Water pump reliability

[mannyo]

Here is an interesting scenario.

My 3.7 D3 is currently away having its cambelt and other parts replaced. However, they have just called to tell me that the water pump bolts are well and truly seized in the block. The current pump is fine and shows no sign of leaks, and the mechanic said the bearing are all running fine.

He cannot guarantee being able to remove the bolts without stripping the head off the bolt, the thread off the bolt or worse the thread in the block.

So they are completing the job minus water pump change, the existing one being left in situ.

So they are changing the belt, thermostat, tensioners, and the aux belt only.

He said the car is in a right state behind the covers, its all in bits now bar the water pump. Its taken them 4 hours just to strip the car to the assembly stage because of the state of the bolts.

Any horror stories of water pump failures?.

[mannyo]

I have the car back, spoke to the mechanic who did the work as he dropped the car off. The bolts are well and truly going nowhere, the only way they are coming out is angle grind the heads off, then drill and retap the engine. Pretty major stuff, and as they would use a third party to remove the old bolts and tap the engine, its not going to be cheap.

[ainarssems]

Depends on each individual case, look ad Dezzy- his A8 is 90k miles overdue for cambelt change so I assume water pump has not been changed.

2 main failures on waterpump are bearing wearing out or seal wearing out. On some cars pump has plastic impeller which hardens and cracks over time. Using proper cooling fluid and changing it regularly helps to condition seal and impeller, lubricates seal and prevents corrosion.

Most of seal failures are caused buy driving with water or not changing coolant. Bearings in pump are pretty good as well and fail either when seal start leaking and coolant/water gets in bearing or when grease dries out/hardens and stops lubricating it.

[Dezzy]

It was the same when i changed the thermostat too tight to undo the bolts, so i had to shock them by using a small cold chisel.
I'd be looking to use a stud extractor if the head shears off rather than a re-tapping in the first instance.

[Delboy]

I have yet to see a bolt that can't be removed from an engine with patience.

Repeated cycles of heat with a brazing torch, cooling, penetrating oil and battering with a hammer will get them on the move.

If your mechanic doesn't have the skills or equipment to do it then I would recommend you find one who does.

[mannyo]

There is still the possibility that this is the original water pump from 2004. When the cambelt was replaced previously by Lancaster Audi, Manchester the invoice simply states replace Cambelt and Ancillaries. no mention of what those ancillaries were. The bolts themselves are not that large, and the mechanic is the same one that did all the work on my D2 and is ex Audi.

[Adrian E]

I'm with delboy and others on this - you can usually shift anything with the right tools and a bit of patience.

I know the guy who looks after my S8 has a kit for freezing fittings that are seized as it basically shrinks them relative to the surrounding area and can be very effective at freeing up seized bolts on things like suspension arms. Obvious caveat to that is you can't get to the other side of the water pump bolts to apply the gas so you have to work via heat/cold soaking which might not be as effective.

Surface drive sockets also help a lot if they start to round off.

On the upside my cambelt was done for the 1st time in 2010 on my 2002 car at 36k miles. As far as I've been able to establish the water pump wasn't changed, although there's a possibility it was and they just forgot to invoice for it as it came to £2400 all in! Assuming it wasn't done there have been no ill effects but I will most certainly have it changed as a precaution when the belt is next due, unless there's obvious evidence that the part fitted is much newer than the car.

[notorious]

Doing nothing here is 'kicking the can down the road'. Consequences of failed pump are dire.
If you plan to keep the car, I'd go to proper place to fix the problem now.