Help!! Water pump or alternator?

[dingsdale]

Car in question is a '99 Toledo TDI 110 with 101,000 miles on the clock. Was driving it for a few hours on the motorway yesterday and it was fine. This morning when i drove off, the alternator warning light started flashing on and off intermittently and the temperature rose very quickly and got pretty hot (towards the 110 mark). But it stopped after about 10 minutes of driving. After letting it cool down the same thing happened again
There is a rattly/squeeky noise from either the alternator or water pump. The belt is in good condition, well tensioned and definetely not slipping. Is there any way to tell which is making the noise? Any advice would be hugely appreciated!

 

[devonutopia]

How's the coolant levels? What light is the alternator light? Was it the glowplug / coil light flashing? I can't see the alternator being at fault as thats simply a voltage thing, but something causing coolant leakage is more likely.

 

[dingsdale]

Coolant levels are perfect and the water is clean. It was the alternator light, wasnt on permanently, just flashing occasionally. When I had it sitting on the drive, it seemed to come on if i revved it to about 3000 and dropped it down, the light came on when the revs dropped.
I'm fairly sure its something mechanically wrong with the alternator or water pump, which in turn is causing the other to not work properly. The problem is, which one, and how to tell...

 

[Deleted member 5241]

Can you remove the drive belt and see if there is any play in the driven end of the water pump or alternator? My "guess" would be water pump as the alternator has a series of bearings to take sideways loads placed on it by the drive belt.

If either has gone then they will be rotating off centre which will cause the drive belt to slacken off, this will cause the waterpump not to pump coolant round the engine as efficiently as it should and therefore show as overheating. At the same time, the alternator will not be driven correctly, the output from the diode pack will drop and the light will come on.

 

[techie]

The water pump is cambelt driven so there isnt a direct connection between both.

 

[dingsdale]

Definetely not cambelt driven mate - unless the alternator is cambelt driven too! The car manual even says so - you must be thinking of a different engine (its a mk2 toledo)

Luckily i've managed to find a car I can borrow for the week, so I can take it to the garage at the weekend. I'm hoping its the water pump as prices for them seem to be about 20~30 quid, and alternators are closer to 100!

 

[Muttley]

dingsdale wrote

Car in question is a '99 Toledo TDI 110 with 101,000 miles on the clock. Was driving it for a few hours on the motorway yesterday and it was fine. This morning when i drove off, the alternator warning light started flashing on and off intermittently and the temperature rose very quickly and got pretty hot (towards the 110 mark). But it stopped after about 10 minutes of driving. After letting it cool down the same thing happened again
There is a rattly/squeeky noise from either the alternator or water pump. The belt is in good condition, well tensioned and definetely not slipping. Is there any way to tell which is making the noise? Any advice would be hugely appreciated!

techie wrote

The water pump is cambelt driven so there isnt a direct connection between both.

dingsdale wrote

Definetely not cambelt driven mate - unless the alternator is cambelt driven too! The car manual even says so - you must be thinking of a different engine (its a mk2 toledo)

Luckily i've managed to find a car I can borrow for the week, so I can take it to the garage at the weekend. I'm hoping its the water pump as prices for them seem to be about 20~30 quid, and alternators are closer to 100!


Sorry, but techie is correct. The water pump on the TDI 110 engine is driven by the toothed belt which also drives the camshaft and the injection pump. The external v-belt drives the alternator, airconditioning compressor (if you have one) and the power steering pump.

I think you have two unrelated problems. The cooling problem has all the hallmarks of water pump failure, a well-known problem with these engines as a lot of them had plastic impellers fitted as standard, and they eventually break up. The problem with replacing the water pump is not the cost of the pump but the amount of work needed to replace it. If you haven't had the cambelt replaced yet, then you should do so at the same time; even if you have had it changed once, it will be due again at 120K miles so it would be best to change it now along with the water pump. Make sure you get a metal-bladed replacement pump.

The alternator issue is more difficult to diagnose. If it is still the original alternator, I'd check the brushes first, they must be getting close to wearing out by now, and it's an easy item to check and replace. New brushes are 12mm long, if they are worn to less than 6mm then replace them.

 

[dingsdale]

That looks like a water pump to me - and its driven by a non toothed, ribbed fanbelt. The car manual also says it is fanbelt driven - talks about not driving the car if the alternator light comes on because it means the water pump also isnt running

 

[techie]

OK that there is a PAS pump.

I've changed a few in my time, trust me.

 

[Deleted member 5241]

Can you remove the drive belt and see if there is any play in the driven end of the water pump or alternator? My "guess" would be water pump as the alternator has a series of bearings to take sideways loads placed on it by the drive belt.

If either has gone then they will be rotating off centre which will cause the drive belt to slacken off, this will cause the waterpump not to pump coolant round the engine as efficiently as it should and therefore show as overheating. At the same time, the alternator will not be driven correctly, the output from the diode pack will drop and the light will come on.

Oh bugger, I'm not used to these new fangled oil fuelled engines My other 48 cars have all been petrol jobbers.

 

[dingsdale]

Fair enough then, just checked what i thought was a water pipe and it does indeed connect to the PAS resevoir....

So, just been out to drive the car again and it was similar to last time, the rattly squeeky noise and the flickering alternator light. The temperature guage sat at the bottom for a few miles then rose to 90 and stayed there, just like it should do. I think the temperature problem was a bit of a red herring, it was quite warm yesterday and i had been driving in traffic. It didnt get hot enough for any warning lights to come on either...

So its looking like its almost certainly the alternator then? The only odd thing is that once the engine got up to temperature, the noise and flickering light stopped completely......

 

[cheshire cat]

check the brushes for length and clean away all the carbon crud that mat be making them sticky, probably just one of the two

 

[TornadoRed]

There is a rattly/squeeky noise from either the alternator or water pump.

Muttley has the right info, I think.

The bearings in the alternator pulley squeak or "chirp" when they are failing. The pulley itself can be replaced -- it is not necessary to replace the alternator itself.

When a waterpump fails, it's usually silent. The impeller just stops spinning, even though the shaft is still turning.

If you need a new waterpump, go ahead and replace the timing belt and other TB components at the same time (tensioner, rollers, all single-use bolts, etc). The parts are relatively cheap, while the labor is about the same whether you do the complete job or only half.