I'm in the process of replacing my exhaust manifolds and while the PB Blaster is soaking I thought I'd try and get some tips on how to remove the heat shield on the front manifold. It appears there are some threaded manifold studs (like the Saturn ones I plan on installing) that the heat shield slides over and are then being held on with a nut. The problem is, despite having the decklid removed and having the engine tilted a few inches back (using that handy dogbone tool) I still can't easily see what size the nut is. Every metric socket I try is either to big or small. It's so rusted that obviously one of the sizes is supposed to fit, but I don't have a whole lot of extra room to work with.
I was hoping I didn't have to reinvent the wheel and someone would have a clever way of getting the shield off. I was thinking of just cutting it off (which would give me much better access to the nuts on the threaded stud) but figured I'd probably want to re-install it to prevent the "new" manifolds from cracking (which is why I am doing this reapir to begin with!).
Any help would be graciously accepted!
------------------ Wesley A. Williams MAFOA Newsletter Director
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11:03 AM
PFF
System Bot
jetman Member
Posts: 7799 From: Sterling Heights Mich Registered: Dec 2002
I have 13 MM nuts on my studs which were purchased from Rodney Dickman, just went out and checked for you. I switched to the studs and nuts because I was told here on the forum that if in a pinch, they can be split off with a hammer and a chisel. I have never done that yet. BTW, I kept my curved heat shield but tossed the large tin gasket/shield that was between block and exhaust manifold as the ports were blown out, reason for the new gaskets.
------------------ jetman Silver 86 SE 2M6 4-speed, with "check wallet light"
Hrmmm....I wonder if mine have been previously replaced. On the front side, the top bolts that hold the manifolds on are the Dickman-type studs. Aren't the OEM ones hex-heads?
The forward manifold uses stud-headed bolts, with the stud portion being used to attach the heat shields. Only three of them, two top and one bottom IIRC, are this type, the other three are normal bolts. The GM nut that holds the shields on are thin sheet-metal nuts, and they frequently rust away enough that the hex portion is gone. They are 13mm, and you have to use a thin-wall socket because the heat shield stamping around the nut has an upturned flange that makes a well that the nut sits in.
Okay I got off the front heat shield! *bows to the crowd*
I know you won't be really impressed until the manifolds are off, and that is gong to be tedious because I can see AT LEAST two bolts that have been previously snapped off. I've also noticed that the heat shield that goes against the block on the front side (the one that causes leaks in the gasket usually) is gone, so the previous owner has done some (shoddy) work on the manifolds previously. My Fiero club has a drilling jig I guess that I plan on borrowing for that job, however to avoid hijacking my own thread, my next question is...
"To heat shield, or not to heat shield?"
Once this thing goes back together, what are the pros and cons of leaving the front shield (the one that surrounds the front manifold) off. One thing I am concerned about is that it will predispose the manifold to cracking since its not protected from rainwater dripping down from the decklid.
I also plan on putting on some weatherstripping (similar to what was removed in the recall) to protect my "new" ceramic coated manifolds.
Thanks again for the advice!
------------------ Wesley A. Williams MAFOA Newsletter Director
[This message has been edited by mtgjudge (edited 08-29-2004).]
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07:55 PM
Formula88 Member
Posts: 53788 From: Raleigh NC Registered: Jan 2001
Well, If I had it to do over, I'd probably use the heat shield that covers the manifold, but omit the one that goes between the manifold and head. That just makes gettnig a decent gasket seal that much more difficult. All that inner shield does is prevent oil leaks from dripping onto the exhaust manifold and catalytic converter. That's an important safety feature, so be warned if you do remove it. Make sure you don't have oil leaks.
I omittted the gasket/shield as the ports were blown out. Went with Felpro gaskets. I did cut across the shield below the blown ports but above the lower mounting bolt holes. This gives me a shield that I can re-attatch with three nuts over the outside of the manifold's three lower studs should I wish to have shield in the future.
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08:20 PM
NEPTUNE Member
Posts: 10199 From: Ticlaw FL, and some other places. Registered: Aug 2001
Well, If I had it to do over, I'd probably use the heat shield that covers the manifold, but omit the one that goes between the manifold and head. That just makes gettnig a decent gasket seal that much more difficult. All that inner shield does is prevent oil leaks from dripping onto the exhaust manifold and catalytic converter. That's an important safety feature, so be warned if you do remove it. Make sure you don't have oil leaks.
I used an old 2 stroke dirtbike trick, and sanded the shield as clean as possible with very fine emery paper. We used to throw away head gaskets on our bikes to raise the compression ratio. Then you spray a liberal coat of aluminum paint on all surfaces before you put it back together. The paint actually contains fine aluminum particles and will fill in any small mismatch between the manifold and the head. It will withstand a lot of heat and pressure, we used it in place of a head gasket! When the paint first burns with startup it will ruin your 02 sensor, so remove it, warm the engine, let it cool and reinstall the sensor, or better yet, use an old one for a while.. This worked for me!
It appears as though some already did some (shoddy) manifold work on this car, so the "gasket" head shield is missing. I still have the 3-bolt one that curves around the front manifold. Should I bother trying to find a used one or am I just being overcautious? (I plan on putting the decklid strip back on.)
Oh yeah, and I do have a small oil leak somewhere (if that effects anyone's opinion), but I'll ask about what to do about that in another post.
As always, advice is graciously appreciated!
------------------ Wesley A. Williams MAFOA Newsletter Director
Those shields are for safety. With the engine in the back, you often don't see you have a fire until it is too late. I know from experience.
Both shields are important.
If you have to, fabricate them out of sheet metal.
The idea of having the lower shield attach outside the head flanges instead of under them is a pretty good idea. I think I'm going to look for a way to do this.
