Oil Pump - Strip Down and Overhaul

With the sump off, the oil pump was removed. As it is such a crucial part of the engine, it's worth giving it a service while you can get at it.

As well as reading the workshop manual (Manual 518, Operation DX. 220-3), I also watched these videos from "DSSMPassion Citroen" several times over:

strip down - https://www.youtube.com/watch?v=4Lz1XY3812Y

and reassembly: https://www.youtube.com/watch?v=UQ5AHbpn2js&t=142s.

The main aim was to make sure the whole thing operated smoothly and was not gummed up with burnt oil and sludge. I also planned to replace the two springs in the valves.

The Bypass Valve and Spring is on the 'Cup'.......

.......The Pressure Control Valve is on the Pump Part

The first job was to get the pump out of the engine block. Even with the locking screw (located on the tower) removed, pumps can still prove stubborn. With a little use of some Plus Gas and some gentle wiggling and rocking, the oil pump slowly began to yield and in this way was 'corkscrewed' out. 

Removing the bracket, the pump body was split into it's two parts. The 'Cup' part actually faces down in the engine and is the part that you fit your oil filter in to.

The Oil Pump Is Located In The Sump

Oil Pump Filter Housing - the Bit You See When You Change A Filter

 Splitting the pump gave access to the pumping parts. The engine cam shaft operates the drive pinion which turns the spindle. The inner, four pointed pump pinion rotates within the outer, loose pinion - which itself is free to rotate. This creates the pumping action. 

Ingenious Pumping Pinions

The loose pinion was easily removed. However removing the pump pinion that it fits around meant releasing the pump spindle from the tower. This is done by pulling the drive pinion off the other end of the spindle. However my three-legged puller was not up to the job and there was a lot of cursing as the puller's legs were too chunky to get any grip under the teeth of the pinion. In the end I asked Doug up at the barn to press the shaft through using his hydraulic press. If I had to do this again I would try and find a suitable ball joint splitter.

Pinion Was Pulled Off - 11 July 2017

With that drive pinion removed the spindle was pushed through the body, allowing the pump pinion to be pushed back along the shaft a little. The spindle was quite sticky and grubby at the drive pinion end and didn't want to come out too easily. 

Pushing the pump pinion back revealed the flat washer/ keeper and half-cotters that had been holding the pump pinion in place. Careful you don't lose those cotters!

Cotters and Keeper Removed

The pump was just about disassembled now.

Main Parts of the Oil Pump

With the body split and the spindle removed, everything was thoroughly cleaned in Jizer, rinsed-off, and dried with compressed air. As the pump was going to back in the sump, I didn't spend too much time on cleaning the body,  but all the moving parts were inspected and cleaned up and the spindle was given a gentle rub over with wet and dry to polish it. Using a small piece of safety glass (courtesy of a fridge at my local recycling centre) and some wet and dry squirted with Plus Gas, the flat sides of the pump pinions were re-surfaced, as were the two mating faces of the pump body halves.

The pinions and spindle were generously oiled for reassembly. The drive pinion on the spindle end was a very tight fit and took some heavy blows with a hammer to start to get it on. Luckily the pump end of the body provided a fairly flat and stable base, but you need to remember that the pump body is alloy and at risk of distortion. Any damage to the pump end of the body may mean that the loose pinion binds and does not rotate freely.

I found the DSSMPassion video confusing in terms of the float that the drive pinion should have (the 2min 20 second mark on the rebuild video refers). The figure given in step 9 of Operation DX. 220-3 of Manual 518 states the gap should be between 0.4mm and 0.5mm.

The oil filter body and main pump parts were then bolted back together. The pistons and bores were cleaned before new springs from Citroen Classics were fitted.

Replacing the Vavle Springs

Everything was given a last generous squirt of fresh engine oil.