Help me identify where this oil is coming from! Pics!

deftsound · Feb 24, 2010

Well i have oil leaking into my air filter and powerpipe thats coming from the rubber tube that goes from the intake tube to the throttle body, the rubber hose has oil residue in it so i know its coming from there. I don't understand where it would be coming from other than the pcv valve, but when i checked the rubber tube that goes from the pcv valve to the intake tube it is clean, no oil or anything.

Where would this oil be coming from?

Here are a couple pics of what im talking about, the green arrows are pointing to the rubber tube that is full of oil residue.

View attachment 228910
View attachment 228911

R.J. · Feb 24, 2010

It is the PCV system allowing the oil to go where it is. If you do a search on this subject you'll see that there are 3 common fixes for this issue. A catch can or oil separator system, Supra PCV valve, or a check valve in the PCV tube. This (Check Valves | U.S. Plastic Corp.) websites check valves had been talked about in other threads.

cooper58d2002 · Feb 25, 2010

R.J. said:
It is the PCV system allowing the oil to go where it is. If you do a search on this subject you'll see that there are 3 common fixes for this issue. A catch can or oil separator system, Supra PCV valve, or a check valve in the PCV tube. This (Check Valves | U.S. Plastic Corp.) websites check valves had been talked about in other threads.

+1 on the PCV system. These Superchargers create a vacuum that just sucks oil from the valve covers. Have the same issue on my Procharger, Bought a oil seperator on Ebay for less than 50 bucks shipped. Going to put it in when i get back to the states.

cooper58d2002 · Feb 25, 2010

BTW, I noticed you have the stock plastic intake. keep an eye on the plastic coolant crossover right behind the alternator. Mine just blew out after around 50,000 miles of Boost going through it.

deftsound · Feb 25, 2010

R.J. said:
It is the PCV system allowing the oil to go where it is. If you do a search on this subject you'll see that there are 3 common fixes for this issue. A catch can or oil separator system, Supra PCV valve, or a check valve in the PCV tube. This (Check Valves | U.S. Plastic Corp.) websites check valves had been talked about in other threads.

Ok i've already got a catch can i was going to use for the problem.

So let me get this straight; oil is being sucked from the intake tube from the supercharger up that rubber tube into the throttle body? I guess im just confused at how oil is getting up that line since its not connected to the pcv system.

So, to solve this i should install a catch can in between that line?

wmburns · Feb 25, 2010

IAC bypass line routing

If anybody ever wonders why Mustangs sometimes have problems idling, take a look at this. Note the routing of the IAC bypass line where is passes under the air tube. This is the lowest point in the run. Any oil in the line has no place to go and will be trapped in the middle. If the line were routed above the air tube, then at least the oil could have an opportunity to drain back.

Consider that if the IAC bypass line is filled with oil, this is going to block/restrict the flow of air to the IAC. In a sense, the line becomes like a plumber's trap.

Many ppl have wondered why the IAC seams to have a short life or needs frequent cleaning. This may offer an explanation how the IAC gets so dirty so fast (PCV blow-by).

OBTW; the oil separator needs to be installed in the PCV line. That puts it closest to the source of oil blow-by.

trombonedemon · Feb 25, 2010

I've heard of cars having lots of issures with blow-by. I put the catch can on my car and had a hell of time getting rid of that crap. Consider buying another catchcan, w/one you will still get blow by, especially with centri-supercharger, buy two to eliminate the problem, its easy to route it, t-it off w/two hoses from both valve covers into one can and connect the cans w/the hoses it comes with. then to your intake. Thats nasty stuff.

deftsound · Feb 25, 2010

wmburns said:
I

OBTW; the oil separator needs to be installed in the PCV line. That puts it closest to the source of oil blow-by.

Yea but why is there no oil residue in the pcv line if thats where its coming from? I can stick my finger inside the pcv line and there is no oil grime at all. On the line that goes to the IAC however there is oil gunk and residue all up inside of it; so thats what im confused about.

Also thanks for all the great info!

wmburns · Feb 25, 2010

PCV vapors cool and condense

Everything that follows is IMO.

The oil in PCV blow-by is mostly a gas. As it cools, the oil will condense. So it makes sense the further the vapors have to go, the greater the chance of condensation. Once the oil condenses, the migration is naturally slower.

So in a car without an oil separator, the oil should remain as a vapor as long as possible to facilitate its return for burning.

