Hi all,

Does anyone know what the inside of a bailey breather tank looks like? The one on my FRST is making a rattling noise as if something has broken inside, is this normal? Could this cause crank case pressure to increase as there seems to be oil forcing its way out from top of the dipstick after the car has been driven on boost, and in turn can crank case pressure affect oil pressure? My oil pressure on idle used to be a solid 20psi on idle i'm now getting 14-12psi. I've done a cylinder compression check and they are reading 130psi, 130psi, 125psi and 130psi, i'm assuming these numbers are ok, which could lead me to believe the piston rings are ok.

any thoughts on why lower oil pressure and build up of crank case pressure? is this related to the rattling breather tank?

 

Comp test is fine as they are within 10%.

I wouldnt expect a drop in oil pressure with an increase of crankcase pressure.
The bailey tank probably just has a form of mesh/wire inside it (almost like wire wool). Suprised if it could "rattle" unless it was glued in place and that glue is hardened and causing the rattles...

 

I took the baileys tank off the car and cleaned all the pipes as I thought they might be blocked but they were fine. That's when I noticed the rattling noise from inside the tank its like a bit of metal. it makes a noise similar to when you shake a aerosol can (if that makes sense!)

 

wouldn't the fact that oil is forcing its way up through and out the dipstick affect the oil pressure?

 

Not sure on the Bailey's but some have a plate inside

 

hmm, what would be causing the oil pressure to drop? I've had a recent bottom rebuild oil pump and bearings. Used to get a good 20psi on idle now around 14psi or 12psi. Is that even safe? The only thing I can think is the oil forcing its way out the dipstick under boost is dropping the oil pressure.

 

A CVH at 14psi hot isnt unheard of, 12 is heading to the more worrying end of the scale tho.
Pump, bearings, clearances - thats all it can be really. Was the pump genuine Ford or a cheapy autopumps pump?
Bearings decent quality?
Cam can have an influence also as the clearances here can lower pressure if worn.

 

genuine ford oil pump and mahle bearings.

What sort of psi for oil pressure under boost is good?

 

Boost shouldnt be affecting oil pressure. Oil pressure is measured against RPM

 

If you have excessive crankcase pressure...sounds like engine's fucked, melted or broken piston or similar ( or you've plumbed the breathers up incorrectly and it cannot breathe at all )

Compression test results seem maybe a little low, but it would depend on CR, accuracy of gauge and how test was conducted. But even though they are even over all cylinders, still doesnt mean everything is good.

And lots of cheap breather tank things would often have a simple baffle plate tacked inside, it's probably just broken off. As long as the engine can still breathe, worst case it would see more oil able to pass through the can.

 

recently had a bottom end rebuild/refresh (oil pump, big ends, small ends, and new seals. Piston rings were fine.) That's why i'm a bit confused and makes me think (hope) its the breather setup. My breather connects back into the inlet manifold, is this the best way?

 

Its the legal way. Best way is to vent to atmos

 

Best way is a proper PCV system which also vents under load.

No idea what way you have yours configured though.

Easiest is just vent to atmos.

 

connected through rocker cover cam side and also the other side. Hose to t-piece into the block and a hose that vents to atmosphere, with vacuum lines to inlet manifold.
I know some ppl have different setups i.e return to sump