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New fuel delivery (?) issue?
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bureau13  



Joined: 07 Sep 2017
Posts: 281
Location: South Florida

PostPosted: Mon Jul 13, 2020 5:40 am    Post subject: Reply with quote

Are OEM seals no longer available?

Looking at all of this again, I started thinking maybe it was that rubber elbow coming off the valve that leads (I assume) to the intake manifold but watching it carefully during the test, I really don't think that's the problem. Unfortunately! However, it did make me wonder if an easier test might be to block off the line at the intake manifold end, with the idea that more air is leaking in there than along the main intake air path. I don't know if that's right or not, but might be worth a look? Only I'm not sure where that line leads, exactly, I can't follow it with everything on the car. Do you know where exactly on the manifold it connects?

Fasteddie313 wrote:
The only seals are under each cover with 4 bolts through them..
IIRC I made new ones out of oil soaked leather from an old welding apron or something..
I think the old gaskets were like red and crystallized when I did mine..

I'm not 100% sure it's possible, but I would definitely attempt to do it without pulling the turbo..

These kind of 4 angle open end wrenches are magic for tight places like that..


And maybe a ratcheting 10mm.. Possibly a stubby one..

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2002
Location: MI

PostPosted: Mon Jul 13, 2020 5:56 am    Post subject: Reply with quote

Yeah.. It connects right under the #1 runner, on the bottom..
If you flip the alternator over to the drivers side you can get at it pretty easy, but the 2 hard lines come so close to eachother, it might be difficult to block..
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bureau13  



Joined: 07 Sep 2017
Posts: 281
Location: South Florida

PostPosted: Mon Jul 13, 2020 6:26 am    Post subject: Reply with quote

OK, thanks. I'll take a look.

Fasteddie313 wrote:
Yeah.. It connects right under the #1 runner, on the bottom..
If you flip the alternator over to the drivers side you can get at it pretty easy, but the 2 hard lines come so close to eachother, it might be difficult to block..

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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poor-sche  



Joined: 06 Jan 2017
Posts: 76
Location: Los Angeles, CA

PostPosted: Mon Jul 13, 2020 6:45 am    Post subject: Reply with quote

Here’s a pic of the pipe with the water pump removed. Ignore the blue circle, separate issue I was having.


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bureau13  



Joined: 07 Sep 2017
Posts: 281
Location: South Florida

PostPosted: Mon Jul 13, 2020 11:45 am    Post subject: Reply with quote

I remember wrestling with that pipe when I changed out my water pump. I had no idea what it was at the time! It looks like I can get to it, and the screw on the clamp by the manifold is clocked so I can access it, amazingly enough. I think I can get it off and get a cap on it, but we'll see. Mainly I just want to prove that's the problem before I try to dismantle that bypass valve in situ. I don't think the elbow is actually leaking in my case, although it probably makes sense to change it.
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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jacobroufa  



Joined: 18 Nov 2016
Posts: 281
Location: Rockford, IL

PostPosted: Tue Jul 14, 2020 1:43 am    Post subject: Reply with quote

If you've not replaced the elbow from the black pipe to the turbo recirculation valve, you should do that to rule it out before continuing. Mine looked perfect from the outside but when I did my water pump I double checked it and it was complete garbage.. It is the same size as a few of the vacuum elbows on the top of the manifold, which you already did also, riiiight?
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1980 Porsche 931
1981 Porsche 924 Weissach
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2002
Location: MI

PostPosted: Tue Jul 14, 2020 2:35 am    Post subject: Reply with quote

Running without the recirc valve shouldn't hurt anything..

Will increase lag between shifts maybe and could possibly reduce the life of the turbo (surge), but not really at low boost..

I don't know if the gaskets are available..
I don't wait for things like that.. I make em.. I make most everything I can myself, because I'm poor, hate waiting, and like making things..

They probably do though because it is the same valve as the 930 but in a different housing, I believe..

All that is in there is a pretty light spring and a piston.. No big deal..
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Last edited by Fasteddie313 on Tue Jul 14, 2020 2:38 am; edited 1 time in total
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jazz guy  



Joined: 26 Nov 2002
Posts: 406
Location: Colorado

PostPosted: Tue Jul 14, 2020 2:37 am    Post subject: Reply with quote

Previously, I've smoked one of mine and it looked very similar to your videos. My lower charge pipe brace was there but the bolt had rattled loose and the extra movement had worn the o-ring. I ended up having to replace both the lower charge tube o-ring and the recirc. valve gaskets. No smoke afterwards. Relatively straight forward and inexpensive jobs.
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bureau13  



