Perkinss 4.236 exhaust

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11 years 2 months ago #146 by John Meskauskas
Perkinss 4.236 exhaust was created by John Meskauskas
My recently-purchased (hull #2) Whitby 42 has multiple issues but the latest is a leak in the exhaust. This system was built by DeAngelo in Ft Lauderdale, perhaps 15-20 years ago. It has a stainless exhaust pipe welded up of straight, 90 degree, and bellows sections which crosses the engine compartment to the port lazarette. There it enters a tall mixer from the bottom while the engine raw water enters from the top. The mixer device is maybe 30 inches tall while the entire weldment is nearly 4 1/2 feet wide at the point it reaches the mixer. The mixed exhaust/water exits about halfway up. Part of the complexity is that the pipe skirts the genset.

The pipe includes two bellows sections of about 8" length. One of these has developed severe cracks.

This may have been a good solution when installed but it seems failure-prone by today's standards. It also seems odd to situate the mixer at such a distance (over 4 feet of stainless weldments) from the engine.

I would appreciate any suggestions of the best (and most economical) way to proceed.

John Meskauskas
Wilmington NC

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11 years 2 months ago - 11 years 1 week ago #147 by Greg Temple
Replied by Greg Temple on topic Re:Perkinss 4.236 exhaust
John,
I'm not Bob, but want to share a couple of thoughts. Your description of your exhaust system sounds very similar to a discussion that occurred several years ago. I will research my archive of messages and try to find that info.

If you have the same system I'm remembering, your muffler is in the lazarette. I was able to locate replacements a few years ago.

My Destiny is an '84 Whitby and I think several changes were made during the production run of the boat. I have a composite water muffler mounted in the port aft corner of the engine room. An exhaust riser, which can be fabricated from threaded black pipe, runs vertically from the 4-236 about 20" / 30" (I'm in Colorado and won't be back to the boat for a week, so I'm going from memory) whereupon the pipe turns down toward the muffler. The water is injected at the top of the downward bend. About 12" / 16" after the downward bend, the pipe curves more horizontally toward the muffler. The pipe portion ends 3" / 4" after the downward bend with angle toward muffler. There is about a 1' fall from the end of the pipe section to the top of the muffler. The section from the pipe to the muffler rubber wet exhaust hose. Exhaust / water go to the muffler and the output exhaust pipe is along the port side to the transom.

The reason I'm mentioning all this is that rather than replace your old muffler, you may want to go with a composite, non-corroding unit. Just a guess, but I'd bet the newer composite mufflers are less expensive than the replacement for yours.

The riser can be fabricated from commonly available pipe. If needed, a new threaded exhaust "manifold" (square plate with mtg holes and threaded pipe fitting ) can be purchased. It's common to wrap the metal riser with fiberglass "tape" to prevent burns and that tape is available at commercial chandleries that sell to the fishing boats. Secure it with copper wire. I've been told to not use galvanized pipe as it emits toxic fumes when heated.

I also have a generator. We've used My Destiny extensively and I'm 100% confidant in the exhaust system and its capacity. I can get you all the dimensions next week. I can also forward pictures. I'll do the research about the other approach and try to post the info later today.

Greg Temple
My Destiny #313, W42
Last edit: 11 years 1 week ago by Greg Temple.

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11 years 2 months ago #148 by John Meskauskas
Replied by John Meskauskas on topic Re:Perkinss 4.236 exhaust
Greg, thanks so much for your reply. It's very heartening. One issue I need to deal with is that most of the switching for both 120VAC and 12VDC is in the area. Wires run over the top of the head counter. My exhaust pipe runs through the aft head's lockers, being secured at the top of the lower locker. I'm not sure where the waterlift muffler itself is but suspect there is one. I'll research that tomorrow.

Thanks again. It was very discouraging to have a fire start from the broken exhaust pipe, burn through the head sink drain hose, and start to bring in (what seemed at the time) significant quantities of seawater.

John

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