How-To: Hydroboost Conversion GMT800.

[LongrangeLauber]

This is a hydroboost conversion on an 02 Silverado. This conversion should work on most Silverado's/ Sierra's from 99- early 07. Heck, it may even go beyond that. Some part numbers may vary, but I looked these up under a 02 Silverado 1500HD and everything worked out fine. I did not take pics during the install process, so I took them afterwards, which means if you have any questions on how I did anything, just feel free to ask. I usually respond pretty quick and can provide any pic you want to see.

 

If your wondering, YES this works on body lifted trucks with the part #'s provided! How do I know? MIne is body and suspension lifted!

 

First thing you want to do is get all the parts you need. This includes the:

 

hydroboost unit (ACDelco NEW part #: 178-0700, or junkyard), do not buy a reman unit like I did, it does not come with the pushrod between the MC and booster

pressure line from power steering pump to booster (ACDelco part #: 36-365454)

 

pressure line from booster to steering gear ( ACDelco part #: 36-365466)

 

return line (from booster to pump) (ACDelco part #: 176-1379)

 

master cylinder for hydroboost trucks (ACDelco reman unit #: 18M1107, or grab the one attached to your hydroboost if you decide to pick it up at the junkyard)

 

hydroboost pedal (GM parts direct #: 15906961)

 

vacuum cap; either get at junkyard, or a John Guest 1/2" plug like i did (part #PI0816S), mine came in a 10 pack, so I have leftovers

 

and then either a PS pump from a truck with hydroboost (ACDelco reman part #: 20756715) or,

a brass T fitting to branch into the steering gear return line.

 

Oh, and a 6 pack of your favorite brewski

 

Most guys buy the MC, booster, and pump at the junkyard, which is not a bad idea. But I suggest getting new pressure and return hoses. You could also get the pedal at the junkyard, but I have heard that some places will charge as high as $70, so why not just buy it new for less than half? The pedal comes pre installed with the bushing and a new pad if you are wondering.

 

You also need a pulley puller/ installer if you are replacing the pump. A drill and assortment of bits (up to 5/8"), and most of the nuts and bolts require a 15mm wrench or socket, with some extensions to access them. The only one I remember that was different was the bolt that holds the pedal, which was an 18mm wrench and then a socket with an extension on the other side. Brake lines to the MC are 9/16" nut. But make sure you have a variety of tools to do this job.

 

Don't forget power steering fluid and brake fluid too

 

Alright, here we go...

 

1) Remove ground terminal from battery (not sure if anything is going to shock you, but I didn't want to find out)

 

2) remove the serpentine belt, no matter if your going to replace the pump or just "T" into the return line. It makes it easier for the install of the new pressure line.

 

3) if you are installing a new pump, remove the pulley using the pulley puller/ installer tool. Once that is complete, then unbolt the power steering pump (3 bolts on the front, then one bolt that attaches a bracket from the pump to the engine block, all 15mm). To make this eaiser, I removed the entire alternator bracket so I didn't have to try and fish out the PS pump. You can actually keep the pressure hose hooked up to the pump and to the gear until almost the end, so your not making a mess with PS fluid. I just set my pump up near the steering gear so it was out of the way. Here is a pic of the rear most bolt holding on the bracket attached to the rear of the PS pump. If you have a ground strap on yours as well, make sure to reinstall it when reinstalling the alternator bracket and pump:

 

 

 

4) Undo the brake lines from the master cylinder and cap off. Then remove the two nuts that hold the MC on to the vacuum booster. Set aside and do what you want to do with it. You will not need it anymore.

 

5) Unhook the vacuum hose from the booster to the back of the motor. The thing on the back of the motor is a push fit connector. You must push the hose in and then pull back the retaining collar in order to release the hose. It is a bit difficult just because there is not much room to work and see back there. Once that is done, install the vacuum cap/ plug.

 

 

6) In the cab, undo the key slot clip on the side of the brake pedal. Stick a flathead screwdriver in the side, and then twist and lift. It should just pop right off. I have heard that some people have trouble getting this off, but mine came off very quickly and easily. Be mindful of how the brake pedal sensor thing is positioned so you know how to set it when reinstalling.

 

7) pop off the pushrod connected to the brake pedal. Then remove the bolt holding the pedal. This is probably the hardest part of the conversion because you cant see what you are doing, and its all slow wrench work. This alone took me an hour or so more to uninstall and reinstall the brake pedal, but I also I have big hands and am quite large myself so that didn't help either.

