Easy Smoke test for 0171 and 0174
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Teching In
Joined: Sep 2018
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Easy Smoke test for 0171 and 0174 After engine rebuild, using stock parts, I ended up destroying pushrods, rocker arms due to my failure to actually measure the required length. It did run for 200 miles before pushrods started breaking, with no codes. I took the top end apart again to replace lifters, and proper measured pushrods, putting every thing back together, and I am getting 0171 and 0174 banks 1 and 2 lean codes. Figured, well dang, got something loose on my intake causing a vacuum leak.
In an hour, I made a home made smoke machine to try to find the leak, using the video here as a guide using parts I had laying around. I unhooked the hose at the intake going to the left valve cover (PVC), and hooked the smoke machine here. I pumped and pumped, and did not see smoke anywhere, except coming back out the air box. It impressed me how I could force smoke all thru the intake, back out the closed throttle body, and back to the air clearer.
I decided to try to get a better view from the other side, and saw some smoke actually coming from below the air cleaner, and it was coming from the air silencer tube between the MAF and the throttle body. Sticking a finger down there, feels like a small split seam in the plastic, but sure could account for setting my codes.
This weekend plan to remove and repair. Right now guessing I maybe cracked a seam taking the silencer back off after the pushrod repair.
I certainly did not expect an issue at the silencer, and If I had tried to spray a gas or liquid to leak detect by rpm changes, I think I would have missed checking this spot. The smoke test was great, and I would recommend as a first test for anyone thinking they may have vacuum leaks, especially since a smoke machine can be made for nearly nothing. Most expensive thing would be a soldering iron, and bet if you look you could find one for a buck or 2 at a garage sale.
It is possible I still have something else wrong causing my codes, but I am thinking I found the issue, and it wasn't where I expected at the intake.
FYI, my entire glass jar, metal lid started to get very warm to touch, so needs to be unplugged just as soon as done testing.
Just wanted to recommend how a smoke test could just about out preform just about any other test looking for vacuum leaks
In an hour, I made a home made smoke machine to try to find the leak, using the video here as a guide
I decided to try to get a better view from the other side, and saw some smoke actually coming from below the air cleaner, and it was coming from the air silencer tube between the MAF and the throttle body. Sticking a finger down there, feels like a small split seam in the plastic, but sure could account for setting my codes.
This weekend plan to remove and repair. Right now guessing I maybe cracked a seam taking the silencer back off after the pushrod repair.
I certainly did not expect an issue at the silencer, and If I had tried to spray a gas or liquid to leak detect by rpm changes, I think I would have missed checking this spot. The smoke test was great, and I would recommend as a first test for anyone thinking they may have vacuum leaks, especially since a smoke machine can be made for nearly nothing. Most expensive thing would be a soldering iron, and bet if you look you could find one for a buck or 2 at a garage sale.
It is possible I still have something else wrong causing my codes, but I am thinking I found the issue, and it wasn't where I expected at the intake.
FYI, my entire glass jar, metal lid started to get very warm to touch, so needs to be unplugged just as soon as done testing.
Just wanted to recommend how a smoke test could just about out preform just about any other test looking for vacuum leaks
