I have an older CX-7 that's got some exhaust leaking somewhere under the hood... What is this thingy? See pictures... It's loose and I can't figure out how it sits down and seals... I see a little exhaust escaping from it...


It moves up and down about a quarter inch but doesn't come off or push down together

 

I was asked what year... It's 2007 touring model... Anyone have tech manuals to share or engine diagram?

 

That looks like the breather hose from the valve cover to intake manifold... the blue clip holds the hose in against a ring in the male filling. You press the clip in at the bottom and can then pull out the hose... reverse to reinsert (will click when locked on).

Are you seeing smoke coming out of the oil dipstick hole too when removed and idling? Or in the oil filler hole while idling? When was the last time you changed your PCV valve?

 

That is the breather hose. If you are seeing vapors, it is oil. You may want to ;
Look and examine spark plugs
Perform a compression test
if compression test shows any cylinder more the 20lbs lower than the highest then do a wet compression test.
Perform a leak down test of the cylinders.
Do a coolant test.
Check your PCV valve and service all the hoses cleaning or replacing.
Have a sample of the oil analyzed

 

Is it normal to have what appears to be blow by near filler cap - I just picked up a CX7 and there is no blow by from the dipstick tube, so I'm assuming it must be turbulence I'm feeling. The filler hole does sit directly over the timing chain.

Waiting on delivery of a compression test tool to confirm...

 

Your response is not the same as the l;ast members question about his Mazda.

Blow-by is not oil vapor and the OP is looking at the breather hose on the intake tube/hose which oil vapor there is not a normal operation. The oil vapor will go directly into the intake manifold oiling up the interior and as it goes into the combustion chamber will carbonize.


For your question the answer is somewhat the same, there will be pressure if the engine is running and the oil filler cap is removed but there should not be oil vapor only air. But don't confuse oil droplets being propelled out the oil filler cap caused by the air escaping out the valve cover oil cap filler tube.

 

It's like a pulsating air pocket hitting your hand. I just asked this question in another forum, and they said it's normal... I'll take it! I'm just used to engines where there is pure suction at the filler cap which is what had me worried! Never seen an engine with air pulsating at oil filler and nothing at dipstick tube before... almost defies physics!

 

Most 4 cylinder engines at least since around 2000 (maybe older I would have to think a bit more) all do that. It reads in your responses like you are "old school" use to American made in USA engine that is you did get excessive blow by from the oil cap or PCV cap when removed while engine is running because of valve guide or valve stem wear compounded with the piston compression ring blowby what you are describing and what you are familiar with would be bad.

 

You are 100% right - I'm used to V6 GMs... have not had a 4 cylinder for two or three decades. Very perceptive of you!

I get the impression the oil filler cap allows the PCV valve to close with drop in pressure so I can feel a pulsating, but when I use the smaller diameter dipstick hole, there is enough pressure to open the PCV and there is no air movement at the dipstick...

That is the best theory I can come to explain the phenomena...