How to Smoke Out a Vacuum Leak
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- čas přidán 8. 01. 2021
- Using a smoke machine to reveal leaks in the carburetor, hoses, gaskets, etc. I see a lot of smoke coming from the valve cover. At first I thought it was an internal vacuum leak, but it was just smoke leaking past the valve guides and seals into the crankcase. This was verified in my video, "Checking for an Internal Vacuum Leak".
- Auta a dopravní prostředky
How do you know that smoke through the breather grommet means an internal vacuum leak at the manifold. How do you know that the smoke is not leaking past the piston rings and into the crankcase?
You are right. It was leaking around piston rings and valve guides. This is discussed at the end of the video. Human nature to watch only the first few minutes, so I get a lot of comments same as yours. After the smoke test, I put a vac gauge on the crankcase and there is a video for that as well.
Hello, where can I find the carb cover to keep the smoke in?
I borrowed the setup from a friend. Not sure where he got the carb cap. I'd suggest checking with JEGS.
Very good, did u make ur smoke canister ? If how?
No, I borrowed it. It's basically a paint cup with two holes drilled in the sides for electrodes. The electrodes are insulated from the cup with nylon bushings. A piece of cotton cloth is wrapped with a solid core wire, small maybe 14-16 AWG. The ends are wrapped around each electrode. The cup is then filled to just above the cloth with baby oil. When you apply 12volts across, the wire heats up and causes the baby oil to burn, producing the smoke.
is the throttle open , is the ignition set to on?
Throttle closed, ignition off.
@@BriansGarageUSA THX
Great video. What was the final outcome?
Vac leaks were not the issue. The engine run-on was caused by the HT383 camshaft early intake valve closing. Cranking cylinder pressure was 210 psi! I ended up changed the camshaft to delay intake valve closing while increasing duration slightly. This lowered cylinder pressure and allowed me to better tune the idle.
@@BriansGarageUSA
Oh wow. As for me it looks like some of my rockers are loose. I have a fresh rebuilt 350, just did the 500 mile oil change. I saw on another CZcams on how to adjust the rockers old school with the engine running. I'm going to give it a try. I'm pretty sure this is what is causing my Vac gauge needle to bounce around.
@@DarthMayers Yes, if valves are too tight, will not fully seat and this will cause vac needle to bounce. For sure do the rocker adjust while running. Just back 'em off until clatter, then tighten to quiet plus 1/4 to 1/2 turn.
@@BriansGarageUSA
Thanks for the tip bud. I'm a novice to this but I am having fun learning. I also went ahead and bought me a set of rocker arm oil deflectors. Hope they work so oil won't make a mess. My car is a 78 nova.
@@DarthMayers Those work, but still remove one cover at a time, keep the idle low (600-700) and work fast so as not to spew too much oil.
Smoke coming from crankcase doesn't automatically mean your intake manifold is leaking. More than likely its going right by your rings. There's always a ring gap, hot or cold. The only way it would be manifold related is if the manifold is cracked on the bottom or the gasket is only leaking at the bottom of the intake runner gasket which is very unlikely. I bet you kept replacing intake manifold gaskets for no reason.
Correct, as previously hashed in the comments, a small amount of blow-by is normal.
No, I did not change the gaskets. It dawned on me pretty quickly that was a possibility. To verify the extent, I actually put a gauge on the crankcase and found it to build pressure for the same reason. There's a video of this on my channel.
It could also go through the pcv