Cat 3412 1997 problems

Per earlier posts from several folks; have you checked the port batteries with a meter? Did you try your emergency parallel?

Bummer, was hoping something easy for you. Are your starter motors easy to get at? Perhaps swap strb to port for a quick test? Or as Ralph suggested, use a bar and compare turning effort from port to stbd.

Not related to your current issue but why would you leave the parallel switch on all the time? That defeats the purpose of having an emergency parallel. With the switch on, if one bank fails it will pull the other one down with it. Suggest you leave this switch off for normal operation.

Indeed don’t run with the parallel switch always on as it will mask a failing battery and leave you stranded.

same with running dual racors with both filters on line. Bad habit but very common.

you can’t upload a video here, only pictures. Put it on YouTube and post the link

If the parallel switch is always on, on when you checked port batteries... you may have been getting a reading from the combined banks instead of just port.

-Chris

Some boats use solenoids to parallel the batteries ( Hatteras for instance) but many others use battery switches which can be left on. Not a good idea indeed

Pretty common to have a basic parallel switch. I have one on my boat and had one on my previous boat as well. A simple battery type ON-OFF switch is all it takes. Normal operation would be OFF and the P/S batteries are kept isolated from each other. If you lose an alternator or batteries on one side you flip the switch to on for emergency starting from other side.

I have never seen that on a boat and don’t see the point. It s just one more potential failure point. Redundancy is critical on a boat so if you have 24v system, you put two batteries in series for each engine and you re done. No need to complicate things. Alternator and starter will both be 24 v anyway.

Typical penny pinching by builders.

when I repowered my hatteras 53, I went the other way. Cummins was charging about $1500/2000 per engines for 24 volts factory reman so i got 12v engines with an 8D per engine but used 24 v for the house. I don’t like 12 v house on anythjng over 40’. Especially for the windlass.

only downside for now is that I can’t charge the house bank with the engines but we always run the gen anyway.

I could probably run a set of wires from the each engine 8 Ds to each of the two house 8Ds with a parallel switch if we loose the gen. But if we loose the gen, we we not staying out without air con anyway

I do hope the OP posts more when he finds the issue or eliminates possible sources from being the problem.

I was wondering if the rust could simply be from condensation and moisture and sitting through the winter in the NE?

At the very least change the oil and filter before trying to fire it up.

I can’t help wondering if firing it up is a good idea without further testing. Apparently you got away with some kind of water ingestion once but this may be pushing your luck.

pressure testing the cooling system is pretty easy at least on the coolant side. When I had our 16V2000s rebuild they pressurized the coolant overnight to make sure it was all good before starting.

I don’t think salt water can get in but could be wrong. Aftercoolers maybe ? Are they fresh or raw water cooled on the 3412s? I don’t remember.

and send oil and coolant samples to a lab to know what s in your oil and if any metal shows up