lxcoupe

iTrader: (9)

Hey ya'll, this past week I decided to undertake the hydroboost swap in my truck. I did it for no other reason than curiosity; I wanted to see if it would improve the brakes and I can say it did, but not amazingly so. That is aside from all the "launch" benefits you apparently get from having hydroboost. My truck could blow all 4 tires off with ease without pushing through the brakes, so I didn't do the swap for launch purposes, only braking improvement.

A couple years ago I bought an LQ9 for a song out of an 02 Escalade, and the gentleman also included the hydroboost, pedal, lines, etc.

Since I had the complete LQ9 with hydroboost power steering pump, I decided to use the hydroboost style power steering pump with the 2nd return port. I've read several posts of guys reusing their stock pump and adding a tee with good results. But, since I had the pump from the LQ9, I figured I would use it. I transferred the entire bracket with pump over to my truck (so I wouldn't have to remove the pulley). A tip of advice when you're doing this: tighten down the pressure line on the pump first, then you can bolt the bracket up to the head/ block without reaching down, cursing and trying to get the line on straight after the fact.

This piece of information doesn't apply to most people doing this swap: Turns out 2002 Escalades are variable assist power steering and use a different flow control valve and pressure line compared to later Escalades, Tahoes, Yukons, or 2500HD trucks. The 2002 pump has a combination solenoid / flow control valve attached to the back of it that varies the assist level depending on vehicle speed. The later OBS trucks also had this. It's total junk, but the pump can still be used. If you do end up with an early NBS hydroboost power steering pump, you just need to swap the flow control valve from a later hydroboost pump. In case you're wondering, this is what the EVO valve looks like:



So... since I could not use the EVO valve, I initially swapped over the flow control valve from my stock 2005 (non hydroboost) power steering pump onto the hydroboost pump. The flow control valve in case anyone is wondering looks like this:



Once I got everything back together, I noticed that the steering was kinda stiffer than stock. I figured, maybe that's just how the hydroboosts were... I was wrong. Turns out the orifices on the flow control valves on the non-hydroboost pumps are slightly smaller than the ones on the hydroboost pumps. To give you an idea of what the orifice differences look like, check out this pic as example:



Anyways, I ended up taking it all back apart since I wasn't happy with the way the steering felt. The brakes were kinda hard as well, but I figured that might be due to the fact that I used the 2002 Escalade disc/ disc master cylinder on my disc/ drum truck. So, I bought a used 2006 Escalade power steering pump, and I transferred over the flow control valve to my 2002 Escalade pump. I knew my 2002 Escalade pump was silent, which is why I reused it instead of bolting up the 2006 pump. Looking at the orifice on the flow control valve of the 2006 Escalade pump, it was considerably bigger than the one on my 2005 vacuum assist power steering pump.

I get everything back together again and the steering feels nice and smooth/ effortless like it did before the hydroboost swap, and the brakes "feel" proper once again. I firmly believe that you need either A. a hydroboost power steering pump (it will come with the right flow control valve), or B. a flow control valve off a hydroboost pump and transfer it over to your stock power steering pump so that the pump can flow more volume. Then, you can tee the return line no problem like you see everyone doing.

Other tips: I used new AC Delco lines off Amazon for the pump to hydroboost and hydroboost to gear. They were cheaper than parts store hoses and it's always nice to use AC Delco stuff. The lines from the 2002 Escalade LQ9 had seen better days, and furthermore the pump to hydroboost line was unusable since it had a different curvature down by the pump to accommodate for the EVO valve. I also highly recommend buying a new firewall seal for your used hydroboost unit, they are only $7.80 on Amazon and they are way thicker than the vacuum booster seal:



Part numbers:
AC Delco 36-353800 pump to hydroboost line
AC Delco 36-365463 hydroboost to steering gear line
AC Delco 88963604 2006 Escalade power steering pump
AC Delco 22872387 firewall seal for hydroboost
AC Delco 178-0685 2006 Escalade hydroboost assembly

As Atomic pointed out, there isn't actually any difference between earlier hydroboosts (with the smaller gas reservoir) and the later hydroboosts (with the larger gas reservoir) other than the fact that *apparently* the larger gas reservoir hydroboosts allow for 10 panic stops instead of 5, should the power steering pump cut out for any reason. I used the smaller gas reservoir hydroboost since that's what came in the 2002 Escalade.

