High Compression, Crazy Oil Consumption - 350Z-Tech

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#1 · Sep 11, 2015 Hey, First of all I never owned a 350z, but I am sure most of you know how to turn a Spanner and are a little bit familiar with it's beastly v6 engine. I own a renault vel satis here in Germany, this car was built 2003, it has the exact engine Block as the 350z, since this engine isn't known here in Germany I'm kinda lost, I even have difficulty buying spark plugs here . Now the serious stuff, my car has a 100,000 original km's and lately has been consuming lots of oil, I would say half the dipstick measuring Portion for a 300km drive. Intake manifold right before the Plenum is full of oil. I checked compression right away and all 6 cylinders have between 165-170 psi (excuse my metric System). I checked the pcv valve and there's a free Ball in it which I could hear by shaking. Now, why could this Motor be burning so much oil with this amazing compression? Is it a Design fault, do I maybe need new rings? I use oil weight sae 5w40. I really pamper my car and never abuse the engine. Any suggestions what could be the culprit here? Sort by Oldest first Oldest first Newest first Most reactions #2 · Sep 14, 2015 While the Vel Satis may use a variant of the legendary VQ engine, it likely has a different block than what we use in the Z33 model. The FWD layout of your Renault means different packaging and layout than the RWD models like the Z. As to your problem, it could be the oil consumption problem is due to excess ring or valve seat wear and you're burning oil. The VQ engines (either FWD or RWD) aren't known to have any known design faults that cause excess oil consumption, so it may be time to pay a Renault specialist to take a closer look at it. #3 · Sep 15, 2015 Here in Australia we had a batch of RevUp engines consuming oil - often Nissan did an engine swap to resolve the problem (my 350z was one of them) Our 350Z's are 10.5:1 which normally gives 180 psi (and psi is actually imperial, not metric) Your Renault has a compression ratio of 10.3:1 so 165~170 psi would be low but certainly within service tolerance (I assume you had the engine hot and the throttle wide open when doing the compression test?) I could be the valve seals and pressure in the rocker covers - as they are vented to the inlet It's remotely possible you could have too much conrod or crank bearing clearance, this would create an oil cloud which can get sucked out the PCV and into the inlet. If so, your engine would have low oil pressure which would be a concern (May not be low enough to cause the oil pressure warning light to come on - but it would still be a cause for concern) I would expect your car to blow blue smoke out the exhaust which will also be killing the CAT If the CAT is blocked that will be creating a lot of back pressure which is bad for the rings (and performance in general) Most likely you need specialist assistance? This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread. Insert Quotes Post Reply

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