D 6 370 HP

[Seastoke]

So someone has told me that the exhaust riser is made of stainless steel , so there is no chance of corrosion so there is no chance of-sea water getting in the engine . The year is 2008 is this right or should they be checked by say V Paul.thanks for replies.

 

[volvopaul]

So someone has told me that the exhaust riser is made of stainless steel , so there is no chance of corrosion so there is no chance of-sea water getting in the engine . The year is 2008 is this right or should they be checked by say V Paul.thanks for replies.

Depends on application and boat builder .
most shaft drive versions have a stainless riser made by the likes of Halyard for example.
On a stern drive Volvo supply a stainless riser and a cast elbow that feeds directly down to the exhaust horn , the cast one is a terrible design, you see rust appearing and it often expands that much it cracks the plastic water pipe attachment.

OP what are you thinking of purchasing?

 

[Portofino]

On a stern drive set up - If its integrity fails seawater will enter the engine room and sink the boat if the bilge pumps can’t keep up .
I can’t see a route back directly to any open exhaust valves due to its goose neck like route .

The elbows on none SS VP parts corrode up first and lead to elevated jacket temps because the water can’t get out fast enough.

 

[Seastoke]

Depends on application and boat builder .
most shaft drive versions have a stainless riser made by the likes of Halyard for example.
On a stern drive Volvo supply a stainless riser and a cast elbow that feeds directly down to the exhaust horn , the cast one is a terrible design, you see rust appearing and it often expands that much it cracks the plastic water pipe attachment.

OP what are you thinking of purchasing?

Hi Paul and I value your reply , yes it’s on a shaft drive and it could be a sealine or fair line .

 

[Portofino]

As a gen side note even stainless steel risers on shaft drive boats degrades to the point of renewal eventually.
Diesel exhaust gases + fresh seawater = nasty sulphuric acids ( and a myriad of others ) which eat stainless .
Stainless lasts longer thats all ……it eventually needs replacing at some distant point .

 

[Seastoke]

So if you are inspecting them what are you looking for.

 

[Portofino]

So if you are inspecting them what are you looking for.

Holes .

 

[volvopaul]

I had 2 fail on stainless welds on a Princess a few years back but due to design they are way above the waterline with exhaust facing downhill then into a water muffler to trap the drain back , the only time water can enter the engine is of course if the boat is sinking or when on transport as the lorry brakes hard water can be forced towards the engine but the mufflers should be drained before transport , I’ve seen a few engine die like that .
From memory I know Sealine fitted the cast elbow on the 42/5 instead of a stainless one , but there exhaust design is through side of hull via a muffler glassed into the hull , the French tend to use the cast one too .

The Fairlines like the later 40/43/46 /50 all use a stainless bespoke one.

 

[Seastoke]

I had 2 fail on stainless welds on a Princess a few years back but due to design they are way above the waterline with exhaust facing downhill then into a water muffler to trap the drain back , the only time water can enter the engine is of course if the boat is sinking or when on transport as the lorry brakes hard water can be forced towards the engine but the mufflers should be drained before transport , I’ve seen a few engine die like that .
From memory I know Sealine fitted the cast elbow on the 42/5 instead of a stainless one , but there exhaust design is through side of hull via a muffler glassed into the hull , the French tend to use the cast one too .

The Fairlines like the later 40/43/46 /50 all use a stainless bespoke one.

You are like the Bank of England , a wealth of knowledge .