How to find Vacuum Leaks

During the course of your rebuild, did you remove any emissions related components? Specificly the emulsion tubes that screw into the cylinder heads just above the exhaust ports?

 

Surprisingly, Sears has a very nice stethoscope in the Craftsman tool department. It's pretty cheap, but it works well for finding odd sounds. I hope that helps.

--Matt

 

A method often used for very small leaks is to spray water around the suspicious area. The reduced pressure at the leak will evaporate enough water to drop the temperature and form a tiny ice plug. This should change the noise you hear or if using a gauge show an improvement in the vacuum.

 

I'll second that. Its how I found the leaks around the throttle shaft bearings on my carbs...

 

If you rebuilt the engine why not use new vacum hoses? Sorry...I'm not trying to be a smart A

 

I have used the " Spray starting fluid and listen for the increase in RPM's" many times on v-8 gas and diesel engines with pretty good success.

 

I second this method ...... that is if it's a sizeable leak ... you'll hear the difference when it starts sucking starter fluid. Just don't blow yourself up thanks to some sparking plug wires!!!

But I've also had very good success with a stethoscope finding a multitude of issues .... I use the Sears model mentioned .... it's amazing what sounds you can isolate and pinpoint using one of these.

Good luck.

 

There are special foam building additives at cheap prices. Even minor leaks will cause a lot of easy visible foam. I used to use them when I was assembling pneumatic devices in vacation during my time at the University.