student.

The 350 though feels great.  A little bit stiffer than before but very smooth and freeplay is negligible.  I reckon there's more of a power steering whirrrr sound than before especially when revved at a standstill but I'm honestly not sure if it's a perceived difference or not.  It's not that kind of loud whirrr that you'd be popping the bonnet for to check the fluid level, which is ok BTW and I don't notice it whilst driving.  It might be due to my adjustment of the box but I'm happy enough with it to just leave it.
Title: Re: Power steering reseal
Post by: koan on 17 March 2010, 10:45 PM
Quote from: oscar on 17 March 2010, 04:34 AM
If you don't mind koan that would be great and I'll keep it for the next seal attempt.

On their way. Couldn't get black seals at short notice due to them being odd sizes so I've sent blue MB seals for both shafts.

koan
Title: Re: Power steering reseal
Post by: oscar on 17 March 2010, 11:04 PM
Much obliged, thanks koan. 8)