The Imp Site

Water pump

Date: Mon, 15 Jun 1998 07:03:00 +0100 (WET DST)
From: Gary Harding
Subject: Water pump

All,
Some months ago we had a discussion on water pumps and the replacement of the bearing before the seals failed. I suggested that the old seals could be reused if the coolant leak wasn't too bad by simply replacing the bearings. Well following my own advice I have recently carried out this task on my Sunbeam Sport which is driven very hard and covers around 300 miles per week. The water pump was a new Q+H component with 42,000 miles from new and good antifreeze and corrosion inhibitor were used at all times.. The story goes like this.

1. A small leak develops from the water pump, progressingly getting worse but never too bad. (Small puddle around 70mm in diameter on the road after an overnight lay-up.
2. After a 1000 miles of this leak I repaired the water pump by replacing the bearings and cleaning up a very small amount of corrosion on the seal face of the impeller (the cause of the leak?).
3. Refit the water pump.
   The water pump continues to leak, but only as it rotates!!
4. Run the car for 200 miles with the radiator cap removed to stop coolant system pressure build up (small leak still present).
5. At 300 miles the leak with the radiator cap removed has stopped.
   Leak still present with the radiator cap fitted. Continue to run the car with the radiator cap removed.
6. At 1200 miles the system no longer leaks with the radiator cap fitted and the cooling system operates at it should.

So what do we learn from this? Any other comments?

It is possible to rebuild a water pump successfully - this is the first time I've been successful?
The seals need to be 'run-in'?
Be patient?

Gary Harding

Date: Mon, 15 Jun 1998 02:36:10 -0400 (EDT) To: imps@coollist.com From: Bert Clewits Subject: Re: Water pump Reply-To: imps@coollist.com

Hi Gary,

Your story sounds very familiar, we have rebuilt several waterpumps, some successful, some not.
The unsuccessful ones which leaked water have been dismantled again and sometimes we found litle cracks in the surface of the carbon seal maybe this was due to the rebuilt.
Some rebuilt ones were leaking a little bit but after a run of about 100km they were ok, no leaks while running or while standing, no waterloss.
Sometimes the waterloss can be due to the fact that the impellors surface is not smooth enough and little pitted holes must fill themselves with the carbon of the carbon seal.
Other failures were:

• pullies which did not fit well on the shaft and ruined the shaft and peg.
• A suddenly stuck bearing.
• Shafts which were bend, pullies not straight.

Hope this helps

Bert

Date: Tue, 16 Jun 1998 16:50:20 +0100 (WET DST)
From: Gary and Carol Henderson
Subject: RE: Water pump

Hi Gary & all

Before rebuilding the Q-H pump, have a look at a REAL one (of the later style, which looks identical to the Q-H externally.) You will soon see why the real one lasted ten times longer before the bearings died; boring the Q-H housing to duplicate the deep water-grooves of the c.1970 Rootes pump should greatly enhance the life.

Your running-in is of course a good idea anyway.

Cheers

GaryH