Tear Down Time

Jimmy 2Coupes

SCCoA Member
Well after owning my 94 SC since new and owning my 95 since 97 it looks like the head gasket monster finally bit me and the 95 in the azz. I haven't really dug into it yet but the strange thing is I have a bunch of oil/coolant in my air box. I've read countless blown head gasket threads over the years but I don't remember ever reading about oil/coolant in the air box. Anyway, it looks like there had to be some serious crankcase pressure to cause this. Check out the pics and any feedback is welcome.

DSC02657.jpg


DSC02658.jpg
 
Yuck, what color is the oil on the dipstick? Looks like it got sucked in from the driver side valvecover then ran down the intake tube.
 
The oil on the dipstick looked black. When I drained the oil the next day the oil still looked black but had a brownish tint to it. The radiator and coolant recovery bottle are both full and the coolant looks fresh like it was just put in. I didn't see any bubbles in the overflow or any steam/coolant out of the exhaust. The only things I really noticed was a lot of oil covering the driver side lower engine compartment and that it seemed to be running on five cylinders getting it home which was about 25 miles. I did pull the three driver side plugs but other than looking used they didn't look bad and there's no hint of coolant. I still have to pull the plugs on the other side.
 
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my best guess would be. Since your from up north, the airbox sucked some mositure in the airbox, and oil from the intake caused this.

what does you air filter, pcv vavle, and the vac line that goes from the driver's side vavle cover to the intake look like?
 
my best guess would be. Since your from up north, the airbox sucked some mositure in the airbox, and oil from the intake caused this.

what does you air filter, pcv vavle, and the vac line that goes from the driver's side vavle cover to the intake look like?

Actually it's pretty dry up here this time of year unless it's raining and when this happened which was last Friday night it had been a sunny day/clear night. I never drive my SC's in the rain or when the roads are wet if I can help it and it's been a couple of years since I've been caught in the rain.

If you look at the second pic you'll see an elbow with a 90 degree bend bolted under the bottom portion of the air box. There is a 9" conical filter in the fender well on the end of the elbow so I cant really see it but I can see where the oil/coolant has run down the elbow so I'm sure it's in there. I haven't checked the pvc valve yet and I'm pretty sure this stuff came through the pvc/crankcase vent hose coming from the driver side valve cover. There's a small puddle of this stuff in my throttle body also..
 
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Intake reversion. Incoming air isn't always moving towards the engine. It mostly does, but for a fraction of the time it actually reverses. If you put it on a graph of time vs +/- air flow(like viewing a/c voltage) you would short spikes in the negative direction in time with intake valve slamming shut. But, to have that much oil meant you had other problems like worn rings. Timing was probly good for a rebuild
 
Intake reversion. Incoming air isn't always moving towards the engine. It mostly does, but for a fraction of the time it actually reverses. If you put it on a graph of time vs +/- air flow(like viewing a/c voltage) you would short spikes in the negative direction in time with intake valve slamming shut. But, to have that much oil meant you had other problems like worn rings. Timing was probly good for a rebuild

You'd only see intake reversion close to the MAF on an N/A car... we just have way too much plumbing and a supercharger in the way to have that happen up at the MAF like that.

Now-a-days, we essentially turn off this function when tuning so we're not flow limited anymore since we don't suffer from this problem like other cars do which can cause fueling spikes because the MAF reads the inversion. It was this function that created that old myth of being flow limited to 1400kg/h with the EEC's in our cars.

Fraser
 
Not so sure about that, given the amount of oil that sits in the intake/intercooler plumbing on these cars with a healthy engine. Seen something similar on an sc before pcv and breather still come in upstream of sc.
 
Not so sure about that, given the amount of oil that sits in the intake/intercooler plumbing on these cars with a healthy engine. Seen something similar on an sc before pcv and breather still come in upstream of sc.

The oil comes from the PCV valve that is plumbed into the inlet plenum just after the TB.

Fraser
 
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