Z3MCJez Posted May 22, 2012 Share Posted May 22, 2012 Sigma engine (140), now burning oil at a reasonable rate (actually, somewhat more than reasonable - over a litre in 2.5hrs of track running at the weekend). What's the most likely cause? Thanks in advance! Jez Link to comment Share on other sites More sharing options...
charlie_pank Posted May 22, 2012 Share Posted May 22, 2012 Is it definitely burning it? At that rate I'd expect to be able to smell it in the exhaust. Perhaps it's breathing it - do you have a catch tank? If it IS burning it then it's either getting past the piston rings, or down through the valve-stem oil seals. I think there's a way of telling which - I think that if it's coming down through the oil seals, it tends not to do it while the engine is running, but only when it's stopped, so you get a puff of smoke on startup, then all is fine. Is it leaking it from anywhere? Link to comment Share on other sites More sharing options...
Z3MCJez Posted May 22, 2012 Author Share Posted May 22, 2012 The exhaust doesn't smell odd. It could be breathing it (but I don't think so). I have a catch tank, but it's not filling up, so if it is breathing it, it would be coming out as a mist and into the engine bay. There is a little on the underside of the bonnet, but nothing really significant, and it's not all over the place. No blue smoke on startup and no leaks when left still. If it's piston rings, would a compression test verify? Jez Link to comment Share on other sites More sharing options...
Racing Snake Posted May 22, 2012 Share Posted May 22, 2012 This is exactly what my engine was doing When stripped the bores/rings had worn due to excess throttle before the oil was up to temp This will need new rings and a hone/rebore Compression test and a leak down test should tell you more Link to comment Share on other sites More sharing options...
johnv Posted May 22, 2012 Share Posted May 22, 2012 but then on the oil warming up thread, not giving it enough throttle while the oil was warming up causes bore wear because the fuel was diluting the oil. Or something. Link to comment Share on other sites More sharing options...
charlie_pank Posted May 22, 2012 Share Posted May 22, 2012 Where did the 'little on the underside of the bonnet' come from - surely this engine is only a couple of years old? How do you know you've lost that much oil? Link to comment Share on other sites More sharing options...
James_Russell Posted May 22, 2012 Share Posted May 22, 2012 Are you sure that all your breathers (if you have more than one) are routed into the catch tank? Was the engine overfilled with oil to begin with? Link to comment Share on other sites More sharing options...
Z3MCJez Posted May 22, 2012 Author Share Posted May 22, 2012 The little on the underside of the bonnet is where there is a hole in the lid of the catch tank. I'm happy that the little there is oil mist coming out of the breather. I'm not accumulating all of the oil that I'm pouring into the engine in the catch tank! I know I've lost that much oil, as I've been measuring what is going in - And keeping a close eye on the oil level. The last thing I want is an expired engine from lack of oil (shell / crank failure). The engine is 3.5 years old, but it's had a pretty tough life. I don't have an odometer any more, but I would estimate around 8,000 track miles. In race engine life, it's done pretty well. I do have two breathers, and they're both routed into the catch tank. There aren't any others. And the oil level is within the min/max marks (as it has been throughout). Jez Link to comment Share on other sites More sharing options...
Racing Snake Posted May 22, 2012 Share Posted May 22, 2012 Quoting johnv: but then on the oil warming up thread, not giving it enough throttle while the oil was warming up causes bore wear because the fuel was diluting the oil. Or something. John i do believe that is referring is the car being left warming up at idle Trust me it does not take much to do a lot of damage if the oil is not up to temp Oil temp gauge is a must Link to comment Share on other sites More sharing options...
Jason Plato Posted May 22, 2012 Share Posted May 22, 2012 mad hatter - i'f your oil is now matched to water temp - is this hot enough ? Link to comment Share on other sites More sharing options...
Racing Snake Posted May 22, 2012 Share Posted May 22, 2012 *arrowup*Yes, i just drive nice and steady until the stat opens. then the lamina does its job and you can see the oil temp needle rising Job done Link to comment Share on other sites More sharing options...
charlie_pank Posted May 22, 2012 Share Posted May 22, 2012 If you're losing oil you must be burning, breathing or leaking it. If it were burning, you'd smell it, breathing, you'd find it in catch tank, leaking, you'd have a mess somewhere. I wonder whether the oil takes a bit longer than you expect to return back to the sump, thus making it look like you've lost some. Has it gone up if you check it now? Link to comment Share on other sites More sharing options...
Bio Posted May 22, 2012 Share Posted May 22, 2012 Pull the plugs out and have a look.....May be oily/ sooty if burning oil. John Link to comment Share on other sites More sharing options...
Martin J Posted May 22, 2012 Share Posted May 22, 2012 Found this on the web & it mentions the crankcase pressure relief valve which if stuck open could cause high oil consumption on the zetec se sigma enginehere Link to comment Share on other sites More sharing options...
mic Posted May 22, 2012 Share Posted May 22, 2012 Almost certainly rings Jez. Link to comment Share on other sites More sharing options...
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