Best method to clean VP exhaust elbow

[SAWDOC]

Hi folks

Any suggestions for cleaning an old VP exhaust elbow? I directed a hose of water into the cooling water inlet and it seemed to be able to take it ok without backing up so it seems to be working ok other than some gunk close to the ope. i am reluctant to go drilling aggressively as the postings here seem to have a common theme of drilling right through the cast iron.

 

[Tranona]

You don't really have a choice. If it is bunged up enough to affect the operation of the engine then it needs removing and the muck cleared out by a combination of physical removal and possibly chemical. Yes, you may well find that there is little of the iron left in its original form so it may well break through.

 

[Leopold Bloom]

You are wasting your time, buy a stainless steel replacement.

 

[vyv_cox]

Cast iron is an alloy of iron (Fe) and carbon, much of which is in the form of graphite. Although graphite is not a metal it conducts electricity and appears on the galvanic corrosion series, where it is more noble than the iron. This therefore corrodes preferentially in seawater. Even when the iron has all been corroded away the graphite network holds the item in shape, fortunately for 100 year old water and sewage pipes. Unfortunately the graphite network does not have sufficient strength to resist physical assault by hammers, screwdrivers, etc., as many have discovered when cleaning manifolds. Unless hydrochloric acid cleans off the deposits, I suggest exposure for no more than about 10 minutes should be sufficient, then be very careful using any tools, avoiding impact.

 

[Ceirwan]

I can second vyv here.
When I got started on removing rust and carbon from my old elbow I just ended up revealing a massive hole that had been sealed by carbon and corrosion.

Ended up having to buy a replacement.

 

[PuffTheMagicDragon]

Similar experience on the one on my MD2B. Very difficult to distinguish between what was carbon deposit from the exhaust and the carbon that was originally cast iron. Launching after 23 weeks on the hard I started the engine and discovered that the elbow had a split right along its spine. Not wishing to lift again and spend more time and money at the yard I literally wrapped the elbow with all the self-amalgamating tape that I had on board, sufficient for the ten minutes or so trip to the pontoon.
I had a replacement made out of stainless steel (316L) at a friend's engineering works. 'Original' VP replacement part would have cost over €700. On an engine that was forty years old at the time (four years ago)? No way!
Get a new one made out of stainless; simple to make, cheaper, cleaner and better lasting... IMHO.

 

[Colin K]

Hi folks

Any suggestions for cleaning an old VP exhaust elbow? I directed a hose of water into the cooling water inlet and it seemed to be able to take it ok without backing up so it seems to be working ok other than some gunk close to the ope. i am reluctant to go drilling aggressively as the postings here seem to have a common theme of drilling right through the cast iron.

Hi,
I have just had both of mine off (1989 TAMD 41b's) and cleaned them up fine. I did not use anything too pointy seeing that there is a cast skin between the exhaust and waterway.
Like you I put a hose on the waterway stub and flushed it clear just a slight build up of crap near the exhaust/water mixing point. Mine had smoke limiter flaps on them which are now fixed open.
I may be wrong but I think ASAP sell them new from £190----£350 ish depending on type.

Cheers, Colin.