Risers on an HP 500
 

I am looking at a boat right now that has soft spots on the outside of the risers (engine is an HP 500). Like bubling under the paint. Everything looks pretty clean. Does anyone know what this might be from. It is on both sides. The boat has been in storage for most of the last 5 years (in and out of the water sporadically). There was also an old mushroom where the exhhaust goes through the hull. Thinking it is just from being wet and then in storage. Any feedback on any of this.

Re: Risers on an HP 500
 

The risers should be Gils and are SS, not painted if original. Do you mean the Merc manifolds? They are powdercoated black. Have seen the PC'ing bubble on some with no problems before.

Re: Risers on an HP 500
 

Yes, it is the water cooled exhaust (SS). It would be the manifold and it seemed to be risers going into the water injected exhuast pipes. But what you noted sounds like what is happening (poweder coat bubling). What is it and is it any concern??

Re: Risers on an HP 500
 

What use to happen with these manifolds is that the aluminum manifolds use to get pin holes in them and leak salt water when they got warm. This would cause a bubble to create in the powder coating. If you were to remove the bubble after time you would see salt start to creep out of the manifolds. The older manifolds use to have freeze plug type plugs in the sides and ends. these were used after the casting was made and machined. They use to leak even worse.

John S. :D

Re: Risers on an HP 500
 

Thanks for the info guys. I am guessing the salt is from a chemical reaction???? So, is this a problem, and if so, what is the fix. New manifolds, headers, etc. If it is a porblem, is it a slow problem that would need to be resolved over time? Thanks! Trying to figure out if the purchase would be worthwhile.

Re: Risers on an HP 500
 

This is a continuous problem. The only fix is to install new. If you like the manifolds performance and don't have issues with reaching the spark plugs then just change out the manifolds. If they are a bear to change plugs in and you want the pretty polished stainless, then get tubular headers. All up to you.

John S. :D

Re: Risers on an HP 500
 

Mushrooms are a bad sign. Check for rot in the transom.

Re: Risers on an HP 500
 

Where is the boat ? Fla. salt or up north need a little more info on the conditions it was run in...
Bryan

Re: Risers on an HP 500
 

Boat was run in lakes in SC and GA. There was one area around the exhuast on the inside of the transom where the mushroom was. Rot in the transom was a concern to me, but was not sure if it could have just been from being in the water and then in storage, etc. Boat has only been in the water approx 30 hours over the last 4-5 years.

Re: Risers on an HP 500
 

Most builders will epoxy any open holes before installing exhaust tips.....Tought to say about this one.
Bryan