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Car Forum / MINI / December 2003pressurized crank
Hi everyone. I posted a little while back about an oil spluttering problem. Basically oil would leak from the grommets around the rocker cover bolts and even from the oil cap. I tried running the engine without the breathers connected to the carb...i.e. to free air and noticed a fair amount of smoke being pumped out from the crank case. I fitted 13mm breathers instead of recirculating these gases through the carb and the problem seemed cured even after a taunton0-oxford motorway trip at constant 4500rpm. Now the problem has started again with oil covering everythuibg in the engine bay as far as the windscreen wiper motor and it seems to come from the grommets and the cap.... HELP The gasket has been fitted with sealant so no leaks there and as far as i can see. running the engine out of gear at 5000rpm i can't see any oil gathering in the rocker cover..... The grommets are new and i'm getting a new oil sperator to mount onto the crank tomorrow but i feel this will only cure the problem for a short time. The cylinder pressures are between 140 and 150 PSI not bad for a 28 year old unit, and all i can think of is that despite this the wear is really bad but cannot currently afford a rebore and pistons. By the way the engine is a 1975 innocenti cooper 1275 with approximately 75000miles under the belt Anybody suffered the same problem???? Anybody have any suggestions???? Cheers > Hi everyone. > [quoted text clipped - 30 lines] > > Cheers From your description of the fault, The most probable cause is worn piston rings, pistons, and cylinders, causing compression to leak past the rings and in to the crank case, causing the back pressure, but it is also possible that the piston rings have become gummed in to the grooves of the pistons, this will give the same back pressure problem, I have used a product called AutoRX, many times on high mileage engines with back pressure problems, it either completely cured the fault, or reduced it to a more acceptable level, www.Auto-RX.com it is a metal cleaner designed and adapted for de sludging and cleaning the inside of modern and not so modern engines,(Ihave used it in my Mini Sidewalk) have a look at the site, Hope it helps, Fitzy > I posted a little while back about an oil spluttering problem. > Basically oil would leak from the grommets around the rocker cover > bolts and even from the oil cap. > I tried running the engine without the breathers connected to the > carb...i.e. to free air and noticed a fair amount of smoke being > pumped out from the crank case. As you realise, your problem is positive crankcase pressure. All engines, even new, suffer from blowby past the piston rings. If you attempt to seal the crankcase then pressure will build up. Back in the dark ages, eg: Morris Minor times, there was a simple vent to the atmosphere to allow these gases out. Typically there was some sort of an oil trap. In Australia from 1970, and around the same time in many other places, positive crankcase ventilation was required, drawing the crankcase gases back through the motor and burning the hydrocarbons in them. This was the first stage of antipollution gear in Australia and this simple measure alone cut pollutants released by something like 75%. > I fitted 13mm breathers instead of recirculating these gases through the carb and > the problem seemed cured even after a taunton0-oxford motorway trip at constant > 4500rpm. You're now running one of the dirtiest cars on the road and almost certainly breaking the law. Your problem must come down to one of (or both of) two problems. Either you've got worn piston rings, causing much more blowby than usual and overwhelming the crankcase ventilation system, or the system itself is faulty. > Now the problem has started again with oil covering everythuibg in the > engine bay as far as the windscreen wiper motor and it seems to come > from the grommets and the cap.... HELP If you pull the oil filler cap off with the motor running and put your hand over the hole, is there a vacuum or a positive pressure. (I don't really expect it will be a vacuum, but it's such a simple test to confirm you've got excess pressure.) > The gasket has been fitted with sealant so no leaks there and as far > as i can see. running the engine out of gear at 5000rpm i can't see > any oil gathering in the rocker cover..... > The grommets are new and i'm getting a new oil sperator to mount onto > the crank tomorrow but i feel this will only cure the problem for a > short time. Gaskets, grommets and oil seperators are all playing with the symptoms, not attacking the cause. > The cylinder pressures are between 140 and 150 PSI not bad for a 28 > year old unit, and all i can think of is that despite this the wear is > really bad but cannot currently afford a rebore and pistons. This is high enough to make me think you might have a problem with the crankcase ventilation system rather than the rings. Since it's much cheaper and easier to fix, it's worth making sure it's working right before you pull the motor down. > By the way the engine is a 1975 innocenti cooper 1275 with > approximately 75000miles under the belt > Anybody suffered the same problem???? > Anybody have any suggestions???? See above. Which sort of crankcase ventilation system does it have? BMC/Leyland/ARG/Rover have used a few over the years. Once we know what we're dealing with, we can offer advice on diagnosis and fixing. > > I posted a little while back about an oil spluttering problem. > > Basically oil would leak from the grommets around the rocker cover [quoted text clipped - 74 lines] > Once we know what we're dealing with, we can offer advice on diagnosis > and fixing. Thanks for the replies they are really helpfull in pin pointing the problem. I have to specify that there is quite a bit of smoke coming from the breather on the crank case but NOT from the breather on the timing cover. This breather is fitted at the back of the engine onto the timing cover assembly with two bolts. Its hard to explain but i have a pdf file with a diagram (the innocenti spare parts catalogue from inno-mini-world.com)and would gladly e-mail it to anyone that may be interested. Obviusly with breather filters connected instead of carb recirculation there is quite a bit of pressure coming from the filler cap. It would appear like worn piston rings but i do not seem to be getting any blue smoke from the exhaust even sudden heavy load throttle openings and oil is not being burned (dry and clean spark plugs) Any ideas? > Thanks for the replies they are really helpfull in pin pointing the > problem. > I have to specify that there is quite a bit of smoke coming from the > breather on the crank case but NOT from the breather on the timing [quoted text clipped - 3 lines] > inno-mini-world.com)and would gladly e-mail it to anyone that may be > interested. Email me a copy thanks. > Obviusly with breather filters connected instead of carb recirculation > there is quite a bit of pressure coming from the filler cap. > It would appear like worn piston rings but i do not seem to be > getting any blue smoke from the exhaust even sudden heavy load > throttle openings and oil is not being burned (dry and clean spark > plugs) > > Any ideas? If your compression is good and you're not getting smoke, I doubt you've got excessive blowby, which only really leaves the crankcase ventilation system. I reckon something is seriously wrong with the crankcase ventilation system (apart from the fact that you've completely bypassed it, that is!). |
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