Marine Diesel Exhaust Risers?

[NickScheuer]

The Feb-Mar issue of BoatUS Magazine has an article about marine Diesel exhaust manifolds and risers. They suggest that these must be examined in detail at least every two years, and even annually by removal for inspection inside. I've owned a 1976 Albin-25 powered by her original V-P MD17C (fresh water cooled now, but not for most of her earlier life) for seven years, and the exhaust manifold has never been removed for inspection over that period.

How'bout the rest of you? What has been the experience of others with the V-P MD17C ?

[Jeremyvmd]

no experience with the md17c - but i will say that the exhaust riser on my 98 peninsular was SCARY and it showed no issues when running. i will be more diligent in the future about keeping an eye on it

[WillieC]

One would imagine, in some kind of alternative fake universe, that when the switch was made to a heat exchanger, that the condition of the exhaust manifold was assessed and deemed worthy. Then again, my whole Albin life has been wrapped up in dispelling these myths about previous work.
Is it leaking at any of the casting plugs? Have you ever drained and flushed your anti-freeze? How bad does it look? Are you able to open the cylinder drains and do they actually flow or are they crudded up? I ask all this because I spent a lot of time cleaning out the cylinder jugs of a non heat exchanger MD17C for my rebuild. I don't see how they cooled at all so much rust came out. The spare engine, another 17C that came with the boat was HX cooled and the liners and cylinders looked much better, but had significantly more cylinder wear than the ones I ended up using.
If you are not overheating, as far as you can tell, nothing is leaking, all your cylinder drains and the one manifold drain is functional, not clogged up, I would not be too concerned. Was your engine mostly run in lake water, not saltwater back in the days before the heat exchanger was installed? That would be a good thing.
Keep your water pumps maintained. One of my exhaust manifolds showed considerable saltwater damage at the aft end where seawater is injected into the elbow. A leaky connection had been neglected, dripping saltwater on the end of the manifold. Not a good thing.
Since no seawater is run through the manifold and you are not showing any obvious trouble, I might just sleeping dogs lie. Then again, it all depends on previous maintenance. Removing the manifold is not that difficult, other than draining the cooling system which might be a good idea anyway, and getting the heat exchanger out of the way. Then you can get a good look at passages and maybe have it boiled out. Carbon build up may need removing too.
Bolts may be stuck and can easily snap off (after I just told you it is easy to remove, oops.) I found a mix of metric and SAE bolts on my engine which added another layer of love for the POs. Those bolts go into the HEADS! Use PB Blaster, or whatever the current hot new bolt buster is being recommended and don't rush it. You would likely want to get new gaskets, get a new Tstat rubber ring while you are at it. How is your exhaust elbow, etc, etc.
I'll stop for now. Having gone through what I have done, depending on your natural tendencies, there may be no end to what to look at next and pretty soon you are grinding valves and replacing liners. I got here having no choice, anti-freeze showed up in the crankcase. Otherwise the old engine ran great, with low compression, started easily, but became undependable. Careful, careful. Forgive the cliche about not fixing what ain't broke. PM me anytime.