Should the Water Pump Be Changed with the Cambelt?

If your car is due a cambelt (timing belt) change, you will almost certainly be asked whether you want the water pump replaced at the same time. It can sound like an upsell. On most cars it is not, and here is why.

Why the two jobs go together

On a large number of engines, the water pump is driven by the cambelt. The belt runs round the crankshaft, the camshafts and the water pump pulley, so the pump sits right behind the timing covers.

That means two things:

• To get at the water pump, you have to take the cambelt off. Most of the cost of a water pump replacement on these engines is the labour of getting to it, which is the same labour as a cambelt change.
• A water pump failure can take the cambelt with it. Pumps fail in two ways: the bearing wears and the pulley starts to wobble or seize, or the seal starts to leak coolant. A wobbling pulley pulls the belt out of line; a seized one can strip its teeth; and leaking coolant soaks the belt and breaks it down. Any of those can snap the belt.

On most engines a snapped cambelt means the pistons hit the valves, and the repair bill runs into four figures, sometimes more than the car is worth. So the question is really: do you want to pay to have the belt off again in a year or two if the old pump fails, or replace it now while everything is already apart?

How often should the cambelt and water pump be replaced?

The interval is set by the manufacturer and varies a lot from car to car. Many fall somewhere between 60,000 and 100,000 miles, or every five to ten years, whichever comes first. The age limit matters: rubber belts deteriorate even if the car does very few miles, which is common for second cars and Island runabouts.

There is not usually a separate interval for the water pump on these engines. It is simply replaced each time the belt is. We look up the exact interval for your engine from the registration.

What a full cambelt job should include

• The cambelt itself.
• The tensioner and idler pulleys. Their bearings wear at the same rate as the belt, and a failed tensioner snaps belts just as surely as an old belt does. A good timing kit includes them.
• The water pump, if it is driven by the belt.
• Fresh coolant, because the system has to be drained to change the pump.
• Often the auxiliary (drive) belt too, as it usually has to come off anyway.

Ask what is in the quote. A cheap price that covers only the belt is not the same job.

When the water pump does not need changing

• Cars with a timing chain rather than a belt. Many newer engines use a chain, which does not have a set replacement interval. See our post on cambelts and timing chains.
• Engines where the pump is driven by the auxiliary belt instead, or is electric. Some hybrids and newer engines have electric water pumps.
• If the pump was replaced recently, for example after a failure a few thousand miles ago, and you have the paperwork to show it.

In those cases we will tell you, rather than quote for a part you do not need.

Signs your water pump is already on its way out

• Coolant level dropping, or a sweet smell after a drive.
• Crusty pink, green or blue deposits, or drips, around the front of the engine.
• A whine, grind or rumble from the front of the engine that changes with revs.
• The temperature gauge creeping higher than usual.

If you notice any of those and your cambelt is anywhere near due, get it looked at before it fails at the side of the road.

Frequently asked questions

Do I have to replace the water pump with the cambelt?

You do not have to, but on engines where the belt drives the pump it is strongly recommended, because the labour is shared and a pump failure can destroy the new belt.

How much extra does the water pump add?

Usually much less than you might expect, because most of the labour is already being paid for with the belt. Ask us to quote it both ways, with and without the pump, and you can see the difference for yourself. Our timing belt costs post gives typical prices.

I don’t know when my cambelt was last changed. What should I do?

Check the service history and any old invoices first. If there is no record, treat it as due. It is far cheaper than finding out the hard way.

Does a cambelt change need coolant?

If the water pump is being changed, yes: the system has to be drained and refilled with the correct coolant, then bled of air.

Book a cambelt and water pump change

Book online at bestgarages.co.uk or call your nearest branch for a quote: Newport on 01983 533360, Lymington on 01590 674776, or Fordingbridge on 01425 561504.