I've been tinkering with old 89 model 4Runner for a few months and have her looking and running good but the ticking of an exhaust leak was really starting to bother me. I just knew it was going to be at the manifolds of the 3VZE so, of course, I had exhaust mods on my mind. Before I got too carried away I decided I needed to know for sure where the leak was and was looking for a good way to test for it without all of the noise from the engine and air from the fan so I came up with this. It's probably already been done but I never saw it so I thought I'd post this method that worked so well for me.

I had seen where a guy had pressurized his exhaust system by putting the exhaust hose of a shop vac in the tail pipe and spraying soapy water on the joints to try and find the leak but I didn't like that I couldn't hear the leak over the noise of the vacuum or the fact that I'd have to clean my filthy shop vac to avoid blowing a bunch of sawdust and other crud into my muffler.

What I did was find a female threaded 1.5" pvc cap and a male threaded unidentified adapter (I think it was part of a pool hose that adapts a rubber hose to threaded pvc). I used a 7/16 drill bit to make a hole in the top of the cap, filed it out just a little more and then threaded in a 1/4" male air tool fitting that would hook up to my shop air. I pushed the black fitting into the tail pipe and found it just a hair too small to seal off well so I added a little electrical tape to it and it fit real tight. I wrapped the outside of the joint with a little more tape just to hold it all together and then threaded on my cap with air fitting.

I turned down my air regulator to about 25 psi. (I didn't want to put 100 + pounds into the system and potentially cause another leak.) Next I got my flashlight and a spray bottle of my kid's bubble liquid (can use any type of liquid that will make bubbles at an air leak but the bubbles work awesome). When I hooked the air line to my test fitting I could hear the air fill the system for about one second and then could hear the hiss of an air leak. Crawled under the truck and started to spray the exhaust and when I got to the inlet of the muffler I didn't even need the bubble solution to identify my leak. Sprayed it down and there bubbles everywhere. It was a really bad leak but I had never been able to track it down before without the back pressure.

I sprayed down the rest of the system and didn't find any other leaks. I'm thinking about upping the pressure a little and testing it again but I'm not sure what the maximum pressure threshold should be on a test like this. If anyone has an opinion on this I'd like to hear it.

Anyway, I hope this helps. Here are some pics of the setup.

 

I like that idea and never would of thought of it. I always put a little diesel fuel in the intake ( a couple of ounces or ATF fluid) and with it idling, have some one with a rag to block off the exhaust end and look for the smoke. I think I like your way better. Great idea.

 

Never seen this either. I too used the rag over the end of the tailpipe.