X51 cloud of smoke
06-19-2013, 10:25 PM
#16
Rennlist Member
Thread Starter
No way was my oil overly hot. Relatively cool day, relatively slow, handful of laps - optimum conditions.
Mcaster's scenario certainly sounds impressive but the only problem w/ it is that I have run this track many times at 8 tenths on R-comps for 30 mins. in 95 degree heat and never had this happen. Something has changed. If he is right, is this a real problem or just transient thing that is more an annoyance than something I need to spend a lot of money on?
I'll check w/ Spencer re the oil pan but I'm baffled why an X51 engine would not come w/ the good X51 pan. And, again, that does not explain why I have this problem all of a sudden.
Mcaster's scenario certainly sounds impressive but the only problem w/ it is that I have run this track many times at 8 tenths on R-comps for 30 mins. in 95 degree heat and never had this happen. Something has changed. If he is right, is this a real problem or just transient thing that is more an annoyance than something I need to spend a lot of money on?
I'll check w/ Spencer re the oil pan but I'm baffled why an X51 engine would not come w/ the good X51 pan. And, again, that does not explain why I have this problem all of a sudden.
06-20-2013, 03:03 AM
#17
Race Director
"or you are faster... "
Yea, that must be it! No, actually the contrary - I was out on street tires just to test my brakes, having just replaced the master cylinder, put on braided lines, and fresh SRF. I was going relatively slow. and when I went back out later in the day to check it out I intentionally slowed down, but it still did it.
Also, if it only happens in high-G LH turns, doesn't that weigh against an AOS failure?
Yea, that must be it! No, actually the contrary - I was out on street tires just to test my brakes, having just replaced the master cylinder, put on braided lines, and fresh SRF. I was going relatively slow. and when I went back out later in the day to check it out I intentionally slowed down, but it still did it.
Also, if it only happens in high-G LH turns, doesn't that weigh against an AOS failure?
OTOH, it is not how fast you go per se but how hard you brake and when coupled with the corner's topology this piles up the oil.
You were testing the brakes and thus braked harder and on street tires probably took your time around the turn. Just more of the g-forces and more time for the g-forces to have their affect.
06-20-2013, 05:58 AM
#18
Rennlist Member
Well, you seem to have all the answers to everyone, so why do you bother asking folks?
06-20-2013, 10:18 AM
#19
Rennlist Member
http://www.suncoastparts.com/product...ory_Code=997sp
search around for 996 x51 pan, may be you will find it, it was $150 or so.
heavy smoke at WOT on the straight is with 90% probability a faulting AOS.
06-21-2013, 12:13 AM
#20
Hi All,
FWIW, I was plagued with a similar, frequent/repeatable situation that occurred only under track conditions. Car was fine on the street, once the smoke cleared. (2003 996 C2, X51 oil pan, KWv3, MPSC, performance brake pads, PCA BLACK run-group/BMWCCA Group 1). Sometimes it was pretty mild - resulting in only a 10-15 sec smoke cloud on restart in the paddock. Other times, it showed up as a big puff after a hard corner, when getting back onto the gas. I had the AOS replaced once (even though it passed the manometer test) - didn't solve the problem.
In the course of tracing this, I found that I could minimize the restart smoke (mostly, but not always) by paying attn. to the following:
- ALWAYS check the Oil Level carefully before each track event. Even the slightest overfill would trigger this. I found that I needed to run approx. 2 bars LOW (when checking on the dash 8-bar gauge) under street conditions, to properly account for track heat oil expansion (to FULL 8 bars when HOT). If the dealer just did an Oil Change, you will effectively be running slightly overfull at track temps. Been there, done that... (many times)
- Don't shut the engine off TRACK HOT. I found that by running the car at light load and/or idle for up to 4~5 mins after the cool-down lap minimized the recurrence of startup smoke. I suspect this gives the motor some running time to properly scavenge out all the displaced oil at the heads.
Eventually, when driving back (on the highway) from MMC after a 3-day DE (during which I was black flagged for the big smoke, again... ) I had a CEL show up, which necessitated replacement of 1 bank of the Cat Converter. It probably got fouled by the oil smoke - maybe. That event, I also had a complaint from another driver following me - he saw a wet, oily residue on his windshield while following me through that corner thru the smoke.
