Water pump - shagged?

scotth_uk

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Hi all,

I set out this morning to flush the radiator, top up with some decent anti freeze and detail the engine bay.

Opened the radiator drain valve and emptied the contents. After that was done, I plumbed the garden hose into the overflow bottle and let it run through the system to the drain valve, until the water came out clean. Once that was ok, I closed the drain valve.

I then added about 4 litres of coolant to the overflow bottle, and it really wasn't in the mood for taking any more. My aim was to get the recommended 4.5l in there, then top up with water. I was a little concerned that it only took that much, but figured that there would still be water in the engine, pump, etc.

After detailing the engine bay, I went to start the car and it sounded sick, sick, sick. I gathered that it was water related and disconnected the HT leads for inspection of the plugs. Found water in spark plug 3, and I managed to get that out ok. After that it ran ok about about 1500-2000 rpm, but idled poorly.

After a few minutes of the engine being generally cranky, it started to run ok - so I took it for a spin in a disused freight road near home. I accelerated a lot (and hard) to get everything back into shape. It behaved beautifully and everything was ok - until I got home.

I noticed that coolant was pouring out of the bottom of the car onto the driveway!!!! I couldn't see where it was coming from, but it appeared to be coming from what I perceived to be the back of the water pump, which just happens to be completely out of view because of the damn air cleaner assembly.

If you take the overflow bottle cap off, the water flows out very quickly. If you replace the cap, the flow is very small.

A thoughts:

Did I screw up and not evacuate the cooling system of air, potentially killing the water pump or a hose somehow?

I am p*55d off now, as I can't drive the car and there are no Merc places nearby that I trust, apart from the Canary Wharf dealer's service centre which is $$$$$++++.
 

andy_k

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not knowing what engine you have

the water pump is generally on the front of the block so any water coming out of that will be at the front of the engine.

suggestions would be to drain the system completely again - from a drain plug or the bottom hose.

check all the hose connections and the thermostat housing.

fill the system with premixed coolant - use about half the recommended amount and let it settle seeing if it leaks and where it is leaking from. Squeeze all the hoses and see if they have coolant in them and see if any are wet from leaks.

It's just a case of finding where the water is coming out, it's also unlikely air in the system would trash the water pump as the air tends to rise to the top of the system.

Can't be much more help without actually getting my head under the bonnet.

Andy
 
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scotth_uk

scotth_uk

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Thanks Andy,

The car is a 92 190e 2.6 auto...... I'll get into it again in the morning and see if I can work it out.

The water is definately coming from somewhere between cylinders 1 and 3 on the right hand side, underneath the air cleaner attachment and it is dribbling down the block to the sump and on to the ground. No sign of leaks on the front anywhere. It's almost as if it is the rear of the water pump.

Just thinking about other things - what's the potential damage if you run the system without the cap on the overflow bottle?
 

Ian B Walker

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Just a thought, there are core plugs there, while flushing the engine has one been either weak or been displaced. Might be worth a look once the air cleaner is off
 
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scotth_uk

scotth_uk

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Just a thought, there are core plugs there, while flushing the engine has one been either weak or been displaced. Might be worth a look once the air cleaner is off

I'll certainly check for that at next opportunity. I am still amused that when you remove the overflow cap it runs straight through onto the ground. The hole must be quite big. Drip rate is about 100ml per minute, maybe a little more.
 
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scotth_uk

scotth_uk

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I managed to get he air cleaner assembly off this morning, with considerable force!

The leak seems to be coming from the underside of the water pump, and is particularly difficult to see no matter what viewing angle you employ.

A quick call to the trusty family Merc technician back in Australia proposed that it might be a drain plug problem on the underside of the water pump (or something to that effect). He mentioned that it is a fairly common problem when flushing the cooling system, and that the best bet would be to remove the thermostat and all associated radiator pipes and blast high pressure water into the pump.

I have been out and blasted every damn part of that cooling system with water, and just have to wait for it to dry. On first inspection, it appears that it has minimised the problem, but there may still be some drip. No solids came out, but as you can imagine, lots of cloudy rust coloured rubbish.....

One question - how do you ensure that there is no air trapped in the cooling system? I am paranoid that it is going to break something. ;-)
 
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scotth_uk

scotth_uk

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Interesting - the complete thrashing of the water pump using a garden hose seems to have cleared up the problem!!!

I probably used more water than africa does in a year to sort it out, but it appears dry once more after a test run. I'll be sure to carry some extra water today in case of problems, but looks all clear.

Interestingly the thermostat wasn't closing fully and the seal was shagged. Must remember to get another during the week.
 

Ian B Walker

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One question - how do you ensure that there is no air trapped in the cooling system? I am paranoid that it is going to break something. ;-)

You could try undoing the heater outlet hose then filling up the system till the water flows out of it, then reconnecting it. It used to work with fords but not sure about Mercs. The theroy is the same though, highest point in the water system and the air rises to it.
 
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scotth_uk

scotth_uk

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Dammit!

I got a few miles from home, and the problem came back. Oh well off to the mechanic tomorrow. :-(

Thanks for the help guys!
 

Ian B Walker

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I would be interested to know what the problem was when you get it sorted, who knows I and others, may just have this problem in the future. Thanks
 
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scotth_uk

scotth_uk

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I would be interested to know what the problem was when you get it sorted, who knows I and others, may just have this problem in the future. Thanks

Will do.

I faxed of a request for quote to GF's this morning. Will be interesting to see what he quotes for a water pump replacement including labour.

I called my local guy (MB Autos) and after I explained the problem to him, he seemed to recall something along the lines of what my old man mentioned - the drain plug hole issue. He's quoted me 2-3 hours to replace the water pump, and I can grab the part myself from eurocarparts.com.
 

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