Breaking the exhaust manifolds free from the heads

[Kenny_Z]

Things started out nice with my exhaust project but by the end of the day I had all but 3 studs break off. The manifolds will not come loose from the head. I don't want to pry against the engine but hitting the manifolds with a hammer is not producing any results. Any ideas?

http://uploads.m-cgi.com/kennyz/Delorean/Projects/exhaust02.jpg

And of course the studs I don't need seem to be the ones that survive.

http://uploads.m-cgi.com/kennyz/Delorean/Projects/exhaust04.jpg

[DMCMW Dave]

Chisel the washers off first, one at a time. They (and a pile of rust) are still holding it on.

[Kenny_Z]

Thanks, I'll give that a shot tomorrow.

[Nicholas R]

Thanks, I'll give that a shot tomorrow.

Cover the area with penetrating fluid overnight while you're at it.

[Citizen]

I don't want to pry against the engine but hitting the manifolds with a hammer is not producing any results. Any ideas?


In addition to what Dave said, use a rubber mallet instead of a hammer if you can. If you don't have a mallet, use a piece of wood between the manifold and the hammer head. Should help prevent damage to the manifolds.

Thomas.

...

[jawn101]

This may be a noob question, but if the studs do break off, are they easy to replace? It seems like everyone's always talking about these things snapping off.

[David T]

The heads can be removed with the manifolds. If you have a lot of broken studs it may be more efficient to remove the heads and drill out the studs. Before hitting the manifolds I would try a lot of penetrating oil but heat works best. The manifolds are cast iron and will not take kindly to a lot of hammering. If you feel you have to hit them use a short piece of 2X4 and hit that with a hammer against the manifolds.
David Teitelbaum

[DMCMW Dave]

This may be a noob question, but if the studs do break off, are they easy to replace? It seems like everyone's always talking about these things snapping off.

No. One of the tougher jobs on the car involving tools you probably don't have. And the cost of doing it wrong (drilling into the cooling system or oil system) is worse.

[David T]

Removing broken steel fasteners in aluminum is among the most difficult jobs an owner may face. It is actually machinist work and you need those skills and tools. You also need good access and for many of the studs that is not possible with the heads on. That is why you try to avoid breaking things in the first place. I do not remove exhaust hardware without the use of an acetylene torch. Too big a chance of breaking stuff. That is another skill most owners do not have or even the torch itself. Some jobs are better to farm out if you are not confident of your skills or do not have the right tools. This is a case where you can take what could have been a small job and turn it into a BIG job. We see all the time where an owner can mess up even a small, simple job like just not putting the distributor cap on right. Enough of us have made mistakes like this so we can give others the benefit of our experience. As for drilling out broken studs, it is difficult to stay centered on the hard steel stud without wandering into the aluminum. And if you do not have enough access you won't get the hole perpendicular to the head.
David Teitelbaum

[Kenny_Z]

I got the passenger side off. There was one washer that would spin on the stud but not actually come off. Once I turned some sand paper on the stud it slid off and I was able to remove the manifold. Unfortunately I came face to face with another issue. One of the studs broke off below the surface. I can remove ones that are level but I can't remove one that is below the surface. I'm probably going to have to pull the head and take it to a local machinist. Odds are I won't be making the March 30th show after all. The headers I bought do not have all four stud holes, it only has the two that are used by the stock system.

I soaked them with WD-40's rust penetrate but I ran out so I switched to PBblaster. I realize now that I should have borrowed my father's butane torch while I was doing this. Live and learn I guess.

[dmc4087]

I got the passenger side off. There was one washer that would spin on the stud but not actually come off. Once I turned some sand paper on the stud it slid off and I was able to remove the manifold. Unfortunately I came face to face with another issue. One of the studs broke off below the surface. I can remove ones that are level but I can't remove one that is below the surface. I'm probably going to have to pull the head and take it to a local machinist. Odds are I won't be making the March 30th show after all. The headers I bought do not have all four stud holes, it only has the two that are used by the stock system.

I soaked them with WD-40's rust penetrate but I ran out so I switched to PBblaster. I realize now that I should have borrowed my father's butane torch while I was doing this. Live and learn I guess.

Is the broken stud easy to get to? You may be able to use a stud removal tool (like an easy out).

[DMCMW Dave]

Is the broken stud easy to get to? You may be able to use a stud removal tool (like an easy out).

I'd never ever try an easy out. They work in wood, but in metal they break off and now you have a stud to remove that is 10x harder material than the broken screw you started with.

[David T]

There are removal tools that work better than E-Z outs but for the most part, if you broke the original fastener you can expect you will not be getting the broken piece out easily. Butane does not get anywhere near hot enough for this kind of work. If the stud is broken off below the surface, in some respects that makes it a little easier to get centered and drill it out. The basic method is to drill a small hole as centered and perpendicular as you can and then follow it up with increasing sizes of drills all the time trying to improve centering and perpendicularlity. Once you get to the root size of the fastener you can try removing it again or you just oversize the hole and tap for an insert. I have had some limited success with left hand drills. Be careful to not go deeper than the original fastener, you can hit internal passages and then you have leaks.
David Teitelbaum

[Kenny_Z]

I'm pretty sure the stud where my exhaust leak was was broken prior to me touching it. When I put the socket on it it fell out on its own. I poked it today with a pick to get a better look at where it broke and another chunk fell out. The driver's side manifold is still attached. I'm soaking it in pb blaster but all the washers except 2 are still fused to the manifold. At least these studs all broke at the washer. I mean every single one of them broke. Only two on the passenger side broke but the ones that broke broke below the surface.