Anyway, my hypothesis is that the AOS used in the street M96 motors is simply not able to cope with aggressive track use. Consider that Porsche has a Tech Bulletin on this (for Boxster/Cayman cars) describing this problem, and a revised "Motorsport AOS" as the recommended fix for cars experiencing this problem. "Blue smoke emitted at high cornering speeds" or words to that effect. Do a google search on "Porsche Motorsport AOS" - you should find this Bulletin.
Hope this info helps.
- Sanjeev
FWIW, I was plagued with a similar, frequent/repeatable situation that occurred only under track conditions. Car was fine on the street, once the smoke cleared. (2003 996 C2, X51 oil pan, KWv3, MPSC, performance brake pads, PCA BLACK run-group/BMWCCA Group 1). Sometimes it was pretty mild - resulting in only a 10-15 sec smoke cloud on restart in the paddock. Other times, it showed up as a big puff after a hard corner, when getting back onto the gas. I had the AOS replaced once (even though it passed the manometer test) - didn't solve the problem.
In the course of tracing this, I found that I could minimize the restart smoke (mostly, but not always) by paying attn. to the following:
- ALWAYS check the Oil Level carefully before each track event. Even the slightest overfill would trigger this. I found that I needed to run approx. 2 bars LOW (when checking on the dash 8-bar gauge) under street conditions, to properly account for track heat oil expansion (to FULL 8 bars when HOT). If the dealer just did an Oil Change, you will effectively be running slightly overfull at track temps. Been there, done that... (many times)
- Don't shut the engine off TRACK HOT. I found that by running the car at light load and/or idle for up to 4~5 mins after the cool-down lap minimized the recurrence of startup smoke. I suspect this gives the motor some running time to properly scavenge out all the displaced oil at the heads.
Eventually, when driving back (on the highway) from MMC after a 3-day DE (during which I was black flagged for the big smoke, again... ) I had a CEL show up, which necessitated replacement of 1 bank of the Cat Converter. It probably got fouled by the oil smoke - maybe. That event, I also had a complaint from another driver following me - he saw a wet, oily residue on his windshield while following me through that corner thru the smoke.
Anyway, my hypothesis is that the AOS used in the street M96 motors is simply not able to cope with aggressive track use. Consider that Porsche has a Tech Bulletin on this (for Boxster/Cayman cars) describing this problem, and a revised "Motorsport AOS" as the recommended fix for cars experiencing this problem. "Blue smoke emitted at high cornering speeds" or words to that effect. Do a google search on "Porsche Motorsport AOS" - you should find this Bulletin.
Hope this info helps.
- Sanjeev
06-21-2013, 10:33 AM
#21
Rennlist Member
Thread Starter
"Well, you seem to have all the answers to everyone, so why do you bother asking folks?"
I am answering questions from helpful posters about the facts of my engine, conditions, etc. I don't know what my problem is, or even if it is a serious problem, and we are trying to work through it. Hopefully, this discussion will benefit others as well.
"heavy smoke at WOT on the straight is with 90% probability a faulting AOS"
I have zero smoke at WOT on straights - it happens only at the end of the straight after the 180 degree left hairpin when I downshift for the next turn.
Not finding it, Sanjeev.
I am answering questions from helpful posters about the facts of my engine, conditions, etc. I don't know what my problem is, or even if it is a serious problem, and we are trying to work through it. Hopefully, this discussion will benefit others as well.
"heavy smoke at WOT on the straight is with 90% probability a faulting AOS"
I have zero smoke at WOT on straights - it happens only at the end of the straight after the 180 degree left hairpin when I downshift for the next turn.
Not finding it, Sanjeev.
06-21-2013, 12:23 PM
#22
Rennlist Member
"Well, you seem to have all the answers to everyone, so why do you bother asking folks?"
I am answering questions from helpful posters about the facts of my engine, conditions, etc. I don't know what my problem is, or even if it is a serious problem, and we are trying to work through it. Hopefully, this discussion will benefit others as well.
"heavy smoke at WOT on the straight is with 90% probability a faulting AOS"
I have zero smoke at WOT on straights - it happens only at the end of the straight after the 180 degree left hairpin when I downshift for the next turn.
Not finding it, Sanjeev.
