# Blocking off/sealing the air shrouded injector feed line?



## ny_fam (Apr 3, 2004)

On 84 and fewer counter flow heads (no -g60) between injector ports #3 & #4 is a extra intake port to supply air to the space around the injectors.
On all the head's I've had with this port, I've had continued problems getting that to seal and stay sealed.
I don't care if the port is used or not, I just want a good seal around it.
The OEM seal is a poor design, bolt on one side of the plastic adapter, and the rubber gromet is long hardened.
Don't know if this part is available anymore.
I've use RTV sealer - didn't work for more than a few months.
I've use vacuum block off caps.
But non have been a seal I can forget about.
What have others done?


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## ps2375 (Aug 13, 2003)

*Re: Blocking off/sealing the air shrouded injector feed line? (ny_fam)*

I used a sealant called Dirko. AFAIK it has worked. It's been over a year since I put this motor together and I don't have any problems that I know of.


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## ABA Scirocco (May 30, 2001)

*Re: Blocking off/sealing the air shrouded injector feed line? (ny_fam)*

Tap out the hole with an 1/8" npt and screw in a barbed fitting.


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## ny_fam (Apr 3, 2004)

*Re: Blocking off/sealing the air shrouded injector feed line? (ABA Scirocco)*

I've got the head installed right now and don't want to remove it this season. But good permanent fix idea.


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## ny_fam (Apr 3, 2004)

*Re: Blocking off/sealing the air shrouded injector feed line? (ny_fam)*

I bet I could stuff a rubber boot in the hole and then safely tap the threads.
Good idea, sounds clean.
Think 1/8" is the right size?
I've got to get a ntp tap, I only have metric.


_Modified by ny_fam at 1:07 AM 9-14-2008_


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## Orangelefty (Nov 14, 2006)

What is the actual purpose of the air port hole? Is it sealed from the factory? I've got it plugged right now with a vacuum hose and a bolt but im curious to know why its there and where it should be going.


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## ABA Scirocco (May 30, 2001)

*Re: (Orangelefty)*

It's for the air-shrouding of the CIS injectors, it's supposed to help better atomize the fuel, I don't know of anyone that's report decreased performance or fuel economy when they've plugged it. It's normally connected to a vacuum hose, I think the other end hose connects up near the throttle body, in the same area as the pcv hose etc.


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## ny_fam (Apr 3, 2004)

*Re: (ABA Scirocco)*

I've also read that the air shrouded was to help keep the injectors cooler preventing vapor lock under some hot start up conditions.

I ended up using a 8mm bolt and vacuum block off cap to close off the port. I like the idea of taping it and putting a npt with a barb. but I'd rather do that when the head is off.


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## ABA Scirocco (May 30, 2001)

*Re: (ny_fam)*


_Quote, originally posted by *ny_fam* »_I've also read that the air shrouded was to help keep the injectors cooler preventing vapor lock under some hot start up conditions.


I'm not buying that. VW ran all of their 1.5, 1.6, 1.7L and a few of their 1.8L engines without them and I can't recall ever hearing about vapour lock because of it. More likely, it's got something to do with emissions during warm-up of something like that.


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## chickenfriend (Jan 31, 2005)

*Re: (ABA Scirocco)*

Better fuel atomization at idle, if I recall.


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## ABA Scirocco (May 30, 2001)

*Re: (chickenfriend)*

That what I heard too and from multiple sources too so I'm inclined to believe it. But, since that makes absolutely zero discernible difference to the driver, I'm wondering why VW would bother, which is why I'm suggesting it might be an emissions thing.


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## chickenfriend (Jan 31, 2005)

*Re: (ABA Scirocco)*

According to Bosch literature, the purpose of the air-shrouded injectors is to promote better fuel atomization, primarily at idle conditions, for better fuel economy and less toxic emissions.

I would guess emissions was more important reason for its inclusion. Fuel economy benefits, if they appreciably exist, would only show in city-type driving.

I think it is safe to say there is no benefit to the power of the engine, since it is primarily a trick used at idle.


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## ABA Scirocco (May 30, 2001)

*Re: (chickenfriend)*

I've heard the fuel economy thing before too but I don't know of anybody that's actually noticed improved because of air shrouded injectors or degraded fuel economy when they deleted the air shrouding. 
It'd be interesting to compare the official fuel consumption figures of the 1983 and 1984 GTIs, two otherwise VERY similar cars except the 84 has air shrouding and the 83 does not.


