turbo oil line check ball/spring

[Alan L]

Trying to understand the function of the aftermarket spring sometimes fitted to the 9mm check ball in the turbo feed oil line.
The only thing I can see it doing is sealing the ball in the closed position more effectively - preventing drain back. It seems it would, if anything, provide more oil feed to the turbo, by not allowing the ball to lift fully up into the banjo slots - if the spring was strong enough.
Trying to solve a turbo/oil dribble problem. Had an earleir post where new 3LDZ (modified) drips oil on to floor after a day of sitting. Thought it was fixed after my trubo guy rebuilt the rebuild. 2 track days later, problem is back.
Can someone explain what the spring is meant to do.
Thanks
Alan

[quattrorunner]

Well the spring won't keep the turbo from dripping, but yeah your right in that it's there to keep the oil from flowing further when not running.

[TurboKraft]

Yes, we can explain since we came up with that idea.

The spring seats the ball to the seat more effectively when the engine is shut off. We had a few cars that dripped after shutoff and/or smoked on startup. Given that the 996T has spring-loaded check valves in their oil supply, it gave us the idea of machining the original hollow bolt and adding a spring. The original oil source becomes a check valve instead of adding another one inline.

It has proven to be a simple and effective way to help resolve some oiling & smoking issues that are a result of excessive oiling after shutoff on the 1976-92 Turbos.

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

The 3K-Warner turbos are trickier to rebuild that some of the regular T3 or T4 Garrett-based turbos. Plus 3K-Warner has stopped supplying most rebuild parts and is pushing the "buy a new cartridge" program. Consequently many turbos are being rebuilt with non-genuine parts, usually out of spec.
If you're confident the problem isn't the turbo rebuild, you can try the check valve approach.
Also test the scavenge pump -- they need periodic re-sealing, often after rebuilding or replacing the turbocharger.

[Alan L]

Thanks guys.
Chris - thanks for the post. Two Qs - what are the dimensions of the spring - presumably it is a soft one so as to add a bit more weight to the seated ball, but not so soft as to stop it fully travelling into the restrictor slots in the banjo bolt?
What do you mean the scavenge pump may need re-sealing? Have checked the scavenge rate - but I am open to any ideas that may solve this problem.
Thanks
Alan

[JFairman]

I don't remember anything other than an o-ring oil seal for the housing and a shaft oil seal in the scavange pump. They keep oil in the pump and have nothing to do with how well the pump sucks and pumps oil. Maybe there is one more I'm forgetting but it only keeps oil from leaking out of it.

If no oil is leaking out of the pump the seals are fine and replacing them will do nothing but lighten your wallet around $40.
Other than that it's pumping performance depends on the oil clearances around the two meshed steel gears inside and how much cast aluminum has worn away inside the housing they run in and any possible oil coke and carbon sludge buildup.

[Alan L]

I have decided to do a test - to identify where the oil is coming from. Hard to replicate the track conditions, but I will take it for a bit of a run on the road, then park it and split the oil line at the catch tank. Then two cans under each end - one under the scavenge line, one under the catch tank. That should at least tell me which side the oil is coming from.
As far as I can tell the scavenge pump is keeping ahead of the oil flow to the turbo - so it must be drain- back from somewhere.
Alan

[Alan L]

What stops the oil from the reservoir tank draining back thru the scavenge pump into the turbo?
It seems the reservoir tank would be the highest point and the scavenge pump feeds directly into the bottom of the tank. There is the loop in the line over the top of the motor, but the reservoir tank would still be higher than that, or maybe the oil level in the tank is just below the high point? But then it could still siphon?
Alan

[oilonly]

I suppose that could happen. Alan do you have a vent in you turbo drip tank? If so would not the oil come out of there first if the oil was siphoning backwards after shut down as you say.

[JFairman]

Oil won't back flow from the oil tank to the turbo because inside the oil tank there is a steel tube that goes from the scavenge pump line fitting down near the bottom up to the top of the tank where the oil comes out of it.

[Alan L]

Ha, JFairman , thanks for the answer to that puzzle. I wondered about foaming/aeration when I saw the pump feed going into the bottom of the tank. But the line of oil could drain back?
Oilonly - no vent. I'm sure if I had one that is where my oil puddle would come from.
Question? Why didn't they dispense with the scavenge pump completely and route the turbo oil into the timing chain case?
Alan

[TurboKraft]

Originally Posted by JFairman

I don't remember anything other than an o-ring oil seal for the housing and a shaft oil seal in the scavange pump. They keep oil in the pump and have nothing to do with how well the pump sucks and pumps oil. Maybe there is one more I'm forgetting but it only keeps oil from leaking out of it.

If no oil is leaking out of the pump the seals are fine and replacing them will do nothing but lighten your wallet around $40.
Other than that it's pumping performance depends on the oil clearances around the two meshed steel gears inside and how much cast aluminum has worn away inside the housing they run in and any possible oil coke and carbon sludge buildup.

Just sayin' based on experience. Can't tell you how many times I've seen a brand new genuine 3K-Warner K27 goes on a car and it smokes. Test the scavenge pump and it's not siphoning fast enough. Reseal the scavenge pump (o-ring, shaft seal, housing gasket, drive seal) and the oiling/smoking problem is gone.
Not saying it makes sense, but that's been my experience.

