Perkins 4108,Swan 431 Exhaust water entering engine

[nigelstgeorge]

I am posting this on behalf of a friend who has a circa 1977 Swan 431 with a Perkins 4108 engine. He is now on his 3rd new/reconditioned bottom half engine due to water entering the engine via the exhaust. He has just had his 3rd Perkins 4108 engine replaced and water is still getting back into the engine via the exhaust. My friend is wanting to find a permanent solution as changing engines is getting expensive.

It looks like Swan Nautor in those days put together a very ineffective solution rather than put something like a waterlock between the exhaust elbow which is where raw cooling water is injected and the exhaust muffler and rest of the exhaust system.

There is a sort of goose neck just before the exhaust elbow with a T piece which I guess is the bleed off of air and water to break the syphon effect. This does not appear blocked but if one connects the pipe at this point there is water in the goose neck.

At the moment the only solution seems to be to turn off the cooling water EACH TIME just before turning the engine off to blow the excess water out of the exhaust to ensure it does not syphon back into the engine. Obviously this is not a failsafe solution.

The boat is currently located near La Rochelle, Western France.

Any solutions would be much appreciated.

 

[vyv_cox]

This problem is often due to either an absent, or inadequately sized, trap below the exhaust manifold. The function of the trap is to contain all the water in the exhaust hose downstream and manifold, etc. upstream when the engine is stopped after running. If it is too small or not there the water can be sufficient to run into the engine via an open exhaust valve. Traps are readily available, Vetus being a well-known supplier but there are several others. Your friend needs to calculate the capacity of the exhaust hose and buy a trap that is appreciably larger. The trap needs to be sited as low as possible, occasionally a problem with some boat designs but can normally be arranged.

 

[youen]

Did he tried to get some answer from the S&S Swan Owner association.Lars Strom is very competent.

 

[nigelstgeorge]

I am sure that this is the answer although space is a bit limited. I am hoping someone with this engine and configuration has an answer. Thank you for your response.

 

[nigelstgeorge]

Did he tried to get some answer from the S&S Swan Owner association.Lars Strom is very competent.

I have not spoken directly to Lars Strom but looking at some other internet postings on the Swan Association page it seems like Lars does not have an immediate answer. See posting: http://www.classicswan.org/forum/post_thread.php?thread=637
Although this was for a Swan 41 I guess the Swan 431 is similar.

 

[VicS]

Adequately sized water trap as Vyv says at the lowest point .

Also antisyphon loop and vent in the cooling water system may be required or may not be functioning.

Should be fitted if the water injection into the exhaust is near or below the water line

The Vetus on line catalogue contains some useful information on exhaust systems.

Btw

A "goose neck" is the joint between the boom and the mast.
Exhaust systems have "swan necks".

I think what you describe is probably an "exhaust riser".

 

[nigelstgeorge]

Adequately sized water trap as Vyv says at the lowest point .

Also antisyphon loop and vent in the cooling water system may be required or may not be functioning.

Should be fitted if the water injection into the exhaust is near or below the water line

The Vetus on line catalogue contains some useful information on exhaust systems.

Btw

A "goose neck" is the joint between the boom and the mast.
Exhaust systems have "swan necks".

I think what you describe is probably an "exhaust riser".

Woops yes of course I meant a Swan Neck. I should know the difference having broken a Goose neck and boom on a Westerly Oceanlord in a Force 8 gale coming in the Needles Channel.!!!

 

[nigelstgeorge]

Adequately sized water trap as Vyv says at the lowest point .

Also antisyphon loop and vent in the cooling water system may be required or may not be functioning.

Should be fitted if the water injection into the exhaust is near or below the water line

The Vetus on line catalogue contains some useful information on exhaust systems.

Btw

A "goose neck" is the joint between the boom and the mast.
Exhaust systems have "swan necks".

I think what you describe is probably an "exhaust riser".

It has an anti syphon loop and vent and it does seem to be functioning.