71c 1:1 problems need help

I have not put this boat in the water yet, due to the fact that the tranny is freaking me out.

It makes a pulsing whine when in forward neutral, or reverse. Oil level is high, in fact, I filled it up as far as I could until it started coming out of the vent while I was running it in the yard. While i was trying to figure out what the whine was, the oil line blew (exiting line from tranny) right at the transmission case.

The oil was not hot, since I was running the boat for about 3 minuites. I'm using flex loc hose with a 250 psi rating. The setup is a 1:1 Borg Warner and an 80 hp subaru gasoline engine. Pressure could not have exceeded 250 psi?

Is the whining noise a problem, or the pump cavitating and pulsing? How do I stop it? Why would the tranny line blow out? Air in the line, restriction at the cooler? Any help is greatly appreciated.

 

Well I calculated my pressure drops and figured out the problem. I'm using 1/4" ID hose for the cooler lines. My cooler is 4 feet away therefore 8 feet of hose. The max ammount of liquid is 10.5 gpm at 180 psi.

Using the given numbers I had a pressure drop of 200 psi, which is no flow at all. If the ID of the hose is upped to 3/8", the pressure drop is roughly 50 lbs. Using 1/2" line, the drop is next to zero.

The 1/4" hose was choking the flowrate of the oil. The hose kept busting directly at the outlet of the tranny, which is where the pressure would have been the greatest.

I don't know whether to get 3/8" line or 1/2". I think that the cooler guts have 3/8" since the cooler has 3/8" NPT fittings. If I use 1/2" , I'll get a drop across the cooler and possibly bust it, but If I use 3/8", the drop will only be 50 lbs across the entire cooling system. What is everybody else using?

 

Both my stock 71C and 72C with beefed up clutches use High pressure reinforced rubber 3/8 lines and are working fine.

 

Whatever kind of line you get, make it expensive and reliable. You'll never be looking when a line gives way and it's gonna be way too late when you finally notice.

A pulsating whine would be someting that's supposed to rotate on a shaft, but is oscillating instead.