Water pump S2 - does it fail?

[Frazerb]

Hi,

Can anyone tell me the symptons of a failing water pump. I have the following - car runs great for weeks then suddenly leaks a load of water from the pump side of the engine. Top it up and everything seems ok until the next time.

While running she runs on the first guage mark - if any hotter the fans kick in and cools.

Do you think the pump is not working and occassionally just purges the water trying to get past it. Are the S2's known for the pump failing?

Any help really appreciated.

Thanks...FB

 

[TTM]

A technical report from Porsche says a minor leak should not cause concern and is not cause for replacement, but if it leaks a lot there may well be an issue with it.

 

[sawood12]

Your water pump is crucial. If it fails or stops functioning for some reason your water temp gauge will rise very very quickly and will keep on rising till your engine stops....permanently. You will also likely get a warning light on the dash. The trick is to spot this and pull over to the side of the road and switch the engine off as soon as you can.

I had these symptoms on a previous Golf on which, for some ridiculous reason I cannot fathom, the water pump is driven by the fan belt and not the timing belt as it usually is. My fan belt broke off and immediately a light came on in the dash which got my attention and luckily I saw my temp needle rising so I pulled up and got the RAC out. Unfortunately he didn't have a fan belt [] in his van so I had to be towed home.

My temp gauge rarely gets much above the first mark unless i'm sat in traffic on a hot day with the A/C on. and even then it hardly gets past halfway between the two marks.

 

[Indi9xx]

Does it leak with the engine running or when you shut down?

Where exactly is the water leaking from? almost dead central in front of the engine?

Are you sure its not comming from the overflow from the header tank and then running along the undertray? because its more likely to be caused by a bad pressure cap than the pump.

I recommend 944 water pumps are changed about every 80,000 miles, or every 3rd cam belt change, as I have never seen one fail at under this mileage, but have seen plenty fail on the 3rd belt if not changed.. Typically the water pump when it fails often becomes noisy, seizes up all together, or leaks constantly or all of these symptoms, but rarely leaks occasionally.

 

[morris944s2john]

Thats interesting- do you think I should change the water pump on mine?? The car has done 168,000 miles and AFAIK the water pump is the original.

 

[pal944]

I changed the water pump in november on my s2 because after i put new belts on a couple of weeks later the water pump pulley started to fail, it was the original water pump at about 175,000 miles !!!

 

[Frazerb]

Jon,

It leaks when running and when off but not all the time. As I said it can go for a couple of months with no leaking. The leak does seem to be from the pump side of the engine, not the header tank for sure. There is no noise from the pump and at all times by temp guage is where it should be.

I am going to have to get it checked I think. My local garage has recomended a pressure test - do you think this would be a good idea?
I am hoping it is a cracked pipe or clip or something and maybe when really warm it leaks??? I'll let you know but thanks for the comments meanwhile.

Thanks....FB

 

[JayKayEm]

ORIGINAL: Frazerb
I am going to have to get it checked I think. My local garage has recomended a pressure test - do you think this would be a good idea?

No harm in a pressure test. It looks like a bicycle pump (with an integral pressure gauge) that screws onto the expansion tank. Just make sure that when some 'trained technician' starts pumping, they do not exceed the blow-off value of your expansion tank cap.

 

[TTM]

ORIGINAL: morris944s2john
Thats interesting- do you think I should change the water pump on mine?? The car has done 168,000 miles and AFAIK the water pump is the original.

My turbo is in the same boat and I will replace the WP as soon as possible. I do not want to tempt the devil any further.

 

[peanut]

the thing about waterpumps is they will last a very long time indeed if left alone. As soon as you put a new belt on, the pump's pulley bearing will rapidly fail due to the additional stress applied by a new belt which is tighter than the old belt.
If you are replacing your belts and not the pump I would recommend re-using the old belt if it is sound and definitly don't over-tighten .

If a waterpump leaks it will do so steadily gradually increasing with time they do not let out a lot of water then none. That has to be the expansion tank cap lifting due to excess pressure in the coolant system .

You need to investigate this because it could be the first sign of other problems typically combustion gases in the coolant system or problems with thermostat, fans,senders, sticking diverter valves, blocked rad or collapsed hoses.

if you had cracked or split pipes it would leak all the time spectactually . The coolant system is highly pressurized when hot (expanding gases) and would force all your coolant out in minutes. My guess is your engine is over-heating after switch off due to your electric fans not cooling adequately. Engines initially get much hotter when you turn them off before they start to cool.

 

[sawood12]

Sorry Peanut I have to disagree - i'd never ever refit the old belt. I'd always replace the water pump. Rubber belts do stretch, but they stretch initally, shortly after installation (which is why you should have the tension checked after about 1k miles post replacement) but after that initial stretch they will not stretch any more. The rubber of the belt is not taking the tension - it is the chord inside the rubber, so after the initial stretch it will not stretch any further and tension will be retained. Over time the rubber degrades and therefore the internal chord is exposed to higher stresses which leads to its ulimate failure unless replaced - so never replace with an old belt.

When I had my belt replaced I took the car in 1kmiles after installation for a tension check. The belt required retensioning. About 10k miles after that I got the tension rechecked and it was spot on.

 

[Indi9xx]

The car has done 168,000 miles and AFAIK the water pump is the original

Mark my words, that water pump is living on borrowed time.

I follow the recommendation of changing the pump on every other belt change, as a 3rd belt often causes the pump to leak, often within a couple of thousand miles of the new belt being fitted... But at the end of the life of the 3rd belt, the mileage could often be at around 120,000 miles, which is approaching the point where the pumps can seize up, causing the belt to burn out and break.

In the case of this car in quesiton (frazerB), I suspect the problem is probably a hose.

In particular, have you had your oil filter changed recently? The reason for asking, is its often easy to disturb or damage the waterpump-to-heater rail hose, which is a small right angle hose next to the oil filter... if this is damaged or disturbed, it tends to leak down the back of the pump, and makes it seem almost like the water is exiting the engine behind the cam belt cover.

 

[peanut]

ORIGINAL: sawood12

Sorry Peanut I have to disagree - i'd never ever refit the old belt. I'd always replace the water pump.

well I did say `if you are NOT replacing the water pump reuse the old belt with the old waterpump
. If you are fitting a new pump then naturally you would fit a new belt.

If the old belt is knackered then again obviously you need to use a bit of commensense.

If it has worked ok for some time and is in good order there is absolutly no reason why your existing belt would not continue to be serviceable for many thousands of miles to come. The existing belt doesn't just fail to be servicable on the day you replace your cambelt .
Same goes for the waterpump. I am happy to accept the recommendations of Porsche ,however If you can afford to replace the pump every time you replace the belts then go for it.