Exhaust manifold stuck to the head

[dzwestwindsor]

Hi guys,

I'm trying to remove the exhaust manifold on a 1971 chevy 350. Since 2 of the bolts connecting the manifold to the cylinder head are rounded, I used a Dremel to grind the bolt heads. Now, I have 4 bolts removed and 2 bolt heads grinded down. That's all the bolts holding the manifold to the head (6), correct?

I'm asking because the manifold will not budge at all. I've whacked it many many times with a mallet and sprayed PBblaster, but to no avail. It would even budge...

Does the exhaust manifold fit into the cylinder head? Like does it fit into the head like a socket? If all the bolts are actually removed, would it stay on by itself or should it just fall off?

Also, is it okay to take a bar and pry the thing off, pressing on the valve cover to get leverage? Or will that damage the valve cover?

I'm having trouble figuring out what's still holding it on. Just flat out rust? Or am I forgetting to remove a bolt from somewhere? Any advice?

Thanks,
David

[too much stuff]

Just rust. The 2 bolts still in are making it tough. You can try to pry on it, but you may bend the valve cover some unless you can get a better pry somehow.

[67CC]

Had the same problem. Tried PB Blaster, Kroil, the freezing stuff, fancy tools for getting off rounded bolt heads, without success. Think there was two of them too. Don't feel bad. Someone once said exhaust manifold bolts are the hardest job on a car. I believe it. Took me three weeks.
There are only six. You need heat. Forget map gas. Oxy-acetylene until they are bright orange. Then I was able to get them out with a vice grips. Focus heat on the manifold only, not the head.

[slikside]

Originally Posted by 67CC

Had the same problem. Tried PB Blaster, Kroil, the freezing stuff, fancy tools for getting off rounded bolt heads, without success. Think there was two of them too. Don't feel bad. Someone once said exhaust manifold bolts are the hardest job on a car. I believe it. Took me three weeks.
There are only six. You need heat. Forget map gas. Oxy-acetylene until they are bright orange. Then I was able to get them out with a vice grips. Focus heat on the manifold only, not the head.

This. heat is your best friend in these situations. Like he says focus the heat on the manifold where it surrounds the bolts. that is the metal you want to expand.

I'm guessing that's why these bolts are rounded...someone tried a little too hard without heat...and they rounded.

Oh, and one more thing. Don't be afraid to tap on those bolts with a hammer after/during heating. The shock will loosen things up too. Just don't miss and damage your manifold.

[Saclandman]

Having the same problem with the pass exhaust manifold on my 67. All but one bolt came out. The last one was rounded off. Ground the head down but still can't get it free. Time to get the torch out.
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[dzwestwindsor]

Hi thanks for the suggestions guys..

Just to clarify, 4 bolts are out, and 2 bolts have no more bolt head on them (because I cut them off with a Dremel since I gave up on trying to get something to catch on those rounded bolt heads). So technically at this point, without rust, the manifold should slide out. But it is dead stuck and not moving at all.

So in this case do I still torch around the bolts? Where's the rust, around the bolts or in between the manifold and cylinder head, that's keeping it from moving?

[my67c20]

The rust is around the bolt and the hole in the manifold. If you cut the head of the bolt off and are left with nothing sticking out about all you can do is to heat the manifold in that area, and try to pry the manifold loose. Another option would be to weld a nut to the stud then heat and try to remove the bolt. Good luck