EGR Pressure Transducer

[benji808]

This is a second diapraghm (I think) that's in line with the regular EGR. Might be exclusive to California emissions. Mine is leaking. Three questions:
1) What does it do?
2) What would happen if I eliminated it (just the transducer, not the egr)
3) Does anyone have one for sale?

Thanks!

[benji808]

I did some searching on the forum and found this thread which provides some help: https://forums.cadillaclasalleclub.org/index.php?topic=164916.msg495917#msg495917

Would still appreciate any thoughts or experience. I'm likely going to try to use the Nissan transducer (or equivalent) mentioned in the article.

["Cadillac Kid" Greg Surfas 15364]

Benjamin,
On my '75 I only have a thermal element in the vacuum line between the carb and the EGR vacuum connection. It is a short (1-1/2" long) cylindrical device.  Is this what you are talking about?
Greg Surfas

[bcroe]

Benjamin,
On my '75 I only have a thermal element in the vacuum line between the carb and the EGR vacuum connection. It is a short (1-1/2" long) cylindrical device.  Is this what you are talking about?
Greg Surfas

The device and circuit you describe sounds exactly like
what all the Olds engines of the later 70s used.  I put
one on my EFI Olds powered Cad.  But I have not yet found
a source of the cylindrical device, just use the ones from
my cars.  Maybe someone put one on the 75.  Bruce Roe

[benji808]

I'm talking about this flying saucer-shaped thing (see picture). Is that the same thing you are referring to?

[bcroe]

I'm talking about this flying saucer-shaped thing (see picture). Is that the same thing you are referring to?

The Olds device I am talking about is shown
here, and as installed near the thermostat.  It
was the only thing between the ported vacuum
source and the EGR on Olds of those years.  So
I put it on my Olds powered 79 Eldo, maybe it
could be on a Cad big block.  Bruce Roe

["Cadillac Kid" Greg Surfas 15364]

This is all my 75 has. Just the thermal sensor in line ahead of the EGR
Greg Surfas

[benji808]

Interesting. I wonder if it's a California car-only thing. Mine appears to have a similar thermal sensor but in addition to the pressure transducer.

["Cadillac Kid" Greg Surfas 15364]

Benjamin
When all else fails, read the FSM. Thats what I finally did and you are correct. This is a California (and commercial chassis) only device. Without going into chapter and verse, it is intended to modulate the operation of the EGR with changes in Exhaust pressure which it gets through the base of the EGR.If you are not concerned with absolute originality and you don't have to smog heck your car then you might consider replacing the EGR and the Pressure transducer with a "Non CA" unit.
Greg Surfas

[benji808]

Final update for this thread: The Nissan part mentioned in the article linked here worked as an essentially direct-fit replacement:  https://forums.cadillaclasalleclub.org/index.php?topic=164916.msg495917#msg495917