Pre-heater for air intake problem

[MaddieCycle]

Hi - can someone share a pic of where their pre-heater hose connects to the intake shield around the exhaust manifold?  The hose on my new-to-me 1986 4x4 with Z24i is just hanging free from the air cleaner but not connected below.  I am having problems with this truck having a fast idle and I am wondering if I have a lean condition because I am not getting hot enough air into the intake.

 

Not sure if there is a fitting or clamp that is supposed to go there, nothing clear on the Nissan fische.  Could probably make one with exhaust couplers from the auto parts store, but would like to know what the OEM looks like.  Thanks!

[weldingrod]

There is a small shield on the exhaust manifold with a stub pipe facing upward. The preheater attaches to that. Unfortunately, often the metal around the mounting bolts gets rusted away and the shield comes loose. I suspect someone has removed it and either didn't bother replacing it or couldn't find a replacement part. I am lucky in that I am a welder, so I repaired mine and made it stronger.

[datzenmike]

The ATC (automatic temperature control) system works separately from the choke. The ATC tries to maintain a constant warmed air to the air filter of around 100F by mixing air from in front of the rad with warmed air from passing over the hot exhaust manifold. It uses intake manifold vacuum and a thermostat inside the air filter. At full throttle the vacuum drops and the gate in the snorkel opens fully allowing only cool air from in front of the rad for best performance. Constant air temperature allows the engine to run consistently in any weather for better mileage and performance. One of the things it prevents is carb icing in high humidity /low temperatures, such as in freezing rain.

 

 

The shield will look something like the one on the right side above. On an L series exhaust I have wrappped a metal coffee can around the exhaust with stove pipe wire. It worked fine.

[MaddieCycle]

14 hours ago, weldingrod said:

There is a small shield on the exhaust manifold with a stub pipe facing upward. The preheater attaches to that. Unfortunately, often the metal around the mounting bolts gets rusted away and the shield comes loose. I suspect someone has removed it and either didn't bother replacing it or couldn't find a replacement part. I am lucky in that I am a welder, so I repaired mine and made it stronger.

 

Well, I just got my first welding machine as a birthday gift and have been looking for an excuse to use it!