[Alan L]

Hmm, hard won experience I suspect Chris.
I'm going to check the system out. I did have the pump apart for inspection about a year ago, and all looked well, and scavenge test was OK, but something is wrong.
Would the spring on the check ball help?
thanks
Alan

[JFairman]

Originally Posted by TurboKraft

Just sayin' based on experience. Can't tell you how many times I've seen a brand new genuine 3K-Warner K27 goes on a car and it smokes. Test the scavenge pump and it's not siphoning fast enough. Reseal the scavenge pump (o-ring, shaft seal, housing gasket, drive seal) and the oiling/smoking problem is gone.
Not saying it makes sense, but that's been my experience.

Then you know none of those seals has anything to do with the pumping of the oil they only keep the oil from leaking out of the pump so in those experiences there was oil coke and sudge that was partially clogging the suction and discharge scavenge pump oil lines, or the ID of the banjo and compression fittings that connect those steel oil lines at each end, and or the inside of the cast aluminum scavenge pump housing where the two pump gears never come in contact with it.

Any working mechanic that wants to keep his job will clean those parts with brushes in parts washer solvent and then blow them out with compressed air before reassembling the pump with new oil seals and installing it back on the end of the cam tower with a new paper oil seal.

If you could do high contrast ultrasound sonography on the scavenge pump oil lines and fittings and the pump housing before servicing them you would see the oil sludge build up in the ID of the fittings and lines and on the inside of the pump housing before they go in the parts washer... and then it would make sense.

Of course thats ridicuous and far from practical during a flat rate or custom street car job so most mechanics never see all the stuff that could be impeding oil flow before it's partially disolved in solvent and then shot out of an oil line under shop air pressure so fast you can't see it.

[fredmeister]

Originally Posted by Alan L

I have decided to do a test - to identify where the oil is coming from. Hard to replicate the track conditions, but I will take it for a bit of a run on the road, then park it and split the oil line at the catch tank. Then two cans under each end - one under the scavenge line, one under the catch tank. That should at least tell me which side the oil is coming from.
As far as I can tell the scavenge pump is keeping ahead of the oil flow to the turbo - so it must be drain- back from somewhere.
Alan

Hi Alan,
I dont understand where the oil can leak from on your turbo since all the connections should be sealed with flange gaskets. Do you mean the turbo housings are dripping oil from where they connect to the center section? If so I suggest you should clean the turbo and then check to see if its leaking at the compressor housing side or the turbine housing side. This would indicate the conditions of the seals at each end of the turbo shaft-ie. intake or exhaust.
I expect a little weeping at the compressor housing connection on the turbo(thats what mine does) because of the oil that gets past the compressor seal and also coming from the crankcase vent into the air cleaner housing and thus thru the compressor intake plumbing. However the turbine housing should be bone dry.
Other than that the turbo sump fittings and the catch can fittings should not leak or they are lose or the flange gaskets are failing.
As a point of reference, I ran for 15k miles on my k27S without the little 9mm ball installed since the previous rebuilder forgot to install it in my engine. When I did my own engine rebuild years later, I saw the discrepency and installed one. I thought I might have damaged turbo seals by running too much oil thru it without the check ball for those 15k miles, but so far 5k miles later the turbo does not smoke or leak so the seals seem fine. This makes me think the check ball does not so much limit the oil flow to the turbo as prevent the oil siphoning on shut down (its intended purpose).

Fred

[fredmeister]

Originally Posted by Alan L

Hmm, hard won experience I suspect Chris.
I'm going to check the system out. I did have the pump apart for inspection about a year ago, and all looked well, and scavenge test was OK, but something is wrong.
Would the spring on the check ball help?
thanks
Alan

Another thought. Check that the drive pins are contacting the oil scavenge pump shaft on the camshaft. Somehow maybe the pins have sheared or the shaft disconnected and its not being driven by the cam anymore.

Fred

[Alan L]

Hi Fred,
The oil comes after it has been sitting for 24 hrs. Drains out the zork. So I am figuring I have a drain problem somewhere.
img]http://forums.pelicanparts.com/uploads20/turbo+leak1342479998.jpg[/img]
My turbo guy tells me if it was pushing past the seals when running, I would know about it - clouds of white smoke.
I had the scavenge pump apart last yr as a routine check while engine out. Replaced drive pin.
Just got car running again - starter motor back in last nite - intermittent fault when race hot.
I intend to run it today and split the line at the catch tank and collect the two oil drains separate and see what I get via the turbo line and scavenge line.
While I am at it, I will pull the scavenge line off and check for crap. I have checked the scavenge rate, and made sure the line is not nicked where it is close to the valve housing.
My catch can is 75 ml and there is a cavity in the turbo body above that. My turbo seems to be flooding with oil after shut down. from somewhere. I intend to find the source.
This turbo has now had 3 rebuilds by two different guys. And is the only turbo that seems to give me this headache.
Thanks
Alan

[Alan L]

pic did not seem to come out.

[JFairman]

I would try a spring over the ball bearing, it's a good idea. Sure can't hurt and it might work especially if you parked uphill after driving.

[oilonly]

If you take off your intercooler and look down your up pipe with a flashlight do you see oil sitting on the bottom?

[Tt surgeon]

I would try a stock 3ldz turbo on there and see if it doesn't stop. Then you'll have your answer, I strongly suspect the turbo.