Exhaust manifold to cylinder head capscrews are frozen- any tips?

[53k]

The '64 Avanti I bought last month had a cracked right side exhaust manifold. This was an aggravation since it wasn't mentioned in the eBay listing, but not a big deal. I had a manifold and the gaskets plus a new heat riser (one on the car was stuck). So, today I get the car up on jack stands and start to take off the outlet pipe. Naturally the first stud I tried snapped off. I expected that and wasn't concerned because I was replacing the manifold anyhow. But, before breaking off the other I decided to loosen the cap-screws holding the manifold to the head. I couldn't budge any of them. I was afraid to put more pressure on them because I definitely don't want to have to pull the head to deal with broken off cap-screws. I have never had cap-screws seize like that. Have I just been lucky? Any ideas on how to get them out without breaking?
I am amazed that the hog troughs, rear cross member, and frame are a good as they are because everything on this car is covered with moderate to heavy surface rust. Should have kept the California convertible- every nut and bolt on it was clean and easy to loosen.

[studeboy28]

When in doubt I always heat frozen bolts first . Then gentle back and forth back and forth. Don't just put pressure counterclockwise.

[sweetolbob]

Paul

The few times that has happened to me, the bolts were rusted to the manifold not into the head. I took a torch, heated the manifold/bolt area and then let penetrating fluid draw back into the area as it cooled. It took time but worked. Also wire brush the bolts as much as you can first and during the treatment.

Heck, if you still had the 'vert your problem solving would disappear. Good luck

Bob

[jallen]

If you resort to using a torch, you might try parafin on the bolts after heating, I think it is somewhat less flammable.
I would try tapping with a hammer/chisel, I agree with Bob, more often than not it's the head of the capscrew that's
frozen, and not the threads.

[bams50]

We deal with this all the time here in the good ol' NE; just finished this job on my 99 Dodge plow truck. Sometimes the solution is to torch off all the bolt heads, remove the manifold, and then turn out the studs with Vise-Grips. Usually they come out decently since the problem was the bolt stuck in the manifold, not the head.

If one is difficult you can slide a nut onto the bolt and weld it to allow wrench use. If you do, slide it down close to the head, that will make it less likely to twist off, and the heating/cooling cycle of welding will assist in breaking the stud loose.

[53k]

If you resort to using a torch, you might try parafin on the bolts after heating, I think it is somewhat less flammable.
I would try tapping with a hammer/chisel, I agree with Bob, more often than not it's the head of the capscrew that's
frozen, and not the threads.

Thanks all for the tips. Heat seems to be the answer. I'm just a little nervous about trying to get a propane torch to where the heat is needed (manifold is very close to the fiberglass inner fender).
The parafin trick is my mechanic son's solution too. He heats the stuck bolt/nut and presses a candle against it. The parafin seems to draw in to the stuck place.

[N8N]

since the manifold is cracked anyway, another option would be to simply break up the manifold with a BFH, then address the bolts or remains of same with the manifold out of the way. BTDT... also, if you can get some but not all of the bolts loose, once you get the manifold "somewhat" broken up, you can often use pieces of the manifold to start some of the bolts loosening.

nate

[53k]

since the manifold is cracked anyway, another option would be to simply break up the manifold with a BFH, then address the bolts or remains of same with the manifold out of the way. BTDT... also, if you can get some but not all of the bolts loose, once you get the manifold "somewhat" broken up, you can often use pieces of the manifold to start some of the bolts loosening.

nate

Not a bad idea, but with my unerring accuracy, I might hit something else.

[Jeff_H]

Another way to heat those bolts is simply to run the engine for a while to get the manifold hot. Then, shut it off and loosen the bolts before it cools again. This may not be do-able depending on access to the bolts and risk of burning yourself though.

The FE block fords (352, 390, etc) have "tabs" for the upper manifold bolts with a through-hole. The end of the bolt is exposed and facing up at a angle so they rust tight into the tab on the head. If those are not too rusted, the run engine trick will sometime work to allow them to be loosened. I've had to pull the heads to drill out the bolts on these since there was no access space with a drill. Used lots of anti-seize with SS bolts the last time I had one apart.

[jclary]

I have had good success using a good quality 1/2" ratchet and socket in combination with well placed taps using a ball peen hammer. Sometimes a good quality box end wrench and ball peen hammer. Space is always a problem if the engine is in the car and the front clip is still on. The last thing I would do is take a big hammer and try to break the manifold off! (I have seen too many so-called mechanics that operated in this manner). Attempting to weld under the hood of an Avanti or any car with a good quality finish would require some very good weld spatter curtains. Your best tool will be patience and a good feel for applying sufficient force to turn the bolt without breaking it. If space is a problem, you can purchase a hand-held propane torch with a flex hose so that all you need under the hood is the nozzle. I sometimes use one in my plumbing business. A few sessions of heat, penetrating agent, and force should eventually free them. Best of luck!

