Official 390 E.C. Thread

The sending units on the cats are under the water tank at the front of the engine. They are easy to replace and inexpensive. Don't lose the little rectangular driveshaft things because you will need those to use with the new sensors because the ones that come with a not quite right
 
nickdcj7 said:
So I looked at another 390 a couple weeks ago, this time an '87 with diesels in Freeport NY. Yet another rot box. Pics on yachtworld must have been 10 years old because it didn't even look like the same boat. I'm starting to think the only good 390's are owned by the members here. Sorry guys, just venting while thinking about the winterizing I have to do on the 250 that I was hoping to have a for sale sign on it by now after finding a nice 390.

oops, I almost forgot.

http://www.yachtworld.com/boats/198...072/Long-Island/NY/United-States#.VkD9grerRhE

don't waste your time. Yes Saverio, I'm talking to you.
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Don't mean to high jack 390 thread, have you considered 1989-1992 420 Dancers. Don't get me wrong, we had a 390 and loved it, we sold and moved to a 420 with 454s, great boat, a little more room. One thing I loved about the 420, was the bow rise was gone. Just something to think about.
 
If you replace the gauges you may have to change the sender anyway. For oil and water I highly recommend. I had to do it when I switched to Faria diesel tachs. The number of pulses per rev that the original senders put out did not conform to the Faria tach specs. Also buy a $12 laser phototach on Ebay because you will need it to calibrate your tachs to match the actual engine RPM

BTW I was getting about 20knts at 2200rpm.
 
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I was thinking that would be my next boat a 420 or 440 with twins diesels.

bahamabreisus said:
Don't mean to high jack 390 thread, have you considered 1989-1992 420 Dancers. Don't get me wrong, we had a 390 and loved it, we sold and moved to a 420 with 454s, great boat, a little more room. One thing I loved about the 420, was the bow rise was gone. Just something to think about.
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Odd Coolant problem.

Prior to my last cruise the bilge was dry. Ran 3 hrs at 2800 RPM all the gauges showed normal values.; Both engine temps showed 180 Deg F.

Went down into bilge today and forward sump had what looked like a lot of coolant. The Port sea strainer and area surrounding were coated in what was probably a water coolant mixture. The light colored items on the forward port engine area were tinged the color of the coolant.

Checked the coolant tank and it was FULL right to thee top of the filler neck. Started the port engine, temps came up to 180 deg and stabilized. I ran the engine for an hour and found no leakage. Coolant overflow tank slowly filled to half full and stayed there.

After the engine cooled enough to remove the filler cap I found the coolant level still full up to the filler neck.

My questions are. Is pressure in the raw water side higher than the engine side? If so would a leak between the 2 systems allow raw water to over fill the engine side causing an over flow?

The cooling system was installed new with the engine 14 years ago and probably has not been opened since. It spent the first11 years in fresh water, 2 years in salt water and the past year in fresh water. Never an issue with temps and good water flow out the exhaust.
 
Airboss said:
Odd Coolant problem.

Prior to my last cruise the bilge was dry. Ran 3 hrs at 2800 RPM all the gauges showed normal values.; Both engine temps showed 180 Deg F.

Went down into bilge today and forward sump had what looked like a lot of coolant. The Port sea strainer and area surrounding were coated in what was probably a water coolant mixture. The light colored items on the forward port engine area were tinged the color of the coolant.

Checked the coolant tank and it was FULL right to thee top of the filler neck. Started the port engine, temps came up to 180 deg and stabilized. I ran the engine for an hour and found no leakage. Coolant overflow tank slowly filled to half full and stayed there.

After the engine cooled enough to remove the filler cap I found the coolant level still full up to the filler neck.

My questions are. Is pressure in the raw water side higher than the engine side? If so would a leak between the 2 systems allow raw water to over fill the engine side causing an over flow?

The cooling system was installed new with the engine 14 years ago and probably has not been opened since. It spent the first11 years in fresh water, 2 years in salt water and the past year in fresh water. Never an issue with temps and good water flow out the exhaust.
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Did you add any coolant prior to this issue? Any water in the oil pan (creamy white oil)?

