Hydro-Boost Leak/Synthetic?

[Hook_'em_Horns!]

My brake pedal has been feeling unusual in the mornings. Today, noticed a leak in the tire well area below the HB. Service was checking the feel with some heavy pedal action yesterday, could be the return line clamp leaking from it. Had a PS system flush on the schedule for in the morning anyway.

Does a failing Hydro-Boost unit leak externally?

Because of the high heat generated, my GM advisor suggested going synthetic. I am unaware of a PS synthetic fluid, anyone?

[DmaxMaverick]

They can leak externally whey they are on the way out. Usually around the accumulator (aluminum cylinder on the inboard side), or at the rear, between it and the MC. If it came on all of a sudden after a service, I'd suspect a leaky connection, like the return hose, or a fitting that isn't tightened properly. Don't just tighten them. Remove the connector (flare nut) and be sure there isn't any debris or damage/dents to the the flare. Then, tighten them back down, holding the line square to the surface (make sure the flare gets a proper engagement). The return line is just a nipple/clamp fitting, so check it carefully to be sure they didn't damage the inside of the line when it was installed (very common).

I use synthetic ATF (Amsoil Universal ATF, but any major brand syn Dex-III should be fine) for the PS system. I seem to have fewer problems with the system than others when I use this fluid, and I've done it on all my vehicles soon after new.

[Hook_'em_Horns!]

Is this unit a Dealer only item? I have not been able to find an aftermarket replacement. GM wants $504 for one. :p I may have to trade it in if that is the case. Anyone have a source?

[DmaxMaverick]

It could be because the model year is still too new. Earlier model year hydroboost units can be had at Napa, Autozone, etc. Try www.gmpartsdirect.com or www.rockauto.com for pricing much better than your dealer. gmpartsdirect will have genuine GM replacements, while rockauto may have OEM, but most of the time is aftermarket. Either online store will be able to cross the GM part number if you have it (provided they stock the part).

[Hook_'em_Horns!]

Thanks, I'll give 'em a try. No listings locally at Auto Parts sources for one, even back to 2001 models.

[DmaxMaverick]

I couldn't find it listed in any of the catalogs. Go to www.gmpartsdirect.com and email or call them. Provide your VIN and they'll be able to locate the unit for you.

[Hook_'em_Horns!]

I couldn't find it listed in any of the catalogs. Go to www.gmpartsdirect.com and email or call them. Provide your VIN and they'll be able to locate the unit for you.
Okay, thanks. Sent an inquiry but just missed ‘em at 5.00p eastern. It is part # 15804059.

After cleaning up the mess this weekend and a little low-key driving today, the fluid is back everywhere on the chassis again, but none on the actual unit itself or the connections. I’m trying to visually see a leak under use, but I’m having no results. It just appears on the frame rail and blows back under on everything. Maybe it leaks when not in use. The fluid on the frame rail is as far forward as the end of the Master Cylinder, which is strange in that it is 6” forward from the back of the HB unit.

More solvent spray to clean and keep looking I guess.

[DmaxMaverick]

Are you actually losing PS fluid? Or enough to explain the volume you are seeing on the frame? This sounds more like a leak in a PS line, or another system, altogether. By the time you have enough fluid leaking from the HB unit, it should be very wet with fluid, or at least the firewall soaked. Check inside the cab, below where the brake linkage exits. If it's leaking here, the carpet padding may be soaked.

[Hook_'em_Horns!]

Oh yeah, the PS reservoir was drained which led me to check all involved components first. Inside and outside firewall are dry. I just now found some residue on the underside of the MC/HB unit so, that must be it although, if it is leaking there, then the inner fender directly below should be covered but, it isn’t.

If it is leaking from the accumulator, that would be directly above the frame rail and make sense but, the residue is 12” forward of that, past the upper shock mount. I just wanted to re-create the leak for visual confirmation before I R&R the HB unit. Losing half a quart at a time, I would think it would be easy to see.

I pulled the heat shield back on the PS lines, and while they’re soaked outside, inside the shield, it’s dry.

Running pink synthetic in the system now but, the residue everywhere appeared clear and had no Diesel odor to it. The MC is full, so it’s not brake fluid, although the viscosity feels like Brake Fluid. Since I can’t make it leak in the shop, I guess I can wrap a rag around it while driving to show more of the flow.

Maybe I’ll here some good news from www.gmpartsdirect.com in the morn. Thanks again for your input.

[Hook_'em_Horns!]

Email Inquiries to www.gmpartsdirect.com have gone unanswered. Anyway to contact them by phone?

[DmaxMaverick]

Strange. I've always received an answer in 24 hours or less (not counting weekends) using the contact form. Are you using the contact form, or an actual email address? Or, is it just a bad week? I dunno.

[Hook_'em_Horns!]

Strange. I've always received an answer in 24 hours or less (not counting weekends) using the contact form. Are you using the contact form, or an actual email address? Or, is it just a bad week? I dunno.

No, I used the contact form and had an instant response of:

Thank you for your customer service request. Due to the overwhelming
volume of incoming requests there may be a delay on our response time.
Thank you again for your patience as we answer all requests in the order
received. Emails are usually answered Monday thru Friday 8:00 am to 5:00
pm Eastern Standard Time. Thanks for stopping by www.gmpartsdirect.com.

Thank you,
Customer Service
www.GMPartsDirect.com

[Roy W]

I've recently had two inquiries to gmpartsdirect go totally unanswered. It's been a month and still no response.

[DmaxMaverick]

Luck of the draw, I guess. I'd send them again if more than a couple days. They used to have a CS phone # listed, but can't find it now. Maybe they're more busy than they have staff to cover the contacts? I'll try to find the number I used before.

[Hook_'em_Horns!]

Never mind, I guess. Today, I just found out the parts counter gave me the wrong part # last week. While their online catalog shows no listing doing a truck build, I plugged in the now CORRECT part # and there is was, $262.00.

To view the parts catalog, you must agree to the disclaimer addressing the errors that may or may not exist. There must be something to that after all. Start with the right part number or, try to check with the dealer parts look-up. In my case, that didn’t work either the first time.

Good deals on GM parts, but with no phone number and my experience with no response to several inquiries, I'd hate to have a problem and need to try and exchange something.