Replacing GT40 Manifold and Riser Gasket

DRAIN THE MANIFOLDS AND RISERS FIRST!!!!!!!!!BEFORE BACKING OFF ANY BOLTS.

Are you supposed to block off the REAR passage so water is forced to flow up and over the riser, and not sneak through the bottom, therefore not transferring much heat away.

Thanks guys I am hoping that the risers and manifold will be in good shape (fresh water only boat). I do believe that they have been leaking for longer than I think and it could mean a whole manifold replacement. I guess I will need to spend time with a scraper ...

So there is no sequence for the 4 bolt on the riser? You can remove randomly?

ricofrancois wrote: Thanks guys I am hoping that the risers and manifold will be in good shape (fresh water only boat). I do believe that they have been leaking for longer than I think and it could mean a whole manifold replacement. I guess I will need to spend time with a scraper ... So there is no sequence for the 4 bolt on the riser? You can remove randomly?

Don't overthink it. I had a manifold gasket that had slipped out and was visible and a slight leaking crack in the manifold. Removed manifold, grinded down the crack, JBWelded it, replaced new gasket, ran all last summer like new. Had no trouble at all loosening the bolts and from all indications it was all original (38 years old).

Pete, Interesting information! I have only ever used PB and WD and PB is the best clearly over WD. Never had to use anything like that on a boat mostly on vehicle suspension parts.

Maybe I will start using Liquid Wrench for the small jobs! PB has just always broken anything loose I couldn't. I don't like breaking bolts so I always start soaking things days before I work.

So I removed the starboard riser yesterday but one of the 2 long bolts broke. I did put a lot of PB Blaster a few days ago but the long bolts looked quite rusted. The good news is that the riser look in perfect condition.

The Manifold looks a bit rusted inside and I would have considered using it again but the price of re-taping will be the same as a new one. It's 16 years old anyway.

I will replace both manifolds but keep the risers. I am waiting until the week end to let the penetrating oil act a bit more, especially on the manifolds bolts. Breaking one of these would be game over, but hoping it should be okay as they are a lot shorter. I wonder why they chose allen over bolts for the manifolds...

Anyway first question, anyone would have anything against replacing the manifolds only and keeping the risers?

Nautique parts seems to be the cheapest place for both manifolds (total $401.95 including discount and delivery) Any other suggestions?

Thanks

Thanks, I do have a shop that would remove for $35 but I am just wondering if after 16 years they are ready to be replaced. Any thoughts?

fresh water only. to be honest i would rather spend money in new steering cables and helm base assembly

I just spent a couple of evening doing the same thing, easiest thing was to grind off the bolt heads. Use a dremel or something small if you want the manifold, I'm replacing mine so I went with a little bigger grinder which mad a mess of the manifold but got the job done quicker.

SNobsessed wrote: If you have a dremel, you could take a metric allen wrench & shave each flat down to a tighter fit to the socket. Trying to hammer in an oversize wrench will probabaly gall up the socket even worse.

Both the socket head cap screw and the hex allen wrench are hardened. I agree that trying to hammer an oversize allen in is not a good idea. Don't go "back yard hacker" on us!!

Yes on the Dremel! Use their cut off wheels as they are small and will get into the tight area.

Get the manifold off, get some decent penetrating oil at the block, vise grip the remaining bolt and work it back and forth until it is loose enough to be removed.

Morfoot wrote: Once you get the manifolds off and before you pay someone to get the bolts out, try using a screw extractor. Drill a hole in the center of the broken bolt, make up a small batch of acetone/ATF fluid, heat up the broken bolt a lil bit with a blow torch, brush on your mixture, it should soak in at this point plus smoke a little bit, insert the screw extractor and hopefully she'll break free. Screw extractor **EDIT**   If pete's suggestion doesn't work.

Tim,
Good idea except:

8122pbrainard wrote: ski-guy wrote: Stripped the 5/16 hex on one of the exhaust manifold bolts. Guessing I'll drill off the head to get the manifold off and then have to try and drill out the shaft to use an ezee out on? Chuck, A socket head cap screw is a grade 8 or better. They are hardened so I doubt you will have any luck drilling. Grind or cut the head off with the Dremel. Then, grab the shank with vise grips since you will have the same problem drilling for an ez-out.

   

Morfoot wrote: It's tough Pete but I'm sure using a #30 drill designed for metal using a little cutting oil (like ATF fluid) you should be able to drill into hardened steel. It aint' easy but can be done.

I actually prefer Anchorlube for stainless and hardened metals. Since it is water based, it really keeps the drill bit or milling cutter cool. I've been using it for close to 40 years and always have a quart on hand.

Once I get the manifolds off, I am worried about dirt going in. The gasket is so bad, I will need to clean it up but don't want to send anything in the engine. Any tips?

I am also going to wait a week or so before installing manifolds back, is it okay? The engine cover will be closed and the boat covered.

Am about to tackle removing/replacing the exhaust manifolds on a 2003 SN 196, 330 Excalibur. Learning a lot as I read this forum! Can you explain the concern on draining the manifolds before you remove them? tks, mac

If the bolt is stuck, please please pretty please don't use an EZ out. Every single case I've ever encountered of someone using an EZ out after breaking a bolt or rounding a bolt head has ended with "sh*t! I broke the EZ out". Then you end up with an even harder steel stuck in an already hard steel that has to be drilled out and you've wasted a new drill bit and an EZ out.