I had the same issue on my Cats. I put a little too much coolant in the tank. Made several low speed cruises with no issues. One day I made a full power cruise which brought the engines up to full op temp. This expanded the coolant to the max and it blew out all over the place. I cleaned up the mess. Since that time I have had no further issues.

You can also check the specific gravity of the coolant to see if it is changing due to dilution by sea water. Always check the specific gravity at the exact same temperature.

Monitor it with another run and see if the issue persists. If it does you may have a heat exchanger issue.

Your system has not been touched in 14 years? There could be electrolysis problems in the heat exchanger (holes in the tubes). What do the cooling system zincs look like? Gone? Oh Oh!
 
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Haven't added any coolant. Prior to last cruise coolant level was about an inch below the filler neck.
Engine and cooling zincs are still in good shape but I probably need to change them to Mg+ as boat is now in fresh water.

No water in the oil and no water in the tranny. Oil and tranny fluid are clean.
 
Saverio said:
I was thinking that would be my next boat a 420 or 440 with twins diesels.
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To be honest, I wish we still had that boat. I liked it better than the current 500DA. Wife wanted 2 heads, you know how that goes.
 
Airboss said:
Haven't added any coolant. Prior to last cruise coolant level was about an inch below the filler neck.
Engine and cooling zincs are still in good shape but I probably need to change them to Mg+ as boat is now in fresh water.

No water in the oil and no water in the tranny. Oil and tranny fluid are clean.
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Get a radiator pressure tester ( an air pump and gauge that attacehes to the radiator cap opening). Balkamp makes a good one but for a one shot deal try ebay or Harbor Freight. Pump it up to 14 psi and see if the pressure drops. If so you probably have a leak in the heat exchanger. I dont know where else sea water can be entering the FWC system.
 
bahamabreisus said:
Don't mean to high jack 390 thread, have you considered 1989-1992 420 Dancers. Don't get me wrong, we had a 390 and loved it, we sold and moved to a 420 with 454s, great boat, a little more room. One thing I loved about the 420, was the bow rise was gone. Just something to think about.
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I actually have, and I like the layout of the 420, but I think they're all pretty much out of my price range. Even a 400 express seems to be double the price of a 390.
 
I think 400 Express is smaller than the 390. I don't see a lot of difference in price between a 390 that needs a lot of work and a 420 in decent shape. They will all need a little TLC.
 
Dr MicroChip said:
Get a radiator pressure tester ( an air pump and gauge that attacehes to the radiator cap opening). Balkamp makes a good one but for a one shot deal try ebay or Harbor Freight. Pump it up to 14 psi and see if the pressure drops. If so you probably have a leak in the heat exchanger. I dont know where else sea water can be entering the FWC system.
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Pressure test and Spec Grav should certainly isolate the issue.

Thanks,
 
bahamabreisus said:
I think 400 Express is smaller than the 390. I don't see a lot of difference in price between a 390 that needs a lot of work and a 420 in decent shape. They will all need a little TLC.
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I have to say I never been on a 400. is there tham much of a difference. I been on a 42 a few times and it looks a lot different
 
Dr MicroChip said:
Get a radiator pressure tester ( an air pump and gauge that attacehes to the radiator cap opening). Balkamp makes a good one but for a one shot deal try ebay or Harbor Freight. Pump it up to 14 psi and see if the pressure drops. If so you probably have a leak in the heat exchanger. I dont know where else sea water can be entering the FWC system.
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Well did the pressure test yesterday and over 30 seconds it bled down. Looks like I'm in for some work this winter.
 
Sorry for the late reply...been busy and actually forgot to check back on this blog. I liked my 20 x 19 x 1 1/2 nibrals the best. I even gave a set to ariend of mine that had an 1988 to try and he bought a set.
I ran about 22 to 24mph depending on the amount of fuel and water aboard. RPM's usually around 3300. Sure wish I had my 1990 '39 back, my all time favorite of all eight of my Sea Rays!
 
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