Table of Contents

11.6.3 How To Check For Intake Manifold Leaks

Q: How can I check for intake manifold leaks?

There are a few ways.
  1. Using Direct Link's recording features, watch for a high spike in AFR readings during acceleration. A sudden increase in air will increase the AFR dramatically and if this occurs in a normally rich condition, such as during acceleration, this is an indicator of a leak. Just be careful not to confuse the similar looking deceleration spikes with this issue.
  2. Another method is to use carb cleaner or PJ1 spray. You have to be very careful not to let the spray curl into the air cleaner as it will give you a false indication. Perhaps make a card board cut away that slides between the air filter assembly and the gas tank. This serves to block the spray from curling into the air cleaner. It has to be tested with motor running. If you spray the manifold and the RPM drops and then returns, you have a leak. Spray from the horn side first very carefully and if no leak is found or the rpm does not change, then spray from the air cleaner side. The key is to make sure the spray does not get into the air cleaner as the rpm will drop giving a false read.