To EGR or not to EGR

[Balmoral1958]

Phil is rebuilding my Throttle body. Should I connect up the EGR linkage or just block it off?

1977 Auto Bay Window
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2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa

[Tcash]

The EGR reduces NOx which has a direct relationship with heat.
Benifits:
Reduced NOx
Potential reduction of throttling losses on spark ignition engines at part load
Improved engine life through reduced cylinder temperatures (particularly exhaust valve life)
https://www.cambustion.com/products/egr

https://www.google.com/search?q=nox+and+temperatur...iZFcvtxCqg

It's up to you
Tcash

[Wasted youth]

If you decide to toss the EGR valve, let me know.

[SGKent]

many years ago before Karl passed he said that when Air cooled buses and Vanagons came into the dealership complaining of knocking, pinging, detonation, in almost all cases the EGR was disconnected.

There was this myth in the late 70's that EGR valves cost power. Reality is that the EGR valve only works during mid-throttle and not at wide open throttle. The inert gasses let the mixture be leaner - getting better fuel economy, run at a higher compression ratio without the additional heat, and reduction of combustion temps while at cruise. The results in longer engine life and less smog. The downside is it is one more engine device to keep up with. When the throttle is wide open and all the power is needed, the EGR closes. Which is an interesting question that just popped into my mind. Are the higher temps we see in a T4 engine when running at higher speeds close to wide open throttle a result of the additional load or are they a result of the EGR valve closing.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Balmoral1958]

Thanks - I will install!
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2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa

[Balmoral1958]

don't have the EGR filter - do I have to have that?
_________________
2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa

[Wasted youth]

The missing filter won't cause the EGR to stop working, but it will add a longer duration of time between cleaning the EGR nozzle that resides inside the fuel/air mixing chamber AKA intake plenum.

If you want to pass a legitimate California smog test, it will need to be there for the visual.

Don't forget to reset the EGR counter on the inside of the front clip. It's roughly above the driver's left foot. It's about 4" X 4" with a cable attached.

EDIT... almost forgot to add that I saved three NOS EGR filters from my guy before he closed his yard. They are not plumbed for busses, but the body of the filter is the same size. I can weld new piping when it comes time... so if you find one but it has different piping, take a close look. You might be able to use it with some crafting.

[Balmoral1958]

Thanks - I live in Texas but will keep an eye out for a filter...

The hole where the EGR connection goes into the plenum is almost blocked.

Is this carbon?

Can i just clean that out?
_________________
2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa

[Wasted youth]

Most likely carbon and oil build up. That is how mine was... clean all that crap out and make sure the perforated tube (nozzle) inside the plenum has all the ports opened up.

I found that work best done on a workbench, in a parts washer and finally with a strong jet of flushing water.

[Balmoral1958]

Thanks - good motivation to finally get a parts washer...
_________________
2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa

[SGKent]

I found a few drops of the kind of carb cleaner that we used to dip carbs in worked. A few drops each night for a week to soften it then chuck a bicycle brake cable in a drill and run it into the passage followed by water to neutralize. Essentially the same process WastedYouth suggested. Sometimes that carbon is really hard like coke (used in making steel). Also - that tube goes about, what? - 4 - 6 inches into the plenum?
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Balmoral1958]

Thanks - going to splash-out and buy an ultrasonic cleaner.
_________________
2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa

[SlowLane]

For what very little it's worth, I saw no discernible change in head temperatures when I finally got a working EGR system on my van. I ran it for many years without one and only went to the effort of sourcing the parts and making them functional when I had to make it pass smog in California. I had rather high expectations of running with lower head temps and was quite disappointed.

If you do go through with it, be sure to get the correct EGR orifice gasket for your engine. I can't recall what the orifice size was, but it was different for Cali vehicles than it was for Federal ones. I think that Steve Kent had some orifice gaskets made up years ago but found that not enough people were interested enough to make it worth his time and effort. He may know what the correct orifice size should be.
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Present:
'81 Westfalia: 2L, manual. Originally Canadian, now Californiated
Back in the day:
'72 Super Beetle
'69 Camper Van - Corvair powered
'71 Window Van - Transferred Corvair from '69

"With sufficient thrust, pigs fly just fine." - Internet RFC 1925

"They say a little knowledge is a dangerous thing, but it is not one half so bad as a lot of ignorance." - Sir Terry Pratchett

[raygreenwood]

[SGKent]

Ray - the engineers knew all that. They were able to lean the mixture at cruise in the design to account for the inert gasses, and then map the AFM to run richer at WOT.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[raygreenwood]

[Balmoral1958]

Thanks - so i assume having the EGR hooked up doesn't hurt?
_________________
2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa

[Amskeptic]

I have done a number of tests with EGR hooked up and not hooked up on my 1978 2.0.

I could not discern a difference in CHT readings on the Dakota Digital gauge.

EGR was designed to reduce peak head temps that occur at lean partial throttle to help reduce nitrous oxides, but I don't believe these particular heat spikes necessarily translate to higher temps of all combustion chamber components, because we are pumping the real heat into those components at full throttle heavy loads.

Late model buses introduced those nice rich vapors from the fuel tank through the EEC valve in exact correspondence with the vacuum advance, and this was also true of the dual carbureted buses that opened the EGR ports in almost exact correspondence with the vacuum advance. And I have noted a correspondence with the hottest CHT readings right at partial high speed throttle. DID VW lean the mixture at this point, because it knew that inert EGR did not require fuel?????? and thus, all of us without EGR have this damn lean-out at partial to moderate load at partial throttle??

I totally recommend that you maintain a healthy EGR filter if you run EGR. It isn't just carbon that is allowed to blow into the intake, you also get rusty chunks of flaking off exhaust pipe metal.

I ran EGR on the BobD for about three years. It was a transparent, maintenance-free experience save for the failures of these cheap EGR filters, and a bit of a fuss with the rubber gasket/diaphragm inside of the mechanical EGR valve.
Colin
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www.itinerant-air-cooled.com

[Tcash]

New EGR Filters
http://www.busdepot.com/catalogsearch/result/?q=egr+filter&dir=desc&order=default_sort_order
http://www.eisparts.com/Merchant2/merchant.mvc?Scr...gory_Code=

EGR Filter gasket
https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

[Balmoral1958]

Thanks - I'll start getting the pieces together ...

PS the ultrasonic cleaner is great for cleaning throttle bodies.

Also cleaned the carbon out of the the EGR hole in the plenum body.

Should have got one of these years ago...
_________________
2x 1974 Karmann Ghia Coup
1984 Citroen 2CV
1956 Citroen 2CV
!984 911 Targa