[urq] Manifold O2 sensor thread stripped

Sun Aug 18 06:53:49 PDT 2013

Lino,

To add to that, I love that the 4kq has the O2 sensor in the CAT itself.
Not sure if you still have yours.
If things get a bit dodgy, you can remove the cat and work on the problem on
the bench, instead of in the tight confines of an Ur-q engine bay.
I suggest plugging the downpipe as Scott suggested and install the O2 in the
CAT (before the matrix).  Or test pipe if that is what you have.
The only downside is that with the O2 placed so far away it needs to be
heated.
I know you have MAC11 harness so a plug for the O2 heater should be there
already.

HTH
Martin Pajak

http://www.quattro.ca 

1981 VW Scirocco, all original
1982 Audi Ur-quattro, SQ project
1983 Audi 80 quattro, Euro 2-Tür
1984 Audi Ur-quattro, 20vt with 6-speed
1993 Audi 90 CS quattro, 2.5 TDI with 6-speed
1993 Audi 80 quattro Avant, 2.5 TDI with 6-speed
1994 Audi S2 Avant, stock

-----Original Message-----
From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
Of Scott Justusson
Sent: 18-Aug-13 09:42
To: lvaladas at sympatico.ca
Cc: urq at audifans.com
Subject: Re: [urq] Manifold O2 sensor thread stripped

IME with helicoils and 02 many years ago, it's a one time 'fix'.
Specifically, the next time you go to replace the o2, the helicoil will come
out with it.  I suspect it's because the heat in that section of the exhaust
tends to weld things that shouldn't be welded.  My suggestion is to buy a
helicoil kit, an 02 plug, and a 02 bung.  Helicoil the downpipe at the cast
section - insert a plug.  Then have exhaust shop weld an 02 bung somewhere
on the downpipe.  

Cheers and HTH

Scott J

-----Original Message-----
From: Lino Valadas <lvaladas at sympatico.ca>
To: Scott Justusson <qshipq at aol.com>
Cc: p.carlier <p.carlier at pandora.be>; urq <urq at audifans.com>
Sent: Sat, Aug 17, 2013 8:04 pm
Subject: Re: [urq] Manifold O2 sensor thread stripped

Thanks Scott et All,

You are right of course.  My O2 sensor is also on the cast portion of the
down pipe my mistake, I should know better it is not on the manifold, I
replaced the original manifold, which was cracked, about 7 years ago with a
two piece one (from a non-Urq engine) and (now) remember inserting the O2
into the pipe not the manifold. The fact that the stripped threads are on
the cast portion of the pipe threw me off.
So I apologize for the confusion, but at the end of the day I still have to
deal the stripped threads.  I will try to re-tap the hole as some suggested,
but I have doubts it is going to help as the O2 sensor popped right out
during some spirited drive and so I believe there is nothing left to cut new
grooves into.
Nobody commented on my helicoil suggestion (I don't think).  Is that because
you don't think it will work?  Or, no one has ever tried it?  Because they
do have helicoil kits to repair O2 threads.

Thanks for all your comments guys. It is much appreciated.

Lino
83 Ur-q (900500)

Sent from my iPad

On 2013-08-17, at 9:27 AM, "Scott Justusson" <qshipq at aol.com> wrote:

FYI, the hole in the exhaust manifold was for the 'old' exhaust feed to the
wastegate (early early turbo audis).  About the only thing I use it for is
EGT, because you will see temps that will cook 02 sensors IME. The 02 sensor
should be mounted in the cast portion of the downpipe just aft of the hot
side of the turbo.  If you install a heated 02 sensor (Bosch 4 wire Planer
type - just run a 12v heater circuit off ignition trigger), you will have
better 02 readings, longer 02 sensor life, and it can be mounted anywhere on
the downpipe.  IME/Measures, the downpipe heat is high enough for proper 02
operation over its whole length.

As Lawson notes, 02 sensor bungs (SS or mild steel - I use mild) are
available at 034 and IME most exhaust shops have them in stock.
http://www.summitracing.com/search/part-type/weld-in-bungs-and-fittings

HTH

Scott J

-----Original Message-----
From: Lino M. Valadas <lvaladas at sympatico.ca>
To: Patrick Carlier <p.carlier at pandora.be>; urq <urq at audifans.com>
Sent: Fri, Aug 16, 2013 3:07 pm
Subject: Re: [urq] Manifold O2 sensor thread stripped

Thanks guys,

This weekend I'm tied up, but next week I will try some of your suggestions.

I will let you know what happens.

