How to Remove Stuck Exhaust Manifold Studs

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stagf15

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Sep 24, 2013
6
Catalina 30 Niceville, FL
Greetings, I've tried to do my due diligence searching the forums for guidance on this, and can't come up with anything. I am in the process of installing the recommended alternator bracket upgrade on my 1986 Catalina 30 with Universal M-25 diesel. The four exhaust manifold studs that would be used by the new bracket are too short on my engine, so I am forced to use the longer ones that came with the kit. Unfortunately I can not get mine out of the manifold/block. They do not turn a bit, and one broke off flush with the manifold.

I'm wondering if anyone has any experience with this upgrade, and possibly this situation. It looks to me like I am going to have to remove the exhaust manifold in order to remove the studs, and I'm wondering if these studs are going to be frozen inside the manifold, which would further complicate my problems.

Thank you for any help!
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,672
Canadian Sailcraft 36T Casco Bay, ME
If the studs are too short it is pretty much a prerequisite that the manifold comes off.

Use good quality penetrating oil like PB Blaster or Kroil on the studs before you break them. DO NOT use WD-40 it is NOT a penetrating oil....
 
S

stagf15

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Sep 24, 2013
6
Catalina 30 Niceville, FL
Maine Sail, thanks for the reply... Have I seen on another forum, maybe the C34 forum that you've actually done this before? I may be out to lunch.

In your opinion are the studs going to be frozen solid to the inside of the manifold, or will I be able to pry the manifold off, and then go to work on the studs where they enter the block with the PB blaster?

Thanks!
 
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stagf15

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Sep 24, 2013
6
Catalina 30 Niceville, FL
MS, another question(s) for you... If I do get the manifold off with all 6 studs left sticking out of the engine, what is the proper method of PB blaster application, and then removal? Should I apply PB plaster every 8 hours or so, over the course of several days (2-3)? Should I use any heat when I try to break them free? Do you recommend vice grips on the studs for removal? That is what I used on the end of the one stud that I broke off.
 
centerline

centerline

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Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
stagf15 said:
MS, another question(s) for you... If I do get the manifold off with all 6 studs left sticking out of the engine, what is the proper method of PB blaster application, and then removal? Should I apply PB plaster every 8 hours or so, over the course of several days (2-3)? Should I use any heat when I try to break them free? Do you recommend vice grips on the studs for removal? That is what I used on the end of the one stud that I broke off.
Click to expand
Your plan sounds like the correct approach...

you say they do "turn" a bit... does this mean they are a bit loose in the hole or are you stressing them to get movement at your tool handle?....
If they are obviously loose in the hole but tighten up when you try to turn them out, then your job is easy. Use the pb blaster like MaineSail suggested, and gently rock the stud back and forth in the hole in its loose spot.... it will eventually work its way loose without you needing to force it and possible causing a broken stud.

As for the one stud that is already broken...
before even attempting the removal of it, you need to decide whether you have what it takes to do the job correctly, or if you need to hire a professional to do it.... it wont be easy and you only have one shot at it.... damage is highly likely if you dont get it right on the first try.

If you decide to use heat, after heating and as soon as the stud starts to cool enough where it does not immediatly burn the penetrant off, flood keep it flooded until it cools down a bit as the cooling metal will absorb a small amount of it and help break things loose.
Also tapping pretty firmly on the end of the stud before its broken off, like you were trying to tap it into its hole, will help to loosen it also, no matter if you use heat, penetrant or nothimg at all....

