Freshwater Dry Joint Manifold

[keysersoce]

Hello,

I purchased a used 2005 bayliner (mercruiser 5.0 mpi dry joint) last year in Iowa. I know it’s been in Iowa for at least 7 years on a lake - not sure prior to that, but assume fresh water. When my mechanic winterized the boat this season he said there was an excessive amount of rust and debris that came out of the motor and manifolds and they are past its life span.

All the research I’ve done says fresh water manifolds/risers should last forever. Should I be concerned if he is seeing a lot of rust/debris coming out of the drain water? Can I risk running the boat without changing them until I see other external signs (over heating, external corrosion, etc.) because they are dry joint?

The manifolds and risers look brand new on the outside. Also, the boat ran great all season last year.

Thanks in advance for any advice you can give!

 

[Scott06]

Normally yes fresh water they will last the boats life if properly winterized.

I would buy elbow and or riser gaskets and inspect what the passages look like. You can take them off and test with acetone If you like.

when you summarize it and use it , open the drain plugs and probe with wire to see what comes out.

 

[keysersoce]

Thanks Scott, I’ll look at having them inspected first before taking the plunge to replace them. Good idea.

 

[Superjetjim]

I've just changed manifolds and risers as a precaution (Dry Joint variant on 4.3MPI) - they were the original factory Mercury ones from 2005. So nearly 20 years of mixed salt and fresh water. The manifolds looked fine (other than flakes of rust inside) - but elbows were in a bad way. I'd say risers/elbows go before manifolds due to mixture of air and water at the ends. But as with all these things its your risk. Pull and inspect as best you can.

 

[keysersoce]

I've just changed manifolds and risers as a precaution (Dry Joint variant on 4.3MPI) - they were the original factory Mercury ones from 2005. So nearly 20 years of mixed salt and fresh water. The manifolds looked fine (other than flakes of rust inside) - but elbows were in a bad way. I'd say risers/elbows go before manifolds due to mixture of air and water at the ends. But as with all these things its your risk. Pull and inspect as best you can.

Ok that’s good to know as well. Thanks for taking the time to reply.

 

[Chris1956]

Slide the rubber tubes off the risers and look at the exhaust tube and water passages. These usually rust out first and is obvious upon inspection.

If they are rotted out, you need to check the manifolds, as described in post #2

 

[Stinnett21]

Is this a single point drain? It may be that your mechanic went deeper into winterization than was ever done in the past and if so this is a good thing. If all was ever done to winterize in the past was to use the single point drain then it would not be surprising if he pulled the quick disconnects and found lots of debris.