Can someone tell me what this is, and how to fix or replace it?

Hi guys, I have a question about my 1976 Betram 46-6. In front of my Detroit 8v71 engines there is a red box with a lot of cables attached. I am preparing to start engines that has been submerged, and this box started to smoke. The box made a click sound when we set engine stop/on to on or stop, but after the smoke-incident it does not click anymore. It seems we have blown something on the printcard where I put an arrow (see attached image). Is it possible to fix this box, or do I look for a replacement? If it needs replacing, can anyone suggest a good replacement part, and where to find it?

Hi guys, and thanks for answering. I wrote that I am preparing to start, not trying to start. I have not done very much with the engines, but I was able to make one of them turn and both the turbos of that engine are spinning free. All injectors are moving when pressed also.

I was originally planning to replace both engines, but I have only managed to find one replacement engine so far. So I wanted to try a trick to loosen the other. I had my frend standing on a 1m longwrench on the crank, and I gave the wrench a nice and hard hit with a hammer. The trick worked and my port engine is now turning.

We are now planning to remove all injectors and poor some diesel in all cylinders, and then turn it much more before we try cranking it. And also change the oil of course. So finding out of this box is just one of many things we are planning to do before we start it.

A special thanks to RER! Now I know what it is, and can start searching for a replacement.

I had to loosen it the"wrong" way, as its the port engine. But we only turned it about half way around that way. After that I have only turned it the "right" way.

The replacement engine I have found is supposed to come from a military surplus outlet, so the seller claims it has never been used(!). It does not look very new though, but it was very cheap.

I specially dont like the way the engine is mounted in the frame, as it seems to be a little rough on the balancer wheel. (Or what it is called) Here are som pics:

I thought that I only had to look for a turbo engine, and it is a turbo. The differences I see first hand is the balancer wheel, the strange exhaustmanifolds (or what they are) and the oil cooler. I dont remember the serial or model number now, but the model number ends on 99 on the new one and 00 or 09 on the old. (Hard to read). Other than that model numbers are the same. Thanks for the advice on taking the serial number to a diesel shop, I will do that and hear what they say. I was hoping to put the complete long block right in, with all my own marine parts.

It is not very important to me that these engines perform at their 100%. I was thinking the new engine would be enough for me to safely drive the boat at low speed, and the other one I only need to work well enough to be able to use 2 engines in harbours. The boat will be used as a live aboard, and will not be moved around very much.

I will not be using the original diesel tank for the startup, but a small tank I can close or disconnect if it schould rev out of control. I also have a large CO2 fire extinguisher in the engine room. The trigger for the fire extinguisher is up on the bridge. Do I need to close all engine hatches for it to work, or will it work also with the floor all open?

And thanks again for all advices! I am new in the yacht game, and eager to learn.

Does anyone know of a video of a Detroit over revving? I would really like to see and hear how it acts out.

Never mind, I found some when searching for "runaway detroit".