Exhaust manifold gasket replacement, detailed with pictures. (Page 6/6)
Dennis LaGrua OCT 04, 10:41 PM
Tip: To prevent future manifold cracks. Coat the gaskets with powdered graphite before installation. This will allow some necessary expansion movement (due to heat cycling) without the manifold developing cracks. Always torque exhaust manifold bolts to their proper torque specs. Too loose and you'll have leaks, too tight and you'll have cracks.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

hobbywrench FEB 26, 05:30 PM
I don't think anyone mentioned the use of a left hand drill bit. (not a joke) A bubble pak is available at H-Frt. Whether you can first center punch a snapped bolt in place is a little hazy to me, but I think I did this many years ago to my 85GT , manifold in place. The out come was that the punch vibration was enough to loosen the broken bolt which I managed to them uncrew....

But what I was leading up to with the center punch is that the reverse (loosening) cut of the drill has a tendency to loosen such a bolt as the drill bit (cutting ) lip digs in. Use a reversible 3/8 hand drill on the REVERSE setting. If the bolt does not loosen, stop and think before drilling for an easy out as you are likely to take out the female threads in the head.

Jetman's good vibrations from an air hammer (gently) probably accomplish what that center punching did for me. If there is "good rust" then dry rust is more crystal -like than the nasty water fed rust which welds metals to one another. The heated exhaust port area can keep some moisture at bay. So jarring the intact or snapped bolts may help. Street physics 101.

Edit: Further thought on heat vs rust... For oxidation (rust) electrolyte is required. In this case water. Another reason (besides oil sludge) to thoroughly warm up car when possible. Street physics 102.

[This message has been edited by hobbywrench (edited 03-28-2013).]

Marvin McInnis MAR 17, 01:49 PM

quote
Originally posted by hobbywrench:

Whether you can first center punch a snapped bolt in place is a little hazy to me, but I think I did this many years ago to my 85GT , manifold in place.




You could probably use a "transfer punch" to mark an accurate center. It would be even better, if possible, to level (i.e. grind or spotface) the fractured surface of the broken screw and then use a transfer punch. If you have the Kent-Moore jig like Patrick's, 5/32 would be the appropriate size for the spotface, transfer punch, and left-handed drill bit.

[This message has been edited by Marvin McInnis (edited 03-18-2013).]

hobbywrench MAR 22, 10:06 AM
Marvin's idea is good about squaring off before center punching, however my broken stud (murphys law) was broken below the surface of the exhaust flange . Also , it's been a long time , but an offset (90 deg) drill head or attachment would probably help. I did not have one, but seems like the most compact 90 deg. unit might be an air die grinder or purpose - built electric drill. Poblem with air is low torque and hair trigger input. Good electrics were available but somewhat expensive.
robert1234 OCT 31, 06:43 PM
This the best write up I have ever found for this. Thank you thank you !
Now I'm ready to tackle it and get myself into trouble, but an outstanding job. I could never repay you for all the work that went into this write up.
True asset to the forum.
Thanks again !
jetman MAY 28, 07:27 PM

quote
Originally posted by robert1234:

This the best write up I have ever found for this. Thank you thank you !
Now I'm ready to tackle it and get myself into trouble, but an outstanding job. I could never repay you for all the work that went into this write up.
True asset to the forum.
Thanks again !



Thanks!! You can pay it forward some day by helping our fellow members with knowledge that you have gained.
reinhart MAY 15, 06:33 AM
Just did this repair for the first time. I can't stress enough that it is so much easier tackling the front manifold from the bottom. The upper A/C bracket is done topside. Remove the metal firewall shield...it surprisingly makes a big difference...it's 4 x 8m bolts...literally took 2 min to remove. Then the front manifold to head bolts should all be accessed from below. The front manifold to crossover bolts (1 above and 1 below). That's it. No need to tilt the engine cradle or remove the decklid. It's really not too bad from below the car. It seems like a lot of people do not want to work on the car from the ground though so...they'll make it 10x harder just to work from above.