If you do source a used hydroboost (any NBS SUV or 2500HD hydroboost will work), more than likely you will need to put a seal inside it. You'll notice there is probably some power steering fluid dripping at the junction between the master cylinder and the hydroboost assembly. That's quite normal, and the Duramax guys have had to deal with that leak for years. The hydroboost unit is fairly easy to disassemble, and you should not be intimidated by putting a seal in it for good measure. I used this seal kit, and I only used the larger piston seal:


Here is a great write-up showing how to replace the seal:

http://www.duramaxforum.com/forum/di...iscussion.html

For fluid, I used tried and true O'Reilly power steering fluid to fill everything up, and I do a 3 step bleeding process. First, jack the front of the truck up so the tires are in the air. Fill the power steering pump reservoir, then turn the steering wheel back and forth about 10 times. Then I put the battery charger on the truck, I disconnect the fuel pump fuse, and I turn the motor over continuously while I turn the wheel left and right. Usually the level in the reservoir will go nearly to the bottom. At this point, I fill the reservoir back up, I reinstall the fuel pump fuse, and I start the truck (front wheels still in the air), and I turn the wheels lock-to-lock another 10 times. You'll likely need to add fluid while you do this if it's the first time you start the truck after the hydroboost swap.



BRAKES and MASTER cylinders. This is an area I did considerable research on. If you have a 2005-2007c truck, you cannot use the stock disc/ drum master cylinder with the hydroboost unit. It won't bolt up. So you'll need to use ANY other master cylinder that came in NBS trucks (besides the 2005-2007c disc/drum master, obviously), or just use the one that came with your hydroboost unit. There are a handful of different bore sizes offered in SUVs, trucks, etc from 1999-2007, but ultimately the difference will be primarily in the pedal feel. Larger bore master cylinders theoretically give a firmer pedal feel, and smaller bore master cylinders give a softer pedal feel. FWIW, I used the 2002 Escalade master cylinder which has a 37mm bore on my 2005 disc/ drum truck and it feels fantastic. Not too firm, and not too soft. To put things into perspective, the 2005-2007c disc/ drum trucks had 31mm bore master cylinders. So I don't think it makes a huge difference which master cylinder you use, as long as you get one that will physically bolt up to the hydroboost unit. If you get everything back together and don't like the pedal feel, I can provide exact part numbers and bore sizes that you can try. I bought several different masters thinking I would try different sizes but the 37mm bore '02 Escalade feels fine, so I'll be returning the others. BIG PLUS: if you have a 99-04 disc/ disc truck, just reuse your stock master cylinder. It bolts up just fine to the hydroboost unit.

I used this Dorman master cylinder bench bleed kit. The fittings are great but I don't like the hose as it's black and you can't see the bubbles going through the lines. There are better kits available I'm sure.

lxcoupe

iTrader: (9)

Lastly, you will probably need to clearance the top of the firewall for the hydroboost unit, where the pedal rod slides through. I've read some threads saying guys had to, and others where guys said they didn't have to. On my 2005, I definitely had to. The cleanest method I found was to use my die grinder and a stone:



My advice, in summary:

1. Use a hydroboost power steering pump to ensure proper braking and steering feel
2. Avoid 2002 and earlier hydroboost power steering pumps as they may include an EVO valve on the pump
3. Take the time to install a new seal in the hydroboost, if you're using a used unit
4. If you are ordering the lines, order them for a 2006 Escalade, they seem to work perfectly for NBS 1/2 ton trucks, although 3/4 ton lines may also work
5. The hydroboost return line is unnecessarily expensive through AC Delco/ Amazon, I suggest getting that line from O'Reilly, Master Pro part # 80403 shown here:
MasterPro Power Steering Hose 80403 - Return Hose Assembly | O'Reilly Auto Parts

wretched73

iTrader: (1)

Thanks for taking the time to write this up!!

thewrx

Good info.

lxcoupe

iTrader: (9)

I'm not exactly the first to do it, but I think there's some confusion regarding exactly what is needed and what isn't. In my opinion, the hydroboost pump should be considered a necessity. Here's my finished unit, I'm stoked on it!

Jetn3

Do you know if that hydroboost flow control valve is sold separately? Part #?

lxcoupe

iTrader: (9)

Not from GM...but you can get a used pump off eBay for $25-30 shipped.

black04

iTrader: (15)

Is there a difference in the power steering pumps between Escalade and 2500 trucks?
I did this swap about a year ago and used a pump from a 2003 Escalade that does not seem to have the EVO valve. But since install the pump whines and is hard to turn at slow speed so I think it's going out. The brakes work fine.

Looking for a new pump I find that the new 2500HD pump is ~$40-50 more than the Escalade pump. Is it a better pump to go with or are they the same?

2500HD 6L pump 15909826 $189
Escalade part number 15909832 or 88963604 (not sure the difference) $142

lxcoupe

iTrader: (9)

Hard to say. The rebuilt / parts store pumps from Cardone and others are total junk 9/10 times and I would not waste my time with them. I would use the Escalade pump, 1/2 ton pump for a 1/2 ton truck.

Do you have your stock non-hydro pump? Maybe compare the hole in the flow control valve to the one on your Escalade pump. Escalade hole should be visibly larger.

black04

iTrader: (15)

Unfortunately I don't have it to compare to. I noticed today that it is hard to turn only when the brakes are applied, so it's most noticeable trying to maneuver in tight parking lots. Is this normal for a hydroboost setup or does it sound like the pump is going out and not have enough power?