Hi guys, I just get a used 2010 Mazda CX 7 2.3L turbo. The car have problem with oil leaking on the back of engine. At first I figured the valve cover gasket exactly on the area was broken. Replaced the valve cover gasket and the leak from gasket is stop. But I figured there is a hole on the top of exhaust manifold on engine head. The location between cylinder 3&4. When first cold start, I only can notice light smoke from the back of engine, but as soon as the car hot, the boiling oil with bubble start leaking from this hole. My question is, this is a weep hole or I have damage on my engine head ?
Any information will be appreciate.
Thank you

 

Probably just the way it was cast. Looking at the seals under the cover bolts. Did you replace them as well as the gasket? They are also an important part.

 

I did put the rtv for the bolt seals. There isn't leak noticeable anymore from all seal. The oil seeping out from that hole, the oil seeping out boiling and bubbling with a lot of amount and very noticeable make the exhaust flood with oil and start smoking hard

 

You really should replace those seals as they play an important part in applying pressure to the cover gasket but you say there are no leaks now. My Guess is that over time oil has leaked ito the cavity in your pic and is now burning off. How long will it take before ot stops is a big guess maybe some method of cleaning it out may help. Fill with degreaser and wash out or a jet blaster.

 

Exhaust manifolds are bolted to the cylinder head using bolts that pass through the manifold and into the cylinder head or studs that are mounted in the cylinder head and pass through the manifold. In other words, the threads are always in the cylinder head, and the holes in the exhaust manifold are smooth.

 

You are back? This thread is a few months old...as the other threads you are coming in late to respond it. LOL

The pictures in question. but what some are calling a hole is simply the head casting itself. That head casting is used on several years and model Mazda's. It is not uncommon on any platform to see these casting to exhaust manifold mating. It by no means creates a leak of any kind or problem. And NO it is not an access hole to mount any part.