Turbo leaking oil
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float_6969
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- Car: CA18DET swapped 1995 Nissan 240sx (too many mods to list)
2015 SV Leaf w/QC & Bose (daily) - Location: Topeka, Kansas
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Turbo leaking oil
Ok, so here's the deal. I've got a rebuild T28 with a modified compressor housing. (larger wheel) When I got the car in and started things up, I kinda had them rigged up a bit and I don't really have the turbo plumbed into anything. (Running the car as if it was NA) The problem that I'm having is that I'm getting some oil out of the outlet side of the compressor housing. What I'm wondering is that if not having any load (no piping on the suction or pressure side) of the turbo could cause this. I know (from experience) that if the crankcase pressure is too high it can cause the turbo to leak oil past the seals, so I was thinking that perhaps not having any load on the other side of the seal could allow oil to leak past. If this isn't then I need to pull my turbo and get the people who rebuilt it to look at. Any input would be greatly appreciated. Thanks!
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NeedCAforS13
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Re: (c-rad)
He drove it like that, not just idled it... if that makes a difference.c-rad wrote:Idling it shouldn't matter though.
Sean
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float_6969
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- Car: CA18DET swapped 1995 Nissan 240sx (too many mods to list)
2015 SV Leaf w/QC & Bose (daily) - Location: Topeka, Kansas
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I got it all figured out finally. After about an hour of research here is what I found out.
Oil seals in a turbo don't work the way that a main seal or cam seal would work. They aren't really a positive seal situation. They work more like a slinger on a water pump. What A slinger is, is just a round "washer" of rubber slid over the shaft of the motor. If any water leaks past the main pump seal it will follow up the shaft till it gets to the slinger. When it does the centripital forces of the spinning rubber cause the water to fly out, away from the electric motor. The exact same principal is applied to a turbo seal. The spinning of the turbo shaft causes the oil at the center to be flung out, away from the center. By the time it reaches the outside of the seal, it's just a fine mist. I also read that a turbo seal RARELY goes out. For it to go out, the bearings have to be in such bad shape that the blades off the wheel would have to be rubbing on the housing. And even then, the seal may still be intact. One of the main reason's for a seal to leak oil on a turbo is because of excessive Positive Crancase Pressures. If the pressure in the crankcase is high enough, it will put backpressure on the drain tube of the oil, not allowing the oil to drain as quickly as it should, and then causing the oil leak past the seals.
With that information, and a little thinking I realized that with no backpressure on the compressor outlet, and my juryrigged PCV system, it was quite possible that I wasn't removing enough positive pressure from the crankcase and causing the oil to leak past. I also thought that if there wasn't any backpressure on the compressor outlet, that perhapse there might not be any backpressure to keep the oil in the center scection. So I tested it...I redid my PCV hosing so that it was all hooked up correctly. Then I wrapped a bunch of tape around the turbo outlet. Not enough to close it off, but enough to seriously restrict it. The wastegate actuator is unhooked, so it doesn't really spin up much anyway. Now off for a drive...And the results......
I WAS RIGHT!!! No more oil leaks. I didn't think to clean the old oil out before, but because of where the turbo is aimed, there is a low spot that collects oil and it was dry. I also know how much oil it spit out before and it hadn't added any to that area of the engine bay. So there ya go folks. I learned something new last night, so that was awesome. Now for that damn wiring.....
Oil seals in a turbo don't work the way that a main seal or cam seal would work. They aren't really a positive seal situation. They work more like a slinger on a water pump. What A slinger is, is just a round "washer" of rubber slid over the shaft of the motor. If any water leaks past the main pump seal it will follow up the shaft till it gets to the slinger. When it does the centripital forces of the spinning rubber cause the water to fly out, away from the electric motor. The exact same principal is applied to a turbo seal. The spinning of the turbo shaft causes the oil at the center to be flung out, away from the center. By the time it reaches the outside of the seal, it's just a fine mist. I also read that a turbo seal RARELY goes out. For it to go out, the bearings have to be in such bad shape that the blades off the wheel would have to be rubbing on the housing. And even then, the seal may still be intact. One of the main reason's for a seal to leak oil on a turbo is because of excessive Positive Crancase Pressures. If the pressure in the crankcase is high enough, it will put backpressure on the drain tube of the oil, not allowing the oil to drain as quickly as it should, and then causing the oil leak past the seals.
With that information, and a little thinking I realized that with no backpressure on the compressor outlet, and my juryrigged PCV system, it was quite possible that I wasn't removing enough positive pressure from the crankcase and causing the oil to leak past. I also thought that if there wasn't any backpressure on the compressor outlet, that perhapse there might not be any backpressure to keep the oil in the center scection. So I tested it...I redid my PCV hosing so that it was all hooked up correctly. Then I wrapped a bunch of tape around the turbo outlet. Not enough to close it off, but enough to seriously restrict it. The wastegate actuator is unhooked, so it doesn't really spin up much anyway. Now off for a drive...And the results......
I WAS RIGHT!!! No more oil leaks. I didn't think to clean the old oil out before, but because of where the turbo is aimed, there is a low spot that collects oil and it was dry. I also know how much oil it spit out before and it hadn't added any to that area of the engine bay. So there ya go folks. I learned something new last night, so that was awesome. Now for that damn wiring.....