If the oil pump parts are worn out, the pressure in the lubrication system decreases and noise appears

When disassembling the pump, check the elasticity of the pressure reducing valve spring.

The elasticity of a spring is considered sufficient if it is necessary to apply a force of (54±2.45) N [(5.5±0.25) kgf] to compress it up to 24 mm in height].

Oil pump repair usually consists of grinding the ends of the covers, replacing gears and gaskets.

UAZ-3151 oil pump drive

Fig. 1. Oil pump drive

When disassembling the pump, pre-drill the riveted head of the bushing fastening pin 2 (see Fig. 1) on its shaft 1, knock out the pin, remove the bushing and the pump cover.

After that, remove the pump roller together with the drive gear from the housing towards its cover.

In case of disassembly of the drive gear and roller, drill the pin with a 3 mm drill.

Replace the drive and driven gears with chipped teeth, as well as with noticeable wear on the surface of the teeth.

The drive and driven gears installed in the pump housing should be easily rotated by hand by the drive shaft.

If there is a significant (more than 0.05 mm) wear from the ends of the gears on the inner plane of the cover, grind it.

Paronite gaskets 0.3–0.4 mm thick are installed between the cover, plate and pump housing.

The use of shellac, paint or other sealants when installing the gasket, as well as the installation of a thicker gasket, is not allowed, as this causes a decrease in pump flow.

Assemble the pump with the following in mind:

Mounting the bushing on the oil pump shaft

Fig. 2. Mounting the bushing on the oil pump shaft

1. Press the sleeve onto the drive roller, keeping the dimension between the end of the drive shaft and the end of the sleeve 8 mm (Fig. 2). In this case, the gap between the pump housing and the other end of the sleeve must be at least 0.5 mm.

2. Drill a hole with a diameter of 4 +0.03–0.05 mm in the drive roller and in the bushing, keeping the size (20 ± 0.25) mm.

3. Countersink the hole on both sides to a depth of 0.5 mm at an angle of 90°, press a pin with a diameter of 4–0.048 mm and a length of 19 mm into it and rivet it from both sides.

If the pump cannot be repaired, replace it with a new one.

Install the oil pump drive and the ignition distributor on the block in the following order:

1. Turn out the spark plug of the first cylinder.

2. Install a compression tester in the spark plug hole and turn the crankshaft with the crank until the arrow starts to move. This will happen at the beginning of the compression stroke in the first cylinder.

You can plug the candle hole with a paper wad or thumb. In this case, during the compression stroke, the wad will pop out or air will be felt from under the finger.

3. After making sure that the compression has begun, carefully turn the crankshaft until the hole on the rim of the crankshaft pulley matches the pointer (pin) on the timing gear cover.

4. Turn the drive shaft so that the slot on its end for the distributor awl is located as shown in fig. 1 B, and turn the oil pump roller with a screwdriver to the position shown in fig. 1 V.

5. Carefully, without touching the gear against the walls of the block, insert the drive into the block.

After the drive is in place, its shaft should be in the position shown in fig. 1 A.

Oil pump centering tool

Fig. 3. Drift for centering the oil pump

To reduce wear on the drive pivot joints, mount the pump in line with the drive bore. To do this, use a mandrel (Fig. 3), which fits snugly into the drive hole in the block and has a cylindrical shank with a diameter of 13 mm.

Center the pump on the shank of the mandrel and secure in this position.