I am answering questions from helpful posters about the facts of my engine, conditions, etc. I don't know what my problem is, or even if it is a serious problem, and we are trying to work through it. Hopefully, this discussion will benefit others as well.
"heavy smoke at WOT on the straight is with 90% probability a faulting AOS"
I have zero smoke at WOT on straights - it happens only at the end of the straight after the 180 degree left hairpin when I downshift for the next turn.
Not finding it, Sanjeev.
The overfill is also an issue reported many times. My shop always says NOT to fill the engine to the top while going tracking, leave min 1-2 bars below full.
06-21-2013, 09:39 PM
#24
"Well, you seem to have all the answers to everyone, so why do you bother asking folks?"
I am answering questions from helpful posters about the facts of my engine, conditions, etc. I don't know what my problem is, or even if it is a serious problem, and we are trying to work through it. Hopefully, this discussion will benefit others as well.
"heavy smoke at WOT on the straight is with 90% probability a faulting AOS"
I have zero smoke at WOT on straights - it happens only at the end of the straight after the 180 degree left hairpin when I downshift for the next turn.
Not finding it, Sanjeev.
I am answering questions from helpful posters about the facts of my engine, conditions, etc. I don't know what my problem is, or even if it is a serious problem, and we are trying to work through it. Hopefully, this discussion will benefit others as well.
"heavy smoke at WOT on the straight is with 90% probability a faulting AOS"
I have zero smoke at WOT on straights - it happens only at the end of the straight after the 180 degree left hairpin when I downshift for the next turn.
Not finding it, Sanjeev.
http://www.renntech.org/forums/topic...-on-a-boxster/
06-30-2013, 05:42 PM
#25
Rennlist Member
Thread Starter
Assuming what I now think is correct, the relief in knowing that there is nothing wrong w/ my car far outweighs the embarrassment that ensues from having to admit it.
I had changed the oil just before the event in question so I started thinking about that being the only difference. I had added 2 "gallon" jugs, which should have left me a qt. low, if what I found online that the S holds 9 qts. is accurate. i saved the jugs to use to return the oil, and checked the labels. Lo and behold, these "gallon" jugs hold 5 - repeat - 5 qts. So I added 10 qts, 1 too many.
Do you think the extra qt. was enough to cause this problem? And that draining a good qt. is all I need to do?
I had changed the oil just before the event in question so I started thinking about that being the only difference. I had added 2 "gallon" jugs, which should have left me a qt. low, if what I found online that the S holds 9 qts. is accurate. i saved the jugs to use to return the oil, and checked the labels. Lo and behold, these "gallon" jugs hold 5 - repeat - 5 qts. So I added 10 qts, 1 too many.
Do you think the extra qt. was enough to cause this problem? And that draining a good qt. is all I need to do?
07-01-2013, 03:58 AM
#26
Rennlist Member
Assuming what I now think is correct, the relief in knowing that there is nothing wrong w/ my car far outweighs the embarrassment that ensues from having to admit it.
I had changed the oil just before the event in question so I started thinking about that being the only difference. I had added 2 "gallon" jugs, which should have left me a qt. low, if what I found online that the S holds 9 qts. is accurate. i saved the jugs to use to return the oil, and checked the labels. Lo and behold, these "gallon" jugs hold 5 - repeat - 5 qts. So I added 10 qts, 1 too many.
Do you think the extra qt. was enough to cause this problem? And that draining a good qt. is all I need to do?
I had changed the oil just before the event in question so I started thinking about that being the only difference. I had added 2 "gallon" jugs, which should have left me a qt. low, if what I found online that the S holds 9 qts. is accurate. i saved the jugs to use to return the oil, and checked the labels. Lo and behold, these "gallon" jugs hold 5 - repeat - 5 qts. So I added 10 qts, 1 too many.
Do you think the extra qt. was enough to cause this problem? And that draining a good qt. is all I need to do?
07-02-2013, 04:16 PM
#29
Drifting
Too much oil will affect the longevity of your AOS so keep an eye on that and drain the oil to the proper level as soon as possible. BTW, did your oil e-gauge indicate that you were over the full mark. I suppose it may not provide the correct readings since you have a 3.8 engine in a Cayman? You can drain about ~1/2 quart at a time by removing the oil filter housing... the rest should not come out.
