Universal M35 exhaust manifold repair.

[skippervic]

The exhaust manifold is leaking at the filler pipe. There are signs of an old repair job around the pipe connection. I talked to a local radiator shop, and they say they can fix it if I bring the exhaust manifold to the shop. I figured while I am replacing the riser, it is a good time to pull the manifold out. However, after unscrewing bolts from the studs, I found that it is not moving at all. Any advice on how to pull this thing out?

[KWKloeber]

 Take a look at mainesail's site and the article on installing the M25 alternator upgrade, it might describe a tip for removing the manifold   

[skippervic]

Thanks for the pointer. I looked it up. It says unscrew nuts from the studs - and the manifold slides off. In my case it doesn't slide off. It is not moving at all. As I mentioned, there was a leak. Probably some of the studs rusted and got chemically welded to the manifold. It is going to be interesting...

[KWKloeber]

Also, probably the exhaust gaskets are stuck solid. You may need to get a thin  sharpened paint scraper  into the joints to break the manifold free.



Post some pics of everything you've got going on.

[Ron Hill]

Skip : You might have to try a putty knife. 
BTW, the stud should not come out. I'd guess they might even be installed with "Lock Tite" ?

A thought

[Stu Jackson]

If the exhaust riser is still connected to the aft end of the manifold AND IT IS STILL CONNECTED TO THE MUFFLER, it is NOT going to move.

Have you removed the riser from the muffler?

[skippervic]

Stu,

The riser was not attached to the muffler. It decided to detach itself somewhere between Pillar Point and Golden Gate (see the picture). We pulled into the guest dock of Brisbane Marina near San Francisco with the exhaust smoke coming out of the cabin and sea water gushing into the bilge. In the retrospect, we were lucky it failed completely like this. If it was a smaller crack, water from the muffler, unopposed by the exhaust pressure could enter the engine and this would be the end of it.

Now, the good news: I was able to pull the manifold out. The bad news: Two of the studs had broken and stuck in the cylinder head. I will have to spend another day driving two inserts into the stud holes. Hope I can do it without taking the cylinder head off. If somebody has experience with that - please share!

Patty knives, utility blades and painter scrappers did not work out. Trying to unscrew studs with a counter-nut did not work either. Ended up stripping the thread on one of them When we had the engine assessed before we got the boat, the mechanic reported a leak in the manifold filler pipe. I had fixed it with plenty-o-marinetex, but I guess the damage was done already. Some of the studs had  rusted and welded themselves to the manifold. What did work was a blowtorch, rubber mullet and a 5 feet crowbar.

I will post some more pictures later.

[skippervic]

The good news is: I was able to pray the old riser from the manifold. The bottom stud rusted and welded itself to the flange (see the picture). It took 3 hours, blowtorch, chisel and pry bar. The bad news is: Two of the studs that fix manifold to the cylinder head had broken. I have to extract them. I hope I can do it without pulling the head out. Project for another weekend.

[KWKloeber]

Vic


Wow.  Do you have enough stub left that you can get a vice grip on it after heating etc?


Dif you have the "new" style alternator bracket on the manifold?


Kem

[skippervic]

I do have enough grip on the manifold side. I was able to extract one stud from the manifold after heating it up to 600 F. The second one did not budge. I can't heat it more with my Benzomatic blowtorch - doesn't go above 600. The manifold is too big of a heat sink. I need a bigger blowtorch. On the engine side it broke flush with the cylinder head I will try Hansen spiral extractor over the weekend. If it doesn't work - I will go with a helicoil. Luckily for me, the broken studs are accessible through the engine port in the shower. I have a good chance to fix it without pulling the cylinder head.

And yes, I do have the new style bracket. I know the old bracket could damage the studs. These studs, however, did not break because of the alternator.  They broke when I was trying to pool the rusty manifold from the engine. If you look at the picture, you can see where water from the cracked filling pipe was sipping into the stud holes.

[KWKloeber]

 Skipper,



What was leaking? Was the filler neck cracked at the base?


I ass/u/me you're using a propane torch, not a blowtorch?
If you could try your torch head with a MAPP gas cylinder ( they are yellow ), which burns hotter than propane.


The old alternator bracket didn't mount to the engine/exhaust manifold studs so they had no bad effect on them.   It mounted to the Gear cover and busted that open  when the alt bracket failed   


Ken

[skippervic]

Exactly. The cracked filler neck was leaking at the base. I fixed it with Marinetex, but it was probably leaking for a while by the time I got the boat - so the damage was done. The manifold is at a local radiator shop now. They are going to clean and boil it, replace the filler pipe and pressure test it. This is not cheap, but a new manifold would cost me $1,500.

I am using the yellow Benzomatic MAAP cylinder (see the picture), but it still has not enough BTU to go beyond 600 F.

My alternator bracket is fixed to the water pump (on the front) and the manifold (on the side). By the way, the bracket is a little too big for this alternator: There is a gap about 1/4" between the alternator mounting ear and the bracket. Whoever mounted it did not care, so there was a lot of vibration. I added a washer on each side to take out the gap. This helped to reduce vibration a lot!

[KWKloeber]

Roger on all that.


I guess an acetylene set up would be next!


When reinstalling, take the time to ensure the belt is aligned (not just the pullys because they can vary in thickness). There is fairly recent posts on here how to stepwise do that. 😉

[Stu Jackson]

When reinstalling, take the time to ensure the belt is aligned (not just the pullys because they can vary in thickness). There is fairly recent posts on here how to stepwise do that. 😉

From Electrical Systems 101

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment  IMPORTANT

http://c34.org/bbs/index.php/topic,7917.0.html

[KWKloeber]

Stu

I was actually thinking about Rod's description and photos in this thread
http://c34.org/bbs/index.php/topic,9380.0.html
Which could also warrant being stickied.

kk