Exhaust fitting identification

[raleighm]

The attached photo shows the fitting that bolts to the exhaust port of my manifold. It obviously performs the water injection function and is stamped with the Universal name so I believe it to be OEM. I have not seen this fitting in any other pictures of Atomic Four engines and hope that someone can explain if it has any function other than water injection. The exhaust hose runs down from this fitting to bilge level, then slightly upwards to the water lift muffler.

Also there is a plug with a square recess in the upper aft end of the fitting. Is this a clean out or inspection hole? Is there any periodic maintenance for this fitting? Thanks for supplying any info.

Raleigh

[BBH]

This must be a Universal water-jacketed riser. When Sketch B of Figure 1, page 7-3, of Don Moyer's Service and Overhaul manual is used, the riser provides the loop shown in the hot section between the manifold and the water lift muffler. Such a riser is used when vertical space is at a premium.

At the right of your photo is the exhaust flange, which I'm sure you know. that attaches to the exhaust output of your manifold, with a 1-1/4 pipe nipple connecting the exhaust flange to the input of the riser. The hose barb shown at the top right of the riser is the water injection point for the water from the manifold, to provide cooling of the riser besides its main purpose as an injection point to the hot section. The output of the riser at bottom left would be connected to the input of a water lift muffler.

Both Universal and Yanmar used to make risers and perhaps still do, but I haven't been able to find any at their Web sites. West Marine lists only Sierra risers in the West Marine catalog.

[dtinder]

Riser

The photo looks very much like the "optional" riser for a Yanmar 4 cly (4JH series). A similar, but smaller and "sleeker" design, is used on Yanmar 1GM, 2GM, and 3GM engines. (While you have it off, clean the cored water passage with diluted muriatic acid). The "other" plugged hole----I've never found a use for. My guess is that it was necessary, during the casting process to use as a core support (or print) for the water passage. Additionally, this access is probably used to remove the sand core after casting.