smoke on start up..
05-17-2005, 12:13 PM
#2
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Would not be concerned yet. If you use lighter grade oil like 0-40 then I would not worry at all. Keep an eye on your oil level.
Use the dipstick not the gauge.
Use the dipstick not the gauge.
05-17-2005, 06:09 PM
#6
If you are getting blue smoke whenever you start up (multiple times throughout the day or only during the initial start-up each morning) then you may be looking at worn valve guides. If you are only seeing blue smoke after the car has been sitting for a few weeks, then you have nothing to worry about (typical).
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05-17-2005, 08:11 PM
#8
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Its a normal ocurrence on flat (H pattern) engines. Residual oil gets past the rings and into a chamber. Gets burned at startup. Ok if it happens after sitting around. Definitively not OK if after warmup or at every start. BMW flat twins were embarrasing after leaning on the sidestand. Smoke looked like a M1 tank smoke screen. Not very cool at the hard rock café, LOL. I understand they included locating webs in the grooves to ensure ring gap faced upwards.
05-18-2005, 05:00 AM
#9
One way I have seen mechanics here in the UK test for worn valve guides is to drive the car till its warm, then let it idle for a minute or so before giving the car a few hefty consecutive revs in neutral and watch for more smoke over the next 10-30 secs when car is idling....its not scientific but I have seen it used as an indicator....
05-18-2005, 08:11 AM
#10
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Originally Posted by Korny993
with only 25K on the clock could the valve guides be worn that quick? Only noticed the smoke this AM
Another cause might be excessive oil level. The correct level is mid-gauge. Too much oil can be drawn back into the engine intake and coat the intake path. Again, as the car sits, oil can migrate downward and into the engine. I believe this was an issue with the 964 and I assume it can happen to the 993.
Some questions for you. Do you still have the under tray mounted beneath the engine? It is a black plastic noise shield.
Where do you live/drive?
As a matter of course, remove the black engine under tray. Porsche put those on to meet engine noise standards in Europe. Remove it and hang it in the garden shed.
Valve guide wear is mainly due to heat. The under tray traps heat and accelerates the wear. Also, if you live in a hot climate, then you are adding more heat.
While the puff of smoke is a sign, a better barometer would be oil consumption. Monitor the amount of oil that you consume from oil change to oil change. Since the oil resides in multiple places within the car, the best way is to keep an eye on the dipstick level just before and after an oil change. If you are using more than a couple of quarts every 3K or so miles you are probably okay, but more than that is due to valve guide wear.
Porsche specifies oil usage to a maximum of 1 quart every 600 miles. That is really too much if you are consuming it at that rate. I would start getting concerned when you approach one quart every 1200 or so miles.
Worn valve guides have dire consequences if left untreated. The valve guide clearance is critical to scavenging heat away from the valve and valve stem.
If excessive guide wear exists, the valves will not stay cool enough and the stem will wear. This, in turn, will start a positive feedback loop. As wear continues, the heat gets worse and the process accelerates. Eventually the valve fails by snapping and it will drop into the cylinder. A loose valve head will find no room to live inside the cylinder and will catastrophically destroy the engine.
Marv
05-18-2005, 08:26 AM
#13
Burning Brakes
ok, obviously getting stuck in traffic for 3 hours a day to cover 40 miles will affect the recommended consumption levels, but it looks like my car uses relatively little. I am still worried about the guides though. Sorry to kind of hi-jack.
05-18-2005, 09:26 AM
#14
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Originally Posted by Marv
Yes, it is possible. The smoke is typically due to oil seeping past the seals and guides into the engine. Normally the seals will stop it, but worn guides tend to wear the seals, too.
Another cause might be excessive oil level. The correct level is mid-gauge. Too much oil can be drawn back into the engine intake and coat the intake path. Again, as the car sits, oil can migrate downward and into the engine. I believe this was an issue with the 964 and I assume it can happen to the 993.
Some questions for you. Do you still have the under tray mounted beneath the engine? It is a black plastic noise shield.
Where do you live/drive?
As a matter of course, remove the black engine under tray. Porsche put those on to meet engine noise standards in Europe. Remove it and hang it in the garden shed.
Valve guide wear is mainly due to heat. The under tray traps heat and accelerates the wear. Also, if you live in a hot climate, then you are adding more heat.
While the puff of smoke is a sign, a better barometer would be oil consumption. Monitor the amount of oil that you consume from oil change to oil change. Since the oil resides in multiple places within the car, the best way is to keep an eye on the dipstick level just before and after an oil change. If you are using more than a couple of quarts every 3K or so miles you are probably okay, but more than that is due to valve guide wear.
Porsche specifies oil usage to a maximum of 1 quart every 600 miles. That is really too much if you are consuming it at that rate. I would start getting concerned when you approach one quart every 1200 or so miles.
Worn valve guides have dire consequences if left untreated. The valve guide clearance is critical to scavenging heat away from the valve and valve stem.
If excessive guide wear exists, the valves will not stay cool enough and the stem will wear. This, in turn, will start a positive feedback loop. As wear continues, the heat gets worse and the process accelerates. Eventually the valve fails by snapping and it will drop into the cylinder. A loose valve head will find no room to live inside the cylinder and will catastrophically destroy the engine.
Marv
Another cause might be excessive oil level. The correct level is mid-gauge. Too much oil can be drawn back into the engine intake and coat the intake path. Again, as the car sits, oil can migrate downward and into the engine. I believe this was an issue with the 964 and I assume it can happen to the 993.
Some questions for you. Do you still have the under tray mounted beneath the engine? It is a black plastic noise shield.
Where do you live/drive?
As a matter of course, remove the black engine under tray. Porsche put those on to meet engine noise standards in Europe. Remove it and hang it in the garden shed.
Valve guide wear is mainly due to heat. The under tray traps heat and accelerates the wear. Also, if you live in a hot climate, then you are adding more heat.
While the puff of smoke is a sign, a better barometer would be oil consumption. Monitor the amount of oil that you consume from oil change to oil change. Since the oil resides in multiple places within the car, the best way is to keep an eye on the dipstick level just before and after an oil change. If you are using more than a couple of quarts every 3K or so miles you are probably okay, but more than that is due to valve guide wear.
Porsche specifies oil usage to a maximum of 1 quart every 600 miles. That is really too much if you are consuming it at that rate. I would start getting concerned when you approach one quart every 1200 or so miles.
Worn valve guides have dire consequences if left untreated. The valve guide clearance is critical to scavenging heat away from the valve and valve stem.
If excessive guide wear exists, the valves will not stay cool enough and the stem will wear. This, in turn, will start a positive feedback loop. As wear continues, the heat gets worse and the process accelerates. Eventually the valve fails by snapping and it will drop into the cylinder. A loose valve head will find no room to live inside the cylinder and will catastrophically destroy the engine.
Marv
wow! good info. btw, where are located in Dayton are you located? Not many Rennlisters in this part of the world.
05-18-2005, 10:08 AM
#15
Rennlist Member
Sorry to pip in on the Dayton thread - are either of you at LexisNexis (50% chance of this being the case?)? If so I'll give you a shout next time I visit.
Cheers,
David
Cheers,
David