Sucessfully Removing a frozen stud without further damage is a matter of preparation and finesse...
 
berner73

berner73

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Jul 26, 2009
291
. . .
Just a couple of comments on the PB Blaster which is a remarkably effective penetrating formula. Multiple applications over several days is the right idea. If there's enough room to allow it, tapping the stud/bolt with a small hammer prior to every application will help too. Wouldn't hurt to take a wire brush to the surface before spraying (don't use a steel brush, pick up a SS one at your hardware store). Take care not to get any PB Blaster on rubber or plastic surfaces. Towel off the area so it won't run all over the engine or into your bilge. Be patient, the stuff works.
 
rmwac

rmwac

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Apr 22, 2011
19
Catalina 30 Watkins Glen
HI all: I did the alternator upgrade last season, and of course, I had the short studs.... They would not budge with a vise grip. So, it was 'game on' for the full fix. First, disconnect the Hump Hose, which ties the exhaust riser to the lift muffler. Then remove all six of the nuts on the manifold studs. Gently begin to pry the manifold off from as many directions as you can. It will eventually move and then slide off the studs. You need the Catalina upgrade kit PLUS a new exhaust manifold to riser gasket, and three manifold to block gaskets. They ought to include these gaskets, but I digress.... Once the manifold is off, what I did was to soak each stud with PB Blaster by placing a few cotton balls around each stud base, and then rubber banding them in place. Then I saturated the cotton with PB Blaster, and let is soak for a few days. When I attempted to remove the studs, they came out effortlessly with a vise grip. You probably know the reassembly procedure, but I took the time and spare $$ burning a hole in my pocket to replace the old and rotting hump tube with a new silicone version from Catalina Direct, as well as splurging on a new exhaust riser thermal blanket to replace the nasty fiberglass mummy wrap. Make sure you read about the sloppy fit of the alternator bolt that comes in the Catalina kit. It will cause a dangerous slop in the alternator mount. There are plenty of posts about this issue. Hope I helped a little. RON
 
S

stagf15

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Sep 24, 2013
6
Catalina 30 Niceville, FL
Thank you all for your great replies. I now am encouraged that I'll have some success with this project. I really like the idea of soaking cotton balls with PB blaster to keep the stud/block area very saturated with penetrant.

centerline, to answer your question, the broken stud is broken off flush with the outside of the manifold, so while this is not optimum, it is not significantly worse off than any of the other studs, once the manifold is off. That one stud SEEMED to turn a bit, maybe about 30-40 degrees (out of 360 deg) before it snapped off. But, I am not sure if that was all just the metal giving way. It didn't seem like it.

I ordered all of the required gaskets, and the two shorter studs from TOAD, they should be in soon. However my dad will be here next week and I am going to wait to accomplish this project until AFTER he's here, because I know how these things go, and I really want to sail with him while he's here!

I've had a thorough read of the pbase/mainecruising article on this, along with several of the posts on the incorrect size of bolts in the kit, so I will hit the hardware store before I get it all back together.

Thanks again, I'll post how it goes and hopefully a few educational pictures.
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,672
Canadian Sailcraft 36T Casco Bay, ME
stagf15 said:
Thank you all for your great replies. I now am encouraged that I'll have some success with this project. I really like the idea of soaking cotton balls with PB blaster to keep the stud/block area very saturated with penetrant.

centerline, to answer your question, the broken stud is broken off flush with the outside of the manifold, so while this is not optimum, it is not significantly worse off than any of the other studs, once the manifold is off. That one stud SEEMED to turn a bit, maybe about 30-40 degrees (out of 360 deg) before it snapped off. But, I am not sure if that was all just the metal giving way. It didn't seem like it.

I ordered all of the required gaskets, and the two shorter studs from TOAD, they should be in soon. However my dad will be here next week and I am going to wait to accomplish this project until AFTER he's here, because I know how these things go, and I really want to sail with him while he's here!

I've had a thorough read of the Compass Marine article on this, along with several of the posts on the incorrect size of bolts in the kit, so I will hit the hardware store before I get it all back together.

Thanks again, I'll post how it goes and hopefully a few educational pictures.
Click to expand
For others who are interested the full instructions for this are at the link below. Three full pages of photos and tips to make it go smoother.

M-25 Alternator Bracket Upgrade (LINK)
 
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