W204 Coolant Leak - Taken to main dealer - Need Advice Urgently

[ragazzi]

Hi all,

I haven't posted for a while as last time I got a good amount of responses due to the auto gearbox transmission fluid service that cost an arm and a leg, anyway my new predicament.

My car is registered September 2010 so it is out of warrant and has done 49k miles.

In January 2015 my coolant light came on, I thought it was strange (it hadn't happened in the many years I had the car and I had kept a good service history etc.)

I rang one main dealer they said top up with water as it is an air bubble that can sometimes happen

I then rang another dealer to verify this and they indeed said it is protocol so I topped it up.

For the next 2 and a half months I topped my car up with water as the light would come on once every weeks initially until it was close to once every 3 days.

I tried a new coolant cap, £18 it cost me and it didn't fix it. The lad on the parts desk said my engine had the code that could have a faulty batch of water pumps.

Mid-March 2015, I rang the main dealer and mentioned my predicament. The nice chap agreed that a car with such low miles and in such an age shouldn't be experience this and then I asked the cost of a water pump he said it would cost £600 but MB will contribute 50% a goodwill as it is strange for it to occur a this point in the cars life.

He then proceeded to mention it will undergo a stress test before they order and replace the water pump as they need to be certain.

He confirmed it was the water pump and I booked it in.

2 weeks ago the part arrive and I had the water pump fitted at 50% cost.

2 days later the coolant light came on again.

I rang the main dealer they said it is the air bubble that could cause the issue and top it up with water

So I put in 500ml of coolant (as I read water isn't the best thing to use)

Yesterday my coolant light came on again, so I rang Mercedes. He mentioned it could be the air lock to which I said it can't be as it was 500ml I filled up with.

Car has gone in today, they have done a stress test and said it is the coolant outlet seal that is leaking ever so slightly.

Then I was told the new pump has restored the original pressure in the coolant tank and that under the stress this has made the sealant go on the coolant outlet.

He said its £4 for the seal but more importantly could cost a few hundred to fix as it is the labour involved. He is speaking with MB for a goodwill gesture to see what they will do as it is still strange.

Am I having my pants pulled down?

My gut feeling is the following :

1. The test wasn't done correctly initially. (took 20 minutes)
2. It has always been the seal

What should I do? I have an invoice sheet that says

Water Pump Remove/Install, Inspect and if necessary replace.

 

[markjay]

To clarify - when your coolant light came on, the coolant level was actually down? Just to eliminate coolant level sensor issues....

 

[ragazzi]

Yes Mark, the coolant level was definitely below the level in the coolant reservoir.

 

[markjay]

I would agree with you that in all likelihood the pump replacement was unnecessary.

I would suggest that you wait to see the quote and the goodwill contribution (if any) made by MB.

Then ask them to credit you for what you have already paid for work which clearly did not need doing.

But the point is that even if the original fault was the seal, you should have paid for this repair anyway, with or without goodwill contribution. So at the same time I would also get a quote from a good Specialist, and if it is not too much then I would get the Specialist to just fix the issue and forget about MB.

So in short I believe you do have a case, but it all depends on how much it would cost to set it right at this point, because at the end of the day your car is 5 years old and any claim you make will be hard work, i.e. the law is not necessarily automatically on your side and you will have to spend some time in properly arguing your case in writing to MB and potentially also to SCC.

The time and effort that you are likely to invest in this if MB do not agree to credit the previous bill will need to be factored-in into the equation when considering the costs.

 

[Merc Owner 2B]

The story is plausible but unlikely. It isn't actually a pump but a circulator. It's the heating of the water that develops the pressure not the "pump". The original leak should have been visible in the first place so that the correct part was changed. Unless there were two leaks of course. If it (outlet seal) cures the problem then you may have paid £300 for a pump you didn't need at this time but at least it's now new.

 

[ragazzi]

Thanks for the advice Mark, I am due to set off on foot to MB in the next few minutes.

I can't seem to find any reference to a coolant outlet seal on the internet, which is what the servicing guy referred to. Maybe I could diy it if its easy to get to?

what would a reasonable amount be? if the part is £4, is it really hundreds in labour to fit it?

On a side note, they also on the visual health check they said I needed front brake pads in which were replaced last year and look fine using the physical eye. My faith is being dwindled, this is something I would have expected if going to a local back street garage.

Edit: I have 2 years warranty with my new pump, which I find comforting.

 

[Merc Owner 2B]

If they want £100's then it's not going to be DIY.

Probably an outlet from the engine or inlet manifold.

 

[Bellow]

Then I was told the new pump has restored the original pressure in the coolant tank and that under the stress this has made the sealant go on the coolant outlet.

