Powersteering pump single or dual diaphragm??? WTF
 

So Oreilly has two listings for pumps: single diaphragm and dual.

THEN there are the pumps with filters.

My steering is already excellent however I'm upgrading to hydroboost in the distant future and want to get a better pump if I can.

The price difference is like 5 bucks between the single and double diaphragm. In googling I find lots of references to brakes which results in lots of boolean search commands revealing tons of store websites with no information.

Aired down in a bind idling I have managed a few times to get the wheels stuck with the pump unable to overcome the resistance.

Anyways what are your guys ideas on the filter too?

I figure if its lasted 220K without one, then I'm fine with that. O and lifetime warranty.

It's all A1 Cardone parts at oreilly's btw.

Looking for some insight!

I've never seen a power steering pump with a diaphram. Perhaps you are referring to single or dual vacuum "brake booster".

Stock Blazers have single diaphram vacuum assist power brakes. You mentioned you plan to move to hydra-boost brakes. I admire your ambition, but should remind you they won't help you steer away from a low tire in a rock crevasse.

As for the hydraulic power steering pump, I try to be clean and I replace both hoses. However, if you don't mind dropping $20 extra, the filtration they mention here might not be a bad idea. My guess is that at normal RPMs and normal driving, the cheap re-man is fine. If you need lots of steer torque at low RPMs, the tighter tolerance pump may do a better job.

They defintely list dual and single diaphragm. Might be just a bunch of garbage.

http://www.oreillyauto.com/site/c/de...2869&ppt=C0031

http://www.oreillyauto.com/site/c/de...2869&ppt=C0031

I dunno if that link works for you guys so here are the details:

Cardone - Power Steering Pump
Part Number: 20-7840F
Line: A1
Remanufactured
UPC: 82617706537
Remanufactured
With Reservoir
With Dual Diaphragm Booster
With Aftermarket Filtration Improvement
Engineered With Magna-Pure Filtration System.

Cardone - Power Steering Pump
Part Number: 20-7840F
Line: A1
Remanufactured
UPC: 82617706537
Remanufactured
With Reservoir
With Dual Diaphragm Booster
With Aftermarket Filtration Improvement
Engineered With Magna-Pure Filtration System.



There are also a few without filters.

The link you sent works and brings up the pump including the -F feature and the UPC you describe. However, the term "diaphragm" does not appear on the page that I get. May be a feature Oreilly offers in your area.

In any case. looks like a good pump.

thats weird. I'll just get the 50 dollar one. It would be nice to get some confirmation on what the hell this diaphragm stuff is all about.

Going for the "dual" one because it's the cheapest by 5 dollars. If it's crap, I'll just warranty that turd out for the "single" one.

print the web page and take with you to O'Reilly's when you order. Ask them where the diaphragms are located.

Hydroboost brakes require a second line coming from the pump to the booster, maybe that is the diaphragm question. The correct pump will have two high pressure lines coming out of it.

I don't think hydraboost pump is any different from the standard pump, at least in the number of hoses. The pressure hose from the pump should go into the hydraboost, the a hose from there goes to the steering box then the return line from there back to the pump.

Once the hydraboost is charged up, fluid flows easily and at low pressure from pump to brake to steering to pump. When a brake is applied, the line from pump to brake pressures up.

When steering is turned, the line from pump to brake and the line brake to steering both pressure up.

Once the brake is released, the hydroboost reservoir is charged and the steering is straight (no force), once again all hoses are low pressure and the pump freely circulates fluid thru the whole system.

From my experience Bilbo is correct in regards to the hydroboost fluid flow properties.

There must have been some sort of confusion regarding the "dual and single" diaphragm because I had them pull pumps side by side. The part numbers were also identical.

It was also slightly interesting at Advance Auto parts because they list them as single/dual return pump however both of them are same p/n. They had no "single return" available so I took the dual and drilled out the back to 5/32. After cursing and screaming it turned out I simultaneously got a pinhole leak in my return line. So after cutting the end off and shoving it back on a little tighter everything seems okay.

Now to drive this beast 3K + miles from here in south texas to michigan and back!

O and my rear left was flat this morning. Looks like I'm getting a new bfg at!