810-05003 810-05001 VACUUM CLUTCH BOOSTER FOR ISUZU NPR115 4BC2 4BE1 4HF1

1. What does a booster do?

A power booster helps assist pushing the master cylinder piston when you apply the brakes.

2. What are the performance of a problem brake booster?

A bad power booster will give a very hard pedal, it will feel like you need two feet to stop the car.

3. What size booster should I use?

For lighter weight vehicles like street rods a 7" booster will work fine for disc/drum set ups. For a 4 wheel disc system a 7" booster will not give enough assist. An 8" dual diaphragm booster is the ticket for 4 wheel disc.

4. The brake pedal is low and soft. I think I need to replace the booster, right?

No. The booster will never cause a low or soft pedal, check for air or other hydraulic problems. A failed booster will only cause the pedal to become hard or not return.

5. After some time of brake applications, the pedal starts to get hard. How do I fix this?

Check the vacuum source to the booster. Not only does the booster need at least 15 in. Hg, it also needs vacuum volume. The fitting normally on the intake manifold or carburetor will get clogged with carbon build up and restrict the vacuum volume.

6. I replaced the booster and now the brakes are locked up and won't release. What should I do?

Replace all brake fluid. Brake fluid is hygroscopic which means it absorbs moisture. Too much water in brake fluid will cause vapor lock and apply pressure to the wheels. Also, carefully check for proper push rod adjustments and stop light/cruise control switch adjustments.

7. The original problem was a hard brake pedal. I replaced the booster and I still have the same thing. What can I do now?

Check for a seized caliper/wheel cylinder, pinched or restricted brake line. Next check vacuum source. Check for at least 15 in Hg. Next check vacuum volume. TIP: An easy test is to park a vehicle with a good brake pedal next to your car and run the vacuum to booster in question. If pedal is OK now, vacuum source is insufficient.

8. I installed a new booster. Why am I hearing an air noise under the dash?

This is usually a normal noise made during brake application due to atmospheric air entering the booster filter located around the push rod. Tip: Moving the silencer (foam seal) may reduce noise level.

9. I replaced 2 boosters in during one year. What may cause the situation?

Check for gas vapors in the booster. If the vehicle's PCV is clogged,