Found Slow Coolant Leak

[ryunk]

I have had a slow coolant leak and finally found it. I was getting the Top Up Coolant message and thus topped it off every once in a while.

I poured a small bottle of UV leak detector fluid in the coolant and drove it around for 30 minutes or so. I got the green florescent light coming from just under the thermostat housing area on the block. I probably would have never found it without the leak detector because there was no visible liquid, it must of been a very small leak or a vapor leak.

I ordered a new Thermostat with Housing (87 deg. C). I hope that will fix it.

[dgiturbo]

Thanks. Keep us posted if any more leaks.

[ryunk]

Originally Posted by dgiturbo

Thanks. Keep us posted if any more leaks.

Ok, I replaced the thermostat housing, replaced a few clamps and drained coolant. I put in the new Blue colored coolant from Mercedes. I will see if that fixes it.


That seemed to fix the leak, I have driven it for over month and no loss of coolant.

[KY ML500]

I know this is an older post, but do you have a procedure for replacing the thermostat? Dealership wants $266 to do it and I would bet it is a pretty easy process. I have a 2006 ML 500 (M113 engine).

[ryunk]

Originally Posted by KY ML500

I know this is an older post, but do you have a procedure for replacing the thermostat? Dealership wants $266 to do it and I would bet it is a pretty easy process. I have a 2006 ML 500 (M113 engine).

I have no pictures or anything but this is actually an easy job on this vehicle. Just pop off the front engine top cover. Drain coolant a bit to avoid the mess when separating the upper coolant hose. Put a tub under the vehicle to catch the coolant. Remove the two torxhead bolts to remove the thermostat housing. Install new housing with thermostat and tighten the two bolts to torque setting and install hose with clamp. Refill the coolant.

This is a good opportunity to replace coolant with the Mercedes blue type. In this case drain all coolant and replace with all new.