Last few days my 190E has taken to drinking a lot of water, enough to put the "fill radiator" light on within 10 miles of filling and properly bleeding it.
The water pump is pretty knackered on it, so I'm hoping and praying that it's just the relief valve in the pump doing it's job.
The temp gauge has /never/ risen above 90 degrees, and the engine has never appeared to overheat in any way.
There is no smoke or water from from the exhaust, and it passed the MOT emissions with flying colours less than a month ago.
There's no signs of water in the oil, and the water that is still in the system when it has put the light on is clean. Just water and antifreeze.
There are no external signs of coolant loss, and when the car is topped up with water and the system bled there are no signs of airlocks, the heater works as it should, warms up quickly and is as hot as you like. The heater has always stayed hot even when the water level has dropped significantly. It takes a couple of kettles full of water to top the system up each time.
The radiator is also pretty tired, but seems to get to a uniform temperature when the engine is hot. The pipes to and from the radiator don't seem to be pressurised significantly - not enough to indicate head gasket failure or a dodgy thermostat.
Tonight I was leaving a friends house and the Merc was pretty difficult to start, as if it was partially seized, two or three turns on the starter and it fired up as it should with no signs of stress - as if the battery was dying.. or there's something like water, bugger, stopping the engine from turning freely.
So, it looks like head gasket, cracked block or cracked head, but there's no external indication, although the water must be going somewhere.
Two questions,
A) WTF is going on? B) Will the 230E engine go in, and is it a direct swap?