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lookforjoe

Hussein's 1998 V70 Xr : The Force Awakens

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Do I smell something in the works with you?

The stock setup is all new (10K ago), it's not that it's not working, it just doesn't vent enough for the output of the 20g over 23psi. I doubt it's a vacuum issue. Russ (with the 500hp850) ditched the stock setup & ran AN lines into a custom can due to crankcase overpressure issues.

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Ok so you have high crank case pressure and billowing smoke clouds. Any chance they are related? I bet they are. High crankcase pressure will make oil back up in the drain line.

You need to do another leakdown test. Personally I would be taking it easy on the car until I had these issues sorted out.

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Ok so you have high crank case pressure and billowing smoke clouds. Any chance they are related? I bet they are. High crankcase pressure will make oil back up in the drain line.

You need to do another leakdown test. Personally I would be taking it easy on the car until I had these issues sorted out.

The oil smoke is there on decel, even at low(er) boost, not under accel/boost. I backed the boost pressure off to 1.55bar & no oil pushes past the cap. I've been driving it sedately, as I don't want to kill it, of course.

I'll do another leakdown & see what I find.

Hahn even suggested an oil restrictor, which doesn't make sense to me, since the oil feed is the same as TD04HL (7mm ID feed, 5mm ports in banjo bolt, 7mm ID), it's not like I'm using generic lines.

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All I am saying is that a ring sealing issue describes all of the symptoms. It explains the crankcase pressure. It explains the smoke (smoke on decel is the opposite, but the same- high vaccuum is drawing oil past the rings). That would also explain why you get smoke at all boost levels but only blowby at higher boost levels (it pulls the same amount of vac on decel regardless of boost pressure). If everything else was perfect- IE the motor didn't seems to have so much crankcase pressure and didn't only smoke when hot, I might be more inclined to point fingers at the turbo.

Why would a turbo center section issue only show up on decel? Should smoke at idle. Guess it depends on the nature of the failure. As you say a leakdown test will tell more.

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All I am saying is that a ring sealing issue describes all of the symptoms. It explains the crankcase pressure. It explains the smoke (smoke on decel is the opposite, but the same- high vaccuum is drawing oil past the rings). That would also explain why you get smoke at all boost levels but only blowby at higher boost levels (it pulls the same amount of vac on decel regardless of boost pressure). If everything else was perfect- IE the motor didn't seems to have so much crankcase pressure and didn't only smoke when hot, I might be more inclined to point fingers at the turbo.

Why would a turbo center section issue only show up on decel? Should smoke at idle. Guess it depends on the nature of the failure. As you say a leakdown test will tell more.

What you're saying makes perfect sense. I don't know if it smokes cold (under high boost), only because I don't ever push it into boost until it's @ normal op. It never smokes @ idle hot or cold, nor does it smoke (visibly) under acceleration. The decel smoke typically coincides with what feels like compressor surge - that slight shudder you get on rapdi decel (although my BOV is set to a very light relief pressure, so I don't see how it could actually be surge) - which I would assume creates more axial (or is it radial?) movement than when under boost.

Anyway, I'm hoping to get the leakdown down tomorrow afternoon - so, we'll see what happens.

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What you're saying makes perfect sense. I don't know if it smokes cold (under high boost), only because I don't ever push it into boost until it's @ normal op. It never smokes @ idle hot or cold, nor does it smoke (visibly) under acceleration. The decel smoke typically coincides with what feels like compressor surge - that slight shudder you get on rapdi decel (although my BOV is set to a very light relief pressure, so I don't see how it could actually be surge) - which I would assume creates more axial (or is it radial?) movement than when under boost.

Anyway, I'm hoping to get the leakdown down tomorrow afternoon - so, we'll see what happens.

It's your turbo . Trust me , ask how I know . Your engine feels like new.

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What you're saying makes perfect sense. I don't know if it smokes cold (under high boost), only because I don't ever push it into boost until it's @ normal op. It never smokes @ idle hot or cold, nor does it smoke (visibly) under acceleration. The decel smoke typically coincides with what feels like compressor surge - that slight shudder you get on rapdi decel (although my BOV is set to a very light relief pressure, so I don't see how it could actually be surge) - which I would assume creates more axial (or is it radial?) movement than when under boost.

