What is the Normal Hg for the Brake Buddy Stealth? Is 10-13 Inches Hg Normal?

Question

Question:

Whats the spec on the Brake Buddys vacuum pump, i.e. how much vacuum should it maintain? Mine maintains between only between 10 and 13 in. Hg. My tow vehicles vacuum system maintains about 18 with the engine running. When I brake while towing, almost no braking action occurs even though the Brake Buddy is pressing on the pedal. I have the brake controller set to maximum sensitivity and power where I would expect to see the tow vehicles wheels lock up during a hard stop on loose gravel. But nothing. I suspect because of the lower vacuum, the power assist from the brakes vacuum booster is minimized, hence almost no breaking occurs. Is only 10 - 13 in. Hg normal for the Brake Buddy pump? Is that range adjustable? Is the pump failing? Help!!

asked by: Jim T

0

Expert Reply:

Hello Jim,

I apologize for the delay. I just resent my email to the Tech at Brake Buddy, my first one must have been overlooked. I am showing that you should be at 18-22 inches Hg, but would like to verify this.

Were you able to get this sorted out already, if so what were your findings?

I will let you know as soon as I have an answer, I will not give up =)

expert reply by: Kate F

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Jim T.

10/27/2025

Hi Kate, thanks for getting back to me. 17 to 22 in Hg is what I'm finding my vehicle ('09 CRV) should be. Mine is a steady 18 at idle. Thanks for not giving up. Regards, Jim

Kate F.

11/4/2025

@JimT Good morning Jim. I now realize on why Hopkins is not answering about the Stealth Brake Buddy, they are part of First Brands who recently claimed bankruptcy so they are having a bit of a staffing shortage. I did some research and found some troubleshooting for you. Since your CR-V holds a steady 18 in Hg at idle, your vacuum system itself sounds healthy, which is great news. The fact that the Brake Buddy Stealth is only maintaining about 10–13 in Hg when the vehicle is being towed suggests the system isn’t quite building or holding full vacuum to the brake booster. That’s enough for it to function, but it can make the pedal feel firmer and slightly reduce braking assist. A few things you can check that usually clear this up: - Inspect the vacuum lines and fittings. Make sure all the hose connections are tight and that there aren’t any small cracks, soft spots, or loose fittings that could be leaking air. It only takes a tiny leak to keep the vacuum from reaching its full potential. - Check the direction of the check valve. There should be a small arrow on the valve showing airflow direction. That arrow needs to point toward the brake booster. If it’s backward, vacuum will bleed off between pump cycles. - Confirm the pump connection. The Stealth’s pump should be tied into the main brake booster line, not a smaller emissions or HVAC vacuum source. If it’s pulling from a smaller line, it won’t be able to reach full vacuum. - Test the pump itself. You can disconnect it from the vehicle and let it run for a few seconds with a gauge attached. A healthy pump usually reaches around 15–17 in Hg with no load. If it stops around 13 in Hg or struggles to get higher, it may be time for a replacement. - Watch how often the pump cycles, If it’s running frequently, there’s likely a slow leak in the system. If it runs briefly and shuts off but never exceeds 13 in Hg, the pump may just be underperforming. I am still in high hopes that their tech will get to me soon. I will let you know as soon as they do. Please let me know how it goes with the provided troubleshooting.

Jim T.

11/4/2025

@KateF The pump by itself, connected to a gauge, runs and stops at 13 in Hg and holds there for a very long time indicating to me that the vacuum switch is the culprit. Since the internal switch is not adjustable or replaceable, out goes the whole pump. I've since replaced it with different pump that stops at 22. When connected to the brake booster on the vehicle it takes about 45 min. to drop from 22 to at 17 where it restarts indicating a very tiny leak. For a 15 yr old car, I can't complain. In my opinion, the system is now working just fine.

Kate F.

11/4/2025

@JimT That’s great news, sounds like you nailed it! You’re absolutely right that the original pump’s internal switch was limiting vacuum at 13 in Hg. Replacing it with a unit that reaches 22 in Hg was the perfect call. A slow drop from 22 to 17 over 45 minutes is excellent for a 15-year-old booster and shows only a tiny, normal leak. Everything’s working right where it should be now.