Hi everyone, My 3800 turbo swap keeps blowing the oïl seal just behind the harmonic damper. The oïl pressure is around 80+psi when the engine is under load and 40 to 50psi at idle. At start up the pressure seems to rise above the 80psi mark. I had fitted a performance pump and spring & piston from ZZP. I thought the pressure might be too high after blowing 3 seals in a row with this so I put the original pump and spring & piston back in. No change: I've just been round the block with the car and it's leaking again. This is the 4th seal to blow!
Where am I going wrong to keep blowing seals like this?
The balancer oil seal isn't affected by pump pressure, it sounds like your pressurizing the crankcase with boost. There is a special PCV valve needed for turbo applications that has a built in check valve to prevent this. I remember a thread about the PCV valve a while back.
Thanks for the reply. I already have the Supra Turbo PCV (the one shown), and I'm not boosting more than 10psi. Each valve cover has a breather filter as well. I don't see how the crank case is getting so much air pressure that it blows out the oïl seal?
What else is going wrong or getting blocked that oïl pressure is building up behind the seal?
Is the balanced damaged? Groove worn in it? Do you oil the seal before installing the harmonic? If it's dry or the balancer is worn, the seal will fail very quickly. If it only fails after making boost, then your probably pressurizing the crankcase as stated already.
OK. After putting on a brand new harmonic balancer and new seal, there seems to be no more leaks! Yeah!! I also blocked off the two holes (with epoxy putty) in the lower intake manifold for the oil breather system. I had a feeling that turbo pressure was leaking past the upper intake gasket and pressurising the engine. I don't really understand how the engine gets pressurised since both rocker covers have breather filters? However, with the Europeen roads and the tight circuits (lots of hard left turns) that I race on, I was getting a bit of oïl surge comming back up the PCV. I'll let you know how it goes.....
Thanks for all the good advice.
Best regards, Rafe
[This message has been edited by Englishrafe (edited 03-13-2015).]
Assuming your running a gutted m90, if you hadn't blocked the pcv vent passage, that would have been your problem. You need to run a breather to allow air into the crankcase if you are still running a pcv valve. But you always need to block the fresh air passage from receiving boost or you will pressurize the crankcase and blow seals. Tapping and plugging or filling as you have done is needed if running a m90 case with turbo and likely what solved your problem. L36/l26 intakes use a external pcv vent, so no issues there, as long as the pcv valve seals.
