Smoke at idle
09-12-2011, 09:53 AM
#31
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Because of this I made a PCV-system on my car like many other turbo-cars have. This is a valved connection between the intake manifold and the cranckase. The PCV-valve opens and lets some vacuum to the cranckase when there is vacuum in the manifold, and closes when there is pressure in the manifold (we do not want pressure in the crankase). I have driven with this about 3000 miles now, and I have not had any smoke at idle at all.
I've been entertaining the thought of adding a PCV valve as you describe so that I can get the 20 psi of vacuum that my intake manifold registers at idle. If that doesn't create enough vacuum through the turbo to drain excess oil, I don't know what will. As Dave suggests, I suspect that I still need to replace that turbo oil drain vacuum elbow to the AOS, I doubt it's sealing much at all right now, but it sure is a PITA to get to and replace!
I've asked for Chris White's help on this too, I hope he'll weigh in with his expert opinion soon. Sounds like many 951'ers will benefit in a resolution to this problem.
09-12-2011, 10:00 AM
#32
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Eric, You having 10 time more smoke makes me think you might have a head gasket leak. Mikjel, how did you make a pcv valve? And is this the only alternative to putting a small vacuum cleaner under the hood and wiring it into an inverter? Yes I am getting that desperate. I will have to try the vaCuum cleaner trick when I get the car together. Maybe C Anderson or Matt could try this too. My car should be back together this week. If it still smokes I will vacuum the oil filler.
09-12-2011, 10:06 AM
#33
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Mikjel, thanks for the crankcase vacuum test ideas - I am going to try your plastic wrap over the fill tube and see if I have slight positive pressure, I suspect I do. I completely agree that these MAF systems nearly (or completely) eliminate vacuum in the tree pipe - how could there possibly be vacuum at that point when there is a HUGE cone filter just 7" away?
I've been entertaining the thought of adding a PCV valve as you describe so that I can get the 20 psi of vacuum that my intake manifold registers at idle. If that doesn't create enough vacuum through the turbo to drain excess oil, I don't know what will. As Dave suggests, I suspect that I still need to replace that turbo oil drain vacuum elbow to the AOS, I doubt it's sealing much at all right now, but it sure is a PITA to get to and replace!
I've asked for Chris White's help on this too, I hope he'll weigh in with his expert opinion soon. Sounds like many 951'ers will benefit in a resolution to this problem.
I've been entertaining the thought of adding a PCV valve as you describe so that I can get the 20 psi of vacuum that my intake manifold registers at idle. If that doesn't create enough vacuum through the turbo to drain excess oil, I don't know what will. As Dave suggests, I suspect that I still need to replace that turbo oil drain vacuum elbow to the AOS, I doubt it's sealing much at all right now, but it sure is a PITA to get to and replace!
I've asked for Chris White's help on this too, I hope he'll weigh in with his expert opinion soon. Sounds like many 951'ers will benefit in a resolution to this problem.
09-12-2011, 10:08 AM
#34
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To create add PCV to our engines, I'm thinking about using a 3/4" tee to tap into the line where the idle air control valve connects to the IC line just before it enters the throttle body. I can find a standard PCV valve at my local Autozone, connect it to that tee, and run a hose back to my AOS or my LR oil can. Seems like that would do the trick?
Something like this:
Found here:
Something like this:
Found here:
09-12-2011, 10:08 AM
#35
I am also desperate about this, my engine has been smoking at idle since first start up.
What kind of PCV do people here use? I find zero info on what crankcase pressure/vacuum should be!
What kind of PCV do people here use? I find zero info on what crankcase pressure/vacuum should be!
09-12-2011, 10:33 AM
#36
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This "Turbo Drain Vent Hose" from LR replaces it, but you have to first cut the fitting off the metal tube, which will be very difficult with the heat shields in place. This is under the intake manifold.
09-12-2011, 10:54 AM
#37
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Special Tool has some great stuff on this issue, such as:
https://rennlist.com/forums/2258087-post23.html
https://rennlist.com/forums/2258087-post23.html
09-12-2011, 10:54 AM
#38
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Last edited by zerMATT951; 09-12-2011 at 11:54 AM.
09-12-2011, 11:19 AM
#39
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Eric, You having 10 time more smoke makes me think you might have a head gasket leak. Mikjel, how did you make a pcv valve? And is this the only alternative to putting a small vacuum cleaner under the hood and wiring it into an inverter? Yes I am getting that desperate. I will have to try the vaCuum cleaner trick when I get the car together. Maybe C Anderson or Matt could try this too. My car should be back together this week. If it still smokes I will vacuum the oil filler.
09-12-2011, 11:25 AM
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Thom welcome to the exclusive Smoke at Idle club. I appreciate everyones insight. I think we are starting to get somewhere. I am not sure we all have the same smoke problem but It would be nice if some of you out there could run the vacuum cleaner trick as mentioned in previous post by Mikjel from Norway.
Matt thanks for the photo of the elbow tube. I will have to look at that later.
Mikjel could you post some pictures of your custom PCV valve that Matt is attempting to make himself. Just so we head in the right direction with this.
Matt thanks for the photo of the elbow tube. I will have to look at that later.
Mikjel could you post some pictures of your custom PCV valve that Matt is attempting to make himself. Just so we head in the right direction with this.
09-12-2011, 11:28 AM
#41
Thanks for the welcome, but though I'm sure you are all of great company I would rather have not entered that club!
Anyway, I may have an idea.
Anyone knows, when the engine idles (TB closed), if the vacuum pre turbo inlet is superior or inferior to the vacuum in the intake pipe?
I feel that vacuum in the intake should always be superior (otherwise Mikjel solution wouldn't have worked), but I'm not sure?
Anyway, I may have an idea.
Anyone knows, when the engine idles (TB closed), if the vacuum pre turbo inlet is superior or inferior to the vacuum in the intake pipe?
I feel that vacuum in the intake should always be superior (otherwise Mikjel solution wouldn't have worked), but I'm not sure?
09-12-2011, 11:35 AM
#42
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Thom, follow Mikjel PCV solution.. Some cars have higher crankcase pressure, and need to pull vacuum to allow the turbo to drain.. I ran this test with Mikjel: use a shop vac to pull vacuum through the oil fill tube (after removing the cap). It'll take the engine a minute or two to clear up. If it does, you need a PCV setup to work while the engine is at idle. (Make sure you use a one way valve to restrict boost from entering the crankcase). ..