520i water pump mystery

Greetings all.

After having just fitted a new water pump to my 1984 520i, we noticed on the old water pump, a spring, loosely fitting around a steel rod which looks a bit like a leather punch, both measuring 6cm long. On the water pump near the top, there is a groove which one end of this spring/rod cradles into. The other end pushes firmly against another part of the motor next to the water pump - you guessed it, 6 cm away. Neither ends of the rod or spring are held with any fasteners but the tight fit just seems to hold it there, leaning downwards on a 45 degree angle from the pump, and has done so through it's years of travel on some pretty rough roads - running over potholes, unseen speed humps, and the occasional cat (NO -- JUST KIDDING !!)

Anyway, after skimming through various forums and info I read about a spring which the author called a tension rod; then a stabiliser spring; finally something was mentioned about an anti-knock device which was described as a springy thing.

Can anyone settle our curiousity please? The new water pump did not come with any such accessories so we'd like to know if this is a neccessity which I've a feeling it is.

Have a great day all.

Cheers
MJ

If your car has a timing belt, then that is the spring for keeping the belt under tension. Your model engine never made it to the US so I'm not familiar with it. The 528e did had a belt (M20 family engine) which needs to be changed every 60,000 miles or 5 years. Ifyou don't know it's age change it immediately! If the belt breaks the pistons and the valves will have some 'intimate contact' that nobody wants to happen! (Ask me how I know!)