280zedx Posted November 11, 2004 Share Posted November 11, 2004 I blew the head gasket and was wandering if the oil residue that's gunked up on the pistons is from this or did it help cause this? http://img.photobucket.com/albums/v186/280zedx/passengerside.jpg http://img.photobucket.com/albums/v186/280zedx/piston6.jpg http://img.photobucket.com/albums/v186/280zedx/piston3and4.jpg http://img.photobucket.com/albums/v186/280zedx/intake.jpg My block breather pipe was dripping when i pulled it out and there's a fair bit of residue in the intake runners as well. The piston tops are wet and you can see trace amount of antifreeze in the cylinder, would this cause the sludge on the pistons? Am i sucking in too much oil fumes from the crank vent? I've removed the hose between the valve cover vent and intake and maybe now with the added SC boost it's sucking in too much? (I'm hoping this would also help explain the blown HG, besides me pushing it too hard without solid tuning -haha) All that residue can't be good could it? Not sure how you tell if your PCV is working right. It's designed to let this oily air blow into the intake isn't it? How much is too much? (oil residue) Also when i drained the oil it was black as molasses (only a few hundred miles on Castro Syntec, and second oil change since rebuilt). would this be caused by the bit of antifreeze in the combustion chamber or could this also be caused by ring blow-by? Because i did everything myself and everything for the first time i worry! What i need is someone with experience to tell me what is normal and what is not. thanks- -i really didn't want to be doing this- damn that head gasket and curses at my own stupidity! Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 12, 2004 Share Posted November 12, 2004 If you're oil is going black that fast, that is a sign of a lot of blowby... the carbon is polluting the oil. I'm not sure if that would also result in getting excess oil in the intake and cylinders. Excess oil in the intake is usually a sign/symptom of a bad turbo oil seal or bearing, but that's easily confirmed by checking for oily residue in whatever pipes you have running from your compressor outlet to your intake, and also oily build up in the I/C if you're running one. Then again I just realized you said SC, not turbo... so... I'm at a loss If it is coming in thru the PCV system, the simple solution would be to either run a catch tank inline with the PCV system and keep it intact... or of course you can just run open breather filters on the vents, but if it's spitting out that much oil, it's going to end up all over your engine, and you'll get some fumes from it as well probably. A lot of oil in the intake can DEFINATELY contribute to detonation. Quote Link to comment Share on other sites More sharing options...
Guest 240zJake Posted November 12, 2004 Share Posted November 12, 2004 Could it be leftover oil from the build up? Howmany miles are on this engine? Quote Link to comment Share on other sites More sharing options...
Guest Magnum Rockwilder Posted November 12, 2004 Share Posted November 12, 2004 It's either from bad rings, bad valve seals, or a faulty PCV system. Oil lowers octane greatly, so it's not a good thing. Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 13, 2004 Author Share Posted November 13, 2004 damn i hope its not the rings. They all seem to have pretty much the same buildup more or less, if it's a bad set of rings or valves then shouldn't a peticular cylinder should be worse than the others? (unless all 6 of them are bad and if that's the case then i'm an idiot who needs to find a better hobby!) Once the heads back on then a compression test should also reaveal this. I'm still wondering if the black oil was caused by the antifreeze breaking down the viscocity, i also had some real rich tuning sessions in the beginning as well. Its not break-in lube, i did the first change after about 5 hours of engine run and have since put on maybe a thousand miles. Does anybody know how the PCV system works? I know the valve cover breather that connects near the AFM (which has been replaced with a valve cover air filter) is a heated debate over its importance (lot's of people have removed it with no negative affects). Would it change the vacuum/pressure that the PCV valve sees? Also, when is that valve supposed to be open? If it was sticking then how would it add oil residue to the intake if that is where it is supposed to dump the crank air pressure anyways? I think i'll put it together, check compression, flush some fresh oil though it, and try a catch tank inline to see how much is coming out there. