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'95 Intake Manifold Rear Seal Pain



I need help. In process of removing intake manifold to replace gaskets and silicone seals for that C4 rear oil leak thingy. Everything I've read says it is an easy job. Yes, it was kind of easy but I'm screwed up and not even half way there. Encountered first problem, when I tried to uncouple the Secondary Air Injection Pipe nut from the pass. side exhaust manifold. Little room to work. I managed to get a 13/16" crows-foot on the thing, but for the life of me I can not get it to budge. About all I can get on it is that 3/8" drive crows foot and a 3/8"-to-1/2" drive adapter coupled to a 1/2" drive x 15" breaker bar.....and that baby won't budge. Starting to round off the nut a little. I've soaked the threads overnite in WD-40, but that does not help either. How can I get that thing off without destroying the whole piece, nut, tube and all? That unit looks expensive! My mechanic bro says I'll need plenty of heat, but I'm not sure if I can get a real good fit with that crows foot any more. Also, that bolt is very close to the dipstick tube, valve cover, plug wires, etc. Burn baby burn! Help. Is there some kind of special adapter for that thing? Any other suggestions? I'll try to attach a picture of the piece for you.

Almost any parts store will have a can of ..."PB Blaster" the best stuff there is for anything that is stuck or covered in rust. It eats up rust and is the best penetrating oil I have found.
The problem is you are using the wrong tool. You need a 23mm tubing wrench. The nut is so thin it is really easy to bend out of shape. When I installed my headers I had to remove them from both sides and re-install on headers. I bent the first one using a standard wrench. When it bends it bends the threads and all. I couldn't reuse the one from the pass. side and had to buy a new one.(about $25) I couldn't find a tubing wrench large enough so I took an old 23mm wrench and used my cut-off tool to remove a section just wide enough to slip around the tube. If it looks like the wrench is spreading just set your vice grips so they just fit the outside of the wrench tight enough to prevent the ends from spreading. It worked like a champ. Removed the other side and installed both sides without another problem. I guess I'll get to try it again when I remove my intake to install my hot cam. You may be able to find a tubing wrench where you live but I had no luck here. Good luck.:bang

PS: I'd like to complement you on your choice of color for your car.
Hey Eagle,

..."PB Blaster"

I'm going to look for the stuff this weekend.

Thanks, Ted
23mm tubing wrench......hmmmmmmm.

Mr. Vetsvette -

Great- I knew there was some very smart vette-a-holic out there, with a comp yellow vette, who knows what he'd doing. Ya gotta love that yellow. I call it "kiss-my-butt-yellow". Don't take that literally though.

I always told myself that any vette other than comp yellow is the wrong color for me.

Back to the wrench........ you know, I ran that idea about cutting a wrench through my head once or twice. I kept thinking of the oxygen sensor socket and how I could dupe that!

Nice thinking!


PS - I took another hard look at that assembly when I got home today. Didn't even take time to take my coat off. I believe I may be able to disconnet the rubber hose on the opposite end, loosen up those two bolts that hold the business end of it to the back of the intake manifold, and gently bend it enough so that it clears the manifold. What do you think. Looks do-able to me.
Vetsvette -

"You need a 23mm tubing wrench......."

What exactly is a "tubing wrench" anyway! Draw me a mental picture will 'ya? I'll shop around for one tomorrow.

Thanks Ken. I've got to take the time and figure out how to post pictures one of these days.:w
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_ken ;)
Thanks from me too, Ken!

Dang, now that's what I call a graphic! Purty as a speckled pup, ain't it?

Problem solved. I looked all over town for a 23mm tube wrench. 23mm must not be a popular size.

Anyway, as a last resort it was a new $125 pipe (I'm guessing; it looks expensive though) or bust. I crunched my old faithful Vice Grips on that bolt (going totally for broke). I turned only a little (didn't take nearly as much torque as with the open end wrench or the crows-foot) and that little crapper started to turn. Now it is off. No damage to speak of either. Funny thing though, one of you mentioned that that bolt was soft. It sure was. My open-end wrenches actually mal-formed the nut resulting in more binding. The way I figgur it, my Vice Grips crunched it in the other direction thereby opening up that hole enough where it relieved the pressure and...voila! Don't worry, I'm not going to leave that nut non-pristine. I plan to file the surfaces flat and clean and then touch it up with a little manifold paint. While I'm at it I think I'll file that nut down to a nice standard 20mm size, or something.

Thanks guys. Ted
I replaced my intake gasket on my 95 lt-1 several years back and wasn't any problem at all. My question is why did you need to remove the smog tube on the passenger side exhaust manifold?
I did not have to remove mine in order to perform this task.

If you haven't completed the intake gasket replacement yet then I think it is important to let the RTV sealant air dry at least 48 hours before starting the engine. It's been at least 3 years since I've replaced the gasket on mine and it hasn't shown any signs of seepage since then.

The problem I've noticed with gasket replacements is that most people do not let the RTV cure long enough before starting the engine. Also make sure you torque the intake bolts to the proper specs.
A good RTV to use is GM part# 12345739

The instructions on the tube will say it's ok to start the engine in 15 minutes after application. Don't do it! Let it cure slowly and your leak problem will be solved.

Good Luck
zikuslt1 -

I removed the A.I.R. tube because I wanted all the room I could get when I hefted the manifold back into place. It is hard to recall what I saw that looked so tight, but I do remember unbolting the diamond-shaped flange (the "sucking" end (no pun intented)) of the tube from the rear of the manifold and then calculating that that flange would get in the way when I tried to work the manifold back down into place without disturbing those precious virgin RTV beads.

Once I found the right wrench, the tube came off quite easily.

As for the sealant, I'm going with the copper RTV. I've heard pros and cons about how soon after applying it to reinstall the manifold. My common sense tells me to go with GM recommendations and reinstall the manifold immediately after applying the RTV. If both surfaces are squeeky clean the goop should adhere well to both surfaces. Allowing the stuff to skim over first is against my better judgement. I'd rather have total adhesion to both surfaces; not more one than the other.

As for total curing time, I believe you are correct. Waiting for an overnite cure before lighting the burner should work better.

Thanks for your advice.


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