Exhaust Manifold and Riser

[go46]

I need to replace the exhaust manifolds and risers on my GT-40, and I seem to recall a post on here about a cheaper place than SkiDim to buy them. I cannot find that post and was wondering if anyone could help.

Thanks.

BTW- I am not enjoying boat ownership at this time.

[skinautique]

Why do you have to replace them? Did they freeze or do you use them in saltwater?

[SANfan]

To that I would add: How old is the boat? If you used in Salt water, did you flush?

The wet exhaust system is subject to corrosion and erosion even in fresh water, but the GT-40 is a relatively new engine. If freezing is the issue, you may have even more serious problems inside the block.

[skinautique]

Looks like he has a 1997. Are you sure it isn't just leaking where the gasket is? If that is the case, it is pretty easy to fix and a lot less expensive.

[go46]

The boat is new to me and the guy I bought it from says it was never used in salt water, but I am not inclined to believe him.

I am not a mechanic, and may not have all of these facts right but I'll try. The boat would not start, and I took it to the mechanic, he did a compression test and I have 3 dead cylinder, and only 1 that is actually in tolerance. So the mechanic is now pulling the heads to have a valve job done. I am assuming (before I know for sure) that water got into the cylinders. The mechanic is hoping (and so am I) that the lower half of the engine is okay. The mechanic said the valve seats had fallen into the cylinder???

Back to the manifolds- I am assuming they leaked water into the engine, and even if they didn't I will probably replace them as I believe the boat was run in salt water.

Anyone have any comments?

[skinautique]

why don't you get the valves and cylinders all fixed up and run it and see what happens. It is alot cheaper to buy new gaskets for the manifolds and go from there. Just a thought.

[M3Fan]

There is a gasket between the manifold and riser/elbow. If the gasket was bad the water could run from the outer jacketed area into the inner area where the exhaust actually flows, and back into the exhaust valves. Could just be a bad gasket. Sounds like a nightmare scenario though, hope all turns out well.

[nms1991]

i would check the cylinder head for cracks and check the riser gasket to make shure it had not failed also check the cooling system. also havee them do a check on the other cylinder head to check it while it is torn down.

[workky]

I use to have a problem with water in the cyclinders also,Go out to the lake, have a session ,turn off the boat.And thats all the wrote,hydrolock.Water doesnt compress to well.This happened quite a few times,We would get it out of the water ,bump the starter ,spit all the water out,and fire it up and keep on going.It turned out it was the riser gasket that was bad,replaced it with some new ones never had another problem .

[go46]

Good and bad news...

Good news is it looks like the bottom half of the engine is in good shape, no problems with the pistons and other crap. Also, it looks to me like the exhaust manifolds and risers are fine, although no telling what shape the old gaskets were in. I am going to have the manifolds looked at by an inboard mechanic tomorrow.

Bad news is the problem is two cracked heads, and several valve problems (which now I guess is inconsequential). So instead of wondering where the best place to get manifold and riser, my new question is......

Where is the best deal on two new cylinder heads? Skidim is $325/ side plus I assume a tremendous amount of shipping.

Also should I try upgrade (for a modest amount of extra coin)?

Should I stick with a marine supplier, or try summit or the like? Can I use an automotive head?

Thanks

[wburg64]

Yes you can, I would see if you have Ford Speed shop handy a lot of guys are getting alumnium heads and have take offs for sale.