In a message dated 5/31/02 12:03:23 AM, trawler-world-list-request@lists.samurai.com writes: << Bob wrote: "After reading Mel's tale of woe re: his Perkins exhaust manifold rusting and allowing water incursion into cylinders the question is, "Could this have been prevented?" Since I have the same engine albeit a few years newer I have more than an academic interest in the replies." >> Admittedly exhaust header failure is a serious and expensive problem. Far more common is failure of the exhaust elbow. Calder says that these have a 5 to 8 year life and my experience confirms this estimate. The problem is quickly locating a replacement elbow for a 25 year old, out of production engine. Fortunately it is possible to fabricate a pretty good exhaust elbow for most engines out of standard plumbing parts in a couple of hours. On my Perkins 4-107 the inflow of the exhaust elbow is a standard 1 1/2" pipe nipple. A 1 1/2" cast iron sink trap, mounted upside down so that the bend is upward can be fitted to the exhaust flange on the exhaust header. It is easier to do this by removing the header first. Drill a hole in the downward leg of the trap in a convenient direction and braze or weld a 3/8" pipe nipple in place. This serves as a cooling water inlet. A 1 1/2" pipe nipple fitted to the end of the downward leg to attach the rubber exhaust hoze completes the job. In operation, the hot exhaust enters the elbow, rises about 3" in the upward leg, makes a 180 degree turn into the downward leg where it meets the cooling water, then out the rubber exhaust hoze and into the Aqualift muffler. Cooling water cannot flow uphill to enter the engine. Even after a full throttle run it is possible to hold your hand on the downward leg of the exhaust elbow and the exhaust hoze is only pleasantly warm. This is better than the factory fitted elbow. The specific design is one of those things that is almost impossible to describe in words, but laying out the parts makes the whole thing clear. Be sure to use cast iron or steel components bought from a plumbing supply store. Most current plumbing stuff sold in WalMart and hardware stores is plastic or stamped sheet metal. The cost of parts for the home made elbow was less than $15 compared with the >$200 price quoted by an engine shop. I've had my home made elbow on for three years. I pulled it in the course of doing some other engine work this Spring and found that it showed no rusting or apparent deterioration. At this rate it should easily exceed Calder's 8 year life span. Larry Z