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Subject Smoke testing / GFB recirc valve replacement
Posted by cherry on May 29, 2023 at 3:00 PM
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Message My car seemed to be slow to build boost. The boost would climb with revs, but wasn't coming on as quickly as it used to. Time for a boost leak test.

In the past, when I had tested for leaks, I would use a crude "smoke machine" cobbled together from a metal peanut can with a plastic lid, a few plastic tubes, and a lit smoke bomb. It worked; I was able to locate a leak using it. But it was less than ideal, requiring precise choreography and timing in order to get enough smoke into the system to find any leaks. To make matters worse, it was difficult to regulate the air pressure, since the plastic lid was flimsy and prone to popping off the can.

I figured I'd up my smoke machine game with a DIY version I'd seen on YouTube. This version uses a PVC housing encasing a thin wire wrapped around a tiki torch wick soaked in baby oil, and powered by a 12 volt battery. I spent around $50 at Lowes and Amazon to put it together (PVC pieces being the most costly part). Using it, I discovered that the driver's side recirculation valve was leaking.

I ordered the GFB Mach 2 T9135 from SpecialtyZ. I also bought a 90 degree, 30 mm silicone hose, but ended up not needing it, since the old stock hose was in good shape, and easy enough to modify to fit.

These photos were both taken after the installation. A second round of smoke testing revealed the intake system held pressure, and there were no more leaks!

The GFB item seems like a convenient replacement for aging recirc valves. I clocked the top of the valve 90 degrees from stock, in order to make the installation as tidy as possible. It seems well made. The valve itself is brass, and the housing is aluminum. Will it last 30 years, like the OEM valves did? Time will tell.

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