[sweetolbob]

Paul

I'd be careful about the BFH, The rust I've dealt with was between the bolt and the hole through the manifold. A BFH blow could strip the threads. I'd use the heat/lubricant cycle for a while and only use the BFH as a last resort.

JMO

Bob

[N8N]

Paul

I'd be careful about the BFH, The rust I've dealt with was between the bolt and the hole through the manifold. A BFH blow could strip the threads. I'd use the heat/lubricant cycle for a while and only use the BFH as a last resort.

JMO

Bob

I agree, I have seen the same, but breaking the manifold can help in that case if you do it right, e.g. let's say that it's one of the end bolts that is rusted as you describe, if you can break the manifold and also remove the other bolt at the end port, you can hit the broken chunk of the manifold and spin the bolt and manifold piece together to loosen the bolt rather than having to free the bolt from teh manifold. I can only remember having to do this once, and this was on an Avanti that JDP had, the head was already off as the engine was stuck as well. Heat from oxyacetylene had already failed to loosen the bolt in question...

nate

[gordr]

If the engine hasn't been messed with, they should be stainless steel capscrews. A little harder to torch off I'd go with heat. Obtain the use of an acetylene torch if you can swing it. Much more concentrated heat than a propane torch, so you can get those screws really hot with less risk of collateral damage. If you fell you must split the manifold away from the screws, drill a couple of holes crossways into the bores for the screws, and use a small cold chisel to split the bores. Less hammer work, and again, less risk of collateral damage.

[N8N]

If the engine hasn't been messed with, they should be stainless steel capscrews. A little harder to torch off I'd go with heat. Obtain the use of an acetylene torch if you can swing it. Much more concentrated heat than a propane torch, so you can get those screws really hot with less risk of collateral damage. If you fell you must split the manifold away from the screws, drill a couple of holes crossways into the bores for the screws, and use a small cold chisel to split the bores. Less hammer work, and again, less risk of collateral damage.

I have been told that the originals were not stainless but nickel plated, and I also believe that that practice had been discontinued by the time the Avantis were introduced. Not sure what years got the good bolts and which ones didn't. I *would* consider using stainless as replacements, but slop lots of anti-seize on them so they don't gall the threads in the heads.

nate

[53k]

Problem mostly solved. Bolts were loosened by a high tech gadget, a flameless magnetic induction heater.
Since I posted about the frozen exhaust manifold bolts it has been so hot that I haven't felt like tackling it. Then a couple weeks ago my older mechanic son told me that he had convinced his boss to buy a $500 electronic tool for heating stuck bolts. It works on 110-volts and something less than 15 amps. It has soft coils that you wrap around the stuck nut or bolt. When it is positioned you press a button on the side of the tool and in a minute or two the bolt is glowing red. Big advantage- no fire near wires, rubber or in my case fiberglass. And the front stuck capscrew was about 1/2-inch from the aluminum crankcase of the a/c compressor which would made use of a torch dicey.
Anyhow, son came over today with the tool. After heating and rubbing with paraffin, all the bolts came loose except the very front one. It's in a very awkward spot anyhow and he couldn't budge it. even broke my 14mm Craftsman socket trying. Second heating- no joy. So, I brought out my air hammer and he chiseled on the bolt head for a while then heated it once more. That convinced it to come loose. When that bolt came out so did the front part of the manifold. It wasn't just cracked, it was completely broken. I crawled under the car and snapped the second flange stud then pulled off the manifold from the top. As you can see in one of the thumbnails, the manifold was really shattered. It was broken at the exhaust flange and even the heat riser was broken open. I put on the new manifold and learned that when Studebaker said 2 and 1/16th inch length for the flange stud, they had a reason for it. I had to take the manifold off and cut off the excess from the studs that I had bought at my FLAPS.
Anyhow, the problem is only partly solved because when I attempted to put on the new heat riser and flange gaskets, the outlet pipe was more than 1/2 inch off from aligning with the studs. The PO had put new mufflers on the car and there was no sign of the pipes being apart (very rusty). So, I think his mechanic must have forced the pipes apart to get the right muffler on and in doing so, broke the manifold. I sure hope the left side isn't the same way. I ran out of light for the evening so I quit before trying a pipe solution. I'll probably have to cut the pipe, shorten it and splice it. I doubt if the old rusty outlet pipe is going to come loose from the next pipe. Hey Don, bring me another set of your pipes for Reedsville this fall.