Power Steering Pump Filter

[Dazbot99]

Hello, I thought I would change the power steering filter on my 1977, 280se

I romoved the old one which looked to be the original one. A circular piece of some type of material that sat on that metal seat you lift out that has a spring attached to it.

I purchased a new one, however! This is an enclosed paper element in a metal covering/ frame, so not sure how to install it as that base plate attached to the spring and thread makes it impossible to push into. Not sure how else to explain it! Thanks for any advice!

[daantjie]

The filter just drops in first and then you add the spring with the hold down washer to tension the spring.

[Squiggle Dog]

I believe that you remove the upper and lower circular plates, as the new style filter has those plates attached as one unit. I'd hang onto the plates, though.

[irvine]

How often should it be changed?? Never thought of it.

Cheers,
Neil.

[Dazbot99]

Thanks all!! I just took the spring off it's base plate and slipped in the new design, used spring to keep it down with that push down washer!!

[UTn_boy]

If it matters to anyone, the original style of filter is still available. 

[ptashek]

How often should it be changed?? Never thought of it.

Every 12k miles or so, i.e. with every power steering fluid change.
It's easy to tell, as the ATF will start changing colour from translucent, bright red to cloudy, deep crimson.
If it's a murky brown-red, that's well overdue a change.

[s class]

The enclosed element style filters can only be retrofitted to the later style pumps (alloy) with integrated reservoir.  The earlier style iron pumps with separate reservoir (typically the d-jet cars) must use the original type filters.  On the v8's, these early pumps have the pressed steel reservoir bolted to the top of the pump, on the 6 cylinder cars the reservoir is off-board, on the left fender.  The enclosed element style filters will physcially fit into these early pressed steel reservoirs, but they will not seal and perform their function.  For these, you must fit the original type sintered element. 

[Dazbot99]

Thanks for the advice SClass! My supplier provided me with that new style paper element, and was wondering why it was different to the old round thing that I removed!!

Thank god for these Merc Forums!!!

[robertd]

I concur with s class

been there done that

[revilla]

I'm reviving this subject as I recently changed the steering oil/filter.  I understand that the alloy pumps with integrated reservoir must use the H85 enclosed element type filter.  No issues.  However, I found in one of the cars the other type filter (cork looking) has been installed.  What's interesting is that this filter was installed with 2 additional metal pieces: an adapter with a few teeth (see pic attached) that fits the lower part of the filter and a plate on top that holds it in place (as shown in EPC).  The first one, the adapter, is not shown in EPC.  This piece is apparently made exactly to fit the cork filter, so it seems original.  But I don't quite understand its function.  Maybe this adapter is installed to avoid the filter from moving laterally in alloy pumps as it was originally designed for steel type reservoirs.  Any thoughts are welcome.
Secondly, I see H85 type filters are installed in alloy pumps without using the top holding plate, but I found interesting that such plate fits exactly the top of this filter perfectly.  I'm pretty sure we should not installed the H85 with the plate on top, however I have a small doubt because with the plate on top 100% of the oil is forced to pass through the filter lateral perimeter, thus performing its job of filtering every drop before entering the pump.  When the plate is not present, on the other hand, part of the fluid (unfiltered) will descend directly to the pump through the 6 holes concentric in the filter.  In essence, the fluid by-passes the filter without the top plate installed.  But with the plate installed the 6 holes are covered so no by-pass possible.  Is this by-pass intentional?
Your inputs are appreciated.       

[TJ 450]

Hi Robert,

With these filters, I'm pretty sure they filter the return, in the same way the suspension ones operate. On the suction side, the fluid flows straight through the middle of the filter. That's my understanding anyhow. Adding the plate in that case is not a good idea at all.

Tim

[revilla]

Hi Tim,

Thanks for your feedback. 

Yes, the filter acts on the fluid return coming from the gear box.  Interestingly, the filter paper accordion is located just at the same height than the return hose hole inside the pump, so I assumed the flow as follow: return hose --> external filter perimeter --> through accordion --> then inwards to filter center (so now "clean" fluid) --> then downwards to pump blades --> exit hose --> gear box --> return hose (now "dirty" fluid) --> pump.  If true (?) fluid must pass inwards/horizontally through the lateral side of the accordion to be cleaned, but if the 6 holes on top are clear then fluid will be sucked vertically straight to the blades, essentially by-passing the filter.

The only other explanation possible is that the system was designed to filter the "majority" of fluid volume but not 100% of it (I doubt it but possible).  The holes on top of the filter will then facilitate the flow to avoid over-loading the pump (?).  The problem with that is that the gear box will get only partially filtered fluid... I'm not convinced of that though.


Happy to be corrected.

Have a good day.

[revilla]

Ok I think I got it after checking closely.
The filter, when correctly installed (6 holes facing up) creates a chamber between the pump internal walls and the accordion. So the returned fluid, which arrives directly to said chamber against the accordion, doesn't exit to the upper part of the reservoir. That way the return oil is "forced" to pass through the accordion horizontally filtering therefore 100% of the volume. In case of leaks in the system hoses/gearbox/etc the flow feeds from the fluid in the reservoir above the filter. Smart in fact!

So you're correct Tim: Blocking the 6 holes is not necessary.

Conclusion (unless somebody disagrees): the filter should be installed alone with the 6 holes facing up and the spring under compression keeps it in place.

It feels good to know the steering just got fresh "blood"