 

8) Remove the four 15mm nuts that hold the booster on the inside of the firewall. A long socket, extensions, knuckle connector, patience, and beer is required for this

 

9) Once those are out, the vacuum booster is ready to be removed from the firewall. Set it next to your MC because you will no longer need it. Now clean off the outside of the firewall, and also remove the plastic/rubber lining on the inside where you removed the nuts for the booster. A new hole will need to be drilled, and you dont want that crap getting in the way.

 

10) Now get your drill and I believe I used a 1/2" or 5/8" drill bit. You will see a dimple on the firewall below the lower two bolt holes. This is to accomodate the hydroboost unit, because it has an offset bolt. Why? Only GM knows, but at least they were nice enough to put that dimple there so there is no guesswork. Now drill that hole with a 1/2" bit and see if the hydroboost unit slides in there. I know I had to ream out the other oblong hole in order to make the hydroboost slide in there. Once you get it to work, then have someone hold the booster while you install the nuts on the inside. NOTE: I used some clear RTV silicone around the bolts of the hydroboost in order to seal off crap from getting in the cab. I did not know that I was suppose to purchase a gasket for right there, so I improvised.

 

 

You can see the old hole from the vacuum booster, and then where the new stud comes thru for the hydroboost unit

 

11) Once you get all four nuts tightened up all good, its now time to install the new brake pedal. The reason for a new pedal is that the hydroboost pushrod in the cab actually sits higher in the hole than the vacuum booster pushrod did. So if you compare the one you removed and the new one, you notice the stud on the side of the pedal is actually higher up, which is closer to where the bolt goes through to mount the pedal. Anyways, reinstall the pedal and push the bolt through and put your nut on the bolt and tighten it up. Your just about done with the hard part of this conversion.

 

12) Once done installing the new pedal, put the pushrod and brake sensor back on the new pedal. Then, reinstall the keyslot tab thing. Should just be able to put it on there and slide it down and it should lock in. But make sure the small tab is under the stud, so you know it is locked in for good. Finally finished with laying on your back for hours. My truck has 9" of lift, so it really sucked. Get up, stretch, grab another beer, and lets continue...

Edited July 7, 2013 by rdnckhntr94

[LongrangeLauber]

13) Now that you have finished the hard part, lets go on to the easier stuff. Let's install that new power steering pump. Mount it to the alternator bracket (3 bolts on the front, and then mount the bracket on the back from the old power steering pump). NOTE: if you did not install a new PS pump, you do not have that second return port. In order to solve this, get a brass "T" fitting that fits the hoses (I believe it is 3/8") and three hose clamps. You can either tee into the return line from your cooler (if you have one) to the pump, OR you can tee into the line from the steering gear TO the cooler. It doesn't really matter where you put it, because there is not much fluid coming out from the hydroboost unit. It is all preference.

 

14) Once done with that, DO NOT reinstall the alternator bracket back to the engine. Take your pressure hose from the pump to booster (#36-365454) and mount it to its rightful place, which is on the back of the power steering pump. The end with a lot of turns is the one that mounts here. Once that is installed, you may now reinstall the alternator bracket back to the engine. Once that is done, reinstall the PS pump pulley. The lip of the pulley should be flush with the end of the shaft, which is how most pulley installers are made (a bolt, nut, and washer will also work for this, but since you already have the tool, might as well use it). You can reinstall the serpentine belt now.

 

15) Connect the other end of the pressure hose to the hydroboost unit. New hoses come with a sleeve of rubber hose over the metal tubing part. I figured it was to prevent rubbing between the booster unit and the hose. Here is a pic of that:

 

 

16) Now you can unhook the pressure hose from the gear, as well as feed the original return line to the same return port on the new power steering gear. Set power steering pump with other parts you will not need.

 

17) Take new pressure hose (#36-365466) and run from gear to booster, or vice versa. The side with a lot of bends goes to the steering gear. I actually had to bend the metal line a little bit in order for the line to set down there properly. I routed the pressure line behind the brake lines, like so:

 

 

Orange is pressure hose from pump to booster

Red is pressure hose from booster to gear

Yellow is return line from booster to pump

 

18) Install return line like shown above. There is only one return port left and it sticks up from the side of the pump. Hard to miss.

 

19) Now you can install your new master cylinder AFTER you have really done a good bench bleed. Make sure there are no bubbles coming from the lines when you bench bleed the unit. It makes it 20X easier to bleed the brakes if you took out the time to really bench bleed your new MC.

