Hey there All,

Hello all,
My 05 MCS threw a rod bearing. I originally misdiagnosed the "pinging" as a bent valve/timing issue and pulled the head. After realizing all was fine up top, I pulled the oil pan and found my problem (it was more than just "spun" it was nonexistent). My S has almost 150k on it so while I had everything but the pistons out I decided to do a "rebuild" sans boring the cylinders and replacing rings.

Work Done:
Replaced all the gaskets
Pulled the supercharger and changed the oil (water pump side was clean amber color, supercharger side was nasty grey with metal flecks in it)
Replaced all rod bearings and cap bolts (as they are torque to yield)
Replaced timing chain and guides
Replaced chain tensioner
Replaced cam position sensor (it's a long story)
Replaced head bolts (as they are torque to yield)
Replaced PCV valve hose (rigid hose on the left of system, I cracked this maneuvering it back into place so ordered a new one)
Replaced MAP sensor (one bolt was seized, actually cracked the flange around the sensor trying to get it off so this was replaced)
Replaced one of the injector O-rings (tore this remounting the fuel rail, bled fuel all over on first start up, found and replaced)
Replaced the super charger intake duct gasket (Leak down test fail after install so I installed it again with some RTV)
Bypass valve rebuilt (It was leaking from around the plastic spring housing so I pulled it, RTV'ed the diaphragm seat and taped the housing, seems okay now)
Added engine break-in additive, oil and anti-freeze
Used assembly grease to assemble all moving parts

I've put it back together twice now. The first time was before the SC inlet duct fix. It ran like **** and threw a number of codes. Got some help here from 1QwkMini and MiniBeagle with my SC inlet issue. After the patch job to the SC inlet I was able to get the system up to 15 PSI. I did this a few times and around 12 PSI I heard what sounds like an electric charging sound. I'm not sure if that was the supercharger spinning up due to the pressure or what... The drop from 15 PSI to 10 PSI only took about 2 seconds, but from 15-0 was about 15 seconds. Put it back together and drove it yesterday. Here's where it gets weird...

There's a pretty loud lifter sound or maybe chain rattle coming from the engine when it's driven. When I idle at a stop light the Low Oil Pressure light comes on. As soon as I touch the throttle that goes away. Took it on the expressway to test out the top end and the sound it still there, but if I drop from 60 MPH quickly the loud engine sound will dissipate until the throttle is pressed again.

I was taking side streets home and at a red light the car just dropped from idle to stall and wouldn't start from 3 tries. Fourth one it went and returned to it's previous behavior...

I got home, plugged in my reader and was surprised that only the 1239 code came up even after the stall and failed starts... I popped the hood to search around a bit and noticed that two of the valve cover bolts looked wet. I gave one a half turn and it snapped off... Gave the second a quarter turn decided to walk away from it for the day before I did something else stupid.

I did add break in oil to the car. It instructed me to fill with normal oil to normal level and then add the additive and drive it from 500 miles. As a result, the oil is showing at the top of the dipstick range. Not sure if this is gumming up the oil pump at idle? Perhaps it's too thick/full to pressurize the chain tensioner and this is the sound I'm hearing?

At this point I'm dreaming up all sorts of stuff... Any help would be appreciated.

Is the 15-10 PSI leak down drop being quicker than the 10-0 PSI normal?
Anyone use a break in additive on these engine or experience a similar Low Oil Pressure at idle/stall?

Happy Friday everyone. Thanks in advance.

 

I would put an oil pressure gauge on it and see where you are at. All the signs point to low oil pressure since the lifters need oil pressure to pump up and the timing chain tensioner needs it to take the slack out of the chain. Perhaps something was missed in the assembly of the engine, like a plug in a galley or a gasket?

 

So too possible was the original vanished rod bearing a result of excessively low oil pressure.

 

So you didn't like the advise you got on the last thread..so you thought you would start again??
Break in oil is just a high zinc additive and doesn't affect the oil pressure or viscosity.

CHECK THE OIL PRESSURE AND GET A REAL MECHANIC !!! YOU HAVE MORE THAN ONE ISSUE.

OVER AND OUT

 

I just re-read the OP's post and it seems that he didn't replace the original oil pump. If so, I would ask WHY? If you had an oil pressure problem and took the engine apart because of it, would it not make sense to replace it? I would also look at the pickup and make certain it is properly installed and sealed. Heck, put in a new pickup while you are in there as it probably has bits of bearing in the screen.

 

Hey Qwk,
No offense meant, just wanted to start a new thread with a proper heading since I agree the issue is no longer a bypass valve or the supercharger gasket. I did take it to a mechanic. Scoped cylinder 1. The connecting rod broke free. He thinks it was damaged when bearing spun. After reassembly he believes that normal operating conditions caused it too sever. Recommending new block. FML.