How to Correctly Seal Power Steering Fluid Tank Bracket Screw?

[Pawel66]

I need to kindly request a piece of advise.

How do I correctly seal the screw holding power steering fluid tank bracket to engine housing?

There are three screws holding the bracket for this tank:
1. First the one that also holds the FIP. I think no sealing issue there, there is a gasket in the flange.
2. Second is the one next to tacho drive. There should be no oil there, I think, but may apply thread seal if I am not sure.
3. Is the one at the bottom, screwed in the engine housing where the ignition distributor drive is. There is oil on the other side (inside) for sure. The way it was sealed so far might not have been perfect. How do I seal it best?

We have there: threaded housing, tank bracket and then screw head. Shall I put copper seakling washers between bracket and housing and another one between the bracket and screw head as well as thread sealant? Is this correct?

Tried to express this on the "picture" attached.

Please kindly advise.

[Tyler S]

Shall I put copper seakling washers between bracket and housing and another one between the bracket and screw head as well as thread sealant?

This is correct but use aluminum washers. If you bought an Elring gasket kit, there are 2 that fit here. Be sure you have the correct bolt as it is part of the timing chain guide system. This bolt keeps the timing chain from jumping on the FIP driven sprocket. If you look at the end of the bolt, it has a rounded taper appearance to it.

[Pawel66]

Tyler, thank you very much!

Hope I did not ruin anything there inside by taking this screw out...

Thanks!

[Tyler S]

No you should be fine. The screws function only comes into play with engine running

[Pawel66]

Thanks again, need to look for aluminum sealing washers...

[wwheeler]

I am curious as to why aluminum sealing rings are specified? I always thought that copper would be used in applications where there is more torque on the fastener and aluminum where there is less. Is there any rhyme or reason which is used where?

Thanks.

[Pawel66]

I have just opened the computer and got to this page in order to ask exactly the same question!
For my knowledge. Normally when you buy generic sealing washers - you get copper...
Why aluminum?

[Tyler S]

Im sure copper would work too but make sure they are not the hollow type.
In the kit I got only aluminum would fit the appl.
I do know its a good idea to use aluminum on a less than perfect surface like an iron block or on an application that does not require high torque.

[wwheeler]

One other thing I thought of is that it may not be a good idea to use an aluminum seal ring on an aluminum surface. Reason being is that two like metals when rubbed together under a high load will gall and create a nasty gouge. Having a copper seal ring against aluminum would not do that. I have personally seen that. Does that have any bearing on the selection? 

[Pawel66]

Thank you for view and learning to both of you. I have both sets now, waiting for what comes from Meredes, but most of the seal washers from them I saw were aluminum.

[wwheeler]

I believe the aluminum used in the seal ring is softer than the base aluminum part, so most damage is done to the seal ring. That is replaceable, so not a biggie. Still would be nice to know which is used where and why.

[Pawel66]

I think I remember when I bought injectors from Bosch, they came with copper (or - at least the colour was suggesting copper - whatever alloy was there) seal ring. Mercedes sells seal rings for injectors and, I think, also injectors with seal rings, if I remember correctly, in aluminum. I do not know if cost plays a role or technicalities or both...

[Shvegel]

I used the washers and applied Locktite 515 sealant to the threads.  I like the 515 over any silicone type sealant because it doesn’t harden in the presence of air(anerobic) and any squeeze out doesn’t harden.  It lessens the possibility that a chunk of sealant will end up stuck in the engine where it shouldn’t be.

[Pawel66]

due to my travelling I had to have my mechanic fit the fluid support to the car. I think we used exactly the same Loctite. NOt sure what my mechanic finally used for seal rings... In any case, Mercedes are supplying ones of gold colour, so probably some copper alloy, some kind of brass maybe...

[Benz Dr.]

You may find that fuel and brakes use copper seal rings while air ( vacuum ) and coolant use aluminium. Not a hard and fast rule though because I see lots of places where they used either one. I think, to some degree, that higher torque or pressure applications are generally copper while lower torque or pressure is aluminum.