Joined: 07 Sep 2017
Posts: 281
Location: South Florida

PostPosted: Tue Jul 14, 2020 2:38 am    Post subject: Reply with quote

From the smoke test, it doesn't really look like that was leaking, but it does look rather oil-soaked. I plan on changing it. It seems the OEM elbows are not available, but I would guess a generic one should suffice. That's why I ahem may not have changed the other ones though...

jacobroufa wrote:
If you've not replaced the elbow from the black pipe to the turbo recirculation valve, you should do that to rule it out before continuing. Mine looked perfect from the outside but when I did my water pump I double checked it and it was complete garbage.. It is the same size as a few of the vacuum elbows on the top of the manifold, which you already did also, riiiight?

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2002
Location: MI

PostPosted: Tue Jul 14, 2020 2:40 am    Post subject: Reply with quote

jazz guy wrote:
I ended up having to replace both the lower charge tube o-ring and the recirc. valve gaskets.


You replace the recirc valve gaskets with the turbo still on the car?
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bureau13  



Joined: 07 Sep 2017
Posts: 281
Location: South Florida

PostPosted: Tue Jul 14, 2020 2:40 am    Post subject: Reply with quote

I did find what I believe to be the official OEM parts. Only a couple bucks. I would never have guessed leather would be an option there, that's interesting!

An added bonus...maybe I get that flutter I hear on some old rally car vids In any case this would be a temporary work-around, really more to prove that's what the problem is before I try to take it apart than an actual fix.

Fasteddie313 wrote:
Running without the recirc valve shouldn't hurt anything..

Will increase lag between shifts maybe and could possibly reduce the life of the turbo (surge), but not really at low boost..

I don't know if the gaskets are available..
I don't wait for things like that.. I make em.. I make most everything I can myself..

They probably do though because it is the same valve as the 930 but in a different housing, I believe..

All that is in there is a pretty light spring and a piston.. No big deal..

_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2002
Location: MI

PostPosted: Tue Jul 14, 2020 2:53 am    Post subject: Reply with quote

bureau13 wrote:
I would never have guessed leather would be an option there, that's interesting!


IDK..
I think it worked.. Sounded like a good idea to me..
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bureau13  



Joined: 07 Sep 2017
Posts: 281
Location: South Florida

PostPosted: Thu Jul 16, 2020 9:24 am    Post subject: Reply with quote

OK, well my "temporary work-around" failed, but I don't think it's because that's not where the leak is. I don't see me getting the connection under the intake off without removing the intake, so nope. I got the old elbow out by butchering it, so whether or not it was a problem it's got to be replaced now, and I see no way to get it on there without removing the bypass valve cover anyway. So, that's the plan. Anyone have any helpful hits or things to avoid when doing this in situ? It honestly doesn't look that bad. I think I can get a tool on all the bolts, it's a bit fiddly, but I think I can do it. I did think I saw someone post that they had done it and it was painful, so any tips, warnings or other advice is appreciated. In any case, I'm betting it's easier than pulling the turbo...
_________________
-----------------------------------------
1982 931
1986.5 Silver 928S
2007 Hummer H3 (Daily Driver)

Past lives (I miss them all):
2004 RX-8 (Wrecked)
1993 RX-7 (Sold)
1987 RX-7 Turbo II (Sold)
1985 RX-7 GSL (Stolen)
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2002
Location: MI

PostPosted: Thu Jul 16, 2020 1:28 pm    Post subject: Reply with quote

The spring will spring like a spring when the spring cover is removed unspringing the spring..

Not a very strong spring though.. You should be able to hold it just fine..
Loosen all the bolts on one side 5mm or so so you can feel for the pressure on the plate.. Hold it in, remove bolts, release cover slowly ready to catch spring..

That's what I'd do probably..

Spring side towards the block, piston side towards the fender..
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1987
Location: Somerset, UK

PostPosted: Thu Jul 16, 2020 5:29 pm    Post subject: Reply with quote

Removing the chassis side of the recirc cover is easy. Removing the engine side may not be impossible, but I gave up

You cannot run without recirc piston, period. You will be drawing air around the compressor wheel without a piston. You will have to insert the spring and piston with some method of forcing the piston to stay closed if you do not remove the vacuum signal coming from under the intake manifold. I did this. Ran for a week, then went back to stock. There is absolutely no benefit in running without a recirc valve for any reason.......noise, lag, etc.

Don't waste your time.......

Getting the spring and piston back in, getting the end plate on and bolts back in is a pig of a job. A second pair of hands would make it far easier.

PS the gasket rings for both covers are available from Porsche. I bought some a while ago.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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