Steve Dabrowski
Member
I completed working on my 48 8N oil pump and reinstalled the engine and started it up and ran it for a couple of hours today. Result was that by eliminating the excess end clearance that came from the new replacement gears that are 0.007-0.008" thinner than the original along with the 0.007-0.008 thick gasket that comes in the kits I gained back 10-15 PSI hot oil pressure.
I re-installed my original pump gears which are flush with the pump face and used a gasket that I got from New Holland which was a couple of thousands thinner than comes in the TISCO pump kits. I further compressed the CNH gasket to about 0.005" thick before installing it. I plasti-gaged the end clearance and ended up with .004-.005 all said and done.
Now at cold start up I have 45 PSI, after warm-up it runs about 35 PSI at half throttle and after a couple of hours drops to a steady 27-30 PSI, where as before after that time it would be around 12-15 PSI. Hot idle is now 18-20 PSI where before it was about 8-10 PSI.
Lesson in this, two fold. First keep a record of pressure before pulling the engine apart and don't fix it if it ain't broke. Second, if you replace the gears be sure they are flush with the face or plan on milling the pump face so they are, then get a good thin gasket from CNH or cut one from paper so you end up with 0.003-0.005 maximum end clearance on the gears. It is a big deal and the 0.014" clearance you will get using the gears and gasket in the rebuild kit will result in low pressure.
I re-installed my original pump gears which are flush with the pump face and used a gasket that I got from New Holland which was a couple of thousands thinner than comes in the TISCO pump kits. I further compressed the CNH gasket to about 0.005" thick before installing it. I plasti-gaged the end clearance and ended up with .004-.005 all said and done.
Now at cold start up I have 45 PSI, after warm-up it runs about 35 PSI at half throttle and after a couple of hours drops to a steady 27-30 PSI, where as before after that time it would be around 12-15 PSI. Hot idle is now 18-20 PSI where before it was about 8-10 PSI.
Lesson in this, two fold. First keep a record of pressure before pulling the engine apart and don't fix it if it ain't broke. Second, if you replace the gears be sure they are flush with the face or plan on milling the pump face so they are, then get a good thin gasket from CNH or cut one from paper so you end up with 0.003-0.005 maximum end clearance on the gears. It is a big deal and the 0.014" clearance you will get using the gears and gasket in the rebuild kit will result in low pressure.