[Supras] Help me locate an exhaust leak

[Khalid Almufti]

Hi!
     I used the stock exhaust manifold gasket.  I did have my exhaust manifold resurfaced by the machine shop when they did the work on my cylinder head and block deck resurfacing, but I did that as a precaution, IIRC there was no noticeable warpage when I checked the manifold.
     If you've concluded that the cylinder head threads for the exhaust manifold studs are not stripped, then that is good news and it looks like you only need to replace the gasket.  As far as your question on removing the three nuts on the downpipe, what I've done was to use a long 1/2" drive wrench with a flexible socket joint and 14mm socket.  You could use impact wrench to remove these nuts as well if you have one.  Otherwise, you'll just have to muscle it.
    I have never tried to get the exhaust gasket out without removing the turbo charger, and I imagine that if you did keep the down pipe in place, at least you have to disconnect the oil pipes and water hoses.  Again, I don't know it this could work.
     I'd say this is a two weekends repair job if you put in a couple of hours every weekend.  Not having to drill and tap threads makes it easier, but removing the turbo charger, down pipe and other lines and hoses does make it a bit involved.  If you can take your time and work carefully, then it will pay off in the long run.
 
Regards,
Khalid, 90T
 
Date: Wed, 23 Apr 2008 15:02:30 -0700 (PDT)
From: LN <studioartist at yahoo.com>
Subject: Re: [Supras] Help me locate an exhaust leak
To: supras at supras.com, Khalid Almufti <kalmufti at yahoo.com>
Message-ID: <211822.77228.qm at web30407.mail.mud.yahoo.com>
Content-Type: text/plain; charset=us-ascii



Hi Khalid,

I undo this last bolt and it came out fine with no stripping.  However the 
nut was frozen onto the stud and came out as a whole assembly when I was 
backing it out.  Havent't had a chance to check the others studs/bolts yet 
as I don't have much time to work on it just yet.  I did however tried to 
snug them up about 1/4 to 1/2 turn without a torque wrench but just by feel 
so that gve me hope that the threads are still intact


Also I bought a Felpro gasket but afterward got to thinking if using an 
aftermaket instead of OEM would it mess up in getting  the true torque spec 
of 29feet-lb and thus cause the stripping of the threads.  I wonder if this 
might be the cause of people that have had stripped thread since I found an 
article that mention gasket material and construction dictates the torque 
spec.  Here is the link for it http://www.boltscience.com/pages/gasket.htm .
Due to shortage of time I am dreading the prospect of helicoiling and just 
know that I would be running into a lot of time wasted in removing the 3 
bottom bolts connecting from exhaust manifold to downpipe in order to get 
access.  And that doesn't include drilling/tapping/helicoiling time .  Was 
told by the Autozone guy that I can avoid removing these 3 bolts since the 
manifold swings out 2-3" to allow me enough clearance to slip in the new 
gasket assuming that I don't have any stripped threads.  Do you have any 
tips or tricks in removing the 3 bolts?

In any case I also purchase OEM Toyota gasket and they are built in 5 layers 
: perforated steel layer-composite abestos layer (guessing on the 
abestos)-smooth steel layer-composite layer again-smooth steel.  All held 
together by rivets.  The Felpro is built in 3 layers , a composite layer 
sandwiched by a layer of perforated steel on each side.

I couldn't find any RTV that can handle the high heat since I am a bit 
concern that perhaps the leakage is due to warpage in the back area either 
from the head or the manifold mating side and was hoping that the RTV 
sealant might address these minor imperfections and allow for a quick cheap 
fix till I have time to do a proper job.  I am awared of warpage allowance 
of  .10mm max on the head side and .75mm on the manifold side and the proper 
way is to machine them down.  But  I also wonder how often does warpage 
happens.  The flow of the leak just like a knife cutting action which lead 
me to believe that it's warpage.

What gasket manufacture did you use and did you use any RTV?  Would love to 
hear from others also on this question.

I know I am asking lots of questions but I truly appreciate your help and 
everyone else on the list that have responded.  I also know now that this is 
the cause of lean reading on my emission report.


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