What will happen if water pump fails

[flyingmachine]

How will water pump fail? Propeller breaks into pieces inside or what? And how do you know if it fails?

If propeller breaks inside, what will happen? Large pressure inside radiator and then blow expansion tank and head gasket?

Some people say it will introduce a coolant leak if water pump fails. Why?

I'm trying to gauge the need of replacing my water pump as preventive measure. I currently have about 70K.

Thanks!

[mrbmwx5]

If it din't break DON'T fix it.

[Big "J"]

A lot of other BMW owners do replace them for the very reason that they can and will fail at some point, unexpectedly. The OEM pump has a plastic impeller and will start to slip on the shaft and lose circulation. I don't think they disintegrate or anything like that. New pumps are made with stainless steel impellers and are better. I have 84K on mine and plan do get it done very soon too.

[FSETH]

Some people will change it at your mileage as preventative maintenance and others wont. From what I have heard, it is the plastic impellers that break. Mine gave out at about 80k.

If you just wait for it to break, you have to be careful that you catch it early. In other words, you only have a short amount of time to notice that it broke and pull over before the car overheats. If you drive too long after it breaks, you can do major engine damage. I don't think it is always very noticeable when it breaks, besides looking at the engine temp. gauge/light.

[lo_jack]

Your water temp gauge will go up, you will most likely not notice until it is too late, and you will damage your bearings and or blow the head gasket, among other things.

By the time the temp gauge goes up for you to notice, the cylinder head temp will be much higher, and it may be too late. I put a scanner on my car the other day and it was reading 212*F when the needle was pegged to normal, dead center. I would not like to know what the temp was when the gauge actually gets to red. I think the engine would burn up before then.

Due to the design of the water pump mount and the problem with the impeller, it is not likely to leak beforehand as an indicator. The pump shaft is still getting spun, but it's not turning the impeller - if it is the typical plastic impeller failure.

Let Mr. BMW play fast and loose with his engine if he wants to - that is his prerogative. If your pump lets go and you lose circulation at 70mph, he isn't buying you a new motor. Unless you know for sure you have a new pump, I would change it at 70k. It's so easy there is no real reason not to - it's a $60 part, and the volume of evidence against the OEM pumps is overwhelming.

[primetime]

Mine failed at 90k miles. I was lucky.. Mine was making a noise while idling. A few days later i took it to the shop and diagnosed it..They said if I drive like that any further I'd have a major engine problem on my hands.

[mrbmwx5]

belive it or not. i'm at 151k miles and mine water pump still original from factory.

[The Cleaner]

I would change it at 100k if it has not already failed.

[BGM]

Originally Posted by mrbmwx5

belive it or not. i'm at 151k miles and mine water pump still original from factory.

Wow that is unbelievable. I'm at 84K miles on my '01 and need to do a valve cover gasket I might need to have the Indy look and see how the pump is doing.

[X5girl]

Definately a good preventative measure to change this from 50k miles. The parts are cheap and it is a good time to do it during a coolant change anyway.

The plastic impellor comes detached from the spindle and circulation is lost. There are a great many instances where the impellor breaks-up and needs removing from the block in bits. Replacement pumps, including aftermarket pumps, generally have metal impellors.

Failure of the pump will cause rapid overheating and if not caught in time, imminent headgasket failure.

The statement that a failed waterpump will show as a leak derives from the shaft bearings failing on a waterpump allowing coolant past the bearing. This failure is uncommon on a BMW but is the general failure process on most other cars.

HTH,

X5Girl. xxx