RRRandy

I got the throttle body off of my ‘86 951 and am cleaning it up. I see where the vacuum hose connects on the bottom, but where does the vacuum go from there? Does it go into the throttle body itself? All I see is a pin hole and I can’t tell if that’s supposed to be there or a nick. Or, is the vacuum routed through the metal housing to somewhere else? It’s awful thin for that. Anyone know?

Randy

Charlotte944

This port goes to the evaporative emissions purge valves. There should be a vacuum routing diagram on the passenger side wheel arch.

35thSLP

The vacuum sender/switch that it is usually connected to is located on the 90 degree piece coming off of the motor that sits between the head and the AOS. One side goes to the throttle body and the other side goes to the EEP valve.

RRRandy

I know where the vacuum tube comes from that connects to the throttle body…my question is, what does the vacuum do once inside of the throttle body? I can see no obvious routing of a cavity to a component on in the throttle body assembly. I think I see a pin hole directly above the inlet port, but it is very small and probably obstructed…or it’s just a nick in the inside of my throttle body and has nothing to do with it. But, if it a pin hole for the vacuum, I want to make sure I get is cleaned out.

Randy

gregeast

When the throttle plate is open a small vacuum is created by the venturi effect caused by the incoming air passing over the hole. In other words, the vaccum is created at the throttle body, it is not acting on the throttle body.

To answer your question directly, yes that small hole is supposed to be there and no, it shouldn't be obstructed.

The system works like this:
- The vacuum 'signal' goes to the thermovalve.
- If the thermovalve is warm enough to be open, the vacuum signal is able to act on the fuel vapor purge.
- Fuel vapor purge valve allows fuel vapors to pass into the hard pipe, just upstream of the throttle body.

The reason for all this complexity? Fuel vapor is to only be purged when the car throttle plate is open and the car is warm (thermovalve open), in other words not at cold idle. Apparently fuel vapor can cause a rough idle.

It scares me that I am this familiar with this little subsystem...

RRRandy

Cool!...That’s exactly what I wanted to know. Your explanation makes good sense. I will make sure the pin hole is not obstructed.

It would seem that, with the residual amount of oil in the intake and that this hole is at the bottom of the plenum, that it would get obstructed quickly? Or more to the point, I would have expected this to be a regular maintenance item and common knowledge.

Thanks!
Randy

Crazy Eddie

I need to move this one to another already prepared TB
Can this be unscrewed ? and if so Lefty loosely?
How is it mounted ... Is it brass ? I don't want to break it.
I need to move it
Thanks in advance
Ed

mikeyoman

It will come out, IIRC think I used some gentle heat and carefully twisted/pulled the angle piece out.
It was a while ago when I removed mine.

Scott H

When I tried to remove that I snapped the nipple off, so use some caution. My solution was to delete the evap system and soldered the hole shut.

Crazy Eddie

Thanks for that info ...

Yeeks by any chance did you heat it first ? ,,,
My plan is to heat the casting and then cool the fitting with ice and try to pull it off
Hope it wks
Regards
Ed

Crazy Eddie

Thanks guys
I was able to get it out ...
Kind regards
Ed

Tom M'Guinn

Say, that's the shiniest one of those things I've ever seen.... Must of been a real new throttle body...

Crazy Eddie

If I ever get this damn thing done, I would love to post a shot ....
I wish I never rebuilt this darn thing !!

Tom M'Guinn

Keep in mind that most truly great artists were tormented by their work...

Crazy Eddie

Especially, a bull**** artist