Steve P Posted September 8, 2009 Share Posted September 8, 2009 Strange question,Anyone know if its possible for an engine to chuck out oil at high revs?,i have a new 2.5 engine which has done about a thousand miles in my Vitesse,if i boot it and go above about 4.5k revs i can smell oil but on Sunday i was going down a bypass with one of those new Renault sport things behind me and booted it up to over 5.5k and on slowing down there was a cloud of smoke,i dont think its coming out of the tail pipes as it seems to be oil burning on the exhaust underneath,i cant get under it at the moment to see but it doesnt smoke at any other time.Pressure is 60-70psi at 3k when hot.CheersSteve Link to comment Share on other sites More sharing options...
Lord Sorbington Posted September 8, 2009 Share Posted September 8, 2009 Odd.The first thing I'd do, having checked for leaks, is to get someone to follow you to see if the smoke is coming out of the tailpipes. If the engine burns oil at high revs / load then that would suggest a bore / piston ring problem.If it burns oil on a trailing throttle, and emits a big puff of blue smoke when you accelerate again then that would tend to indicate a valve guide issue.If It's leaking oil and you get a general oily smell I'd check the engine breather system to make sure it's working properly. I suppose it's possible that your new piston rings haven't bedded in properly yet and you're getting a bit of crankcase pressure at higher revs which is forcing oil out of a seal or a breather somewhere which then burns off on the exhaust? Link to comment Share on other sites More sharing options...
DJB_Harvey Posted September 8, 2009 Share Posted September 8, 2009 Oil level too high ?..sometimes caused by using the wrong dipstick , there are more variations of these than people think and could be the cause of up to 1 pint of extra oil being in the sump. Link to comment Share on other sites More sharing options...
GT6 M Posted September 8, 2009 Share Posted September 8, 2009 You will be geting a lot of crank pressure at high revs, and if the rings have no bedded ,then oil will be forced past them,also , a high crankcase pressure, will force oil doon the valve stems, not just on over run either , [ high vac, on overun,= sucky sucky ]Take the plugs oot, and get a small torch, and shine doon plug ole, turn engine with a spanner, and look at the tops of the pistonschances are they ..full of oil ..It should go,!! but some times it just ..does not ..When I did mine, it was awfull, all 6 pistons ..full of oil..now after time, they are all starting to seal, 4 and 6 are still a little ..wet.. but are ..drying up.. as the miles go on, regards Marcus Link to comment Share on other sites More sharing options...
Nick Jones Posted September 8, 2009 Share Posted September 8, 2009 Agree with Marcus - rings may not be fully bedded at 1000 miles.What breather arrangement do you have?I take it you don't have an external rocker feed fitted?Nick Link to comment Share on other sites More sharing options...
Steve P Posted September 9, 2009 Author Share Posted September 9, 2009 No external rocker oil feed,breather pipe from the rocker box goes straight into the HS6`s via the pipes at the side of the carb.CheersSteve Link to comment Share on other sites More sharing options...
GT6 M Posted September 9, 2009 Share Posted September 9, 2009 The rocker box breather , really is no big enough, its the same size as a 4 pot and a lot less cyls,really need to either make it bigger, or put in another [ prefferably ] on the crankcase, regards Marcus Link to comment Share on other sites More sharing options...
junkuser Posted September 9, 2009 Share Posted September 9, 2009 Assuming the rings not yet bedded, there could well be excessive blowby, particularly at higher revs, carrying oil fumes to the intake manifold, resulting in smoke.Try running rocker breather pipe to a catch bottle (any old drink bottle), sealing the pipes to the carbs/inlet manifold and taking it for a burn. Think there will then be no XS exhaust smoke.If there is still smoke then oil is getting past rings or down intake valve guides. Link to comment Share on other sites More sharing options...
Steve P Posted September 10, 2009 Author Share Posted September 10, 2009 Thanks for the replies,i`ll junk the carb intakes and fit a catch tank and breather.Steve Link to comment Share on other sites More sharing options...
junkuser Posted September 13, 2009 Share Posted September 13, 2009 Did you get to the bottom of the problem Steve? Link to comment Share on other sites More sharing options...
Steve P Posted September 14, 2009 Author Share Posted September 14, 2009 Well i blanked off the carb breather pipes and left the rocker breather with just a pipe for now,i think it definiteley runs better but after blasting down a dual carriageway i could smell oil and there was smoke,from the front not out of the tail pipes.Its as if oil is burning on the exhaust somewhere but i cant see anything with a torch although i havent been underneath it yet.It maybe from the front of the exhaust as the Pheonix 6-3-1 collector is blowing.Im going to get it up on a four poster ramp next Sunday and have a good look.Steve Link to comment Share on other sites More sharing options...
GT6boy Posted September 14, 2009 Share Posted September 14, 2009 redoxideVit wrote:...It maybe from the front of the exhaust as the Pheonix 6-3-1 collector is blowing.Im going to get it up on a four poster ramp next Sunday and have a good look.Steve Forgive the edit, but given the known propensity for the 3-1 units to have a relaxed interpretation of the word seal( :X), you could easily be getting the fumes coming out there under high revs, as opposed to dashing down the exhaust. I agree about the blow-by via the piston rings, but the collector box issue will confuse the symptom. :) Link to comment Share on other sites More sharing options...
junkuser Posted September 14, 2009 Share Posted September 14, 2009 If you stick that breather into a bottle you'll be able to get some idea of the amount of oil vapour it is blowing out as much of it will condense in the bottle.The bottle will also obviate the risk of the blowby hitting the exhaust, however i suspect that what you are seeing and smelling is just the oil fumes and blowby gas.Hope this is not a ring problem such as breakage during assembly.A compression test would be in order as the blowby seems excessive if I am interpreting this correctly. Link to comment Share on other sites More sharing options...
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