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Tech Talk with Master Power Brakes

Measuring Engine Vacuum and How It Can Affect Brake Performance

Posted by mpbrakes1 on Apr 2, 2016 1:34:11 PM

pressure-guagePeople who are helping diagnose certain brake problem conditions - in particular a hard brake pedal - often suggest that you measure the vacuum pressure. The advice will sometimes mention that your engine must produce more than 18” of vacuum to give that nice easy pedal feel.  In fact, we just provided that explanation in our recent Teck Talk article on diagnosing causes of a hard brake pedal.

So you’ve measured your engine vacuum and it is less than the desired amount. This may explain the hard pedal, but what is causing the low vacuum problem? While cruising around the internet recently, we found a great article posted up by the folks at onallcylinders.com. In the article they provided a really slick chart that explains what your vacuum gauge is telling you.

Based on their story, step one is checking to confirm that all vacuum hoses are connected and not leaking. To begin measuring, connect the vacuum gauge to an intake manifold vacuum source. You can either add a tee-fitting into an existing vacuum source or alternatively, disconnect one of the vacuum lines like the hose that leads to your transmission. Once your engine has warmed up to operating temperature, you can begin reading your vacuum gauge.

Now that you are warmed up, the readings on your pressure gauge are going to tell you a story. It might point you in the direction of something simple like engine timing or something significantly worse like worn rings or a head gasket that has failed.

Once you have determined your engine’s health, we can now look at your options. If you were fortunate enough to find that your engine timing was off, you can simply adjust the timing and hopefully be where things are happy and your pedal is now nice and easy to press. Now, if you have gone through everything and determined that your engine is healthy and maybe is never going to make adequate vacuum, we have you covered.

If that is your situation - we have good news! Our NEW Silent Drive Electric Vacuum Pump Kit runs 70% quieter and at 10x the efficiency of any other system on the market.  Solve those problems with our electric vacuum pump system and get rid of that aggravating pump noise. Our system exceeds all OEM quality standards and includes everything you need for installation including up to 8' of new vacuum line.

Hopefully now you understand what engine vacuum means and also understand that there is a solution for you should you need to go that route.

Topics: Brake Troubleshooting, engine vacuum, measuring vacuum pressure

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