another smoking exhaust thread...
#1
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another smoking exhaust thread...
Some of you may know that I do a lot of autocross. I've had white smoke on startup once two years ago when my codriver shut the car off right after a run when the car was still hot. It was also right after an oil change so the level might have been high.
Fast forward to a couple weeks ago; the car had the oil changed before nationals 2 weeks ago and the dash gauge would sometimes show all the bars full depending on the ground it was on but other than that the level seemed good. No smoke at all at nationals.
Today at an autocross, after a few runs I was smelling a burning smell, which at first i thought was my tire blankets melting onto my headers (it wasn't). Then I thought it was the highly modified lotus next to me. At the end of the day when I cranked the car to put it on the trailer, I got a pretty big cloud of white smoke but didn't think too much of it since I figured maybe the oil was a bit full and I didn't let it cool enough before shutting down. When I revved the gas to get it on the trailer likewise it blew a little blue smoke.
Before I cranked it up again to offload, I drained out about 1/3 of a quart I'm guessing (just loosened the drain plug and let it drip into a pan for an hour or so). The oil looked like used oil; dark amber. No smells or coolant contamination. The coolant looks good. Nothing on the dipstick or in the oil fill cap or tube. Digital gauge reading one below full now or at full depending. Cranked it up to offload and same thing big white smoke cloud that cleared up as soon as it cranked. I let it idle for a few minutes and everything seemed normal. I drove it around the neighborhood (20mph maybe) and it was randomly smoking some, bluish/whitish after it would pull away from a stopsign or something and I started smelling the same smell again. Oil didn't even get warm and was 3-4 bar at idle, bouncing a bit. I didn't see any oil leaks under the car but am going to go inspect to see if a valve cover or something is leaking.
I have use of a durametric, a borescope, and a lift although I would rather not crank the car again even to put it on the trailer and take it to the lift. Any suggested troubleshooting steps? Can an AOS inspection be done with the borescope?
Fast forward to a couple weeks ago; the car had the oil changed before nationals 2 weeks ago and the dash gauge would sometimes show all the bars full depending on the ground it was on but other than that the level seemed good. No smoke at all at nationals.
Today at an autocross, after a few runs I was smelling a burning smell, which at first i thought was my tire blankets melting onto my headers (it wasn't). Then I thought it was the highly modified lotus next to me. At the end of the day when I cranked the car to put it on the trailer, I got a pretty big cloud of white smoke but didn't think too much of it since I figured maybe the oil was a bit full and I didn't let it cool enough before shutting down. When I revved the gas to get it on the trailer likewise it blew a little blue smoke.
Before I cranked it up again to offload, I drained out about 1/3 of a quart I'm guessing (just loosened the drain plug and let it drip into a pan for an hour or so). The oil looked like used oil; dark amber. No smells or coolant contamination. The coolant looks good. Nothing on the dipstick or in the oil fill cap or tube. Digital gauge reading one below full now or at full depending. Cranked it up to offload and same thing big white smoke cloud that cleared up as soon as it cranked. I let it idle for a few minutes and everything seemed normal. I drove it around the neighborhood (20mph maybe) and it was randomly smoking some, bluish/whitish after it would pull away from a stopsign or something and I started smelling the same smell again. Oil didn't even get warm and was 3-4 bar at idle, bouncing a bit. I didn't see any oil leaks under the car but am going to go inspect to see if a valve cover or something is leaking.
I have use of a durametric, a borescope, and a lift although I would rather not crank the car again even to put it on the trailer and take it to the lift. Any suggested troubleshooting steps? Can an AOS inspection be done with the borescope?
#2
Race Director
If all the smoking was due to something else I think you'd have the engine acting up showing some symptoms, maybe even have the CEL on with misfire error codes, and possibly making some scary noises.
Reads more like an AOS is failing.
I think you can put the borescope away for another day.
Reads more like an AOS is failing.
I think you can put the borescope away for another day.
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Ratchet1025 (12-05-2020)
#3
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Okay...I'm calling out the big guns for this one and Marky522 is going to help me drop the transmission and do this on a lift. My LN bearing and clutch have less than 30k miles. Not worth messing with?