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 13, 2004 Share Posted November 13, 2004 Okay, #1, a compression test will not always reveal bad rings. I recently had to rebuild the bottom end of my motor... it was smoking like crazy, burning oil, oil on all the spark plugs when I checked them... I did a compression test and got an even number (140psi I think) all the way across. But after checking everything else (valve stem seals, turbo seal) we figured it HAD to be the rings. Rebuilt ONLY the bottom end, and sure enough the smoking and oil in the cylinders stopped. So the rings were definately bad, even though the compression test showed all was well. A leakdown test would probably be an accurate indicator though. #2 a blown HG and coolant in the oil wont cause it to turn black, rather, it will cause it to turn a milky brown or green, like coffee with 3 creamers in it. Black oil means carbon contaminates in the oil (old oil or lots of blowby), or can possibly mean abnormal or extreme internal engine wear. #3 with the PCV system, I'm not sure exactly what debates you've read... but I'm sure most everyone here agrees it's really an all or nothing thing. In other words, ALL = you run the PCV system fully intact, with both the valve cover and block breather vents connected in their stock (or approximate) locations. Or NOTHING = Leave them BOTH open. If you leave only one open, with the other routed to the intake, you will end up with unmetered air entering your system (basically a vacuum leak). Yes your motor will still run okay this way... you may not notice a thing, but there WILL be a vacuum leak there and you dont want that. With either method, a catch tank is a good addition, either to keep the intake or the sides of your engine clean of the oily residue that your engine is constantly fuming. And dont' block either one of them off, as this can cause excess pressure to build up in the engine and that pressure can ruin main seals or gaskets in a hurry, literally 'blowing them out'. The PCV system is there for exactly what it's name suggests... to ventilate the crankcase. Under vacuum, the PCV valve opens, and air follows this path - air passes thru the air flow meter and is measured -> a small amount of this air is diverted thru a hose into the valve cover vent -> this air circulates it's way down into the crankcase, picks up some of whatever blowby/dirty air/oil steam is there -> then gets sucked out of the block breather vent thru a hose and thru the open PCV valve into the intake, to be burned along with clean air in the combustion process. With any motor running a PCV system... the motor being 100% sealed becomes important, as removing the oil dipstick while the engine is running or even having a leaky engine gasket for instance will allow unmetered air to get sucked into the crankcase and then in thru the PCV valve to be burned in the combust process, causing your motor to run leaner. I want to say this is an emissions thing, but of course, PCV systems are present even on pre-emissions cars. So I'm not really sure why the engine designers want your engine to suck up this oily dirty air. Especially since in many cases it can actually be harmful to the engine, causing all that oily buildup in the manifold, deteriorating seals and gaskets and hoses and such, and of course possibly causing detonation. Running open filters on both vents will allow the dirty air and any blowby pressure to exit the engine freely (all over the sides of your engine if you dont use a catch tank). When running open filters, you don't need to worry about the engine being sealed... heheh well of course... leaky gaskets will still suck because they're leaking all over the place! But lets say you had an oil dipstick that didn't seal well... it wouldn't cause a vacuum leak with this setup. I like the open setup better for it's simplicity... just gives you less to worry about. Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 13, 2004 Author Share Posted November 13, 2004 thanks, great info. In my case the unmetered air isn't an issue since i don't have the AFM (megasquirt). I'll definately look for a catchtank for the crank breather and i can assume i can block off the PCV valve completely on the intake? I guess i'll just have to settle for bad rings/blow-by. There's no sense doing the bottom end until it gets worse (it's not smoking at all). So i'll just start using cheaper oil (non-synthetic), changing it more often and trying to add more boost to push the limit, heh heh. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 13, 2004 Share Posted November 13, 2004 don't get me wrong... I'm not trying to predict bad rings at all... just saying don't rely on the compression test to tell you for sure. Just get it all back together, run both vents open and see what happens then. If you do start getting smoke, or getting oil on the spark plugs... then you know something else is up. By the way... no matter what you do, the oil in a turbo motor will get dirty faster than on a non turbo car... but you still shouldn't have to change it more often than every 3k miles if it's just a street driven car. I'd say stick with synthetic, and running a good filter is VERY important... no Fram crap. yes if you run open filters on both breather vents, just block off the PCV valve or better remove it and just put a plug/bolt with some thread sealer in there. Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 13, 2004 Author Share Posted November 13, 2004 i think your probably right about the blowby. I never redid the bottom end totally, just glazed it with new rings and stuff, i am measuring about a 2thou difference with a feeler gauge and an old ring between the top area of the cylinder and the top of the piston (dirtiest one at bdc). That and the added boost is probably causing some blow-by, combined with the extra oil fumes from the crank vent would explain the oil buildup. The only thing to do...add more boost! haha Would a specific oil vescosity help with the blow-by? Would a little heavier oil limit it a bit? Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 14, 2004 Share Posted November 14, 2004 I recently isntalled new rings and bearings as well... a backyard rebuild I did with help from friends with the motor still in the car even. With the new rings, I notice I do get a bit more smoke from the valve cover breather than I would expect to be normal... I figure maybe because my broke/lazy ass didn't hone the cylinders, the seal is probably not like brand new. I will say, the cylinder walls did look perfect when I was doing the job...... no scratches, but whos to say if they were at all out of round. I didn't care because even if they had been, there wouldn't have been a damn thing I could do about it anyways. Well the motor runs great, puts down great power, right where it should be given my setup, and except for that bit of smoke, everything else checks out okay with the new rings... compression is good, spark plugs are clean, and no smoke from the exhaust. Sounds like you're in the same position I was... yeah... I say... just put it back together and run it, if it breaks it breaks and well... just fix it some more... by then you'll have more money right? Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 14, 2004 Author Share Posted November 14, 2004 well i put it all back together with a temporary makeshift crank vent filter. Started up fine but idled leaner than before, maybe due to the lack of PCV valve (bolted shut). A little tweak in Megatune and she was back to normal. I only did a couple of blocks to check it out, plates have expired, 0 degrees and winter coming, but it ran pretty good. I babied it a fair bit but it was still good and snappy...gotta love the supercharger. Now i can move on to the bigger and better things to work on like rewiring the dash electronics and more boost. thanks all for the insight into my first (and hopefully last....for a while) blown headgasket. Quote Link to comment Share on other sites More sharing options...
Kazuya1274 Posted November 19, 2004 Share Posted November 19, 2004 Bastaad, If it makes any difference, I did run my lower PCV hole from the block back into the intake before the turbo, and left the top one on the valve cover open. It ran fine like this for quite a while. I think you can get away with routing one back into the intake, but I had bad luck routing BOTH back into the intake. Now I'm running both open, and plan to use a catch can. Do you know how it would run if I put both the block PCV and the valve cover PCV hoses into the same catch can? Or should I just run the block hose into the catch can? Quote Link to comment Share on other sites More sharing options...
Guest Cronic Posted November 19, 2004 Share Posted November 19, 2004 I see a couple of strange things here. First the crap on your pistons is shit left over from burn in the chamber, it could be charred pistons from detonation, could be crap and dirt your intake has sucked in, could be lots of stuff. You really should try to sand some of it off, and clean those pistons up as much as possible. Second, why is there an NA header on there? I thought this was a turbo motor? About the rings and good compression. The reason that shows up good compression, and the car burned oil is because the oil rings were bad, probably didnt seat, or were installed improperly. The compression rings had seated fine, which is what holds the compression. Edit -- Never mind, I just read you're S/C'd. That could have lots to do with detonation. Are you running a cooler? Quote Link to comment Share on other sites More sharing options...
280zedx Posted November 27, 2004 Author Share Posted November 27, 2004 i was "playing" with detonation a number of times while setting up my megasquirt settings, not good-i know. what can i say...i'm learning. Yes it's intercooled and yes i cleaned them up good before i put it back together. There is that chance that my oil rings didn't seat well also. -We can only patiently wait till spring.... Quote Link to comment Share on other sites More sharing options...
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