[W126 Coupe] Coolant Leak

[dolans1 at verizon.net]

That's how the water pump starts leaking. Leaks then stops, then it starts the grinding noise. The weep hole is a waste of time looking at, due to none will be apparant. Mine stopped for about three months. Then turned into a water fall. Same deal front passenger side drip... time to pull the dist. and harmonic balancer.
Not a fun job.


>From: Dick Spellman <spell.yy at verizon.net>
>Date: Sun Jan 29 16:01:01 CST 2006
>To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>Subject: Re: [W126 Coupe] Coolant Leak

>Hi Mike:
>
>Obvious stuff would be the expansion tank cap, remove the cap and check 
>the condition of the rubber gasket. While there look for any sludge 
>(white gunk) on the coolant cap or on the surface of the coolant (brown 
>spots) in the expansion tank if oil was getting in there from an 
>internal head gasket failure. Sounds like your describing a leak along 
>side the block itself. If so, you've got the freeze plugs and the head 
>gasket. Pressure test (leak down) would have shown some activity in this 
>area if either were bad and/or you have a small external head gasket leak.
>
>If the leak is closer to the passenger compartment maybe check the two 
>heater hoses that feed into the intermediate firewall and one that runs 
>through the auxilliary pump on route to the heat exchanger? You've 
>checked the top seal on the monovalve for leakage? The heat exchanger 
>itself could have a leak but you would smell the anti freeze for sure 
>when driving with heat applied any leakage would follow the two center 
>drains to either side of the tranny. These are self closing rubber 
>snouts that are not easily seen but sit directly under the inner firewall.
>
>Not much else I can think of where the water pump, top & bottom hoses 
>and vent hoses are all solid.
>
>Regards,
>
>Dick
>
>Mike R. wrote:
>
>> I have a coolant leak that I can’t find. The anti-freeze drips off the 
>> passengers side of the engine, up front but there isn’t anything 
>> obvious for the source. The water pump weep hole is dry and as far as 
>> I can see, even with an mirror, there isn’t any leakage from it the 
>> water pump/motor gasket. I’ve looked at the thermostat housing as well 
>> as the upper and lower radiator hose connections, but nothing there 
>> either. I looked under the intake manifold just a little (place on the 
>> passenger side in front of the front intake runner), but no puddles 
>> under there either.
>>
>> I tried some air pressure in the system through the overflow tank and 
>> did make it drip a little faster, but nothing apparent for a source. I 
>> drove the car and that seems to have _slowed_ down the leak. Went out 
>> to a restaurant last night and back, nothing on the ground under the 
>> car at the restaurant or my garage this morning. Self healing leaking? 
>> Any ideas where to look??
>>
>> There is a hose, ~1”, that starts somewhere near the water pump and 
>> goes toward the back of the engine compartment over the air pump – 
>> what’s that for?? Nothing apparent from it but I couldn’t see where it 
>> attached on the front of the motor.
>>
>> Thanks,
>>
>> Mike R.
>>
>>------------------------------------------------------------------------
>>
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