Anyway, I'm hoping to get the leakdown down tomorrow afternoon - so, we'll see what happens.

So you have to boost it, then decel? In other words if you ran it up to high rpms with light throttle, no boost, then let off it doesn't do it?

If so then I agree it's actually probably the turbo, that makes sense. It it were engine related it should do it on high vac/rpms even if you weren't boosting - because vacuum is vacuum. In other words if it only does it when the turbo shaft speed is high and then you slam the throttle shut then it makes sense that it's the turbo. Should wind it out in 1st or 2nd with no boost then let off and see if it smokes.

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I had a similar problem with my Hahn 16g. I was blowing oil smoke out of the exhaust, presumably due to high crankcase pressure from oil blowby. I added a catch can and the problem got even worse. I ended up setting up a simple road draft tube, meaning I ran a hose from the PCV outlet all the way down to the bottom of the car and just left the tube open there. After that mod, no more smoke out of the exhaust, just a bit of oil smoke from the PCV vent to atmosphere. Its by no means a permanent solution, but its a good test, I thought the turbo was blown until I tried the draft tube approach.

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So you have to boost it, then decel? In other words if you ran it up to high rpms with light throttle, no boost, then let off it doesn't do it?

If so then I agree it's actually probably the turbo, that makes sense. It it were engine related it should do it on high vac/rpms even if you weren't boosting - because vacuum is vacuum. In other words if it only does it when the turbo shaft speed is high and then you slam the throttle shut then it makes sense that it's the turbo. Should wind it out in 1st or 2nd with no boost then let off and see if it smokes.

That's exactly it.

I have. It doesn't. No boost, no oil smoke.

I had a similar problem with my Hahn 16g. I was blowing oil smoke out of the exhaust, presumably due to high crankcase pressure from oil blowby. I added a catch can and the problem got even worse. I ended up setting up a simple road draft tube, meaning I ran a hose from the PCV outlet all the way down to the bottom of the car and just left the tube open there. After that mod, no more smoke out of the exhaust, just a bit of oil smoke from the PCV vent to atmosphere. Its by no means a permanent solution, but its a good test, I thought the turbo was blown until I tried the draft tube approach.

Thanks for the encouragement. I'm glad it's not just me. I'll try something along those lines before I pull the turbo.

It's your turbo . Trust me , ask how I know . Your engine feels like new.

Thanks!

I've ordered a rebuild kit, I can't afford to Remove, ship to Hahn, wait a month for diagnosis, then return. At least, I won't do it that way unless the shaft shows wear.

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Leakdown test:

1 2 3 4 5

5% 5% 5% 7% 5%

Compression:

1 2 3 4 5

160 160 160 145 160

Number 4 is lower, but certainly within tolerances.

I also vented the breather hose to the atmosphere (via check valve) to check for any smoke reduction or crankcase pressure relief.

I was thinking of adding a vent into the head breather line..... but I think I'll just tee-off the vent to the CC inlet, so that I can purge to the atmosphere if needed. DTR I'll look into a custom breather, along the lines of 500hp850.

Made no difference to the oil smoke on heavy decel from boost. Still no oil smoke on heavy decel from any rpm. No oil leak around filler cap @ 1.6bar. I did also change the cap seal, so I need to reattach the vent hose & check again for pressure leak from filler cap, it may just have been the aftermarket seal.

Once my rebuild kit gets here, I'll pull the turbo. I can't deal with Hahn's BS on the warranty unless the shaft is worn, then I have no choice.

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Good luck H. This is just another little hiccup on the road to perfection...your car is pretty damn close.

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Remember that any venting off the crankcase ventilation system that does not return to the intake tract will effectively be a vacuum leak. Just something to keep in mind

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Remember that any venting off the crankcase ventilation system that does not return to the intake tract will effectively be a vacuum leak. Just something to keep in mind

This is something a check valve will take care of though, no? Just clean it out relatively often :lol:

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