#4
Race Director
I can't help you regarding the LN bearing. What does LN have to say about a replacement interval, if anything? I'd go by what LN says in this regard.
As for the clutch is it slipping? Does it have a grabby engagement? Making noises especially when the pedal is depressed? These are indications the clutch needs looking at.
There is a call out on the disc wear. Check it. Be sure you check it right. A new disc starts out with 1.7mm of material from its surface to the flanged side of the rivet (at least for my Turbo's clutch). The minimum limit is 0.3mm. Clutch disc wear is not linear so if there's say 1mm of material left the clutch should have more than half its life left. But you track the car and who knows what impact that will have on clutch life so with the tranny out and the clutch exposed you might just consider a new clutch now a cost of tracking. Up to you and your mechanic.
#5
First thing to check is the AOS. Start the car and remove the oil filer cap. Put your hand over the opening to seal it. You should feel the slightest amount of vacuum, hardly detectable. The motor should also change, running a little rough with your hand off the opening. If you feel a lot of vacuum, it's the aAOS.
If not, then another cause of smoke at start up is when you run the car hard and immediately shut it down, the scavenge pumps don
T have enough time to pump the oil out of the heads which results in a smoke cloud the next start up. The fix is to let the car idle for a few minutes after you have driven it hard.
If not, then another cause of smoke at start up is when you run the car hard and immediately shut it down, the scavenge pumps don
T have enough time to pump the oil out of the heads which results in a smoke cloud the next start up. The fix is to let the car idle for a few minutes after you have driven it hard.
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Ratchet1025 (12-05-2020)
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Hooked up the dura metric and did the cap test and all seems well. Drove it this morning no smoke. I admit I did not let it high idle as much as I usually do before shutdown so I think that May have contributed. No smoke today hope it holds out.
#7
Captain Obvious
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You don't need to let it idle before shut down for it not to smoke. Something is wrong. As for the clutch, measure the disk and if its low, just replace the disk and the release bearing leaving the pressure plete and flywheel alone.
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#8
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The high idle before shutdown procedure after "spirited driving" is in the owner's manual.
Transmission won't be coming off and the clutch is still feeling great so forget the IMS bearing / clutch questions.
On a separate note, the car will REALLY launch on 315 width Hoosier A6s on concrete.
Transmission won't be coming off and the clutch is still feeling great so forget the IMS bearing / clutch questions.
On a separate note, the car will REALLY launch on 315 width Hoosier A6s on concrete.
#10
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Went through a similar problem on my race car recently. Perfect leakdown numbers, compression excellent, boroscope came back clean. Replaced the AOS with a Porsche Motorsports one. Hope this does trick. I'll be watching this thread. Good luck.
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The manual isn't handy but the lowest I can get the car to idle by toeing on the gas is about 1800 rpm, and 2 minutes is the prescribed time I believe. Since autocross involves a good bit of idling before and after 60ish seconds of extreme driving, temperature will spike in the grid since you've got no airflow after that minute of hard driving. I'm actually considering bring the durametric to events so I can manually trigger stage 2 fans and engine bay fan while it sits in grid. Normally I'll hit the A/C to get the radiator fans going.
Car's been fine I didn't do anything other than drain out that bit of oil. Apparently the motorsports AOS won't fit on X51 cars due to the aluminum intake taking up too much space in the engine bay. Jake Raby has something in the works but not yet for sale.
Car's been fine I didn't do anything other than drain out that bit of oil. Apparently the motorsports AOS won't fit on X51 cars due to the aluminum intake taking up too much space in the engine bay. Jake Raby has something in the works but not yet for sale.
#13
If all the smoking was due to something else I think you'd have the engine acting up showing some symptoms, maybe even have the CEL on with misfire error codes, and possibly making some scary noises.
Reads more like an AOS is failing.
I think you can put the borescope away for another day.
Reads more like an AOS is failing.
I think you can put the borescope away for another day.
#14
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#15
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^^^ I think the "WHITEOUT" car was the LS3 swap that was sold, and the buyer subsequently crashed and killed himself in...