In the course of some other maintenance
, I decided to remove the exhaust
riser and waterlock on our 1984 Universal M50 diesel
. It crossed my mind that in our previous boat
riser rusted through, and sure enough in the course of removing this one it too fell apart where one of the pipes was nearly rusted through. The riser is a series of 1 1/4" black iron pipe coming right off the engine
exhaust manifold with one section containing a 5/8" hose nipple for water
injection. The waterlock is a Vetus LP 40. The M50 is a 44hp diesel
, our previous boat
had a Universal M25 21hp diesel, however the exhaust systems are identical.
I would like to replace the waterlock, and had considered using a Vetus NLP 40 which is supposed to provide more muffler
function. In looking at the specifications for each, I was a little alarmed to see that both are recommended for engines up to 24hp. Most retail sites use the diameter of the exhaust hose to determine the waterlock - whether it is Vetus, or Centek (Vernalift). Our exhaust hose is 1 5/8", and the exhaust manifold on the engine
only has a 1 1/4" square opening transitioning to 1 1/4" pipe. Anectdotally, the system has worked fine for 35 years, and upsizing the hose to use a bigger waterlock doesn't seem practical since the current
system is based on the outlet size of the engine exhaust manifold.
Ultimately, I'm inclined to go with a Vetus NLP40 for the additional sound reduction unless there is compelling reason not to, in which case I will probably just replace what is there with same model. For what it's worth, both our previous boat and current
boat have always been freshwater boats.