c4220 Posted April 28, 2009 Share Posted April 28, 2009 The last time that I had my Z on a track I experimented with letting the engine spend more time near 6400 RPM than typical to avoid making and up shift and immeadiatly followed by a down shift for a corner. After the session was over (30 min, 2.4mi 15 turns per lap) I opened my hood to find oil sprayed all over the engine compartment. Since a little oil can go a long way we are ony talking about an ounce or two of oil lost. It appears the source is the filter breather that I have on my valve cover. So it appear there was positive pressure in the crank case. I checked the PCV valve. It is free and clear. Important modification info may inculde megasquirt II Turbo oil pump 14 psi hot at idle 50 psi hot 2000RPM ~80 psi hot above 3000RPM Head was ported and hot tanked within 5000 Mi Head drains verified clear of abstruction Mobil 1 full syntethic 10W-30 If more info on current build is need let me know. I have a desire to modify this build to utilize a shift point between 7000-7500 RPM It appears this problem wil get worse with RPM so I am very interested in a cause and solution to keep all of my oil in the engine. Thanks, Chris Quote Link to comment Share on other sites More sharing options...
burninator Posted April 28, 2009 Share Posted April 28, 2009 You should probably do a leak down test to see if you loosing pressure through your valves. It seems like that's the only way positive pressure could get into your valve cover. Someone will probably chime in to let me know how wrong I am, but the PCV valve should just vent the crank case. On my car I don't think there is any way for air to get into the valve cover from the crank case. Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted April 28, 2009 Share Posted April 28, 2009 You should probably do a leak down test to see if you loosing pressure through your valves. It seems like that's the only way positive pressure could get into your valve cover. Someone will probably chime in to let me know how wrong I am, but the PCV valve should just vent the crank case. On my car I don't think there is any way for air to get into the valve cover from the crank case. Except through the front cover ( ; Quote Link to comment Share on other sites More sharing options...
Challenger Posted April 28, 2009 Share Posted April 28, 2009 You should probably do a leak down test to see if you loosing pressure through your valves. It seems like that's the only way positive pressure could get into your valve cover. I dont think pressure can get into the valve cover through the valves either... Quote Link to comment Share on other sites More sharing options...
zxtman Posted April 28, 2009 Share Posted April 28, 2009 Check to make sure your valve cover has the baffle in it that creates a chamber within the valve cover. If you take off the valve cover, you should not be able to see the opening where you have the breather filter installed. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted April 29, 2009 Share Posted April 29, 2009 New valve stem seals? Brand? Cam? Quote Link to comment Share on other sites More sharing options...
rztmartini Posted April 29, 2009 Share Posted April 29, 2009 oil cap on? (ive never done that one before...) Quote Link to comment Share on other sites More sharing options...
burninator Posted April 29, 2009 Share Posted April 29, 2009 I dont think pressure can get into the valve cover through the valves either... I meant to say through the valve stem seals, which I'm pretty sure can happen. Though maybe that wasn't obvious the way I phrased it. Quote Link to comment Share on other sites More sharing options...
zxtman Posted April 30, 2009 Share Posted April 30, 2009 just to be clear, is it the breather filter on the valve cover that oil is leaking from? Quote Link to comment Share on other sites More sharing options...
c4220 Posted April 30, 2009 Author Share Posted April 30, 2009 Yes the oil cap is on. I have an open element filter on the valve cover. If I had a typical Z induction I would not have seen any oil spray because the pressure would push the oil to the intake manifold and I would see blue smoke. I will check for a baffle in the valve cover. The whole area inside the valve cover where the oil drains at the rear of the head to the oil pan and at the front of the head (timing chain) can drain to the oil pan is all part of the crankcase. How else can the valve train get oiled and return the oil to the drain pan. Oil can not get pushed up through valve stem seals. High pressure oil from cam and valvetrain lubrication can leak into the combustion chamber and go out the tail pipe as blue smoke. The leak down check is good advice to get an idea of wether or not I have excessive blow by which will cause high crankcase pressure. The other responders need to learn more about how engines are built and operate. Thanks, Chris Quote Link to comment Share on other sites More sharing options...
aarang Posted May 1, 2009 Share Posted May 1, 2009 You may want to check the PCV side. Try running a filter on the block breather instead of up to the intake/PCV valve. The wire mesh inside of the block behind the block breather tube may be clogged as well. When at idle, is there suction through the valve cover breather? Quote Link to comment Share on other sites More sharing options...
woldson Posted May 1, 2009 Share Posted May 1, 2009 The other responders need to learn more about how engines are built and operate Your statement of how the system works made that point, this piece is redundant. Alot of people try to have a "thicker skin". (besides, the extensive knowledge of some here is uncanny, and sometimes impossible can happen;)) If someone wanted to argue the point, you can PM a administrator, its up to you;). Quote Link to comment Share on other sites More sharing options...
rejracer Posted May 1, 2009 Share Posted May 1, 2009 I'd agree some of what's said above is shed worthy. If you have a blow by problem, it's not coming from your valves. Anything leaking past the seals is negligible as far as being a contributor to the problem to which you describe. Combustion gasses of any relevant volume are being blown by your pistons, not your valves. Intake and exhaust port pressures are not high enough to blow a significant volume through a valve guide with proper clearances/seals to dirty an engine compartment. It sounds to me you have one of the following: 1. Broken pistons 2. Scored cylinder walls 3. Worn rings 4. Stuck rings A leak down test will tell you if it's 1 through 4. Remedy as necessary. For your sake hope it's only stuck rings. Sounds like you know the condition of the upper end is, do you know what shape the lower end is in? I don't know what kind of trouble shooting you have done, and your statement "It appears the source is the filter breather" needs to be confirmed. Also pay attention to your front main seal. I had one leaking on my Z car and the oil ended up everywhere! If your running the stock fan inspect it. On drop of oil flung at high speed does cover a surprisingly large area. I'd start with a through engine bay cleaning. Then I'd go for a short drive and inspect the common leak areas, front main, oilpan, pump, valve cover. A little bit of blow by is going to be normal. Make sure that the external filter is not a scape goat for something very simple. Me personally... Id put a hose on your valve cover leave the hood attached with just the safety latch and run the tube up under your wipers or secured to the cowl. If that is your source, it will be obvious in short order. Also note: Coolant with excess water evaporated looks an awful lot like oil, especially with dirt mixed in. Don't forget the basics, and assume something is broken when it's not. Happy wrenching. Quote Link to comment Share on other sites More sharing options...
rejracer Posted May 1, 2009 Share Posted May 1, 2009 Other thoughts. Did you recently switch from conventional to synthetic? Synthetic oil molecules are smaller. It's not uncommon for engines to start leaking after making the switch. How many miles on the short block? Oil pressure above 3k seems a bit high. You can actually cause accelerated wear with excessive pressure, as well as reduce power. Read up on bearing "wash out" I don't think it's a factor to your issue though, nor do i think you are to the point of wash out. Quote Link to comment Share on other sites More sharing options...
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