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Finally got my 73' 240z started a couple of days ago and I have some problems. I have a significant amount of smoke streaming out of my valve breather and my pcv. My engine idles fine and runs strong, other than this smoke. Over the last couple months have rebuilt my triple webers, installed a new header, gone through the whole fuel system ,etc..the car also has a different cam, What's going on? Is this normal? The cam also seems a little loud. Does any body have any ideas before I decide to rip the head off. I will also note the car has sat for approx. 3yrs prior to this.
 

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With all the repairs / modifications you've done it may be that this is a totally banal and inane question, but here goes; How old is the oil in the engine? Is this the same oil that sat in the engine for 3 years?

If you just recently did the cam work, and did change the oil at that time, did you use some sort of extra thick or different kind of "break in" oil?

I'm not a mechanic, but these are the questions that come to my mind right away. I'm sure the engine guru's will come up with more.
 

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It may be a broken ring or worn rings & bore.
This type of smoking is called by blow by.The best fuel system
will make no difference.
Cheers DavidU.(aust)
 

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Where do you have the pcv and vent out of the side of the engine plumbed? You should run the vent from the engine left side up to a pcv valve screwed into the intake manifold. You very well may see some blowby coming out of the valve cover vent too. It actually should be plumbed into one of the air filters but with the Webers you likely don't have a hole there so you are running a small clamp on filter? If you don't have the pcv attached to the side vent you may have an overpressure that is not being corrected the way it should be by pcv. The idea is to suck some of the fumes out of the crankcase, or they will pressurize and come back out of the breather.
 

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Adjust valves and do a blowby test.

Blowby test, you get an adaptor for an air compressor, bring each cyl to TDC, pump the cyl full of air, see how fast it leaks out, and use a stethescope to listen to where its coming from.

Hopefully your valves just need an adjustment, but for some reason I doubt thats the case.

I dont know how worn rings would cause smoke to come out of the valve breather. Usually smoke coming out of there indicates a valve problem.
 

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would really bad valve guides and worn rings cause this? the oil gets into the cylinder and gets blown by into the crankcase?


kwon is there smoke coming out of the real of the car also?
 

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hello do you have a new pcv valve ??? take it out and check it i may be clogged ??? my car did the smoke thing out of the valve cover and pcv and it turned out to be a clogged exhaust down tube.. the gasket was out of place..once i replaced that..all ok...check your exhaust for free flow??? if it's not your going to get exhaust backed up into the engine and it will excape anywhere it can...hope this helps... michele
 

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smoke or steam?

If you've got foamy stuff on your dipstick, then it could be coolant in the oil (or condensation) boiling in the engine. Smells nasty, and it's messy!
Nathan
 
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