94 W202 C280 Water Leak

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Hi all

I have had a water leak on my 94 C280 for about 2 years now. It is hard to see where the actual water leak is coming from but it appears to be near to the front of the nearside engine block Possibly around the water pump area but it is just so difficult to see.

I had an independent garage take a look at it about 18 months ago and they could not tell either, and said that they would have to take the manifolds off just to get a better idea, but advised that this would be a lot of money just to get a diagnosis. They put some K-Seal in at the time and this stopped the leak for about a year but then it came back and needed about 2 litres of water a week.

I lived with it like this until recently the leak became worse. I added another dose of K-Seal in the hope that this would fix it again but this time it made no difference, and I now have to top up the coolant every couple of days. I still cant tell exactly where it is coming from but it could be the water pump gasket?

Any ideas - and if it is the water pump gasket is this a simple job to tackle?

Any feedback most appreciated.
 

rpe2

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If you keep filling it up with K seal, you run the risk of blocking a water gallery.

The water pump isn't much fun on a M104 engine. Suggest visiting John Griffiths in Reading for add'l help (www.jgriffiths.co.uk)
 

kth286

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Agreed.

See my more comprehensive answer to your post on other forum.
 

MissyD

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Agreed.

See my more comprehensive answer to your post on other forum.

is it possible to post your more comprehensive answer on this forum, as many members cant access the 'other' forum :cool: and it could be useful to members here too
 

rpe2

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Agreed.

See my more comprehensive answer to your post on other forum.

I've seen it, very good too.:D

One other thing. If it is the pump and you are tempted to DIY (I still don't suggest it), be very careful where you get this pump from as there were about 3 or 4 versions, all slightly different, and are not interchangeable. e.g. some have more water outlets than others.. Order referencing your chassis number.
 
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television

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The 124 pumps can leak,,putting your finger under the pump housing would confirm it (engine off)
 

kth286

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is it possible to post your more comprehensive answer on this forum, as many members cant access the 'other' forum :cool: and it could be useful to members here too

Sure thing.

I said the following:


It is very likely the water pump itself.

It is a big job on that engine (I think 6 hours is quoted
by Merc) and needs to have an experienced person that has
done it before ideally as there is a set of thin wobblies
required for the inaccessible water pump nuts, and
specialised knowledge re the dismantling and various pipe
connections such as the one to engine oil cooler etc.

If you are into DIY make sure to get everything prepared
before hand with all proper Merc instructions.

I did mine over a long weekend and took the opportunity to
change hoses, thermostat, polybelt, new coolant, etc etc
whilst everything was dismantled.

Used all Merc original parts.

Never leaked since (3 years ago).
 

Alex Crow

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as has been said, this is a dead ringer for the water pump. although why your 'specialist' wanted to take the manifold off is beyond me!!

we would expect to take around 3.5-4 hrs for this. the biggest problems are the polybelt tensioner (they use bonded rubber and it can come apart on retensioning) and access to the bolts securing it to the block, as has been said.
 
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Hi all

Thanks for all your posts, which do reinforce my fears that it could be the pump - although I could not see any leakage from the spindle behind the pulley and had rather hoped that it may have been something else. Maybe if it had been the gasket it could have been sealed externally with one of the propriety sealants.

The independent garage had suggested removing the manifolds so as so get a better view of where the leak was coming from, as in their opinion at the time, the drips were too far back for it to be the water pump.

I won’t be putting any more K-Seal in as I agree that this could block a water gallery, and anyway the last lot made no difference.

Although I used to be a mechanic, I don't feel that this water pump is a job I could tackle these days (bad back and all that) especially after reading the potential problems and length of the job.

I will have to get a few quotes and weigh up the options.

Thanks again for your helpful posts.

Best regards
 

Alex Crow

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they never leak from the spindle, there is a hole in the casting below and behind the spindle with a pipe to duct the water away. typically you see coolant running down the block behind the water pump, rarely/never see water at the front or in the polybelt area.
 
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they never leak from the spindle, there is a hole in the casting below and behind the spindle with a pipe to duct the water away. typically you see coolant running down the block behind the water pump, rarely/never see water at the front or in the polybelt area.

Thanks very much for that information. It seems as though it has got to be the pump from what you say - Where does the pipe emerge - if it is visible that would provide a definite confirmation.
 

kth286

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On my 104 engine there was no drip pipe on the water pump as standard but was available as a retrofit.
 
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