Detroit Diesel Heat Exchanger Failure

Following this thread with great interest. Good point that many of these older engines are out there, including my pair of 1980 12v71n's.

Do you believe the fix is as simple as installing a new/replacement HE?

Does not take too much to crack one of these C.I. castings, yrs ago when I was replacing a section in a commercial cast iron heating boiler, the owner wanted the boiler tested to 60 psi to be sure the new section would not leak he was warned that the existing relief valve was too high a setting as the system only needed 12 psi to operate, was a cold water test, at 35 psi we had a crack in an older section , ex ray showed just porosity in the casting at the crack and leak location. The owner paid for another new section and wanted a new test to 30 max with a corresponding change in the relief valve sizing to suit, was fine after that, as far as I know.

Was that for steam or hot water?

What's the alternative?

There may or may not be overheating damage but until the system is restored and the engine restarted and trialed, short of a speculative tear down, there isn't really a practical means to determine the extent of other problems, if any.

Okay.

Water skiing behind a Superyacht - YouTube

Hi,

The yacht in the video is the White Rose of Drachs if anyone is curious.

Re Marmots ?? was a HW htg boiler...8 section, oil fired.

I am not asking for an alternative, just wondering if the fix, after such a catastrophic incident, "could be" as simple as a new HE.

Maybe, maybe not.

It could be, and like Marmot says you cannot tell until you run the engine. Short of tearing it apart. However, depending on the temperature the motor actually got to I've seen all sorts of things in DD's that have been overheated and sometimes they show their head 100 hours later. Stuck coolant/injector tubes, dropped valves, egg shaped bores creating very unusual and premature wear in the liners, cracked heads, a valve seat getting dropped later, and on and on. If the engine overheated at idle (low load) and was shut down soon enough there's less chance than if it overheated at 80% load.

Got you. Hard to imagine that the heat needed to shatter the HE, would also not damage many other parts, BEFORE the explosion.
The fact the alarm did not forewarn the problem is disconcerting:
Yachtjockey:
“Most temperature senders will not alarm if there is no water and in one case I was involved in the DD got so hot the wiring harness went up in flames, burnt all the way up to the fly bridge, Halon system went off, shut downs did not work and engines sucked the good old halon in resulting in two new engines and two new generators.”

Back to you Marmot re: “A flow switch in the raw water side might have been a good investment given the propensity of Jabsco impellers to fail.”

I’d appreciate some direction on doing this, it seems like a very economical and straightforward addition that would be as useful as the other gauges to keep an eye on.

Go to Ebay and search for "paddle flow switch" and you will find a multitude of very good switches for very little money.

Wire one on each engine and generator to an idiot light and/or a buzzer. Wire it so that it is on with no flow so the circuit will be self testing.

Kafue,

alternatively you could go to someone like these guys.

Home - Bürkert Fluid Control Systems

In either case:

You want to get a switch that will close some contacts and compete a circuit when there is no or very low flow and give a signal to a stand alone alarm klaxon or to the already installed alarm system and will remain quiet the rest of the time.

A pressure indication for the SW Supply to the HE's is also a good idea, if you get the alarm you can see at a glance which one it is or you can see restricted strainers as they develop if you get used to the normal pressure when underway at various engine speeds.

Thanks, seems it should be a regular addition in any case
Cheers

kafue wrote:

Are you saying the halon destroyed the engines and generators?

Hi,

I think he was using a previous post by another member:

Ah so, Post #14, sorry.

I look forward to the response from the original poster of that tale.

Halons

No K1W1, I had not seen any other posts similar to what I wrote and No Marmot, I did not mean the halon destroyed the engines although if you remember 20+ years ago it was thought that Halon would cause problems on the internal parts.

What I was meaning, and sorry for any confusion, due to sensors and shut downs not working the fire which came about due to the overheating engine caused major engine room damage. The yacht was less than one year old and it was decided to renew just about everything including the engines and generators.

If I remember correctly there was a DDEC control box mounted on the engine that the wiring harness from the fly bridge was plugged into. The first sign of trouble the owner noted was when smoke started coming out from his helm console.