[HandsFree]

Just bought a 1996 3700 open with CAT 3208's 435 hp. Does anyone have any tips or insights to this model and engine.  I want to learn all I can about this boat since I plan on keeping it a very long time. I had CAT come out and do a complete tune up i.e. oil change, new hoses, adjusted the valves, fuel filters, etc.. The only issue that I noticed ( so far ) is that the volt meters start out at 11 and after a while they are down to 10.  Any thoughts on what I should be looking into? Any and all comments are welcome and very much appreciated.

Thanks
Dennis

[jclark003]

The 3208 is a very good engine. 435 is the high end of the HP range for that engine however. They will be less tolerant of abuse and if run hard and or run over loaded, engine life will be significantly reduced. Make sure it is propped to exceed rated rpm by 2-3% with the boat loaded up. Follow maintenance schedule especially as it relates to cooling system and keep it under 80% load while cruising. Go to boatdiesel.com and you will find loads of great knowledge on how to run and maintain them.

In terms of volt reading, mechanical gauges can be notoriously inaccurate. Start by connecting a digital volt meter to the battery bank, turn off battery charger and run up the engines. You should see 12+ volts before starting engine and closer to 14 volts when over 1000 RPM. If no change then time to look at charging system. At 10 volts I doubt you would even be able to start engines. Check both banks. Typical to have one engine charging start bank and the other charging house bank.

[HandsFree]

Thank you jclark003, I appreciate any and all information.

[Sans Peur]

I just went through this on my 3208's except they were going to other way and putting out too much voltage. After confirming the gauges were correct (follow jclark003's advice) it boiled down to the old Balmar ars-4 regulators on the firewall in front of the engines. They are known to cause issues after awhile. I changed them out to the newer ars-5's and everything is good now.

[Lured Away]

Great boat and congrats. I have the same boat/engines but a 1998 and have been through or replaced pretty much every system in the past 5 years from turbos and elbows to aftercoolers to fuel tanks.

On the engines, if don’t know when aftercoolers were cleaned, have it done and make sure intake tubes are good.

Key to these engines is they are sensitive to overheating so suggest running at a 2200-2300 cruise. I added EGT gauges and think this is one of the better tools for monitoring temps.

Not sure what props you have but just upgraded mine to 4 blades and was a great improvement.

Feel free to contact me with any questions.

Ryan

[HandsFree]

Took our first long run on our new to us 3700. What a great riding and handling boat. I do have a question though, what is normal for the transmission pressures to be at?  Both pressures were very close to the same but they seemed very high.  I never had Trans pressure gauges before so any input would be great.

Dennis

[ReelMagic]

I own a 2003 38 Open w/450 Diamond Cummins tied to ZF-280 transmissions.... My trans pressure is around 350-400PSI when in forward/Reverse...  In neutral pressure is around 50 PSI.. M2C

[HandsFree]

Thanks Reel Magic, I have twin disc but they seem to act the same way, around 50 psi at neutral and around 350 - 400 psi in gear.

[Lured Away]

Just checked and look like mine are about 275-280 at 2250 rpm.

[Sans Peur]

Go to boatdeisel.com and register with that site. It cost to be a member but not much. The information and people on there are invaluable. If you have a problem or question with anything related to the engines or trannies you can find it there.