Exhaust/manifold questions

[legoman67]

Well, We are trying to figure out our exhaust system and have afew questions

The old system had center risers and went into the Y pipe and out the leg, 3 out of the 4 risers were cracked, and the Y pipes are both shot, very expensive repair. The new engines came with aft risers. But due to limited space there is not enough room for the pipe to bend down and then go out through through hull under the water line. It is a fresh water cooling system

1. If the risers were cracked, does that mean the old center manifolds are shot aswell?(no cracks on the outside)or are they fine? how can you test?
2. Can you put the manifolds on backwards, so instead of aft riser, the riser would be at the front(put the left one on the right side, right on left)?
3. what sort of bend radius can you get with the rubber exhaust hose?
4. If we were to get custom 3" stainless pipe bent to fit, how much rubber pipe should we have to allow for engine movement?

 

[navis]

Re: Exhaust/manifold questions

#1- Cracked risers will most likely be a sign that water was not drained from the exhaust system prior to last use, which would also mean that water would not have been drained from the manifolds interior cooling channels, in-tun freezing and cracking them as well. Better to be safe than sorry.

#4- Good rule is to use 1x the diameter of the pipe on each side of joint for a good couple and double hose clamps (it's the law in Canada) A 1-2" gap should be plenty for engine movement, if the engine is moving more than that you have way bigger problems!

also, what type of engine blocks? etc.

 

[legoman67]

Re: Exhaust/manifold questions

engine block does not matter. this is not about the engine, also can you please expand what you mean in number 4, i cannot figure out what you are saying, i know the pipe needs to be the same size. the length is what i am wondering. Also how is anything in number 4 common sence?

 

[navis]

Re: Exhaust/manifold questions

engine block does not matter. this is not about the engine, also can you please expand what you mean in number 4, i cannot figure out what you are saying, i know the pipe needs to be the same size. the length is what i am wondering. Also how is anything in number 4 common sence?

PS, Navis is just trying to get me back for an earlier post, he seems to have a grudge against me atm... Very immature.

I will better explain number four, if you have 3" pipe, you need to have a three inch overlap of rubber hose on each side of the couple.

Engine block does matter as bolt patterns and their symmetry need to be examined to find out if the manifolds will match up when turned around, as well as if the ports will match.

 

[legoman67]

Re: Exhaust/manifold questions

the manifolds bolt on both engines in the normal orientation, im just wondering if it can be reversed.

 

[Bondo]

Re: Exhaust/manifold questions

the manifolds bolt on both engines in the normal orientation, im just wondering if it can be reversed.

Ayuh,....

Navis asked this Twice, With an Explanation,+ you continue to Ignore,...

What motor are you working on,.... It DOES Matter.....

PS, Navis is just trying to get me back for an earlier post, he seems to have a grudge against me atm... Very immature.

All of the answers you've been given here are Correct,....
At this point,... I'd say You're the 1 with a maturity Problem.....

If you're working on a boat that the Block Froze,+ Blew the Risers,...
The Manifolds are JUNK....

Btw,....
Most Aft riser manifolds have Risers that make a 180? turn, Down......
These can NOT be reversed,.... There's No Way to run the exhaust from there, at those angles....

 

[chiefalen]

Re: Exhaust/manifold questions

Seems this boat restoration project is giving you both a lesson in life, as well as rebuilding a boat, very early in your life.

When you have a partner than every decision must be agreed upon.

So next time, if there is a next time, any endeavor you undertake, the first
decision is, do i want or need a partner ?

So put your differences aside, and discuss the proper way to finish this project,
with your partner.

Than with the proper course of action agreed upon, move forward.

 

[180shabah]

Re: Exhaust/manifold questions

....he seems to have a grudge against me atm... Very immature.

Toughen up there chief. navis responses in post number 2 were both valid and non-confrontational. If you get a reputation for whining you will find that many on this board will ignore your postings and you will have a hard time getting the help you need.

Answer the questions asked of you and lets move on.

 

[legoman67]

Re: Exhaust/manifold questions

you guys missed half of what was going on behind the forums. Anyways, we have worked it out between us and we are good now. The old blocks are not cracked, it was only the risers. And the aft risers are 90 degrees, so if we swap it around they will still face to the stern. just at the front of the Engine

Also Navis knows perfectly well what engines i was working on because he is working on the SAME boat.. but for the rest they are merc 350's replacing crusader 307's

 

[legoman67]

Re: Exhaust/manifold questions

Well, i had a closer inspection of the old manifolds today, with a flashlight and they really dont look all that bad, going to give them an acid bath and see how they come out. The would work alot better then flipping around the manifolds that came with the new engines.

 

[Gary H NC]

Re: Exhaust/manifold questions

Any chance of the place you bought the new engines from swapping out the ones they sent with the engines? Or are the old type no longer available from Merc?
I would worry really bad about using the old manifolds and risers on 2 new engines.

 

[legoman67]

Re: Exhaust/manifold questions

the engines arent new new, just new to us, they were running takeouts out of a larger boat that was underpowered. We bought them privately, so there isnt any manifold trading. one of the old manifolds is soaking right now in acid.

the old aluminium steering fork i was just using to test what the acid does to aluminium.

 

[Gary H NC]

Re: Exhaust/manifold questions

Oh ok,gotcha!

 

[180shabah]

Re: Exhaust/manifold questions

The acid bath will help make them pretty, but how will you determine the remaining thickness between the exhaust and cooling passages?