My mk 3.5 Focus 1.5lt ecoboost is losing coolant via the exhaust, at first it was just running rough so I changed the plugs and one of the old plugs was really messed up. Thinking this was the problem solved I motored on it was later that I realised I was losing the coolant - has anyone else experienced this problem or have any ideas what’s going on?

john c

May be the head gasket although there are other possibilities

18 minutes ago, John Curran said:

My mk 3.5 Focus 1.5lt ecoboost is losing coolant via the exhaust, at first it was just running rough so I changed the plugs and one of the old plugs was really messed up. Thinking this was the problem solved I motored on it was later that I realised I was losing the coolant - has anyone else experienced this problem or have any ideas what’s going on?

john c

On a 4-cylinder 1.5 ECOboost these symptoms point to a damaged/cracked cylinder liner of either cylinder 2 or 3. This is a well known problem of this type of engine. 

These engines are extremely sensitive for warming up properly before demanding any serious power. Demanding power when the engine is still cold causes uneven warmup of the engine. This is mainly caused by the exhaust manifold that is integrated into the cylinder head (close to cylinder 2 and 3). This will result in excessive movement of the cylinders (open deck construction).

The problem usually starts with a broken headgasket. If noticed by the owner at an early stage the problem can be solved by replacing the head gasket.

If not noticed by the owner at an early stage the hot exhaust gasses will burn away the aluminium at the top of the cast iron liners. This damage can only be repaired by machining the engine block and replacing the liners.

 

In this case you should be prepared for either  a very expensive rebuild or replacing the engine. 

 

 

Exactly that. Modern engines are built to well calculated tolerances. The MGF I have is famous for needing a new head gasket every week. On a cold morning, the vibration and piston slap can be heard and felt several streets away. Mine hasn't blown up. I never exceed 3000 RPM before the oil temperature gauge reads 90 degrees. The engine by then is quiet and smooth. Everything is up to working temperature and it can then work, redlining at 7,250 RPM regularly and being used as intended. It was a very advanced engine when new (The first to have variable valve timing,) and today, a lot of engines are engineered like it, the open deck block for example is very similar. Today's engine is far from the agricultural lump of cast iron that you would find in a Sierra and far less tolerant of abuse. they need to be gently warmed up.

design feature - check bbc youtube video and go argue with ford - issue on early ecoboom disaster engines