I started working on the 3/4 side of the plenum’s air intake, and went about doing the slow job of disassembling the throttle body.
I’ve reached about the end of what I can do with scotch pads, sand paper, a pick, and solvent in terms of cleaning up the aluminum.
I just can’t get into some of these crevices and such, and it makes me realize how much I had with I had, or had easy access to, a small medium blasting cabinet. This would all be a piece of cake to clean up and so much better on the fingers and wrists.
Now the throttle body itself actually has the worth of the filth.
I slowly began to disassemble everything. and dropping each bit into the solvent the loosen up years of crud.
However, when it came to tackling the butterfly in the throttle body itself, I discovered something awful that I had not noticed before.
Now I noticed when I pulled it off that the rear facing screw holding the no longer available throttle body sensor was missing, but I failed to notice all of the actual damage to the plastic itself.
And entire corner is broken off and you can even see other stress cracks in the plastic.
This is truly worrisome, since I’ve had to jostle this around a bit and I’m hoping that I haven’t caused any problems to the switch itself.
The actual switch itself is pretty simple. As the accelerator is pressed, it pulls the cable all the way at the engine and this opens the butterfly letting more or less air in. The butterfly pivots along this pice, with different contacts hitting different parts and sending a signal to the ECU. It is all about air motion and air volume getting sucked in, hence the L in L-Jetronic, L being short for the German word Luft which means air.
Now there is one O-ring that will be easy to replace, but then I discovered 2 bushings that hold the throttle body shaft into the housing (on on either end).
They are in adequate shape. The one more so than the other. These would perfect pieces for 3-D printing. I have to find something to possibly replace the one that is slightly crushed.
Now most of the grime on the interior of the throttle body and the plenum are the result of the the emissions systems and the EGR systems, other wise it would be just air.
So you’ve got the fumes coming from the charcoal canisters getting sucked into the air filter, the blowback of oil particles from the breather hoses, and then the recirculated parts of the exhaust that were sucked back in to recombust. I don’t know when or which prior owner cut the EGR filter and crimped it below the tin, but it was obviously a working system for some time given the amount of soot I cleaned out of the pipes as well as the interior diameter of the throttle body.
Absolutely none of this is visible on the engine itself once everything is back together.
But I’ll know it is clean.