Sunday 4 February 2018

Engine Rebuild (Part 8) - Water Pump and Housing

In 2014, when I was planning to get my DS running again, I thought back to the last time I had seen it running: probably back in 2002 and on one of the short trips between barns at the farm. One thing I remembered about that start-up, was that there was a dribble of water from a small hole on top of the water pump shaft.
'Breather' Hole on Water Pump
Research back at that time had told me that it indicated that the ceramic seal on the pump shaft had been breached - probably because the car had sat idle for a long time. There is a small chamber into which any water that leaks past the seal, can escape to. There is then a drain hole on the bottom. The hole on the top is an air vent to allow air in to replace escaping water. leaking water is a pre-cursor of impending bearing failure. In my case the bottom hole was silted up (not a good sign anyway) - so water bubbled out of the top hole.....

If the seal leaked with the car parked up between 2001 and 2002, what kind of state was it going to be in having been laid up between 2002 and 2014! I bought a new replacement water pump ready to fit.

As anticipated, removing the water pump and housing as part of the engine strip down revealed lots of silt and rust......
Water Pump Housing On My DS - 6 August 2015

Water Pump Housing Off My DS - 28 May 2017
Now 2017, and with my cylinder head recently fitted, I turned my attention back to fitting the water pump. The new pump looked lovely, but sandwiched between my new pump and the vapour blasted cylinder head would be a grubby water pump back housing. Shiny replacements were very expensive and could only be considered a luxury. They also seemed to have a different shaped mount for the centrifugal regulator and I couldn't risk a replacement not being suitable. 
My Mount Point for Centrifugal Regulator
Later Style Mount Point?
I decided I would re-use my original Citroen one, but the thought of a grubby 'sandwich' on my rebuilt engine was enough to convince me to get it vapour blasted.

The studs of various lengths for mounting the water pump were removed, as was the 'boomerang' bracket for lifting the engine, and the remains of the gaskets were scraped off. The water temperature sender was unbolted. these have a reputation for being tough to remove but it came off pretty easily and without damaging itself or the pump housing. The housing was sent for blasting. The results were great, other than they highlighted the pitting where the top radiator hose fits. No matter, refitting the hose would cover those again.

I struggled for a while to match the long water pump studs to their correct locations. Putting them back where they'd been removed-from looked odd, as some of the lengths were uneven?
Water Pump Studs - 28 May 2017
Details of the replacements that you could buy didn't help as they didn't correspond to the lengths of the ones I'd removed! Also, one of the five after-market studs you could buy was an M9? All mine were definitely M8s. A quick check of the parts books confirmed that later cars had one M9 stud out of the five and also that the lengths had changed several time. I had to go right back to a parts book from 1966 to confirm mine were the right lengths for their time.

Parts books didn't help with telling me which stud went in which hole though. Some studs not only hold the water pump on, but also hold the bracing bars for the alternator and centurial regulator. Two of the studs also hold the 'boomerang' bar used for lifting the engine. Only by looking at the lengths of the threaded parts and working out where these bracing bars went was I able to work out which stud went where. Phew!

With the studs replaced another hurdle.... A trial fit of the new water pump on the studs showed it had a lot of free play: the holes through it were considerably larger than the diameter of my M8 studs. A refit of my old, dead pump showed that it didn't exhibit this free play. I was concerned about the free play because it meant there was a lot of sideways movement. With the pulley belts fitted and under load, would they pull the pump sideways and break the seal - allowing coolant to leak? I got around this by putting some heat shrink over each stud. It took up the free play and, being heat shrink, should be able to cope with temperatures under the bonnet.
Water Pump Studs With Heatshrink - 28 January 2018
Manual 814 says to fit the gasket dry but I decided to include a thin smear of Hylomar Blue - partly out of concern for those studs in over-sized holes. The final hurdle was how tight to tighten the bolts holding the water pump on? Advice from the CCC forum was about 22lbs/ft BUT advice from Aussie Frogs was that this was too much. In the end it was irrelevant as I found that the pulley wheel got in the way of the end of the studs - meaning I couldn't fit a torque wrench anyway.

With the pump back on the car, I refitted the Jaeger temperature sender that I had cleaned up.

I haven't done it yet, but I will re-make the wire that attaches from the sender to the main loom. 





2 comments:

  1. HI Paul, nice pics of the resto project. I also have a an ID 21 Familliale that has been sitting a long time, and when started hit has a lot of noise from the water pump so I want to rebuild it. How did you get the double groove pulley off the pump shaft?

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    1. Hi. Glad you like the pics. The pulley is not designed to come off. It is 'spun on' - which i think means the pulley is rotated (to shape it) and pressed onto the rotating shaft until it 'fuses'. They can be removed by pressing or pulling the pulley but they are brittle and break. If you remove it, the problem becomes one of finding new bearings and seals that fit. For these reasons, most people simply replace the whole waterpump. Compared to some other Ds parts, they are relatively cheap and widely available.

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