 

20) Attach the brake lines FIRST on your MC and then install the MC on the hydroboost unit with the 15mm nuts from your old vacuum booster. I had trouble installing the brake lines after I mounted it on the hydroboost unit, because the hydroboost sits higher than the vacuum booster, which in turn pulls the lines up. So do as I say, not as I do

 

21) Reinstall the ground to the battery

 

21) Now fill the power steering fluid reservoir up, but not all the way. Jack the front wheels off the ground and place on jackstands (I do not want to be liable for anyone getting hurt if I don't put that in). With the motor OFF, turn the steering wheel, lock to lock, 20 times total, but do it 5 cycles at a time. After every 5 cycles check the level of your power steering fluid. Fill up, and continue. After 20 cycles, make sure fluid level is good, and then fire her on up. cycle the steering wheel lock to lock (keeping in mind the fluid level is good) until you feel confident that all the air is out of the lines and booster, and gear. You will normally get some crap fluid back from the steering gear, so I always like to keep a turkey baster handy to suck it out and replace it with fresh fluid.

 

22) Shut vehicle off. Jack up, take out stands, set back on ground, and check the level of your power steering fluid. Get it about halfway between the Cold and Hot mark.

 

23) Bleed the brake system. Keep bleeding until you get new fluid spewwing out of all four corners. Start with passenger rear, then driver rear, then passenger front, then driver front (furthest to closest from MC). Make sure you hit each corner at least 3 times. I just wanted to make sure I got at least 99% of the air bubbles out, so that's just my .02

 

24) Obviously this requires two people, unless you got one of those fancy machines. So "Grab Some Buds" and get going

 

24) Reinstall wheels, and go test drive**. If there feels to be any air in the lines, rebleed all four corners again. After going around the block a few times, check the level of the PS fluid, and make sure it is in operating range

 

25) Now marvel at the stopping power of hydroboost. And goodbye squishy pedal feel (maybe thats cause I put braided hoses, new calipers, bigger front brakes and dual rear pistons on my truck). But you can definitely feel the difference, night and day, from vacuum assist.

 

 

**(Disclaimer: Please do not drink and drive. It is stupid and is completely avoidable. If need be, have someone else test drive your truck. Thanks!)

 

 

 

 

[CapitalTruck]

My friend, top notch post. Also, way to go in that job. The thought of converting to hydro-boost never even occurred to me. I probably won't do it, but kudos to you for doing it. With the significantly larger wheels/tires it probably makes sense.

[LongrangeLauber]

My friend, top notch post. Also, way to go in that job. The thought of converting to hydro-boost never even occurred to me. I probably won't do it, but kudos to you for doing it. With the significantly larger wheels/tires it probably makes sense.

 

Aw man, with the hydroboost, bigger front brakes, dual piston rears, slotted and dimpled rotors, EBC green stuff pads, and braided stainless brake hoses, this truck easily locks up tires. I showed my friend last night. Nearly threw both of us through the windshield if we werent wearing our seatbelts. I cant wait to try it out towing a 5000 lb. trailer. Now I have no problem putting 37's on without the fear of stopping

[RyanbabZ71]

Thanks for the write up. Moving to the How To section for future reference.

[kstruckcountry]

Awesome write up!

[music]

Best post of the year award?

[LongrangeLauber]

Best post of the year award?

Do we have that on here? Haha

[RyanbabZ71]

Best post of the year award?

 

Do we have that on here? Haha

 

We do now and the winner has to buy a round for all members

 

 

Ryan

 

 

[LongrangeLauber]

We do now and the winner has to buy a round for all members :lol:Ryan

Aw man, guess I better start saving now haha

[Chris]

Aw man, guess I better start saving now haha

 

And I only drink top shelf

[LongrangeLauber]

I guess I'll just go get a loan so I know we are all covered haha

[LilJon3191]

On 7/7/2013 at 3:04 PM, rdnckhntr94 said:

13) Now that you have finished the hard part, lets go on to the easier stuff. Let's install that new power steering pump. Mount it to the alternator bracket (3 bolts on the front, and then mount the bracket on the back from the old power steering pump). NOTE: if you did not install a new PS pump, you do not have that second return port. In order to solve this, get a brass "T" fitting that fits the hoses (I believe it is 3/8") and three hose clamps. You can either tee into the return line from your cooler (if you have one) to the pump, OR you can tee into the line from the steering gear TO the cooler. It doesn't really matter where you put it, because there is not much fluid coming out from the hydroboost unit. It is all preference.

