Pancake manifold frozen to stud

boosted79 · 01-25-2016, 01:32 PM

I'm tearing down my '79 and the intake is frozen to the pass. side middle inside stud. I haven't tried a torch yet. Are these intakes magnesium or aluminum? I've tried a heat gun and PB but no luck yet. Maybe I''ll try a double nut and try turning the stud to break it free but not sure I can get a good purchase on the bottom nut with the way it sits in an indentation in the manifold. Anyone else run into this?

Jim Wolf · 01-25-2016, 02:00 PM

I suggest you patience !
Leave PB overnight and try to tap the manifold with a rubber mallet...
These studs are quite long and I am not sure if it will come out easily in one piece...

Good luck,

dap930 · dap930's Garage

Yes, the intake is magnesium. Be very careful.

WERK I · WERK I's Garage

boosted,
Had the same problem getting mine off. I soaked them as suggested above, but after I eventually got the manifold off, the studs showed a calcium deposits which probably came from water getting in between the bore and the stud.

boosted79 · 01-25-2016, 06:05 PM

Well, it's encouraging that I'm not the only one. I hit with the propane and then PB numerous times and had a crow bar between a block of wood on the valve cover and another on the bottom of the manifold. I managed to get it up about a 1/4" so I called it a night. I'll let it soak and try again tomorrow. I guess the last resort will be to MIG a nut on to the stud and either back it out or break it off. I wonder what a little muriatic acid would do? It works great for cleaning aluminum off carbide burrs and aluminum off 2-stroke bores after a seize and it reacts with Mg. Maybe I'll give that a shot . I'll have a spray bottle with a baking soda mix ready to neutralize it .

pkabush · 01-25-2016, 06:50 PM

I took mine off last night. I had to smack it with a rubber mallet several times to free it up
My studs have allot of calcium build up as well. I was planning on pulling the studs cause I'm swapping heads but, I'm probably better off just buying new ones.
Good luck.

Alan L · Alan L's Garage

The acid will LOVE your Mg manifold. I would try other methods first, and again, before plunging over the cliff.
Alan

boosted79 · 01-26-2016, 05:37 AM

Yes it will, it would probably do too much damage to it before it is able to get to the corroded part around the stud. I think I'll try an acetone/ATF mix on it today.

Ruf1969 · 01-26-2016, 04:45 PM

Time and patience and a rubber mallet.

boosted79 · 01-26-2016, 07:12 PM

I tried it again this morning with the crowbar and blocks of wood, no go. So I mixed up a 50/50 mix of acetone and ATF and let it sit for 10 minutes. Then I saw the mixture drain from around the stud which never happened with the PB. I tried the crowbar again and bingo, it came right off. Whether it was the acetone/ATF or letting the PB Blaster sit overnight I don't know but Ill be using this acetone/ATF again when I need a penetrant.

Alan L · Alan L's Garage

Great result.
Alan

WERK I · WERK I's Garage

Congrats!

WERK I · WERK I's Garage

boosted79,
I found this thread describing your difficulty removing the pancake manifold. Well, it has bitten me too. One stud, on #5 cylinder, inboard, is refusing to budge. The pic below shows the pool of Kroil that won't drain into the manifold stud bore. Kroil worked on all of the others, but not on this one. Do you think the 50/50 blend of acetone and ATF would work?

jsveb · jsveb's Garage

Can't say if it works, but I've used the ATF/ace. as well with great success

boosted79 · 06-08-2016, 10:55 AM

WERK1 - All I can say is try it. I don't know if that is what did it with mine or letting it sit overnight with the PB Blaster. Rock it back and forth as much as you can too. Good luck.

WERK I · WERK I's Garage

Jesper & boosted79, thanks. Can't believe how much of a PIA this is. I soaked all the studs with Kroil three days ago. All but one released in one day.
I rebuilt this motor back in 2002 and did not have this much difficulty getting the manifold off.

boosted79 · 06-08-2016, 04:36 PM

Try a heat gun on the manifold . Maybe it will expand the mag. enough to break it loose.

Speedy Squirrel · Speedy Squirrel's Garage

The lower intake is aluminum guys. Only the upper is Mg. not that it helps this situation. FYI, I used double nuts and it snapped that stud right off. Not a good thing. I wound up drilling it out and helicoiling it.

Rawknees'Turbo · 06-08-2016, 05:27 PM

Dave, if the primary intake manifold is aluminum, like the Squirrel says (I didn't know that), then you can put a few drops of muriatic acid on there and all corrosion between the stud and aluminim will dissolve . . . just a few drops at a time, don't allow it to sit too long, and clean the surfaces right away with water after you get the manifold off.

WERK I · WERK I's Garage

There is no part of the intake manifold that is aluminum.....all cast magnesium, unless Speedy Squirrel is referring to the injector blocks, which I still have the bakelites.

I was able to raise the intake about 1/2", but it will rise no further....today.

Tomorrow night I will try a heat gun. If that doesn't work, I'll try a 10% solution of muratic/water....with a water squirter at the ready. Thanks for the input guys...much appreciated.

btw, the studs in the pic look like they are curved. They are not (optical illusion).