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Discussion Starter · #1 ·
Ok Turbo guys I need some input. I am working on a ZX-11 with a Westech turbo kit (RHB5 turbo). The issue is relating to the oiling system. I have noticed oil in the intake (airbox). More than should ever be there! After doing some research I am leaning toward a bad check valve at the oil inlet on the turbo. I took it out this evening to see if it was working and became a bit perplexed. It definitely is not working as a check valve. I could blow through it both ways with the same amount of force. It also didn't appear to have any internals to make it a check valve and the supply line connected to it didn't drip at all when removed' but the turbo was full of oil. Based on research my thought is that the when the bike is shut down the oil is draining back (since the check valve isn't working) from the scavenge pump in the tail section and overfilling the turbo. This is then allowing it to leak by the turbo seals into the turbo outlet and end up in the intake the next time it's fired up. Am I nuts?:headscratch.
I am also curious as to whether or not I should have another check valve at the inlet to the scavenge pump as a secondary measure to help prevent the bleed down of the circuit or if the scavenge pump is even necessary. It looks like the oil out line could go straight to the pan without issue. Good idea or not?










 

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not to filmiar with that turbo but here is where i would start is the turbo bushed or ball bearing. If it is ball bearing do you have a restrictor in the feed line. next as far as not running the scavenge pump it may work without it but the oil level in the pan would be high when the bike isnt running might cause a issue with the oil drain back line. most of my turbo experince has come from cars porsche turbos from the factory come with a scavenge pump. but you always want the drainback above the oil level if not a pump is used.have you checked the play in the shaft to make shure it isnt a turbo issue. i would have a check valve on the drain back to keep oil from flowing from the pump back to the turbo so when it isnt running oil wont be sitting on the seals under the pressure of the amount of oil. I might have one laying around ill have to check ill pm you if i have it
 

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Discussion Starter · #4 ·
The Turbo is a bushed style not ball bearing. With the pump mounted so high and the apparent failure of the current check valve I am pretty confident there is excess oil and pressure on the seals when it's shut down.

I have spent some time on the ZRXOA boards looking around but I haven't joined yet. Should probably do that and glean a little more info from those guys and see what they say. I'll most likely order a couple of check valves from RBRacing this week and see what happens.
 

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Is there a pcv valve between the crankcase and the airbox? Is the oil all over the airbox or just in one area? I would think that a faulty pcv valve is more likely the culprit than the turbo blowing oily air into the airbox.
 

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just get a new check valve should solve the problem you never want oil just sitting in the turbo thus the reason for the pump and not just straight back to the pan. one thing i guess you could do is a switch for the pump that you could run the pump after you shut it off but dont know how well the pump you are using takes a prime and could have a issue when it is trying to pick up the next time the engine is run.
 

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I don't have a scavenge pump, but run off of the bike's oil pump and have a check valve in both the feed and return.

 
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