Exhaust risers

[RichRab]

2002 merc 5.0 mpi. I changed exhaust using Barr parts 3 years ago. I see rust behind risers on tops of manifolds so I think the risers are leaking at high speed and want to fix it before putting boat in the water. Can anyone think of something special to look for? I have read bad things about never seize on marine parts. Should I put some grease on the threads? I am planning to remove studs to get risers off and then reuse studs. Thank you. RR

 

[achris]

Re: Exhaust risers

When you remove the elbows, clean the threads out in the manifolds, and make sure the ends of the bolts are also clean. You could also put some grease on the ends of the bolts if you wish... Just make sure you use NEW gaskets and the gasket surfaces on both the manifolds and elbows are clean and true (flat)... Also, use the Merc genuine gaskets (there are grey and appear to be a graphite compound), NEVER the thin green paper ones....

Chris......

 

[Bt Doctur]

Re: Exhaust risers

Might want to check if your actually seating the risers to the manifold. I have had some where the plugs were a bit too high and prevented the riser from fully seating on the manifold. After you install a riser ,see if a business card goes between the riser and the manifold gap.

 

[RichRab]

Re: Exhaust risers

If the rain stops job will be done Sat. Thank you. RR

 

[RichRab]

Re: Exhaust risers

I changed the riser gaskets and aside from rust on top of manifold all looked good. With boat running there is water dripping out of the top of what I would describe a cup like "t" fitting that has two hoses attached to it under the starboard manifold. Does the whole thing get changed or is there an o ring in there? Thank you. RR

 

[achris]

Re: Exhaust risers

... With boat running there is water dripping out of the top of what I would describe a cup like "t" fitting that has two hoses attached to it under the starboard manifold. Does the whole thing get changed or is there an o ring in there? Thank you. RR

Photo?

 

[RichRab]

Re: Exhaust risers

. The picture is not clear but it is part number 863786a 1 and o ring part no. 47632. Thank you. RR

 

[achris]

Re: Exhaust risers

There is an 'O' ring in there. I would take it apart and assess what needs to be replaced...

Chris.......

 

[RichRab]

Re: Exhaust risers

Tried spinning the bottom of it. It just spins, tried prying it apart but afraid to break it. Tried to unscrew the whole unit but it will not turn and I am afraid to break then I will have bigger problem. Any ideas? Thank you.