WEIMWGN

I need help installing a new oil pump in my 3.8.
The inner and outer rotor turn freely until I torque the bolts then only the inner rotor turns. Seems to me there's something wrong. Any ideas?
Both the new and old pump give me the same problems.
TIA for any help.

JFish'n

I'm wondering if you bought an oversized pump kit used when the pump pocket needs to be machined.
What kit did you purchase?

WEIMWGN

I bought the Melling K417.

WEIMWGN

II tried re installing the OEM pump and it binds up as well. I even got a new timing cover and the pump in that one was hard to turn also.

JFish'n

I see two pumps from Melling.
Standard that's "K417"
then the "+.015 thickness" that's K417-OS
Make sure you don't have that one.

There is a process that's supposed to be followed, measuring the pump thickness and how far back it sits in the front cover.

INSPECTION

1. Inspect mating surface of the chain case cover. Surface should be smooth. Replace cover if scratched or grooved.
2. Lay a straightedge across the pump cover surface . If a 0.025 mm (0.001 in.) feeler gauge can be inserted between cover and straight edge, cover should be replaced.
3. Measure thickness and diameter of outer rotor. If outer rotor thickness measures 7.64 mm (0.301 in.) or less , or if the diameter is 79.95 mm (3.148 in.) or less, replace outer rotor.
4. If inner rotor thickness measures 7.64 mm (0.301 in.) or less, replace inner rotor .
5. Install outer rotor into chain case cover. Press rotor to one side with fingers and measure clearance between rotor and chain case cover . If measurement is 0.39 mm (0.015 in.) or more, replace chain case cover, only if outer rotor is in specification.
6. Install inner rotor into chain case cover. If clearance between inner and outer rotors is 0.203 mm (0.008 in.) or more, replace both rotors.
7. Place a straightedge across the face of the chain case cover, between bolt holes. If a feeler gauge of 0.10 mm (0.004 in.) or more can be inserted between rotors and the straightedge, replace pump assembly . ONLY if rotors are in specs.
8. Remove oil pressure relief valve. (Refer to 9 - ENGINE/LUBRICATION/OIL PRESSURE RELIEF VALVE - REMOVAL)
9. Inspect oil pressure relief valve and bore. Inspect for scoring, pitting and free valve operation in bore . Small marks may be removed with 400-grit wet or dry sandpaper.
10. The relief valve spring has a free length of approximately 49.5 mm (1.95 inches) it should test between 19.5 and 20.5 pounds when compressed to 34 mm (1-11/32 inches). Replace spring that fails to meet specifications.
11. If oil pressure is low and pump is within specifications, inspect for worn engine bearings or other reasons for oil pressure loss.

JFish'n

Also, if you happen to have a spare cover (assuming you didn't return the new one), I'm in need of one that didn't pump metal through the oil system.

WEIMWGN

I did all the measuring on the new and old oil pumps. All four rotors are at either 309 or 310. So they're well within spec. I also laid a straightedge across the timing cover and there is no sign of it being warped.
I did get another cover from somebody that was doing an engine swap but he needed mine so he could return his motor to get his core charge back.