Strange oil leaks
#1
Instructor
Thread Starter
Strange oil leaks
I’m tackling a handful of projects at the moment. Replacing badly leaking timing chain cover gaskets. There’s been a few leaks I’ve noticed over the last few years, but I couldn’t quite figure out what was wrong.
-First leak is under the air plenum and coating the tops of cylinders 1-3 at the bases against the case.
-Second leak is the underside of the intake manifold mostly near what I assume is a resonance flap.
-Third leak is inside the manifold, coating it almost evenly down the runners. I assume this has something to do with the second leak.
#2
RL Community Team
Rennlist Member
Rennlist Member
Are you possibly overfilling the oil where the excess is being consumed by the intake where it collects and gets all over the place?
If so you are not alone in this, a very common situation.
I ran across the following comment in the 993 Rennlist Forum:
“How full do you keep the oil tank? When I kept mine at the full level I'd go through easily a qt. per 600 miles, now I keep it at min - 1/4 I use barely a qt. every 2500 miles. Even now, after spirited driving, the oil can expand to over 1/2 full.”
The implication here is that a true measure of a full oil tank is somewhat variable and overfilling may be an issue for some.
I may also contribute to an erroneous perception of an oil leak, a faulty air injector system due to clogging, or even the conclusion of an oil loss due to valve guide issues prompting an unnecessary top end rebuild.
These days when I change my oil I fill it to 1/3 of the fill range on the dip stick with a running very hot engine.
Andy
If so you are not alone in this, a very common situation.
I ran across the following comment in the 993 Rennlist Forum:
“How full do you keep the oil tank? When I kept mine at the full level I'd go through easily a qt. per 600 miles, now I keep it at min - 1/4 I use barely a qt. every 2500 miles. Even now, after spirited driving, the oil can expand to over 1/2 full.”
The implication here is that a true measure of a full oil tank is somewhat variable and overfilling may be an issue for some.
I may also contribute to an erroneous perception of an oil leak, a faulty air injector system due to clogging, or even the conclusion of an oil loss due to valve guide issues prompting an unnecessary top end rebuild.
These days when I change my oil I fill it to 1/3 of the fill range on the dip stick with a running very hot engine.
Andy
#3
As said most common cause of oil in the inlets is over fill. My inlets are off and I have a coating oil probably due to crankcase pressurisation (it's a 170k engine). I have similar oil stains around the flap valve, there are small oil seals each end of the shaft which are cheap and can be replaced. All high milage engines will have this to some extent. Your tank breather will probably have a coating of gunge. My 993 had a lot of use commuting last year so rarely got up to full working temperature which does not help. I wouldn't be too worried if leakdown is good and the engine stops smoking when it warms up. I used to get an occasional brief puff of blue smoke from cold but it soon ran clear. It's a '94 so same inlet same oiliness but not quite as bad. The crankcase breather to pipe gasket was leaking a bit as well. Mine would benefit from at least new rings and a head job but it will have to wait.
#4
Are you possibly overfilling the oil where the excess is being consumed by the intake where it collects and gets all over the place?
If so you are not alone in this, a very common situation.
I ran across the following comment in the 993 Rennlist Forum:
“How full do you keep the oil tank? When I kept mine at the full level I'd go through easily a qt. per 600 miles, now I keep it at min - 1/4 I use barely a qt. every 2500 miles. Even now, after spirited driving, the oil can expand to over 1/2 full.”
The implication here is that a true measure of a full oil tank is somewhat variable and overfilling may be an issue for some.
I may also contribute to an erroneous perception of an oil leak, a faulty air injector system due to clogging, or even the conclusion of an oil loss due to valve guide issues prompting an unnecessary top end rebuild.
These days when I change my oil I fill it to 1/3 of the fill range on the dip stick with a running very hot engine.
Andy
If so you are not alone in this, a very common situation.
I ran across the following comment in the 993 Rennlist Forum:
“How full do you keep the oil tank? When I kept mine at the full level I'd go through easily a qt. per 600 miles, now I keep it at min - 1/4 I use barely a qt. every 2500 miles. Even now, after spirited driving, the oil can expand to over 1/2 full.”
The implication here is that a true measure of a full oil tank is somewhat variable and overfilling may be an issue for some.
I may also contribute to an erroneous perception of an oil leak, a faulty air injector system due to clogging, or even the conclusion of an oil loss due to valve guide issues prompting an unnecessary top end rebuild.
These days when I change my oil I fill it to 1/3 of the fill range on the dip stick with a running very hot engine.
Andy
I change oil once a Year and fill up to 2/3 and then I drive the whole season and never check the oil again! I'm pleased if I see the oil level nedle move just a tiny bit when the engine is hot!
Last edited by Railmaster.; 12-13-2018 at 06:49 PM. Reason: Typo
#5
Instructor
Thread Starter
Consensus seems to line up on overfilling. I’ve had the car for a little over a decade now. I’m pretty sure I didn’t overfill, but I could be wrong. I’ll take more notice next time.
Can anybody explain the oil on top of the cylinders. I feel like it’s unrelated.
Can anybody explain the oil on top of the cylinders. I feel like it’s unrelated.
#6
Then You have probably overfilled the oil!
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#8
RL Community Team
Rennlist Member
Rennlist Member
The total range of the oil fill on the dipstick may be a quart. The car holds about 12 quarts of oil and ten of them are refreshed at an oil change. With this in mind, I would think if oil registers even at the bottom of the fill range on the dipstick there is no real risk of loss of lubrication due to underfilling the oil on a street driven car. Remember the engine is a dry-sump oil system where there is this big reservoir of oil at all times in the oil tank.
Do others care to comment on this?
Andy
Do others care to comment on this?
Andy
#9
RL Community Team
Rennlist Member
Rennlist Member
Oil most likely leaking out of the intake manifold, dripping through the engine sheet metal onto the cylinders. If the cylinders were leaking it would be wet on the bottom of the engine not on the top of it.
#11
Hopefully not the through bolts, from the state of the inlet manifold I would think a lot has been coming through the resonance flap shaft oil seals, Generic G8x12x3 or Porsche 999.201.371.00 good thread here:- https://rennlist.com/forums/993-foru...-manifold.html
messy on variorams.
messy on variorams.
#13
OP that doesn't look too bad. Through-bolt o-rings are under a great deal of oil pressure so if they're bad you typically get a real oil leak or real dampness, not the kind of built-up crud you have. I had a resonance flap leak on my Vram and it was messy. Thought it was a much worse than the manifold, but it was just that tiny o-ring.
#14
I was interested to hear that the flap bearings can be replaced cheaply as I need mine to be done.
#15
Not the bearings just the seals are cheap (about $3). I got them from a local bearing supplier and they are the identical SKF ones that came out. The oil on those cylinder fins is the typical appearance of oil misting rather than a persistant drip.