Help On lower intake manifold

Here is where I am. I have a 1992 Lumina Euro with a 3.1 (3100) engine. I had to replace the O-rings on my injectors to fix a flooding issue. When, placing the plenum back onto the lower intake manifold I snapped a bolt when using my torque wrench. To stop the people saying, "never torque intake manifold/plenum bolts." The torque wrench read ~14-15 ft-lbs. Normal torque specs are 16-18 lbs.

The point is the bolt snapped and after grinding the bolt level and drilling out the bolt, the EZ out snapped. This has lead to going though several tungsten, titanium nitride, cobalt and black oxide bits. I now have noticed that I have drilled partially into the lower intake manifold. Do I have any options other than replacing the manifold? Is taking the lower intake manifold to a machine shop an option?

it may be cheaper to just get a wrecking yard intake than to have a machine shop work on it but you can take it to one and see what they say.

Now, I am not sure which bolt broke on you, but for future reference not all the lower intake bolts are the same torque spec.


From a quick Google I found this

Tighten the lower intake manifold center bolts in sequence to 7 N·m (62 lb in/5.2 lb ft) on the first pass.
Tighten the lower intake manifold center bolts in sequence to 13 N·m (115 lb in/9.6 lb ft) on the final pass.

Tighten the lower intake manifold diagonal bolts in sequence to 13 N·m (115 lb in/9.6 lb ft) on the first pass.
Tighten the lower intake manifold diagonal bolt in sequence to 25 N·m (18 lb ft) on the final pass.

...and/or have the calibration of the torque wrench tested.

The cheaper torque wrenches can likely use a scrap-metal bin as a new home.

Once you broke-off the easy-out, chances of success plummeted like a paralyzed falcon. Professional bolt removal (EDM, or very skillful drilling) or manifold replacement seem the best options now.

I would at least take the manifold to a welder. Ask him the cost of welding a rod to the ez-out and then perhaps when it is hot you might be able to twist it out. Same thing with the bolt. Of course it's all dependent on the cost of new or good used manifold. So a new Dorman manifold from Rockauto is about $170. Good luck.

I believe the torque for those upper plenum bolts are only 89 inch pounds, not 16-18 foot pounds....