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  #1   IP: 199.116.169.104
Old 02-08-2017, 08:10 PM
BobinSF BobinSF is offline
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Unhappy Broken Manifold Studs

While attempting to remove a threaded plug from the top of the exhaust mixing elbow, I felt something give way; I had broken all three of the studs holding the manifold to the block. The looked very rusted.
My path to repair seems to be the following:
1. Remove the manifold, after unbolting the carburetor and disconnecting the water inlet and outlet hoses and the tube from the bottom of the carburetor to the intake manifold.
2. Try to remove the three stud stubs from the block with the stud remover tool.
3. Failing in the above, drill out the stud stubs, tap and place three repair bushings in the block.
4. With new manifold studs and manifold gasket, replace the manifold and reconnect disconnects from #1.
My A4 is very tight in my Tartan 27. If #2 fails, it probably means removing the engine to do #3. All this definitely pushes my skill level, so having the boatyard repower with a Moyer rebuilt A4, or going electric, looks tempting. Any advice would be most appreciated.
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Old 02-08-2017, 08:44 PM
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Bobin,
I'd be curious as to where the studs broke? At the base of the nuts, at the block, or elsewhere? The possibility exists that the studs failed because the block and studs corroded from inside - studs corroding in preference to the block (high nickel). Hopefully you'll find that the studs corroded and the block is OK.
Your plan sounds good except you're going to have to disconnect the exhaust.
Once you can see the side of the block, check the wall thickness in way of the studs (corrosion). Hopefully it will be 1/4" (or more) - 3/16 or less is not enough metal to hold new studs and heroic measures will be needed (inserts/bushings).
Hope this helps..
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Old 02-08-2017, 10:45 PM
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sastanley sastanley is offline
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Question

Bob,
Hang on...we need pictures. I understand your access is tight. I found a bad manifold stud (that had already been "oversized" with a Moyer oversized stud by the P.O. I learned from other members of the forum)...I was able to replace it with another oversized stud..the block held strong, the stud went bad. I simply cleaned up the threads, and with advice from Ken in the Moyer parts dept. used JB Weld to seal up the threads and I have been a happy camper for several years now.

Pictures help, A LOT! like this one..this was the block after I got the bad stud out. Ken, and all the forum members assured me it would hold (and it has!) The manifold studs enter into the water jacket, and they like to rust away.



Take some pics and let's go fix it!
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Last edited by sastanley; 02-08-2017 at 10:53 PM.
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Old 02-13-2017, 04:12 PM
BobinSF BobinSF is offline
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Thanks, Al and 'sastanley', for your helpful responses.

I disconnected the water inlet hose so now have about an inch between the block and the manifold; still not enough for useful photos. The three studs broke off within where they thread into the engine block. At two of them, the 'inside' half of the stud is still there; on one, I can probe all the way through the threaded hole. Next step is to remove the manifold for a closer look; probably drilling out and tappingfor the 1/2" to 3/8" threaded inserts is needed.
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  #5   IP: 98.111.100.107
Old 02-13-2017, 05:04 PM
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Failed manifold studs

Bob, can you post a photo of the failed end of your studs? I don't want to give you false hope, but it would be very unusual for a part of a stud to break off halfway into a threaded hole - let alone all three. All manifold studs, and all but one head stud, enter a water jacket; and what we have seen happen several times over the years, is that some studs didn't hold up very well and they literally became something like sacrificial anodes. The result was that as the end of the stud corroded away, it left behind a hard calcified deposit that can give the impression that part of a stud broke off and got left behind. When this happens, you can take a small screwdriver and use it as a "star" drill, turning it as you gently tap through the calcified deposit and then chase the threads with a 3/8" coarse tap. Don
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  #6   IP: 108.66.129.43
Old 02-16-2017, 10:37 PM
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Here are 3 photos: the manifold studs (actually bolts); and the holes for them in the block. On the hole to the left, the wider recessed area is about 1/16" deep.
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Old 02-17-2017, 08:24 AM
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If you can, I would remove the engine to work on that.
I have been in that situation and the repairs I could do in place needed repairs of their own soon enough
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Old 02-17-2017, 10:49 AM
JOHN COOKSON JOHN COOKSON is offline
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Quote:
Originally Posted by BobinSF View Post
All this definitely pushes my skill level, so having the boatyard repower with a Moyer rebuilt A4, or going electric, looks tempting. Any advice would be most appreciated.
A couple of observations that will help you to decide whether to work on the current engine or replace it: A compression check; and also do you remember what the oil pressure was engine warmed up at cruise throttle setting?

TRUE GRIT
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Old 02-17-2017, 11:26 AM
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Originally Posted by joe_db View Post
If you can, I would remove the engine to work on that.
I have been in that situation and the repairs I could do in place needed repairs of their own soon enough
It may be possible to just move the engine. Move it somewhere in the cabin where it can be more accessible, if possible.

But there is never a substitute for working on an engine on a bench in a shop!
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Old 02-17-2017, 12:35 PM
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Thumbs up

It looks to me like the hard work is on the manifold..I think you will find what Don suggests above...gunky leftovers of bolts in the holes in the block. I'd poke around in those holes with a pick and then get the 3/8" tap on that bad boy (or "thread chaser" if you have a set..I think they do less damage to the block than a tap when you trying to simply clean up an existing threaded hole)

I bet if you can get the gasket off the manifold, the nasty old bolts will come out. I am trying to figure out what was holding the manifold to the block..probably the rust!

