Slightly oily exhast port - problem?
Thread Starter
Track Day
Joined: Feb 2002
Posts: 21
Likes: 0
From: UK
Slightly oily exhast port - problem?
I've just taken my exhast manifolds off and, looking up into the exhaust ports, I can see five very healthy looking pale brown valves and exhaust ports and one (#3) which looks slightly oily. The car has done 76,000 miles, runs fine and I haven't notice any smoke. Should I be having sleepless nights?
Gordon,
'86 3.2
Gordon,
'86 3.2
RL Technical Advisor
Joined: May 2001
Posts: 11,870
Likes: 75
From: Portland Oregon
Hi Gordon:
I'd be curious to know what your normal oil consumption is but offhand, I'd say that its a valve guide or guide seal issue.
I surely would not worry about it unless you using oil at a quart/600 miles or so.
I'd be curious to know what your normal oil consumption is but offhand, I'd say that its a valve guide or guide seal issue.
I surely would not worry about it unless you using oil at a quart/600 miles or so.
Thread Starter
Track Day
Joined: Feb 2002
Posts: 21
Likes: 0
From: UK
Sorry for the delay in responding, I've just become a dad (got 2 kids now - and still hanging onto the Porsche!).
I hadn't noticed an increase in oil consumption, but then I've done hardly any miles in the last year (resulting from the first child!). I'll try and measure the consumption over the next few weeks and report back.
The thing that worries me most is that it's just one cylinder that is affected. Do you often get valve guides or guide seals going like that? I was thinking about getting a cyclinder leakage test done to see if #3 is down on the others. I have the results of a test carried out a couple of years ago which sowed it was fine at the time.
Thanks for your replies,
Gordon.
'86 Carrera.
I hadn't noticed an increase in oil consumption, but then I've done hardly any miles in the last year (resulting from the first child!). I'll try and measure the consumption over the next few weeks and report back.
The thing that worries me most is that it's just one cylinder that is affected. Do you often get valve guides or guide seals going like that? I was thinking about getting a cyclinder leakage test done to see if #3 is down on the others. I have the results of a test carried out a couple of years ago which sowed it was fine at the time.
Thanks for your replies,
Gordon.
'86 Carrera.
Thread Starter
Track Day
Joined: Feb 2002
Posts: 21
Likes: 0
From: UK
Walt,
Actually, one of the reasons I took the heat exchangers off was to see where my oil leak was coming from. Not a major leak, but enough leave a couple of drops each time the car is parked up.
There is a little bit of oil coming from the joint between the heads and the cam carrier on both sides. This is quite common I'm told. None of the head-to-barrel joints are leaking though.
Just thinking about my problem a bit more...can you actually get oil running down a valve guide and into the exhast port? There would be positive pressure within the exhaust port and the exhaust valve itself is actually sloping uphill (I think)?
-Gordon
'86 3.2
Actually, one of the reasons I took the heat exchangers off was to see where my oil leak was coming from. Not a major leak, but enough leave a couple of drops each time the car is parked up.
There is a little bit of oil coming from the joint between the heads and the cam carrier on both sides. This is quite common I'm told. None of the head-to-barrel joints are leaking though.
Just thinking about my problem a bit more...can you actually get oil running down a valve guide and into the exhast port? There would be positive pressure within the exhaust port and the exhaust valve itself is actually sloping uphill (I think)?
-Gordon
'86 3.2
Advanced
Joined: May 2001
Posts: 64
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From: Green Mountain State (Vermont)
Valve guides can go bad in either the intake, exhaust, or both. The exhast valve leakage will not foul plugs as quickly as an intake valve. I just did a top end as a result of the #6 intake valve going bad. I was fouling plugs in #6 and the consumption was down to about 400 mi/qt. Several oil leaks were found upon disassembly (contributing to consumption).
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Thread Starter
Track Day
Joined: Feb 2002
Posts: 21
Likes: 0
From: UK
Okay folks. I've got a new theory....
Just before replacing the heat exchangers, I had a closer look at the offending port - it still looked wet. I poked my finger in there and it came out smelling of petrol! My theory is this: The engine comes to rest at some point in the cycleand in my case, that is with #3 inlet and/or #3 exhaust cracked open. Any petrol left in the inlet manifold finds it's way to the lowest point and into the #3 cylinder, then out through the #3 exhaust valve. The oil I saw was actually normal carbon deposits soaked in petrol.
What do you think, feasible theory or bullsh$t?
-Gordon
'86 3.2
Just before replacing the heat exchangers, I had a closer look at the offending port - it still looked wet. I poked my finger in there and it came out smelling of petrol! My theory is this: The engine comes to rest at some point in the cycleand in my case, that is with #3 inlet and/or #3 exhaust cracked open. Any petrol left in the inlet manifold finds it's way to the lowest point and into the #3 cylinder, then out through the #3 exhaust valve. The oil I saw was actually normal carbon deposits soaked in petrol.
What do you think, feasible theory or bullsh$t?
-Gordon
'86 3.2
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Could be. Or excess oil from inside the valve guide has leaked down into the chamber after the car has been turned off. I have seen odd oil deposits like these on freshly rebuilt engines that have sat for a while after being run in. The 3.0L in 101 Projects has had this symptom in the past (when it was on jack stands being taken apart for all of the other projects - the engine rebuild was first). The engine runs strong, passes smog with flying colors, and has outstanding compression.
If there are no other symptoms, I wouldn't worry about it. Of course, a simple compression check might give you a few more clues about the rest of the engine...
-Wayne
If there are no other symptoms, I wouldn't worry about it. Of course, a simple compression check might give you a few more clues about the rest of the engine...
-Wayne
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Joined: Mar 2002
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From: Ft. Lauderdale, FL
I had the same problem in a 3.2. Leakdown was great, slight smoking. Problem was a valve guide. I had a similar oil leak and it was the seals of the cam carriers. No big deal.
Best of lucks and congrats on the kids!
Best of lucks and congrats on the kids!