Clean the heck out of the EGR circuit all the way through the manifold, if possible.
I can confirm the bolts are not torque to yield. It is imperative to use the factory bolts with a stud tip, not threaded tip.
This stud bottoms in the holes to prevent crushing of the plastic.
However, when using the upgraded gasket, torque spec may prevent the stud from bottoming out.
This means cleaning any thread locker or sealant from the manifold bolt holes, has to be very clean/blown out.
** This is a good thing. When installing either the Fel-Pro thick paper or the metal gaskets, torque sequance may NOT bottom out the stud tips on the bolts.
Quoted from the 99' Dealership repair manual:
"Applying excessive amounts of sealant may prohibit the gasket from sealing properly"
"The lower lower intake manifold must be installed and the fasteners tightened while the adhesive is still wet to the touch."
1) Apply 4.0mm patch of adhesive GM Part P/N 12346141 at each end. (I was asked to select "The Right Stuff" by my machinist).
It shows a picture of the extreme outer lowest edge of the gasket. The very edge it touches the china wall.
1/4" wide by 4mm tall finger of sealant. |__|
Not much and not up the sidea of the edges.
It is inferred this is the back side of the gasket which goes onto the head, before alignment on the locating pins.
The front tabs get sealant later.
3) Apply 5mm bead to the front engine block.
4) Extend the bead 13mm (0.50") on to each lower intake manifold gasket.
So 1/2" up the rake, or onto the agle of the headmating surface. 5mm wide. Don't over do it, or globs of sealant will end up in your oil passages, filter and oil pump circuits.
The smallest chunk of sealant can clog a lifter and ruin everything.
Then it repeats the same instructions for the rear.
Resist the urge to add anything else. This is why the metal gaskets are highly recommended and the thick paper likely works as well.
8) Apply thread lock GM P/N 12345382 to the manifold bolts. Thread lock is not gasket sealant.
Here is where a lot of people screw up, especially with the plastic manifold.
Borrow the correct torque wrench or buy a new bar type in lb.
Torque sequence is as follows:
7-1-3-5
<---------- Front of manifold
8-4-2-6
9.1) First pass: 27 lb in
9.2) Second pass: 106 lb in
9.3) Final Pass: 11 lb ft (130 lb in)
The trick is finding a 3/8" Beam torque wrench. The 1/4" version only goes to 80 lb in. You run out of wrench for the final pass.
The GearWrench 3/8" will not read as fine on the first pass measurement, so take it easy.
The scale gets you on target for the second and third pass more accurately.
$59 on Amazon.
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Here's the Ares 70214 at $32.00 on AZ. It comes with a 3/8" to 1/4" adapter. :
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Paying attention to inch pound specs is really where the installation works without deforming the plenum or failing.
*** It is going to take "a day OR TWO" to harden the china wall seals.
If you try to start it and your timing is off more than 10 degrees, either way, you could suck the un-cured gasket sealer out and cause another leak.
Especially at the rear china wall, near the oil pressure sender port, where the china wall casting is thinner.
This is the exact area where the plastic gasket is known to leak and fail, at the coolant port.