Both halves of those mating surfaces do need some cleaning up though.
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"Twice Around" - '77 Catalina 30, #511 with original A-4 & MMI manifold - for sale - PM me if interested
"Holiday" - '89 Alura 35 #109 (uh oh, two boat owner!!)
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Last edited by sastanley; 02-17-2017 at 12:38 PM.
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  #11   IP: 137.200.32.6
Old 02-17-2017, 01:36 PM
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How is your time vs. money meter calibrated?
If several thousand dollars was fine with my wife, I would be very tempted to get the Moyer short block and get it all over with.
If the money side is tight, this might actually be an easy repair if nothing else is wrong. The amount of corrosion I see there gives me pause ....
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Old 02-19-2017, 06:45 PM
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Happily, I was able to chase the manifold stud threads in the block to what seems their full depth, about 1/2 inch. The threads seem to be in good shape. So it appears that I can buy new studs, gaskets, etc., from MM and pursue the repair.

Concurrently, I want to remove much rust from the manifold, block,, head, etc. It seems that a needle scaler is the way to go. I will carefully try it on the machined surfaces between the manifold and the head to see if it mars the surfaces.

The inside of the mixing elbow (pic) is full of rust. Getting it loose from the manifold looks impossible. Another Forum reply said that soaking his in muriatic acid for a month worked.

I thank all of you for your advice on the broken manifold studs.
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  #13   IP: 32.211.28.40
Old 02-19-2017, 08:14 PM
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Bobin,
Removing the mixing elbow from the manifold is a piece of cake - a recip saw with a carbide blade will do it in about 30 sec. This will leave half of the nipple in each part - also removable using the same tool. Each half gets two saw cuts on the inside about 1/4 inch apart - try not to get into the female threads. Knock out the pieces between the cuts, then collapse what's left of the nipples.
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  #14   IP: 108.66.129.43
Old 02-21-2017, 05:37 PM
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Removing the mixing elbow from the manifold is a piece of cake - a recip saw....

Al Schober, your method worked just fine; thank you.

Needle scaling is proceeding well, and I am able to do it on the machined manifold-to-block surfaces without marring them.
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Old 02-21-2017, 06:39 PM
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Do not forget:
Water can and will follow the studs into the manifold and get water into the cylinders (intake side) and/or feed water into the exhaust, which may back up into the cylinders and WILL rust out the riser where you would think it was dry.
Found that out the hard way
Do a good job sealing the new studs!
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Old 03-01-2017, 07:57 PM
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While needle scaling the head, I created/exposed a hole into the water passage (pic). It seems to me that on this flat surface, I can do a durable repair by: making an inside and outside steel cover plate each with a centered small bolt hole, removing the adjacent freeze plug, placing the inside plate and nut, gooping JW Weld in the hole and plate surfaces, placing the outside plate and bolt, and tightening the bolt and nut to form the JW Weld to seal the hole. Any comments or suggestions would be greatly appreciated.
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  #17   IP: 32.211.28.40
Old 03-01-2017, 09:35 PM
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Bobin,
That's an ugly picture. Was the PO of this engine using it for a mooring? I hate to say so, but I suspect you're going to find additional holes when you progress with the needle gun.
I recommend you consider a different head. Our host sells new ones, and used ones are available on eBay now and then. Depends on your budget. I had a couple of spares but got rid of them when I moved two years ago. Perhaps one of the other denizens of this board has a spare head - anyone? I suggest you start directing your efforts toward getting that head off rather than removing the rust from it or repairing it. Scrap value is higher with the rust..
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Old 03-01-2017, 09:41 PM
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Ditto the above, call the coroner on that one.
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Old 03-01-2017, 10:20 PM
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My opinion for what it's worth is that head is toast. You might get a few more hours out of it with your repair but the rest of it can't be far behind for failing. My abvise. Save yourself a lot of grief, bite the bullet and buy or find a new head. I played around for awhile with different heads of questionable ingetegrity without much success until I purchased a new one from our host and then relaxed and never looked back.
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Old 03-01-2017, 10:25 PM
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There's no reason to expect that was the only thin spot. All the passages are the same age and subjected to the same water.
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Old 03-02-2017, 06:49 AM
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Including the block


Quote:
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There's no reason to expect that was the only thin spot. All the passages are the same age and subjected to the same water.
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Old 05-01-2017, 10:33 PM
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Finishing, hopefully, my broken manifold studs adventure, I completed the needle gunning and Dremel rotary brushing of rust down to bare metal without creating/findng any more holes. So I patched the hole in the head as described in my 3-01 post (pic, patch at center). I then primed and painted and reattached the manifold and mixing elbow. The engine now runs fine. As several responders warned, more holes may occur.
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Old 05-02-2017, 01:49 AM
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As several responders warned, more holes may occur.
I'll send good karma your way and hope you have many happy hours of good motoring.
If karma doesn't work there is always FWC.

TRUE GRIT
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Old 05-02-2017, 11:09 AM
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I'll send good karma your way and hope you have many happy hours of good motoring.
If karma doesn't work there is always FWC.

TRUE GRIT
As much of a huge PITA as it was, I love knowing the block now holds glycol, not salt water and random small sea creatures
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