Thank You

Lino
83 Ur-q  (900500)

-----Original Message-----
From: Patrick Carlier
Sent: Friday, August 16, 2013 5:48 AM
To: Lino M. Valadas ; urq at audifans.com
Subject: Re: [urq] Manifold O2 sensor thread stripped

Best chance imho is to take it to a machine shop and have it repaired .
The way I fix those is by machining a kind of bung and weld it in .
The old one has to be cut out on the mill , or fi with fi a hole saw and
then the new one can be welded in .
End tapping should be done after the bung is welded in .

The sensor thread is M18*150 btw .

Altough I'de advise against it , a decent machine shop should  also be able
to weld a pass on the worn thread , and then drill it to size and re tap it
.
Done it a couple of  times like thgis , but it causes problems the next time
you have take the sensor out .

Pat

----- Original Message -----
From: "Lino M. Valadas" <lvaladas at sympatico.ca>
To: <urq at audifans.com>
Sent: Friday, August 16, 2013 3:45 AM
Subject: [urq] Manifold O2 sensor thread stripped

> Gentlemen,
>
> The threads on the O2 sensor hole are completely gone on my 1983 Ur-q 
> manifold.  I need some advice on the best way to correct the situation:
>
> 1) Tap new threads and screw in a helicoil
> 2) Weld in an O2 bung
>
> The first option might be tricky due to the tight quarters.  Has anyone 
> ever done it?
> The 2nd option, also tight to weld in there, but also concerned with the 
> O2 tip not being close enough to the exhaust flow.
>
> Any advice would be welcome.  I would prefer no to have to replace the 
> manifold.  The one in there isn't the original, it is a two piece 
> replacement and I would like to keep it.
>
> Thanks a lot
>
> Lino
> 83 Ur-q  (900500)
>
>
> -----Original Message----- 
> From: Brandon Rogers
> Sent: Thursday, August 15, 2013 3:39 PM
> To: 'Keith' ; urq at audifans.com
> Subject: Re: [urq] general overheating question
>
> A few months ago my '01 S4 gauge would show the engine as overheating 
> however oil temp was normal, fans operating as normal etc.
>
> It was a dead water temp sensor - which on the V6TT is on the back of the 
> motor - so-so access - prolly similar location but better access for the 
> 1.8T.
> It's a cheap sensor - replacement was a pain as it uses these, ahem, funky

> (insert foul language here) plastic clips.  Apparently the trick is put 
> them in boiling water for a few minutes first to give them some 
> flexibility.  I'd buy 5 tho, JIC.
>
> Hope it something simple-
>
> Brandon
> '01 S4
> '91 911 Turbo
> '84 urq 20VT gone but not forgotten
>
>
>
> -----Original Message-----
> From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf

> Of Keith
> Sent: Thursday, August 15, 2013 11:20 AM
> To: urq at audifans.com
> Subject: [urq] general overheating question
>
> Evening All
>
> Apologies for this being a bit off (urq) topic but I could really do with 
> a bit of general diagnostic help with an overheating issue on our Audi A6 
> 1.8t (2001).
> The symptoms are:
> Sudden overheating issue.
> No steam
> No bursts
> The coolant level had dropped a little but there were no obvious leaks 
> although there was some coolant on the lip of the coolant reservoir 
> suggesting that this might have blown out past cap through overheating. 
> The low coolant level alarm sounded when this all occurred which drew my 
> attention to the temp gauge. Got towed home to hopefully now fix it.
> The oil seemed to have got hotter than normal too.
> Bought new filler cap to rule this out.
> Then.....
> Starting from cold, it rises very quickly to 90c (normal operating temp), 
> hangs there for a bit and then goes on rising.
> Viscous fan and electric fan both working fine and when they are supposed 
> to.
> Heater just blows cold air even when overheating.
> Whipped plugs out – all normal colour.
> Tops of pistons look normal – no evidence of steam washing.
> No obvious evidence of oil in water or water in oil.
> Engine starts fine and runs as smooth as normal.
> Thermostat is less than 12 months old. Changed when previously car was not

> getting warm!
>
> My two main suspects are thermostat despite it being almost new and water 
> pump.
> Have I overlooked anything simple and blindingly obvious?
> Before I start taking it all apart though, what can I do to narrow this 
> down to the the definite culprit?
> I really need to fix this by Monday when I have to use it for work (no 
> pressure eh?) so any suggestions of next steps will be greatly appreciated

> (as always).
> Cheers folks. Will look forward to hearing from you.
>
> Keith
> ‘87 WR
>
>
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