7m consuming oil. no idea why

[Beefy_Heafy]

Hey guys, ive got an issue with my 7m. Ive finished building it up and it runs great and is extremely powerful except it consumes oil. somewhere in the order of 500-1000ml per 1000km. That seems like quite a bit imo.
The symptoms are puffs of oil smoke on start up and when taking off from a standstill at lights etc, as well as the obvious loss of oil when checking the dipstick from time to time. This along with the fact that the car has perfect compression of 160psi (9:1cr) on each cylinder within 5 winds of the engine would lead me to believe that i must have a poorly seated or faulty valve stem seal. After removing the spark plugs i found that the plug for pot 3 was blackened and a little wet as well as the top of the no 3 piston as best i could see it through the spark plug hole. all the other spark plugs looked like new albeit a little bit scorched and white.
I set upon the arduous task of replacing all the valve stem seals for pot 3 not easy without removing the cylinder head! One of the 4 seals for pot 3 was discolored compared to the other 3 so i assume it was the leaky one. Since completing this i have driven the car around for about 1500km and noted that it is still blowing smoke when being started in the morning and when taking off from lights etc. Although now that spark plug and inside of pot 3 looks nice and dry / non oiled just like the other 5 cylinders.
However the cars symptoms and oil consumption still persist. I am at a loss. What could be causing this?
Also of note is that im using an accusump and dont quite know what kind of pressure i should put into it before making sure the oil in the sump is at the full mark. A mechanic friend suggested that i might be overfilling the system and it is burning oil off the excess. is that even possible?
All your help is appreciated. Thanks guys.

Oh also something else. The engine has only done about 5000km and has no external leaks. of any kind.... ever

 

[Beefy_Heafy]

i think that perhaps because it still has most of the same symptoms as leaky valve stem seals i might go thru and change all of them out. my engineeing shop put them in for me when they did the headwork and if one was seated wrong or faulty i figure more could be also. It isnt obvious by the colour of the spark plugs tho.
Ill see if i can get a high qual set and change them all in the next few weeks.
Changing these with the head on is an absoloute pita :s

 

[whitemike]

Definitely sounds like leaky valve stem seals. Perhaps more than one is leaking a small amount. It doesn't smoke on decel or accel at all does it?

 

[7M-KDL]

I have similar issues, mine does smoke on decel though

 

[Beefy_Heafy]

I cant see whether or not smoke is coming out on accel or decel by looking in rear view mirror. but after some hard mountain running and it does seem to have lost some oil. I do see a decent sized puff when moving from traffic lights after idling.

 

[IJ.]

PCV Mods?

On the Accumulator charge it to 100psi then bleed it back to 10Psi.

 

[boostcraver]

PCV Mods?

On the Accumulator charge it to 100psi then bleed it back to 10Psi.

^clarification please. Charge what and how? I am also having this problem with oil consumption and would like to figure it out.

 

[89supra7mgte]

Oil in ic pipes at all?

 

[Beefy_Heafy]

PCV mods are pipes from cam covers go to catch can and then vent to atmosphere.
Catch is dry or as dry as can be expected.
No oil in IC pipes.
Ill do the accusump bit so that i have a proper oil level. Atm im just charging it to about (2.5bar) ~37psi on my in car oil pressure guage. works out to 30psi on the accusump guage??? and then filling to full mark from there.

 

[IJ.]

^clarification please. Charge what and how? I am also having this problem with oil consumption and would like to figure it out.

Only applicable to an Oil Accumulator

PCV mods are pipes from cam covers go to catch can and then vent to atmosphere.
Catch is dry or as dry as can be expected.
No oil in IC pipes.
Ill do the accusump bit so that i have a proper oil level. Atm im just charging it to about (2.5bar) ~37psi on my in car oil pressure guage. works out to 30psi on the accusump guage??? and then filling to full mark from there.

You should see Gauge pressure +10 PSI Tom.

You also need to pull a vacuum on the catch can for it to have a chance of working.

 

[7M-KDL]

i have pcv hooked up like stock except that i have a catch can between the cam covers and acordian hose

 

[Beefy_Heafy]

So I should plump the catch back into the intake pipe or into the standard location on the throttle body. I just don't trust the valve on the throttle body to not pressurize the crank case under boost.
I thought the difference between oil pressure gauge and accusump gauge must have been taking +10psi air cushion into account.
So when refilling oil i should have accusump empty. then charge it up to a large pressure and bleed it back to 10psi before double checking levels. That would mean 20psi on my in car oil pressure gauge?

