Time for a new exhaust riser?

[mforum]

1986 Catalina 27. I’m noticing at times a very slight exhaust smell in the cockpit when motoring. Engine compartment can look a little foggy too at times. I put in a CO detector in the engine compartment but it didn’t alarm. I noted trace brown dirty water at the mixing elbow. See photos. I have no idea when this was last replaced if ever.
Reading other posts it sounds like mixing elbows in the exhaust riser are high failure points given hot exhaust and saltwater and should be replaced every 5-8 years.

Also, what is the purpose of this tube coming from the top of the engine in second photo? I couldn’t find it in the typical diagrams. Is this the crank case ventilation or something else? I can feel a little puff of air coming from the end of the tube where it ends near the starboard side of the heat exchanger but it doesn’t feel hot or look steamy. There’s a touch of oil just inside the tube if I put my finger on the end but never any oil actually leaking or dripping out.

Questions:
1. Is a little put of air coming from this tube concerning?
2. Should I consider a compression test before changing the mixing elbow and exhaust riser?

Thanks in advance.

 

[kloudie1]

The mixing elbows on Universals is a lot less prone to failure than on Yanmars but you may have a problem because of a leaking weld where the water hose attaches. It may be that the hose is loose and the clamp needs tightening.. or that the hose itself is leaking at or under the clamp.
The other hose is indeed a crankcase ventilation hose and will puff lightly and will have condensed oil mist in it from the crankcase breathing. On most of the Universals that I've messed with, the breather hose is led to a fitting under the air cleaner (inside the element) so that the crankcase vapors are sucked in and burned. If yours doesn't have the fitting , you can easily make one from pvc or metal fittings from Home Depot or Lowes or Ace..

 

[dlochner]

Take the elbow off and inspect it, that will be the only way to tell for certain. The fiberglass wrapping on the elbow looks pretty new, I wonder if someone has been there before. If the weld is beginning to fail, it will undoubtedly fail at some really inopportune time. Been there.

 

[Stu Jackson]

Is this the crank case ventilation

Yes.

Many of us have stuck the end in a plastic can to avoid dirt in the engine compartment. Other choice is to reroute it back into the air intake, like this:

Breather Hose 101 (w/ K&N Filter Pictures from Rick Allen)

K&N air filter breather hose

and Noah's: Oil "breather" hose to Air intake

and Kloeber's PDF and wiki link: Options to route crankcase breather to air intake

 

[Richard19068]

Yes.

Many of us have stuck the end in a plastic can to avoid dirt in the engine compartment. Other choice is to reroute it back into the air intake, like this:

Breather Hose 101 (w/ K&N Filter Pictures from Rick Allen)

K&N air filter breather hose

and Noah's: Oil "breather" hose to Air intake

and Kloeber's PDF and wiki link: Options to route crankcase breather to air intake

Routing that hose to the intake through a K&N air filter cleared up the "little foggy" and smell my engine compartment sometimes had. I also added one of these: JEGS 52205: Air Oil & Water Separator [4 1/2 in. Height x 1 3/4 in. Diameter] - JEGS

I'd be more worried about the exhaust mixer. Kloudie1 might be right about it just being a loose or bad hose but you do need to check it out.

 

[dlochner]

I'd be more worried about the exhaust mixer. Kloudie1 might be right about it just being a loose or bad hose but you do need to check it out.

@kloudie1 is an optimist.

I once had a small leak in a similarly built riser/injection elbow. It had a small leak that I thought I had repaired with some JB Weld. After motoring through a T-storm the wind died, the exhaust elbow blew and more storms were brewing. Oh, and we were 14 miles off shore sitting becalmed in the middle of a shipping lane.

Pull the riser, inspect it, and replace it. Salt water and exhaust gases are not friends of mild steel.