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Bad LT
 
Uncle's Avatar
 
Join Date: Dec 2008
Location: Newcastle Australia
Posts: 675
Lazy oil scavenge pump?

So I just swapped out my stock headers and drip tank for a set of new Fabspeed headers and drip tank. After getting it all buttoned back up I took it for a run to burn of my greasy paw marks and to check the oil.

Car was fine when in motion at first but after sitting idle at a couple of sets of traffic lights I started to get some smoke out of the exhaust. Take off from the light and the smoke would be gone. As soon as it sat for more than a few seconds it would start to blow smoke again. Got it home and let it sit for a second while I waited for the shed door to open and it was getting crazy.

Anyway seeing as I did no other mods I'm wondering if the pump hasn't always been lazy but the stock drip tank has had enough volume in it to cope with sitting idle for a while. The Fab speed drip tank is quite a bit smaller with no vent so I'm thinking its getting full and oil is sitting in the core until the motor gets a rev and the oil is pulled away.

Thoughts?

Old 10-09-2014, 06:55 PM
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Bad LT
 
Uncle's Avatar
 
Join Date: Dec 2008
Location: Newcastle Australia
Posts: 675
So I did the standard Dip tank pipe into a measuring jug (Don't tell my wife I stole her spare) test with 100ml in the jug. Initially there was little suction but once I added a some rubber hose over the fitting it was sucking like a champ. Turned the car off the residual oil run into the jug. I ended up with 150ml in the just. Turned the car back on and the pump sucked it all up on the spot.
I thought hmm maybe I had a slight air leak in a fitting not being properly home last time. So I put it all back together and took it for a run.
Was great while I was taking it easy but once it was warmed up I started to give it more revs. After about 10 minutes the smoke was back at idle or trailing throttle. WTF.

So I took it home and repeated the test while it was still hot. After the first few seconds of oil burning off it was back to nice and clear without any smoke.

The only difference I can see hear is the fact that the jug was working as a vent. IE the drip tank was not under vacuum. Seeing as the only change I've made to the oil system is the drip tank I can't help but think it needs a vent?

Again this makes little sense to me as lets face it almost all aftermarket headers come without a vented drip tank. Clearly the factory tank has got a vent that runs to the air box.

Old 10-10-2014, 11:13 PM
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TurboKraft's Avatar
 
Join Date: Mar 2005
Location: Phoenix, AZ
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Uncle,

That's a hard one to figure out.

Capacity problem? Not likely, as Ruf used a tiny drain can under his K27 and "große K27" turbos, no issues. This size worked for years on B&B and other headers.

Ventilation? Again, these same drain cans were not ventilated.

Scavenge pump falling behind? You've done the normal test, checking flow vs. suction into a reservoir you can see into. I do recommend testing at idle, midrange, and higher revs as I've seen some fall behind at idle yet work at revs, and the other way around -- work at idle, fail at revs. Regardless, they're very durable a re-seal kit almost always resolves all scavenge pump issues.

Solutions we've found for this problem:
1) We upgrade the check valve mechanism at the turbocharger's oil source:
TurboKraft Inc : Turbocharger Oil Feed Check Valve [930 107 706 TK] - $52.00
2) Ventilate the drain can. Often all that's needed is a tiny weep hole atop the canister, even a 0.5mm hole is plenty.
If this causes oil mist to accumulate on the back of the car, route a hose from the breather up above teh engien sheetmetal, all the way to the airbox if you wish.

TurboKraft manufactures drain cans for Garrett GT-series turbochargers, and they have a provision for a vent *if* the installer wants to use it.
A lucky second function of this: should your pump fall behind, oil bleeds out the vent rather than bypass the turbocharger's seals and contaminate your muffler...
__________________
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TurboKraft, Inc.
Tel. 480.969.0911
email: info@turbokraft.com
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Old 10-11-2014, 07:55 AM
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oilonly's Avatar
 
Join Date: May 2008
Posts: 1,148
I agree vent your drip tank, i have mine vented with a hose going up maybe 12 inches then a breather element,it gets slightly oily some times but never leaks. Just my opinion but I think the plumbing system is helped with a vent.
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'87, Modified WUR, Billet valve, 965 downpipe, Kokeln intercooler, GHL headers, Garrett T04B K27 hybrid, Tial w/.8 bar, WEGO IV, RarlyL8 dual out, LSD
Old 10-11-2014, 02:30 PM
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Join Date: Jun 2009
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Doesnt the original setup have a check ball also ? How is your different ?
Thanks
Quote:
Uncle,



That's a hard one to figure out.



Capacity problem? Not likely, as Ruf used a tiny drain can under his K27 and "große K27" turbos, no issues. This size worked for years on B&B and other headers.



Ventilation? Again, these same drain cans were not ventilated.



Scavenge pump falling behind? You've done the normal test, checking flow vs. suction into a reservoir you can see into. I do recommend testing at idle, midrange, and higher revs as I've seen some fall behind at idle yet work at revs, and the other way around -- work at idle, fail at revs. Regardless, they're very durable a re-seal kit almost always resolves all scavenge pump issues.



Solutions we've found for this problem:

1) We upgrade the check valve mechanism at the turbocharger's oil source:

TurboKraft Inc : Turbocharger Oil Feed Check Valve [930 107 706 TK] - $52.00

2) Ventilate the drain can. Often all that's needed is a tiny weep hole atop the canister, even a 0.5mm hole is plenty.

If this causes oil mist to accumulate on the back of the car, route a hose from the breather up above teh engien sheetmetal, all the way to the airbox if you wish.



TurboKraft manufactures drain cans for Garrett GT-series turbochargers, and they have a provision for a vent *if* the installer wants to use it.

A lucky second function of this: should your pump fall behind, oil bleeds out the vent rather than bypass the turbocharger's seals and contaminate your muffler...
Old 10-11-2014, 02:50 PM
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Bad LT
 
Uncle's Avatar
 
Join Date: Dec 2008
Location: Newcastle Australia
Posts: 675
Yeah Chris I conducted the test at idle,Mid and High RPM. Pump seems fine at all RPM. After checking the oil level I even tried adding an extra 500ml of oil to the jug and seeing if the pump would keep up. By the time it took me to crank the car over and get back to the jug the pump had sucked up the oil.

I'm going to fit a vent to the tank and give it another try. It's the only thing that has changed in the system so logically it makes sense if you rule everything else out it should be the one thing you have changed. So while the system "shouldn't" need a vent it would appear I do lol.
Old 10-11-2014, 04:04 PM
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Bad LT
 
Uncle's Avatar
 
Join Date: Dec 2008
Location: Newcastle Australia
Posts: 675
I happen to also have one of your check valve set ups here left over from my last project. I plan to fit it after I sort this problem out. If I change it before then I will of added another variable.
Old 10-11-2014, 04:07 PM
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Bad LT
 
Uncle's Avatar
 
Join Date: Dec 2008
Location: Newcastle Australia
Posts: 675
As a test I vented the drip tank today. I used a 4mm I.D silicone hose and a speedflow filter with a clear sight I had floating around.

Ran the hose out from the tank 100mm (4") to the filter and another 100mm post filter venting in a curve so it won't pull any road grime back in as I drive. Took the car out for a good run and all is right in the world once again.

The clear outer case of the filter let me see that while it had some oil fumes there was no oil in the filter itself.

Tomorrow I'll weld on a -8AN fitting to the tank and make permanent set up.

Old 10-11-2014, 11:56 PM
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