If using an oil separator, the idea is to provide a spot for the vapors to expand and cool thus allowing the oil to condense in a more suitable location. A real race oil separator is physically large and has internal baffles to force the vapors to cool. It also has facilities to drain the captured oil. That is why they are so big.

This is where I think most people miss the mark. It is not possible for a small in line air filter to offer enough surface area to remove all of the oil under all conditions. Does it help? That depends. Every drop captured is a drop not in the intake.

So in answer to why there is no oil in the PCV line. IMO, it is because it is still in hot gaseous form having just come out of the engine. As it moves through the air system, it cools (and your air system is much longer than the typical air intake path). At some point it cools enough to condense back into oil.

I am somewhat confused as to why the by-pass line draws so close to the super charger. I would have thought it should be closer to the TB butterfly. Is it possible that there is pressure differential between to two points? If so, the oil could be coming backwards out of the IAC when the throttle is closed (a theory).

Anyway, I have zero experience running/tuning/modifying supercharged cars. So I really can not help much beyond a basic understanding of how motors work.

deftsound · Feb 26, 2010

wmburns said:
Everything that follows is IMO.

The oil in PCV blow-by is mostly a gas. As it cools, the oil will condense. So it makes sense the further the vapors have to go, the greater the chance of condensation. Once the oil condenses, the migration is naturally slower.

So in a car without an oil separator, the oil should remain as a vapor as long as possible to facilitate its return for burning.

If using an oil separator, the idea is to provide a spot for the vapors to expand and cool thus allowing the oil to condense in a more suitable location. A real race oil separator is physically large and has internal baffles to force the vapors to cool. It also has facilities to drain the captured oil. That is why they are so big.

This is where I think most people miss the mark. It is not possible for a small in line air filter to offer enough surface area to remove all of the oil under all conditions. Does it help? That depends. Every drop captured is a drop not in the intake.

So in answer to why there is no oil in the PCV line. IMO, it is because it is still in hot gaseous form having just come out of the engine. As it moves through the air system, it cools (and your air system is much longer than the typical air intake path). At some point it cools enough to condense back into oil.

I am somewhat confused as to why the by-pass line draws so close to the super charger. I would have thought it should be closer to the TB butterfly. Is it possible that there is pressure differential between to two points? If so, the oil could be coming backwards out of the IAC when the throttle is closed (a theory).

Anyway, I have zero experience running/tuning/modifying supercharged cars. So I really can not help much beyond a basic understanding of how motors work.

Wow awesome explanation! I really appreciate your help. Well i guess today ill go ahead and install my UPR catch can in line with the pcv hose. Thanks!

mogs01gt · Feb 26, 2010

I hope guys realize the second picture is his IAC? The PVC system is to vent crank case pressure.

When running the oil separator for the PVC system, you cannot run a line for the IAC into that system. It would most likely cause erratic idle.

deftsound · Feb 26, 2010

mogs01gt said:
I hope guys realize the second picture is his IAC? The PVC system is to vent crank case pressure.

When running the oil separator for the PVC system, you cannot run a line for the IAC into that system. It would most likely cause erratic idle.

so what are you saying? that i have to disconnect the iac line?

wmburns · Feb 26, 2010

I knew the green line was the IAC.

The OP was also asking why oil was in the IAC line if the oil was coming from the PCV line. I believe an explaination was offered and accepted.

I also stated in my reply the oil separator needed to go on the PCV line. I agree. Do not put an oil separator in the IAC line.

If it were my car, I would think about re-routing the IAC line so that there is not a low spot in the middle of the run. Then the oil would have a chance to drain back while the car is setting.

Once the IAC line is cleaned of oil, suggest monitoring to see if it comes back and where it is coming from (IAC side or intake tube side).

Note: I also think it is possible that the routing of the IAC line is such that any small amount of oil that gets in the line gets trapped. Over time, a large amount of oil could build up. Esp if it is never looked at.

mogs01gt · Feb 28, 2010

deftsound said:
so what are you saying? that i have to disconnect the iac line?

You cannot disconnect your IAC, you could maybe put in an inline filter but I doubt that would make much of a difference.

With the blower, you can going to create extra crank case pressure and have extra blow by. Not many ways you can prevent it with forced induction.

Going to an inline filter setup on the PVC will reduce the oil in your induction path.

deftsound · Mar 1, 2010

Ok guys great! I really appreciate all your responses and knowledge! Once i get the right size fittings for the upr oil can i bought ill be installing it!

Help me identify where this oil is coming from! Pics!

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