32-3 Exhaust Manifold Removal

[JohnW]

I am in the process of installing the revised alternator bracket. I have removed the 6 stud nuts but the exhaust manifold is stuck on. I searched for past articles and it seems like once the nuts are removed the exhaust manifold should come right off. I tried Kroil on the studs and the engine block/manifold seams, then tapping with a dead blow hammer, but still cannot remove the exhaust manifold.

I've also remove the hoses from the exhaust elbow to get better leverage to pull on the whole assembly, but that didn't work either.

What's causing the exhaust manifold to be stuck on? Rust? The hastily sprayed paint? Should I tap harder with the dead blow hammer or try using a pry bar?


thanks,
John

 

[Christian Williams]

See if the new bracket will fit on the existing studs. On my M25 that worked. I believe the stud length on that engine varied and some could take the bracket without new studs. If you've already tried that, disregard message with appropriate muttering.

 

[Kenneth K]

John, I did this job in 2017. With the nuts removed from the studs, the only thing holding the manifold to the block should be the compressed gaskets. I suppose it's possible you might have some rust bonding one or two of the studs to the manifold, but the gaskets should have kept the manifold and the block from "rusting together."



I'd probably try some prying, and maybe prying and tapping together till something breaks loose. If you can get a bar in from the back side, that might give you the best leverage.


The block and manifold are both solid, so I don't think you'll damage anything with some light-to-medium duty prying.

 

[gabriel]

with a rubber mallet you will be able to put a nice shock to the piece that might dislodge it. Harbor freight.

 

[JohnW]

I ended up using a couple pry bars plus Kroil working from top and bottom to get the exhaust manifold off.

It looks like some sort of adhesive was used in addition to the rubber gasket between the elbow and the exhaust manifold. I saw Christian's video on using Barnacle Buster for cleaning out the heat exchanger so can I dunk the heat exchanger and the entire exhaust manifold into the Barnacle Buster or should I remove some of the fittings, like the ones with salt?/calcium?/corrosion? around the threaded interface, and separate the elbow from the heat exchanger first?

 

[bigd14]

Nice work. While you have that apart it would be a good time to replace the exhaust riser. Those are a known failure point in the system. If you can’t get the riser apart from the flange on the end of the manifold like I couldn’t, replacement flanges are available at Catalina Direct

https://www.catalinadirect.com/shop-by-boat/catalina-38/engine/exhaust-system/engine-exhaust-flange-rectangular/?SearchResults=1

Risers are also available but this one looks like it has more accessory parts than you might need. https://www.catalinadirect.com/shop...t-system/exhaust-riser-c-350/?SearchResults=1