Trojan Boat Forum

I have 440's with a closed loop cooling system with raw water for the exchanger and exhaust manifolds.

My question; is it possible to eliminate the close loop system and go strickly raw water?? the boat is only used in lake erie..

Don't do it. But if you do, I have a set of 440s that I would love to put your hardware on.

curious about your earlier post -- What temps were you seeing when your engines seemed to be overheating? The closed systems run at higher temps than raw water systems, by design. If there really is an overheating issue, though, a place to start is probably the raw water pumps -- impellers may be overdue for replacement. The closed system heat exchangers need raw water flow for cooling.

Aren't zebra mussels a problem there?

I have 160 degree thermostats on both engines. the temps were reaching the 200 degree mark when I back down to idle and the temps dropped. looks like I have good water coming out of the exhaust.

What looks like good water may not be . it will fool you

I tinkered around with the fresh water system this past weekend and I am convinced that I want to remove the close loop system. Thinkin of only doing this on one engine at a time to see if it makes a difference. Just a much simpler system to deal with.

But what I need are photographs of an original set up for a 1975 chrysler. I have the manuals with the sketces but I have not seen how they are set up without the fresh water cooling system.

Don"t remove the closed cooling system until you've checked the raw water pump, engine heat exchanger, transmission heat exchanger and exhaust dumps for restrictions. While that Lake Erie water may be fresh it is always better to have stale water in the block than fresh. Not to mention the increase in incomplete combustion created from the lower block temps.

good point , plus you still could have the same issues

Sounds to me like you have a blockage in the raw water system somewhere. Have you tried back flushing yet? If you backflush, don't forget to catch the blockage stuff in a bucket or screen. I had the same problem when the intake screens on the bottom of the boat were pushed in and painted over and partially blocked. I cleaned the paint off and straightened them out and everything was perfect.

Check your exhaust risers!
once gone they will most certainly block water flow and cause your heat exchangers to be less effective

If all else fails, Take your heat ex-changer apart. Go to your local hardware store and buy some muratic acid, (The stuff boatyards use to clean outdrives and bottoms). Poor it into a five gallon bucket. You'll need at least 3 gallons. Put your rubber gloves on, along with your respirator. Then take the tubes from your heat exchanger and dunk them in the acid. Hold it in there for about ten seconds,then take it out and flip it over and dunk again. After a while of doing this you may have what looks like translucent thin tubes slide out of you heat exchanger tubes. Make sure you don't leave the acid in the tubes for too long. This also works better if the entire heat exchanger is drained, washed, rinsed, and dried before the acid treatment. I have had to do this many times over the years working on older boats. What happens is, Even though you don't see any blockage in the tubes, Over the years, a calcium, iron, And mineral plaque builds up on the surface of the tubes, So thin you can't see it there, But it works as a great insulator, and won't allow the heat exchanger to do its job. What ever you do, Don't take your closed cooling system off those engines, and change it over to raw water cooling. That would NOT be the right thing to do. Make sure you rinse everything extremely well after doing this procedure.

I would use rydlyme marine its a lot safe then muratic acid

Well everyone convinced me that removing the close loop system is not the right thing to do.

This past past weekend I removed both pumps replaced the impellers, backflushed the raw water system, checked both the oil and transmission coolers for blockage, took the risers apart and no blockage there either. Didnt get into the heat exchanger.

did find that the thermostat was a 140 not 160 as specified. and the 140 was sticking.

took the boat out for run and the upper temp gauges read anywhere between 180 and 200. lowers were 20 to 15 degrees cooler.

Now here is the real kicker! while on the run the friends on the back deck kept hearing a random pop and or bang, like something was rolling around in the engine room. coming in from the main lake to the channel, cruising around 1000 rpm's, the port engine volt meter dropped to zero and the engine stalled, the gas fume detector went off, hit the blower and the alarm turned off, and got into the marina on starboard engine at the dock had to keep the emergency start switch pressed to the starboard side to keep the port engine running to get docked.

once at the dock I check the timing.....both engines were set at 9 degrees after top dead center!!!!!!!! Which would definitely cause the engines to run hot! (I had the battery tested last week, was good, had napa test the alternatorr "they said it was bad" but didnt have a replacement that would accept a double pulley. after some searching found a replacement. and put it on before we went out. }

would the ceramic resistor cause this problem??

Don't thing its a resistor .maybe a bad connection somewhere