Exhaust Manifold rust

[skicraz]

If the exhaust manifolds and risers have flaky rust in them, should they be replaced or would they be ok if you get most of it knocked off?

[DavidF]

RE: Exhaust Manifold rust

Not unusual. Knock off what you can and you should be ok. So, what you are seeing inside your exhaust manifolds is what happens inside the engine block if you just drain the water during winter layup and do not fill the block with anti-freeze.

[skicraz]

RE: Exhaust Manifold rust

Hey thanks for the info DavidF.

I thought it would be ok but wanted to make sure before I bolted them to my new engine!!! There is a $400 bill I don't have to spend!!

[EchoLodge]

RE: Exhaust Manifold rust

I have never inspected my 90 Sport with 1100 hours of fresh water use and recent 50 hours of saltwater use. I guess the only way to do this is to take the risers off and do a visual. Do you just look for rust?

[Roy]

RE: Exhaust Manifold rust

It is normal for flaking to occur in the water passages, a sure sign of excessive build up, is when you see an increse in the water temp while under load. Time to change manifold and risers.

[Hollywood]

Re: RE: Exhaust Manifold rust

a sure sign of excessive build up, is when you see an increse in the water temp while under load. Time to change manifold and risers.

Can you be any more specific? Don't all engines get hotter under load?

[EchoLodge]

Risers

That makes sense. If the water is being restricted than things would heat up!

[bobchris]

RE: Risers

You need to atleast have the manifolds dipped and cleaned before you install them on a new motor. If it is flacking on the outside then they need replaced, inside is normal but eventually they will rust through and you'll have to replace them, the risers usually don't wear out unless they have been in saltwater, but that's not the case for the manifolds.

[EchoLodge]

RE: Risers

So a visual inspection would be a good idea of a 16 year old boat with 1100 hours that just started being used in salt?

[bobchris]

RE: Risers

I would give it a quick look but you are going to have to replace them very soon if your running in salt all of the time, just stay on top of it because it only takes a small hole in one cylinder to hydrolock the motor and bend rods and junk a motor.

Old worn manifolds are going to deteriate faster in salt water than new ones but no need to waiste money on something that doesn't need replacing yet. Flush it after everytime out and get a closed cooling system for the engine (if you don't already) before the salt starts to eat the block up.

[richard]

RE: Risers

Man, don't think use the 16yrs manifold, change all new will save more bucks for you later,the pic is the 3yrs old use in salt water, the reason for change is water leak to cyclinder,make spark plug wet sometimes, and some times can't start, but I doubt that it's gasket leak due to few time over heat (200-220f) or rust of the metal,change all and works fine so far. may be some of them still can use if have a way to test them.

[bobchris]

RE: Risers

those belong in the scrap pile, there useless and cannot be used, well they would work for an anchor

[Hollywood]

RE: Risers

Aww come on, just a little rust those will buff out! :mrgreen:

[EchoLodge]

RE: Risers

I always flush right after we take it out of the Marina. I will just replace them at the end of the season for peace of mind. Skidim has the manifolds for 180 a side and riseres for 99. Anyone else come across a cheaper place to purchase?

[bobchris]

RE: Risers

best place is www.marineexhaustmanifolds.com j.a.chamberlain