 

14) Once done with that, DO NOT reinstall the alternator bracket back to the engine. Take your pressure hose from the pump to booster (#36-365454) and mount it to its rightful place, which is on the back of the power steering pump. The end with a lot of turns is the one that mounts here. Once that is installed, you may now reinstall the alternator bracket back to the engine. Once that is done, reinstall the PS pump pulley. The lip of the pulley should be flush with the end of the shaft, which is how most pulley installers are made (a bolt, nut, and washer will also work for this, but since you already have the tool, might as well use it). You can reinstall the serpentine belt now.

 

15) Connect the other end of the pressure hose to the hydroboost unit. New hoses come with a sleeve of rubber hose over the metal tubing part. I figured it was to prevent rubbing between the booster unit and the hose. Here is a pic of that:

 

 

16) Now you can unhook the pressure hose from the gear, as well as feed the original return line to the same return port on the new power steering gear. Set power steering pump with other parts you will not need.

 

17) Take new pressure hose (#36-365466) and run from gear to booster, or vice versa. The side with a lot of bends goes to the steering gear. I actually had to bend the metal line a little bit in order for the line to set down there properly. I routed the pressure line behind the brake lines, like so:

 

 

Orange is pressure hose from pump to booster

Red is pressure hose from booster to gear

Yellow is return line from booster to pump

 

18) Install return line like shown above. There is only one return port left and it sticks up from the side of the pump. Hard to miss.

 

19) Now you can install your new master cylinder AFTER you have really done a good bench bleed. Make sure there are no bubbles coming from the lines when you bench bleed the unit. It makes it 20X easier to bleed the brakes if you took out the time to really bench bleed your new MC.

 

20) Attach the brake lines FIRST on your MC and then install the MC on the hydroboost unit with the 15mm nuts from your old vacuum booster. I had trouble installing the brake lines after I mounted it on the hydroboost unit, because the hydroboost sits higher than the vacuum booster, which in turn pulls the lines up. So do as I say, not as I do

 

21) Reinstall the ground to the battery

 

21) Now fill the power steering fluid reservoir up, but not all the way. Jack the front wheels off the ground and place on jackstands (I do not want to be liable for anyone getting hurt if I don't put that in). With the motor OFF, turn the steering wheel, lock to lock, 20 times total, but do it 5 cycles at a time. After every 5 cycles check the level of your power steering fluid. Fill up, and continue. After 20 cycles, make sure fluid level is good, and then fire her on up. cycle the steering wheel lock to lock (keeping in mind the fluid level is good) until you feel confident that all the air is out of the lines and booster, and gear. You will normally get some crap fluid back from the steering gear, so I always like to keep a turkey baster handy to suck it out and replace it with fresh fluid.

 

22) Shut vehicle off. Jack up, take out stands, set back on ground, and check the level of your power steering fluid. Get it about halfway between the Cold and Hot mark.

 

23) Bleed the brake system. Keep bleeding until you get new fluid spewwing out of all four corners. Start with passenger rear, then driver rear, then passenger front, then driver front (furthest to closest from MC). Make sure you hit each corner at least 3 times. I just wanted to make sure I got at least 99% of the air bubbles out, so that's just my .02

 

24) Obviously this requires two people, unless you got one of those fancy machines. So "Grab Some Buds" and get going

 

24) Reinstall wheels, and go test drive**. If there feels to be any air in the lines, rebleed all four corners again. After going around the block a few times, check the level of the PS fluid, and make sure it is in operating range

 

25) Now marvel at the stopping power of hydroboost. And goodbye squishy pedal feel (maybe thats cause I put braided hoses, new calipers, bigger front brakes and dual rear pistons on my truck). But you can definitely feel the difference, night and day, from vacuum assist.

 

 

**(Disclaimer: Please do not drink and drive. It is stupid and is completely avoidable. If need be, have someone else test drive your truck. Thanks!)

 

 

 

 

Just wanted to say great post! I took the hydroboost system off of a 2004 Tahoe and converted my 2004 Silverado to hydroboost and this really helped me out to go over every step and make sure I did everything right. 

[LilJon3191]

Just did the conversion on my 04 1500 Z71. Everything is working perfectly brakes are like night and day compared to the vacuum booster system. There's just one little problem I've got, anyone out there know how to shut the "Service Brake Booster" light off of the dash? And I also just realized my cruise control isn't working for some reason. Any tips?

Edited March 7, 2019 by LilJon3191