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## chickenfriend (Jan 31, 2005)

*Re: (ABA Scirocco)*

For a 1984 GTI, the numbers are 36/26 mpg (source: VW literature). 

The only information for the 1983 GTI I have is a picture of a window sticker showing "26 mpg estimated".



I would compare any benefit, against the additional complication of yet another vacuum hose and need for modified injector systems, like the unique one-piece holders for the 1984 injectors.


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## ABA Scirocco (May 30, 2001)

*Re: (chickenfriend)*

I suspect a little BS'ing on Bosch's part. You've got to remember what was going on in the late 70's and early 80's, the automotive industry was in a transition from carbs and other mechanical fuel systems to efi systems. The manufacturers were struggling to come to grips with ever tightening emissions regulations. The performance of these "smogger" motors had suffered severely as a result, consider the 1979 Pontiac 400cid putting out a miserable 220ish HP when just a decade earlier, they made close to twice that. The public, particularly in the U.S., had come to associate lower emissions with lower performance and their appetite for more of the same had worn thin so, there was very little incentive for Bosch (et al.) to talk about emissions reduction except to the regulatory authorities.


_Modified by ABA Scirocco at 6:58 PM 9-28-2008_


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## B4S (Apr 16, 2003)

*FV-QR*

The MkIV 2.slo has air shrouded injectors too. Maybe they've adopted it for the same reasons as the early cars?


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## ABA Scirocco (May 30, 2001)

*Re: FV-QR (B4S)*

I'm surprised to hear that. I'm not very familiar with the MK4 engines but superficially anyways, it looks like an ordinary efi set up. Are you sure you're not mistaking the pintle caps on the injectors for air shrouding?


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## B4S (Apr 16, 2003)

*FV-QR*

Nope, I no longer have that AEG 2.0 head, but the injectors clearly had a secondary port on them, next to the connector, that routed back to pre-TB/post-MAF in the intake. I can get the new owner to snap some pics if need be, but I was surprised to see them as well.


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## chickenfriend (Jan 31, 2005)

*Re: FV-QR (B4S)*

http://forums.fourtitude.com/z...60255


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## B4S (Apr 16, 2003)

*FV-QR*

There you go, that's what I'm referring to.


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## ABA Scirocco (May 30, 2001)

*Re: FV-QR (B4S)*

How about that? I'll have to look more closely the next time I get the chance.


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## Orangelefty (Nov 14, 2006)

anyone have a pic of where the line should hook up?


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## JimLill (Dec 17, 2003)

*Re: (Orangelefty)*

does it get it feed from before or after the TB butterfly?


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## ABA Scirocco (May 30, 2001)

*Re: (JimLill)*

Before, it connects up a plastic fitting on the rubber boot on the throttle body along with two other hoses, one hose is for the idle boost valve and the other is for (I think) the charcoal canister. It's kind of tough to see but here it is on my 85 Scirocco.


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## EuroKid83 (Jan 26, 2005)

*Re: Blocking off/sealing the air shrouded injector feed line? (ny_fam)*

There are lots of resources for high temperature o rings on the internet, just replace it. The later air shroud heads had a press in metal hose barb, apparently they knew there was a problem. Taping it for a 1/8 npt hose barb is a good idea as well.


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## Svedka (Jul 4, 2008)

*Re: Blocking off/sealing the air shrouded injector feed line? (EuroKid83)*

I have a 026H solid head with bigger valves 42-34 on a audi 2.1 with MS2.2 and I got a new plastic insert for the back of the head tapped it to fit a small allen filled it with JB weld and inserted the allen have had no issues with it. Has been in my car for 4 years and thats how I ran all my other ones when I was racing my aba rocco with a 026H solid head if you want pics let me know.
Not sure if you figure this out or not but this is what I did. has worked for 8years plus for me.


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## JETBLK (Jun 27, 2007)

this thread may be dead, but those involved. is it common that oil leaks from this area, or more likely that i have a bad valve cover? i checked the air shrouded barb thing and mine is garbage. i put a screw through it for the time being, but my exhaust manifold has smoke coming from it when the engine is warm and i didnt know if i have a blown head gasket or im just in need of making a similar block off as you have all suggested? thanks for any help at all. i have another 87 with the welded barb, and i want to put that head on if in fact my head is garbage. any help at all would be greatly appreciated. thanks. :beer:


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## cuppie (May 4, 2005)

Yes, the thread's long dead.  

