LegendsRacer - Legends & Bandolero Racing Forum
LEGENDS => Engine Care & Tuning => Topic started by: Scratcher on June 25, 2014, 04:15:50 am
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Firstly, I need to let you all know that my knowledge about engines is at best, stuff all. Whilst on the track during a recent practise day (dirt speedway), a large amount of smoke came out of the crankcase breather filter so I quickly returned to the pits and found that oil had been spat out all over the place. The engine wasn't making any funny or knocking noises nor was it down on power. Unfortunately, I don't run an oil temp or pressure gauge so cannot ascertain info from that. I brought the car home and let it sit overnight and started it up the next day. Oil level was fine and car starts ok however there is still smoke coming from the breather albeit not as much as the day before. There appears to be no oil leaks around the head or engine which I would expect if the head gasket has failed nor is there any smoke coming out of my exhaust which would indicate an issue with the rings etc. I did however notice that when looking in oil view glass after the car had been running for 5 or 10 mins, a clear / white mixture (about 2mm) could be seen sitting on top of the oil (like the oil had separated or something). Does anyone have some idea of what maybe happening? Regards Scratcher 60A
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Are you running a good quality synthetic motorcycle oil? Inferior oils will froth like that, also if overfilled
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Jim, I am using the fully synthetic Legends motor oil imported from the States. I buy the oil from the Legends car supplier here in OZ. I have used the same oil since owning the car without any issues. The oil in the car when the problem occurred was brand new.
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compression and leak down test next.. sounds like rings and cylinders wearing out..need to test..
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Where is your oil level set at? Too high of an oil level will froth it up too
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I will list a couple causes... Wrong oil in the motor or has been in the motor (No polymers in the oil or no friction inhibitors). No polymers in the transmission oil will make it foam from gears meshing together breaking the oil down, causing milky oil and vaporizing from the filter breather. No friction inhibitors for the wet clutch causes the clutch to slip and boil the oil (foam) with the same result. When the wrong oil has been used in the engine in the past, that oil's additives will bake to the clutch discs and when the clutches get hot (they will heat up sooner when coated) they will cause the engine oil to look milky or foam when hot. On occasion this baked on oil (to the clutch discs) will burn off when the clutches get hot causing the smoke. Foam once again caused by the oil boiling from heat.
Another cause would be a transmission bearing going bad or a starter one-way clutch (assembly inside the engine bottom end case that the starter end gear contacts.. internally it slips when the starter is not energized as the starter is constantly in contact with this assembly). If the one-way assembly is partially grabbing while the engine is running, it will get hot and break down the oil causing foaming and crank case smoke.
Myself, I would rule out top end issues or water in the fuel causing the smoke or oil foam level....
~Gimpster~
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Gimpster, Jim,
Thanks for your input. I have a race this Sunday and will monitor the situation and let you know how I go. Hopefully nothing goes "bang"
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I must be the only one that's had a motor push oil out the vent because of bad cylinder.. some use oil recirciulation cans to cycle the oil back to the motor. not a fix but a solution..your motor is not going to fix itself, there is an issue that needs to be addressed before you run it.. jmo..hank scotts son is on here message him for advice too.
joe
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Do you have a catch can attaced to the vent?
Steve
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Last year we had pouring smoke and some oil out the vent tube, a fresh rebuild. kept being told to race it, 4 races later it burnt a piston.
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We also have an old motor that spews oil out under decel. has low compression so might be first and best place to check, this motor had snapped head stud in middle of motor.
Also noticed a lot of the newer cars coming out spewing oil out the breather on diff. They only have a little fitting on there so we have put a longer hose up and back down to try help the issue.
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Gents, finished doing a compression test. The results are (1250 motor - reading from front to back) 140 - 133 - 120 - 123. I had another person do the test to confirm my results and he came up with the same figures. I have no idea what the "normal" readings should be so I will have a look on the forum to see if there is a topic on compression numbers. I've also been told by a few that have some knowledge on these motors that running it won't be a problem (I note s10customs post) whilst others are saying it's best to take off the head and do some digging to find the cause. I am leaning towards taking the advice from Joe (amp racing) as I agree, the car will not right itself. Once again, I appreciate all the input and will keep you posted on what I find.
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That compression difference could be from valve adjustment, or the head needing re-torque...
Yup, seen them smoke out of the breather before from top end issues.. completely agree as a cause for smoke from the breather. When he mentioned foam, made me think more oil issue or bottom end. I've seen this on other engine platforms also when a feller bought Castrol GTX at Walmart for the oil change in their motor . The oil does not have polymers (similar to gear oil) for the gear mesh transmission. When the oil is compressed between the gear teeth, it breaks down and foams. (causes foaming and smoke from the breather). Or like I said, the friction modifiers in the oil are not wet clutch friendly. You can find more on that topic from other factory techs on BMW, Harley, Yamaha, Honda forums.. If you fill a rear end with regular motor oil instead of diffy oil, the rear will smoke out the breather too after a hard run.
I have been wrong before, the end result here will be interesting to find out... like I said before, if it were not having a foam line in the oil, I would say top end
~G~
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Gents, I decided to take the car to my local engine doctor in order to find out what the problem was. The doc performed open heart surgery and unfortunately, the engine didn't pull through. The cause of the smoke / oil blowing from the crankcase breather was due to cylinders 3 and 4 (No 4 being the worst) being scoured to the point that Chad Reed would have had trouble jumping the "whoops" which had been made in the bore. I'm told that I basically have two options - Purchase a new motor or buy a re-built top end motor. I suppose that's the cost of racing. Thank you to everyone who posted a comment regarding the issue I was having.
Regards
Scratcher
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If it has the steel inex upgraded bores on sealed motors, just buy oversized piston and ring kit and have bores machined? why buy a new motor when that one can be freshened up for a third to half the price.......If the bore was that bad the compression would have been a lot worse than those numbers..
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Hey Adam, I've had a few people mention the suggestion you have posted so I will make some enquiries as to why this may not be an option for my particular problem. The mechanic did state that the cylinder bores 3 and 4 were the worst he had come across but as you state, you would expect the compression figures would be lower. I have a feeling that the head has been warped and may cost the same to replace rather than repair. As I mentioned, I will at least enquire about the options. Hope to be on the track for the Bega race in the coming weeks.
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Hell ya rebuild it, should be no problem resleeving it and cleaning up the head.
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White smoke is associated with water/condensation usually. However oil smoke can appear very similar. How hot is the engine when you disconnect the hose from the air box? Fuel in the oil is not going to give you any type of smoke, it will destroy the engine however. Smell the oil, if there's fuel in it you'll smell it.