Hi guys.

I want to put an external cooler on each of my NP203 and NP205. Any ideas where I can find a nice, small (preferred) electric pump that will handle synth. gear oil?

--Rob

I have a buddy who builds racecars, and he uses the Holley blue pump (Summit has them for about $97) to pump gear oil, and has for years.

Craig

I use a military 24V electric pump in my BJ40 to pump gear oil up to the planetary overdrive (in the rear PTO hole) in the upper part of the transfer case, there's a drain-back line to the main part of the T-case.
So a Holley red pump should work especially after the oil gets warm; the pump seems reliable despite the viscosity of 85W-140.

But why would you need coolers for a 203/205 doubler? Certainly not trail use. Do you have it in a heavy pickup and do heavy towing? The ORD 203/205 setup in my 10,000 lb F350 gets warm with speed driving but not hot. These boxes have stood the test of decades in terms of reliability. I saw a 205 in a "homemade" 15,000 lb medium truck powered by a 6BT Cummins and Spicer 7 spd which has towed up to a GCWR of 30,000 lb!!! It's a tough gear box for something that small.
Did you know that the basic design of the 205 was the NP200 used in WW2 WC62/63 6X6 1.5 ton trucks starting in late 1942, so the design has been around for 60 years?
I have a NP205 with NP200 output shafts and yokes and housings on it, that's how interchangeable and unchanging and reliable the design is.
Charlie

The truck is geared pretty slow. Both cases are spinning ~4000rpm. The cases get too hot to touch after some 20 miles of highway driving. According to the temp. sensor I put in, the oil is upwards of 180-200F. With acceptable ranges, but I'd rather have a cooler on them anyway. No concerns for the trails, though. I think I'll be going for blue pump...

--Rob

Better let it get hot before you cool it. It will pick up a ton of moisture if it never gets hot and things will rust and or get gummy.

That is fast. I think in my M37 the case will turn at ~3000 with engine going 24-2500 in 5th; and in my F350 like wise the doubler will be doing about 3000-3200 at 23-2500 7.3 speed at 70-75 mph. 4000 will get one of these cases quite warm.
Charlie

Originally posted by Charles Aarons
That is fast. I think in my M37 the case will turn at ~3000 with engine going 24-2500 in 5th; and in my F350 like wise the doubler will be doing about 3000-3200 at 23-2500 7.3 speed at 70-75 mph. 4000 will get one of these cases quite warm.
Charlie

...thus the reason for an external cooler on the cases...:-)

Thanks, guys.

--Rob