Thumper Posted February 23, 2005 Share Posted February 23, 2005 When I dynoed my car I found out my valve cover gasket is leaking and on the exhaust manifold side I have some blue smoke that rises after a pull. The valve cover gasket is fairly new but i'm going to try and replace it anyways, making sure I remove all old gasket material. I have already replaced my pcv valve just incase. I think it is either blow-by from piston rings or a blown head gasket with a bad valve cover gasket. I did a compression test and it was 75psi on one gauge but 105 on another. Both gauges are in question of accuracy. I also checked my oil and there is no water on the dipstick or when I drained it. So what do you guys think blown HQ, piston rings, or just a bad valve cover gasket. Thanks for your help. Ted Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted February 23, 2005 Share Posted February 23, 2005 I am betting cracked ring lands. It is a pretty common thing. Many of us have been in your shoes before ... Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted February 23, 2005 Share Posted February 23, 2005 not really enough details there... first off, when you compression tested you did all six cylinders? and they all got about the same numbers? Given that you dont trust the accuracy of the gauges, I wouldn't look at the number, but rather, just look at the spread. The rule of thumb is that the lowest cylinder reading should be within ten percent of the highest reading... so if you're reading from 90-100 across all cylinders, I would think you are okay, even though the general number is pretty low. Anyways, if you have a blown headgasket, you almost always will have one or two cylinders will read much lower than the others (if two they will be adjoining which means it's blown in between those two). It's also odd that you're seeing smoke coming from the area of the head/exhaust manifold... unless your manifold bolts are loose or the manifold gasket is not sealing right? Or you mean the smoke is coming out from the valve cover where the gasket is leaky? Where exactly is your valve cover gasket leaking from? Maybe a stupid question, but is it leaking on the side of the manifolds? Maybe oil drips down onto the manifold and burns off as blue smoke? If your rings or ringlands were bad, you should be noticing smokes (puffs or constant) from the tail pipe. If you're rings were bad, you wouldn't necessarily get low readings on the compression test... I had bad rings, really smoky engine, but compression test showed 145psi all the way across... you need a leakdown test to really tell if your rings are bad unless they are REALLY bad. You might just be getting normal blowby... even after rebuilding my engine top to bottom, I get some smoke coming from the valve cover breather (open with a K&N filter on it), especially when it's being run on the dyno, you can see some puffs coming from there. If you dont have any smoke in your exhaust and no watery oil at all and your compression readings are consistent across all six cylinders you probably dont have anything to worry about. Quote Link to comment Share on other sites More sharing options...
Thumper Posted February 23, 2005 Author Share Posted February 23, 2005 Sorry I was in a rush to type it so no details. When I did the compression test all cylinders showed the same psi within 5psi. I also did them mutliple times. Actually the numbers were 90psi on the first gauge and 105 on the second gauge. On mikes (on3go's), a week old motor, got 75psi on the first gauge on all six cylinders. As far as I can tell the valve cover gasket only leaks in the front passenger side area right above the power steering bracket or alternator. But when I dynoed the car I did notice blue smoke come off of my exhaust manifold from an unknown source after a pull. I do not see a valve cover leak or any other leak in that area. Has anyone else noticed what bastaad525 says about even a rebuilt engine has a small amout of blow-by. Thanks for your time. Ted Schmidt Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted February 27, 2005 Share Posted February 27, 2005 I'm not even 100% sure that this smoke is blowby... I mean... every car I've ever owned, if I opened the oil filler cap after driving it, I would see a little bit of smoke come out of there... I mean very little you know? Anyways, since no one else answered I will say, I panicked the first time I saw this smoke come out of the breather filter on the valve cover as well, and asked about it here, and was assured by a few other guys here that a little bit of smoke from there (think a lit cigarette just sitting there burning, and maybe cut that amount in half) was normal. If all your compression numbers came up within 5psi I can almost guarantee you dont have a blown HG. And if you're not getting any oil smoke (blue smoke) from your exhaust (tail pipe) then I can almost guarantee you dont have bad rings either or valve stem seals (another common cause of smokey exhaust) either. Sounds to me like you have an oil leak somewhere and it's getting onto your exhaust. Or maybe a cracked/damaged PCV hose somewhere allowing a bit of smoke to escape? OH I just thought of one other thing you should check... the turbo oil drain hose! This is like a 3" long section of hose that connects the turbo drain to the oil pan. When I first installed the motor, this hose had a crack in it, really bad, but it was right at the top of the hose, so very little oil actually leaked from there even with the car running, but man sometimes I would get a LOT of smoke until I finally found that crack. Also check all your fittings supplying oil to and from the turbo and be sure they are all tight and no obvious leaks there. Quote Link to comment Share on other sites More sharing options...
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