Unless the cooling system is of a type I've not encountered, that statement is suspect. The pump cannot pressurise the system as as it pushes water out it also draws water in (from the system).
The source of pressure in a cooling system is the heat expansion of the coolant and is exploited to lower its boiling temperature.
Either there is a weakness in the sealing or, the system is operating at above design pressure - a failed head gasket being the likely cause.
If the pump gave no respite from having to top up then suspect the seal now under scrutiny as being the culprit all along, but as a caveat, if they did find a fault in the pump then almost certainly it would be the next failure point.

editPS.
Post#5 had not appeared before I posted. We are in agreement though.

 

[markjay]

With regards the leak... coolant was clearly escaping so the system was not sealed.

The logic in replacing the coolant pump in such circumstances is only valid if the coolant pump itself is leaking.

If the coolant pump was not suspected to be leaking, I don't see how replacing it was expected to resolve anything in the first place.

A failed (but not leaking) coolant pump can cause overheating which will cause the expansion bottle cap to allow steam to escape, but this will be accompanied by high coolant temperature which you would have noticed on the temperature gauge and possibly also warning light on the dash.

 

[Merc Owner 2B]

With no visible leaks (if that is the case) the head gasket / head / block have to be tested for integrity as it must be throwing the water down the exhaust.

 

[Bellow]

With no visible leaks

Good point. There should be tell-tale trickles of coolant at the leak sites.

(if that is the case) the head gasket / head / block have to be tested for integrity as it must be throwing the water down the exhaust.

Or into the oil...(though with the volumes being discussed the oil level would be up close to the camshafts by now!)

 

[ragazzi]

Apparently the part I need is
MBA651 142 02 81 T010604 Elastomer-molde 3.55 each

However could take 2 hours to fit @ £175 per hour. I can't find any documentation on this part anywhere, has anyone ever had to fit this or found somewhere so I can benchmark the cost against?

 

[markjay]

With no visible leaks (if that is the case) the head gasket / head / block have to be tested for integrity as it must be throwing the water down the exhaust.

Good point. There should be tell-tale trickles of coolant at the leak sites.



Or into the oil...(though with the volumes being discussed the oil level would be up close to the camshafts by now!)

I don't know about the OP's engine, but some type of engines have a 'heat exchanger' (a small internal radiator that runs engine oil through coolant), and when it leaks will cause coolant to escape into the engine oil. But you will see evidence of this on the dip stick ('mayo').

I have also seen small leaks that left no trace, either because it was a small amount of steam, or because it trickled straight on top of a hot exhaust section and evaporated. So coolant leak that leaves no visible trace is not always internal e.g. not always head-gasket or oil related.

 

[m500dpp]

£175 an hour? Find an independent!!!!!

 

[ragazzi]

I am going to see whether there will be any goodwill from MB. If not I guess it's a ticking time bomb on how long it lasts v price to get fixed.

I checked the oil and no mayo just oil, I was thinking of changing my car next year, maybe it has to be this year. I have to say MB provide the best driving experience I have had but I've always been let down by the dealers from servicing to waiting 3 months for my second key because it got "lost" to this.

 

[Bellow]

Head gasket failure doesn't always involve intermixing of the oil and water - it can fail cylinder to water way. In which case it can draw water on induction stroke (when off-boost) into the cylinder and pressurise the water during the other three strokes. This could easily be the cause of external leaks and needs some checking before attempting a goodwill claim. Look for a 'steamy' exhaust on start-up/idle and have the water expansion bottle checked for HC content if there are any doubts.
It could just be they wrongly diagnosed a leak source but don't discount either the water being ingested by the engine or being unduly pressurised and forcing leaks.

 

[ernie]

MB will contribute 50% a goodwill as it is strange for it to occur a this point in the cars life.

Isn't this engine notorious for water leaks due to the number of plastic components it uses, like the water pump for instance? I think they speak with forked tongue!


Ernie

 

[ragazzi]

I will be contacting MBUK in Milton Keynes today, try and find out their advice, low and behold I received no call from the dealer yesterday. I am pretty sure the original check they did was just a visual check to see if it looked like things were broken, rather than a full leak test.

 

[grober]

OM651 Engine EGR Cooler Rubber Gasket P/N A651 142 02 81
PICTURE HERE

Here's what I believe is a picture of the EGR and its coolant radiator assembly

#
where said gasket is I don't know.

 

[ragazzi]

I haven't seen a picture of the: MBA651 142 02 81 T010604 Elastomer-molde 3.55 each
part.

After speaking with MBUK, the dealer rang me within 30 mins to an hour, it was the friendly chap on servicing - he said he has managed to get 50% off the labour bringing the price in at roughly 118 ex VAT.

I've booked it in for Friday to get fixed.

The problem is I love this car and how it drives, I was seriously being silly and considering a focus ST, knowing full well I wouldn't get the same quality of drive but it would have more gadgets and a lot more speed. But I don't think I could step down to a ford as good as they are.

What else is a common problem with this car? After a new pump and a new seal thingy which is a common problem, what can I expect to go wrong?

edit:

I can't believe such a small thing is causing me such a huge issue.