Secondary Air Injection Valve?

RhinoRover

Well-known member
Sep 13, 2016
54
0
Palmer Lake
Does anyone know the function and how the secondary air injection valves work? The two that sit on top of the air lines going into the heads. One of mine is ticking upon start-up when the engine is cold. It only lasts 10-15 seconds. Just curious. Thanks.
 

squirt

Well-known member
Nov 13, 2008
824
13
Los Angeles
The ticking is likely an exhaust leak. The intent of SAI is to push outside air into the exhaust to complete the combustion cycle, but it is possible for exhaust to leak through the lines if the valve is not closing, or if there is a leak at one of the joints.

Another possibility is that you have an exhaust leak at the manifold due to a loose fastener or something similar that simply seals as it warms and expands.
 

RhinoRover

Well-known member
Sep 13, 2016
54
0
Palmer Lake
The ticking is likely an exhaust leak. The intent of SAI is to push outside air into the exhaust to complete the combustion cycle, but it is possible for exhaust to leak through the lines if the valve is not closing, or if there is a leak at one of the joints.

Another possibility is that you have an exhaust leak at the manifold due to a loose fastener or something similar that simply seals as it warms and expands.

I was thinking an exhaust leak too, but it feels and sounds like it's coming from the sai valve. I'll look into it closer. It's not super loud or anything, just want to stay ahead of any problems.

What's your thoughts on the purge valve that's in the same vicinity?

Thanks!
 

Dangeruss

Well-known member
Mar 28, 2007
104
1
Ontario, Canada
Maybe it is not closing fully and warming up closes it. If it's leaking you should be able to feel the pipe warming up more than the other side, as long as the pump isn't blowing, I had one of these fail open before a 4 hour drive and the exhaust heat melted the plastic hose to the pump. It also melted into the bottom of the brake booster vacuum line which was resting on the SAI pipe, this created a small vacuum leak so I had no brake boost at low speeds.