250sl reservoir mounting question

[hands_aus]

Recently I had major FRONT brake work done on my 'early' 250SL.

Included was a NEW ATE Master Cylinder but re-using the existing reservoir. (I wasn't being cheap... the new reservoirs are slightly different in shape and I wanted to keep the 'original' look.)
I supplied a new ATE seal kit for reservoir to MC.

I noticed on the day I picked up the car that the reservoir was tilted towards the front of the car, ie not sitting flat.

This was evident because the brake fluid looked unequal in each of the sections.

This is the 230sl, early 250sl reservoir that uses for mounting a screw in one section and a rubber plug on the other.

This afternoon I used my torch and a mirror to look at the reservoir mounting on the master cylinder.

The screw end is mounted flush on the MC and is being held securely by the hollow threaded bolt.

The rubber plug is not pushed all the way into the hole of the master cylinder and the small hollow tube on the reservoir is not pushed all the way into the rubber plug.

At this point there are no leaks and given that last weekend I did a 200KM trip with no problems, I don't really expect any in the near future.

My questions are...
Is it really safe to drive the car as it is?
should the reservoir be mounted flush on both connecting points on the master cylinder?

attached is a pic of the reservoir on the old MC and as can be seen the fluid is equal in both sections.

Download Attachment: BrakeResOld_1.jpg
64.64 KB

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Naj ✝︎]

I think the resevoir is not all the way home.

When I installed mine, I put the rubber plug on the m/c first and then pushed the resevoir on. It may be that your fitter installed the rubber plug on the resevoir first???

If the resevoir is under stress, it could eventually crack.

I would correct the situation.

Just my .02pence  :oops:

p.s: I used a syringe with a length of tube to empty the resevoirs.
If you refill gently with a syringe as well, you may get away without having to bleed the system.

naj

[merrill]

Bob,
It took me a while to get my new m/c and reservior to seal and look correct (to me) on my 66 230 sl.  
on the 230 the rubber plug / grommet that is inserted into the rear most hole in the m/c would not seat.  I had to trim a small amount off the plug till it would stay in the m/c. (lower part of plug)

from there I inserted the new reservior and just made it level.  on my car you can see the rear tube from the reservior going into the plug.  not much, yet it is there.

I do not have any leaks or problems that I can tell. so I have just left it.

matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[hands_aus]

Hey Naj and Bob,
Thanks for the replies.
As I said there are no leaks but the unit doesn't sit level and as such the fluid level doesn't look right.

Monday I will see the mechanic.

Naj, The 'stress' comment could be very relevant, as the front mounting point provides all the strength for holding the reservoir on the MC. I know the front seal is only an O-ring type.

Bob, shorten the plug ? Maybe that is what my mechanic will have to do.

I was wondering how they push the back section into the MC without breaking the 40 year old reservoir.
Maybe some sort of L shaped tool (MB??) that would go in through the filler hole and provide leverage pressure on the back section.
It would be very job specific.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Naj ✝︎]

Bob,

 

quote:I was wondering how they push the back section into the MC without breaking the 40 year old reservoir.

With a bit of brake fluid for lubrication, it should just slide in....

naj

68 280SL

[Longtooth]

Bob,
fwiw, when I replaced my MC & rebuilt my booster, I didn't have any problem getting the original reservior to reseat properly on the MC.  I had the reservior out and cleaned it inside before re-installing... but I don't recall whether I put the seal into the MC first or not.  It slipped right in though.

If it's not correctly seated you will add stresses that weren't there before (nor intended by design) , so you're subject to a crack appearing and then propogating.  Also remember that it's probably been at least a decade or two (if not 40 years) since the reservior was last removed from the MC or seal reaplaced.  The plastic reservior material over time under stress has "crept" (plastic creep)over time and temperature changes into it's stress equilibrium (stress relaxed distribution) position..... so that putting it back and applying stresses to new locations will tend to cause fractures to develop at those higher stress and stress concentration area'st   on an old plastic material (which has long since lost most of it's "plastic" property.

When you take the car back to the mechanic, make sure he doesn't just use a lot more torque on the screw to force it down.  Being an engineer, I would find out first precisely what's not seated where it should be, & precisely why.  It could just be as simple as the hole too small for the new seal so it's going to tilt one direction or the other trying to get seated.  OR... heaven forbid, the screw got cross threaded on reinstalling!!!.  My recommendation is that you inspect the seal and mating surfaces carefully when the mechanic removes the reservoir again... and threads of the screw and MC.  I know you do detail work on your 250SL.  

BTW, remember that bleeding the breaks is a simple, cheap, though time-consuming affair compared to a wrecked reservior or crack in it developing later.  Brake fluid all over the interior paint in the engine bay is a real mess... it'll wreck the paint. You've spent hundreds of hours on details on this car already.... spending another 3-4 hrs if necessary is peanuts.

Longtooth
67 250SL US #113-043-10-002163
'02 SL500 Sport

[hands_aus]

Before going to the mechanic this morning, I wrapped a piece of fencing wire around the MC and reservoir just to emphasise my concern about the incorrectly mounted reservoir.

It seemed to work.

While I was buying parts from the parts shop the mechanic took my car.

He said 'in for a penny in for a pound'... he is English, so he just pushed down on the offending end until it clicked and locked in the correct position.

I checked with my torch and mirror and there were no leaks from either end.

It now looks correct as it should have been.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Naj ✝︎]

Bob,

 

quote: so he just pushed down on the offending end until it clicked and locked in the correct position.

I think the mounting screw in the resevoir shuold be rechecked for tightness.
I believe the torque setting 'FT' means 'fairly tight' in this instance.[:p] :oops:

naj

68 280SL

[hands_aus]

quote:Originally posted by naj

Bob,

 

quote: so he just pushed down on the offending end until it clicked and locked in the correct position.

I think the mounting screw in the resevoir shuold be rechecked for tightness.
I believe the torque setting 'FT' means 'fairly tight' in this instance.[:p] :oops:

naj

68 280SL

Hey Naj,

I will check it as you suggest.

thanks, mate

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto