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Discussion Starter #1
i have a 2004.5 and the hydroboost is leaking. I have read a number of threads about using the LML hydroboost but seem to find more than one part number... Any wisdom is much appreciated!

Is the LML hydroboost part number : 19371365, 22745516, 178-1040 or is it something else...

Is the LML hydroboost direct replacement or not? Ive found some posts that say: yes direct fit, some hose mod required, actuator rod is the wrong length...
 

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I put AC Delco 178-0853 which Amazon says fits 2011 (but not our 2004.5's, but they're wrong). Here's the review I wrote:
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I learned about this upgrade for the older trucks on a diesel truck forum. I also installed ACDelco 20756713 GM Original Equipment Power Steering Pump as an upgrade. Since new, my vintage of the diesel had 2 less-than-great problems: (1) idling, turning, braking at the same time often suffered a hard steering wheel, and (2) not the greatest stopping and pedal feel during heavy braking.

The pump solves problem #1. This hydroboost seems to solve #2 (I've only done a few test drives so far, but I am impressed!!). This hydroboost, unlike the 2004 original, actually increases power braking assist the harder you press.

The push rod, where it attaches to the pedal, has a little slop (on purpose). As you press the pedal, the rod presses the brake switch first, then as you press further,the eyelet in the rod makes contact with the pin on the pedal. Fearing this problem, I slightly elongated the eyelet towards the hydroboost to ensure the brake switch engages. It might not have been necessary.

Also, the rod is slightly longer so the brake pedal is raised slightly (sorry, I didn't measure before and after). Since I always thought the pedal throw was a little short, this is a good thing.
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It's been over 7 months now and several trips, and the brakes still work WAY better than they ever have. Some people had problems with the brake light switch, which is why I elongated it just a little. If I was assigning a letter grade, I would have given the original brakes a C+, and my upgraded ones a B+.

I suggest buying a new clip that holds the rod and brake switch on. Good thing I did because after fighting to get the old one off for an hour, I gave up and ripped it off (still wasn't easy!).
 

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Discussion Starter #3
Awesome! thanks for the writeup. I don't know why, but i didn't find that on the dmax forum. must have used the wrong search words. I have read of some drilling out the actuator rod and others swapping the rod from their old unit. wonder which works better?


Also the Delco part number 178-0853 on amazon says the OEM part number is 20940394.

If i put that number into the GM Parts website it says its been discontinued and replaced with OEM part number 19371361. If you search on Amazon 19371361 it gives you Delco part number 178-1036. Wonder whats different except $100...

the 178-0853 is $349.95
the 178-1036 is $243.44
 

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Discussion Starter #4
If I look up 2011 silverado 3500 duramax on rock auto it gives the 178-1036 part number...
 

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LHN...We ARE the Joneses
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178-1036 is $200 @ Rock
https://www.rockauto.com/en/moreinfo.php?pk=10576556&jsn=258

Always replace with new....you don't want to be playing contortionist up under the dash again in 6 months.....plus with new, there's no swapping the plunger over.
PULL the driver's seat out....4-bolts and you'll be in Heaven, stretched out and comfy with your legs in the back seat. :howdy

One of the original draws toward using the 2011 HB, it was cheaper.
There is info posted on the exact drill bit size to open up the plunger hole a tad bit, so that the brake switch works properly.
17mm (about 43/64) drill bit
Some just use a step bit drill...and guess at it.
 

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I suggest buying a new clip that holds the rod and brake switch on. Good thing I did because after fighting to get the old one off for an hour, I gave up and ripped it off (still wasn't easy!).
Save yourself some headache time, pick up one of these tiny extended length screwdrivers to release that demon clip.
 

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Discussion Starter #7
Thanks Hook Em! I appreciate the advise.
 

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Sigh......guess I'll add this to the ever growing upgrade list.


Sent from my LG-H831 using Tapatalk
 

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TXLLY, I put that review on Amazon. I don't understand GM part numbers and pricing. For at least a few months after I bought mine (178-0853), that part showed as no longer available, and the other (178-1036) showed up when searching for 2011, and it was $100 cheaper than what I paid. Was it essentially the same one? Why $100 cheaper? Does it work as well? I have no idea!!

I think the one for 2004 (178-0683) is well over $500, and doesn't work as well. Don't know why!! GM has a lot of these that sure look alike, with prices all over the place, maybe with internal or plunger differences.

Stick with new AC Delco on this one.
 

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Discussion Starter #10
Thanks for all your help and wisdom!

I ordered the AC Delco 178-1036 hydroboost on Rock Auto. As Hook'Em said its $201. That's $49 cheaper than amazon. Guess next weekend will be install time. I need to get it in before we pull the 5th wheel to Port Aransas for Labor day week.
 

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Wish I knew about this two years ago when I replaced hydroboost and steering pump. I've never been a fan of the brakes and sometimes get a grinding noise in the steering when turning while parked

Sent from my SM-N920V using Tapatalk
 

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I have done everything except replace the Hydro and the brakes still suck. I have done the Hydro check and it's in my opinion kind of inconclusive as a test goes. Also, remember when you add volume pressure decreases so adding the cooler can add to an existing problem. I will be performing another Auto bleed this weekend with an immediate vac bleed on the system to see if it helps BUT I absolutely LOATH the brakes on this truck.

New calipers
Rotors /Pads
flushed a gallon and half of DOT 3 fluid through the brake system
Bleed Master cylinder
PSC power steering pump Higher Pressure unit and GM Cooler ( completely Flushed with flushing oil ) Then SEWPCO 715 fluid.
New SS lines on the Hydro system

I am hoping from everything I have read that Vac bleeding will be the final fix, All the years of wrenching on cars I have never had such an issue with brakes.
 

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Also, remember when you add volume pressure decreases so adding the cooler can add to an existing problem.
This is not true with adding a cooler to the mix with the HD.
The cooler is installed on a low pressure return line back to the pump reservoir tank. It has nothing to do with the high pressure side, except improving performance with the reduced heat load.
 

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. . . I ordered the AC Delco 178-1036 hydroboost . . .
Please let us know if you notice the big improvement some of had with the older (obsolete?) 2011 unit!
 

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There is more than one way to skin a cat. When I remove that clip from the brake rod at the pedal I usually use two screw drivers. I wedge a smaller pocket screwdriver between the pin and the arm on the clip and then use a longer screwdriver like Hook showed to pull it back to the release position. I'm sure there is a special Kent-Moore tool for the job as well as a dozen other options but that is what works for me.

The nice thing is that the clip goes back on with just fingers. I'm sure that is why they use it in the first place. It's all about assembly, not disassembly.
 

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Discussion Starter #17
Just an update:

I installed the 178-1036 Brake booster today. No modifications at all. works great. Big improvement in feel, modulation and you can definitely feel it has more power. Clip came right off. I just slid the small screwdriver between the locking tab and the brake arm pin and it came right off.
 

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I have a brand new one, still in the box, GM part number 19371365. I got it from GM Parts direct, ordered by mistake. Will sell it for $200 shipped.

Fitment is for a 2012 LMM
 

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These part numbers are ridiculous. I search one and get a result for another. Can anyone confirm if 178-1036 will fit a 2008 LMM?
 

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Yes....see post #5 (and the needed hole size improvement).

Years ago, the original draw to the newer (2011 year only) HB, was mainly cost. Extra push on the pedal was a plus, but cost was the draw. For some reason at the time, new HB units for the LLY, LBZ, LMM, were ridiculously high and most were Remans, not new.

However, I see now @rock, the '11LML 178-1036 is $185 (no core $).
while the '08 LMM 178-1037 is $167 (ag'n, no core $).

Your choice. But as stated in post 5, don't go reman. It won't last and you'll be back in playing contortionist up under the dash in 3-6 months. Plus the mess of leaking PS fluid, and the danger of toasting the pump from low fluid levels.

And, by the time you add in the core charge, the reman is more expensive than new...PLUS you don't have to remove any parts and swap over to the reman, the new unit comes ready to bolt in.
 
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