 

[IJ.]

There is no valve in the TB it's an orifice.

To "Charge" the accumulator you leave the valve open with the engine off, pump the Accumulator up to 100Psi then bleed it back so it's gauge shows 10Psi.

This sets the air piston so the gauge on the accumulator will now show Oil Pressure +10Psi, if you don't do it this way it won't work as intended.

 

[jdub]

So I should plump the catch back into the intake pipe or into the standard location on the throttle body. I just don't trust the valve on the throttle body to not pressurize the crank case under boost.

And, the orifice will not pressurize the crankcase if the PCV hose is routed across the valve covers to the accordion hose (stock set-up). The flow will take the path of least resistance from the orifice, across the valve cover nipples, to the intake. Positive crankcase pressure + the venturi effect at the nipples will ensure any vapor produced is carried to the intake.

 

[Beefy_Heafy]

Oh yes i charged it like that when i first installed it as per instructions. Sorry i wasn't following, i thought u were trying to tell me to get the oil pressure really high for some crazy reason. Although the accusump gauge doesn't seem to be functioning quite like you said. The accusump gauge reads more like in car oil pressure minus 10psi.
I will charge it again to make sure its right.
With my accusump, i rev my engine to make about 2.5bar (~37psi) of oil pressure and capture it in the accusump to use as pre-start lubrication. I then make sure that the dipstick is at full with this additional oil stored in the accumulator. What do u other guys that use accumulators charge them to for pre-start oiling?
Would it also be acceptable to route pcv from valve covers to catch can and then to accordion hose. That would create a venturi effect also and not dirty my intake yes? How is yours set up Jdub, IJ?
So are you guys suggesting that perhaps my poorly set up PCV system is contributing to my oil consumption issue? or is that just the direction the thread has taken?

 

[jdub]

Personally, I don't use a catch can - on a well maintained, relatively fresh motor it's not necessary. If you are getting the kind of blowby that's pushing that amount of oil/gasoline vapor to make a can worthwhile, it's time to change your rings

But if you want to run one:
1) Route both valve cover nipple to the condensation side of the can.
2) Route the TB orifice to a T fitting.
3) Put a one way check valve (a PCV valve does nicely) between the T-fitting and the orifice - orient the valve so it allows flow toward the orifice. This prevents pressurizing the can under boost.
4) The other side of the T-fitting (straight side) routes to the accordion hose. This allows some flow from the can to the accordion hose.
5) The 90 deg angle side of the T-fitting routes to the suction side of the can.

For the PCV system to work correctly, it requires vacuum from the intake manifold (orifice). Keep in mind 90+% of the time the intake manifold is under vac (off boost). Without this vac, the crankcase can over pressurize and, yes, it can cause excessive oil consumption.

 

[Beefy_Heafy]

That is the most bad ass answer ever. Thanks Jdub.
Ill get onto fixing that up.
Would that also explain the leaky valve stem seal like symptoms, smoke etc?
Ill fix this and see if it stops the other.

Isnt it amazing how every modified car u look at in a magazine has an incorrect pcv system. they all just go from cam covers to can to atmo or to intake just behind air filter. So misleading.

 

[jdub]

Make sure the TB orifice is clear - if it's clogged, it will cause the crankcase to pressurize. If you are getting blue smoke out the back (other than start up) - it's the rings or you are forcing oil our through the turbo bearing. A bad PCV system will cause the latter

 

[Beefy_Heafy]

Im excited to make these changes.
The standard setup doesnt have a one way valve off the orifice. Doesnt this cause a massive boost leak.
Thanks guys for contruibuting and helping me fix my retarded problems yet again.
Ill post back here with results as soon as ive made changes over the next few days.

 

[jdub]

The orifice is a boost leak, but it's my no means "massive" - it's a very small diameter hole designed to flow enough air to carry PCV vapor to the accordion hose efficiently on the stock set-up. The only reason I told to you insert a PCV valve in the hose to the T-fitting is to prevent any possibility of pressurizing the catch can...that would not be good. The" boost leak" is metered air - routing it to the accordion hose after the AFM has zero effect on any fuel computations done by the ECU. The stock PCV is designed quite well - you can run it (no catch can) without any issues.