You most likely just have a leaking valve cover gasket. 
http://www.germanautoparts.com/Volkswagen/Cabriolet/Engine/102/1
I'd highly suggest that you spring the extra $10, and get the rubber-gasket upgrade kit. It really does seal better than the 3-piece cork-and-rubber factory set.


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## Fred Mann (Nov 10, 2010)

Well then let's bring this thread back to life, dammit!!
I have an 84 with the head off, and this is an issue I'd like to address once and for all.
Also, does anybody know if I need the fiber o-rings that go between the long plastic injector holders and the head? They were present when I removed the old holders, but I'm not sure if that was the stock setup. And the Bentley doesn't mention this one way or the other. Not even a single picture/diagram showing the holders in the Bentley ... for shame.


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## Glegor (Mar 31, 2008)

Fred Mann said:


> Well then let's bring this thread back to life, dammit!!
> I have an 84 with the head off, and this is an issue I'd like to address once and for all.
> Also, does anybody know if I need the fiber o-rings that go between the long plastic injector holders and the head? They were present when I removed the old holders, but I'm not sure if that was the stock setup. And the Bentley doesn't mention this one way or the other. Not even a single picture/diagram showing the holders in the Bentley ... for shame.


i used rubber o-rings for the injector insulators when i re-o-ringed my 86 GTI.

i believe they were rubber o-rings that came factory, not fiber.

ive never had any issues with the air shrouding, i actually popped the caps off all my injectors and cleaned them before i re-installed them. when i took them out, hardly any air could get thru the cap, they were all clogged with junk.

is that air shrouding fitting really that much of a vacuum leak?


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## Fred Mann (Nov 10, 2010)

Hi Glegor,
I think you have different injectors ... i.e. the ones with the pintle caps (they look like hats)? The 84 GTI injectors on my car looks just like the older injectors-- a straight cylinder with a groove for the rubber o-ring (just beneath the nut). It's a bit of an oddball/uncommon setup, as far as I know (which is not far).
My 84 uses a long plastic holder like this:
http://www.germanautoparts.com/Volkswagen/Rabbit/Fuel/93/5
And, as I am posting this link, I am noticing that the newly-revamped GAP site now shows the fiber seal ring as a required part. This was nowhere to be found on GAP a few weeks ago. So I guess that answers that...
Still, third-party confirmation would make me feel good.


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## Glegor (Mar 31, 2008)

your 84 rabbit came from the factory with air shrouded injectors, should have the SAME injectors as my car, because they have the same fuel system. both cars run CIS-Lambda. 83 DID NOT have air shrouded injectors tho. 84 was the first year that VW implemented them..

all the cars ive dealt with, had a rubber o-ring, about half way up the injector insulator.

my 86 uses a brass holder, with a plastic tip on it. looks exactly like the one you posted a link to, but its brass and plastic, instead of just plastic.


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## WaterWheels (Aug 14, 2005)

Yes, your *84* engine uses a unique injector insert, one long piece, found only for a year or so until the two piece inserts came out. Yes, your *84* used the older style injectors without the pintle cap (top hat) as the long single injector insert did all the air control for the shrouding. Yes, your *84* came with a fiber seal between the cylinder head and the insert. Here is a link to at least one place that you can get them from http://www.car-stuff.com/carparts/v...1985248.html?prodSlot=Product+Listings+Page:2 there are many others to include the dealer. You can install them without the seal but it will sit a little lower and may not seal 100%, so I would spend the $4 or so and do it right.


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## happybunny (May 7, 2005)

I left the plastic fitting on and used ITW/Devcon Plastic Welder. It's been on there for almost a year with no leaks so far. I got it at AZ, but it should be available most anywhere.


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## Fred Mann (Nov 10, 2010)

A belated thanks to everybody!! 

WaterWheels -- thanks for the info. I was mainly concerned with how the injectors would sit ... $4 was not the issue. And I found 'em for 50 cents each, anyway . 

As for the air shroud tube, I drilled and threaded a hole opposite the one factory bolt, so now there's two bolts holding it on ... very secure. Also, replace the o-ring, of course. 
Caution, do not drill too low or you will drill into the air shrouding passage/tube that runs through the head. Then you will have to waste time sealing it up. Don't ask how I know this.


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