Need new risers?

[jons13569]

This boat has been sitting for at least 4 years now. Both engines started right up and sound good. After reading threads on this site, I decided i should check the risers and bellows......it is a 1987 268 Sundancer with 500 hrs on twin 205's. I pulled the risers off yesterday.....I am assuming that these need to be replaced as well as the exhaust manifolds? or are these not to bad and just need to be cleaned up? sorry to ask, but I want to make sure before I put out the money on new ones.

 

[rcknecht]

I would change those risers/elbows... Is you engine RW or FW cooled? If it is FWC where does the raw water enter. It would be either the riser block, elbow, or into the manifold. If it raw water goes into the manifold, you will probably have to change them too. If not, they are probably good... Be prepared with a good set of easy outs when you try to get those manifolds off...

 

[jons13569]

Well,
not to sound stupid.....but I am assuming that these are raw water cooled engines. This is the first I/O I have ever owned......how would I know if I have raw water or fresh water cooled? and if it is raw water cooled....where does it suck the raw water from? I know that on my friends Bayliner is get the water from a sea cock under the boat......I don't see one one mine.

 

[rcknecht]

If you don't have anitfreeze, it is Raw Water Cooled; and then you will probably need to change the manifolds too....

 

[JV II]

and if it is raw water cooled....where does it suck the raw water from? I know that on my friends Bayliner is get the water from a sea cock under the boat......I don't see one one mine.

It probably comes in through your outdrives. Follow the raw water hose to the hull.

 

[KRB64]

When you started the engines, were you in the water or dry docked where she sits now?

 

[jons13569]

The old owner started them when it was dry docked. I know he had water hooked up somewhere, but I really didnt pay attention.

 

[rondds]

jons
what concerns me is the condition of them mating surfaces. They really need to be absolutely FLAT to prevent seawater or coolant (whichever system you have) from working it's way back into the exhaust passages and possibly into the cylinders. You should probably replace these components.

 

[jons13569]

I am going to order new risers and manifolds.......bite the bullet now...

 

[Nehalennia]

The indicator if you have Fresh water (read: closed circuit) cooling will be a tank in the front of the engine. It will have a radiator cap on it and in the tank is coolant like a radiator in a car.

Without FWC:

With FWC:

It looks like your risers, and more than likely as mentioned above, manifolds are due to be replaced.

 

[rondds]

Hey, where's the tupperware? Amazing but when you add a heat exchanger, all the scuz in your bilge miraculously disappears!

 

[KRB64]

The old owner started them when it was dry docked. I know he had water hooked up somewhere, but I really didnt pay attention.

Good. Probably had a hose running to some muffs that clamped onto the lower unit?

 

[jons13569]

Is there anyway to convert a raw water system to a closed system? woud it be cost effective if so?

 

[Nehalennia]

Hey, where's the tupperware? Amazing but when you add a heat exchanger, all the scuz in your bilge miraculously disappears!

Yeah, The picture with the scuz was when I first bought her.

Is there anyway to convert a raw water system to a closed system? woud it be cost effective if so?

The pictures I posted are before and after shots of me adding fresh water (closed) cooling. The only way I justified adding it was that it was a primarily fresh water boat and only 94 hours when I bought her. The common thinking is that if you add FWC on a higher hour engine that has already had exposure to saltwater the cost may outweigh the benefit. If you have a higher hour engine and you were to just keep it a raw water cooled engine and the $2-3K you would have spent on a FWC kit, you'd be $2-3K closer to your repower money.

Mine just made sense since it had such low hours and only had been in saltwater 2-3 times in it's 7 years before I bought it. It lived on a lake her whole life.

 

[Matt89GT]

I would have started the boat up on water and let it run before I took them apart, if it ran cool I would have left them alone until I put it in the water, the hose will have colder water than the river or lake,however if it cooled on the hose I would have checked it out in the river or lake to then see if it stayed at temperature. If its not broke dont fix it. However a pressure test will reveal any cracks and potentialy save you a pocket full of money, If the manifolds arent leaking water into the cylinders and arent clogged why replace them? If its not broke dont fix it.

 

[SCORPIO]

On looking at the RWC example I noticed that there are no hoses from the Tstat housing to the risers. My RWC setup has hoses going to the risers. Why are they different? I would think that the hoses to the risers would help cool the exhaust and the rubber hoses/flappers more than just letting the water go out thru the maniflold/riser joint.

 

[jons13569]

I started working on the risers and manifolds this weekend. Got the new manifolds on.....now working on the risers.
2 questions.......
1. Does the riser gasket require any sealant? or does this just go on dry?

2. How does one go about removing the exhaust elbow from the riser?? i cut away the rubber boot...It looks as if the elbow slides over the riser...but I cant get the thing off....am I doing something wrong?

Thanks for all the great help I've received on this site!!

 

[JVM225]

I started working on the risers and manifolds this weekend. Got the new manifolds on.....now working on the risers.
2 questions.......
1. Does the riser gasket require any sealant? or does this just go on dry?

2. How does one go about removing the exhaust elbow from the riser?? i cut away the rubber boot...It looks as if the elbow slides over the riser...but I cant get the thing off....am I doing something wrong?

Thanks for all the great help I've received on this site!!

No sealant is needed, just use the gaskets.
Cut away the rubber boot?
Is this the rubber immediately aft of the riser? if so? there is no need to cut it.
Just loosen the clamps, and twist the old risers back and forth while working the riser back out of the exhaust hose. They wil loosen up and come out for you. The new risers go in the same way, but usually go in a lot easier than the old ones come out.

 

[rondds]

Word of caution! When you put the new elbows in, insert the nozzle into the "rubber boot" (exhaust hose) then drop the elbow into it's place. If you put the elbow on and then try to get the hose back into the nozzle, you're gonna have a REAL tough time b/c it does NOT bend or flex. You'd then likely have to take the elbow off again and, in so doing, kill a set of gaskets.

If you do have to remove the elbow/riser assembly after tightening down, do NOT reuse those gaskets as they will likely not hold water after the second torquing.

 

[jons13569]

Right after the riser is a rubber boot...that connects to a cast iron elbow.....In my case I couldn't get the elbow off at all.....the boot was cracked, so I cut it off......It looks like the "elbow" is actually slid over the riser outlet a bit.....Ill have to see If I can post a picture...