The heads are definitely going to the machinist I used when I did my Monte Carlo's rebuild. I stopped by his shop today while I was out buying a 35mm socket and asked him about the issue. He was actually removing some broken bolts from a Malibu's heads when I stopped by. The first thing he asked if I'd tried to remove them myself. He told me horror stories about broken ez-outs and misdrilled heads. I told him no, as soon as I saw where they broke I stopped and decided to let someone else handle it.

I removed the broken studs in my Monte Carlo's heads with a welder because they were flush with the surface and the heads were only 200 dollars each. If these were flush broken then I'd go for it but they are not and the heads are not cheap. I'm going to take them to a professional that has the correct tools.

At least will force me to do the VOD work I was going to put off until after the March car show.

[Kenny_Z]

Here's a couple shots of what was broken.

http://uploads.m-cgi.com/kennyz/Delorean/Projects/exhaust08.jpg
http://uploads.m-cgi.com/kennyz/Delorean/Projects/exhaust09.jpg

That gasket isn't just torn. I did not find the rest of it anywhere.
http://uploads.m-cgi.com/kennyz/Delorean/Projects/exhaust07.jpg

Another question. Should I go ahead and change the freeze plugs while I have the heads out? The engine has never been overheated as far as I know. It got close at a parade but I shut it down at about 230-240. The whole reason I pulled my Monte's heads were because of a rusted through plug. Those things do not like me.

[DMCMW Dave]

I'm pretty sure the stud where my exhaust leak was was broken prior to me touching it. .

Not unusual. The manifolds warp from overheating and if the bolts are rusty they can break. You can tell from the bolt-end that this is not a new break.

[David T]

Do not touch the freeze-out plugs unless they are leaking which is uncommon. When I see broken studs, not broken because of attempted removal but an old break, it is usually because the car was run for a LONG time with an exhaust leak. I would attempt to drill the studs out, it is a LOT of work to remove the heads but if you have to, then go for a whole "top job". Have the heads and valves ground. BTW, if you don't have the dummy block or lock for the timing chain that means you are also pulling the timing cover. Do NOT move the motor without liner locks or you will disturb the liner seals and now you are also doing a bottom job. At that point the motor might as well come out!!!!!!!!
David Teitelbaum

[Kenny_Z]

Yeah, she's had a noise going since I bought her. She didn't sound all that different that the old Volvos I'd heard around town. I had no idea how bad it actually was until I drove Ben's Delorean.

I'm not planning on moving anything once the heads are off and I'll have one of 1batt4u's flywheel locks in place. Will that be enough to keep things in place?

[DMCMW Dave]

I'm not planning on moving anything once the heads are off and I'll have one of 1batt4u's flywheel locks in place. Will that be enough to keep things in place?

Ideally you lock the cylinders down with the Renault tool or with short headbolts and huge flat washers. Without that you run the risk of turning the engine and popping the cylinders out of the block. A very good practice is to be sure that the transmission is out of gear so in the event that someone bumps the car and rolls it the engine won't turn over. Your flywheel lock will help with this too, but it does not take much to pop the cylinders out.

[dmc4087]

I'd never ever try an easy out. They work in wood, but in metal they break off and now you have a stud to remove that is 10x harder material than the broken screw you started with.

With a cheap kit I'd agree.

I dont like the term easy out, but we used a high quality set from a mechanic on my broken studs last year. They werent tapered like the wooden ones.. The process was to drill a hole using the guide supplied, then tap in the 'easy-out' which griped the stud and allowed it to be screwed out.

It is nerve wracking - and my engine was removed for easy access.

[dmc4087]

Also, we found that with enough heat (like a quick blast from a welder) the protruding stud would screw out relatively easy.

[Kenny_Z]

I got the heads back from the machinist yesterday. We talked about what he did to remove the studs on the driver's side. He said he started with a torch after they soaked for a day but the first one broke off. Next he tried the welder and nut trick and another broke off. Then he soaked them for 3 days. The torch and welder both still snapped bolts. Finally he just snapped the remaining two and put it on the mill. So he broke 6, I broke 2, and my wallet is a bit lighter because of it. Between the parts and machine work I've probably got somewhere around three to four hundred into this exhaust not including the purchase of the new exhaust kit. I think that might be cheaper than having taken it to a shop, especially with the condition of these bolts. However, if I had a time machine (ha ha) I would take her to a shop. This is very hard work.

[David T]

As long as you had to take the heads off you should clean up the valves, make sure the head is flat, and install the hotter cams to go to what is a Stage II with the improved exhaust. Of course it will take even more money to do it!
David Teitelbaum

[Kenny_Z]

I would have loved to put in the hotter cams but I really didn't have the money saved for that expense. I didn't expect to get into the engine this deep already. As much as I complain about it I did enjoy the work so maybe in a few years after my Mustang and Nova are done I'll do this again but go further with higher compression pistons and hotter cams.

http://uploads.m-cgi.com/kennyz/Delorean/Projects/engine29.jpg

Please excuse the weird angle on these pictures, my camera and image size conversion software appear to have gotten into a fight. I'll probably sort it out tomorrow. I'm exhausted.

http://uploads.m-cgi.com/kennyz/Delorean/Projects/engine30.jpg
http://uploads.m-cgi.com/kennyz/Delorean/Projects/engine32.jpg
http://uploads.m-cgi.com/kennyz/Delorean/Projects/engine33.jpg