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Blown turbo? oil leak from Bov

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Old 10-18-17, 10:54 PM
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Blown turbo? oil leak from Bov




So yea. Made a drive out and when I parked at a store for a quick drink I noticed a lot of burned oil smell. I looked underneath and sure enough it was covered in oil and everything was wet. Oil dripping drops by the second

After looking around and checking for busted lines narrowed down to the bov. While full throttle on the lift oil sprays out from the outlet of the bov. And thats 0 load and max boost.
wonder how much oil it was spraying out while cruising and boosting on the freeway.

are my twins done for ? From my understanding. Blown internal seal is pretty much a bye bye twins ... need some help. I want to go to sevenstock goddamnit lol
Old 10-18-17, 10:56 PM
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my BOV is a pettit racing one and I position it so the outlet is downstream of the car
good thing I did that or else the engine bay would of been a MESS!

Last edited by kensin; 10-18-17 at 11:17 PM.
Old 10-19-17, 06:51 AM
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If you are not using an oil catch can, then oil is dumped into the primary turbo inlet elbow whenever there is too much oil or too much pressure in the pan. Disconnect the hose that points down from the filler neck. Cap the nipple and go for a drive, if the BOV is not blowing any more oil then it is not the turbos. If you recently changed the oil and overfilled it, it will pump into the primary turbo.
Either way chances are that the IC has oil in it also.
Old 10-19-17, 07:28 AM
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Originally Posted by Banzai-Racing
If you are not using an oil catch can, then oil is dumped into the primary turbo inlet elbow whenever there is too much oil or too much pressure in the pan. Disconnect the hose that points down from the filler neck. Cap the nipple and go for a drive, if the BOV is not blowing any more oil then it is not the turbos. If you recently changed the oil and overfilled it, it will pump into the primary turbo.
Either way chances are that the IC has oil in it also.
no catch can is installed. the car is pretty stock engine wise. just a 3inch downpipe and catback. stock boost stock ecu with a ported 99spec twins. 10years old with 35k miles

thank you so-much banzai. i was hoping it wasn't the oil pan since i have resealed with your brace. and its been dry and pretty
i was actually going to uncap the oil cap and go for a drive since i also suspect the PCV valve is stuck

I changed the oil maybe 2.5k miles ago and oil isn't really burning a lot . the drive I took yesterday was about an hour long and pretty decent boost for the entire route(uphill). and it just developed on the drive when I stopped . so it happened during that that

it pretty much happened with out warning .

ill try it both ways and report back
Old 10-19-17, 08:36 AM
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You might want to change your oil. Sounds like you just got the oil hot and it thinned out. You can just remove the oil filler cap which will allow crank case pressure to vent to the atmosphere.
Old 10-19-17, 08:52 AM
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Originally Posted by Banzai-Racing
You might want to change your oil. Sounds like you just got the oil hot and it thinned out. You can just remove the oil filler cap which will allow crank case pressure to vent to the atmosphere.
I just did the test drive with out the cap and it seems like it wasn't spilling. I did 1 tiny pull in the parking lot

while idle I put the cap back on and did a few free revs to redline and it started drippjng again

I'm gonna change the pcv at a local auto parts store real quick to see the difference.

With the oil thinned out it would cause something like this ?
so odd. I use 20w50. But it is due for a change



***ninja edit. I just had a gentlemen help me free revs with and with out the oil cap on. Can confirm. With cap on. Oil spits out
with out. Just air mist

Last edited by kensin; 10-19-17 at 09:04 AM.
Old 10-19-17, 09:04 AM
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Thinner oil might slosh a bit more, but it shouldn't be the root cause of your leakage. Something else is not doing its job.
Old 10-19-17, 09:24 AM
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Originally Posted by DaveW
Thinner oil might slosh a bit more, but it shouldn't be the root cause of your leakage. Something else is not doing its job.
i took off the pcv valve and blew through it. It works like a 1 way valve should. I can blow towards the manifold but not the other way around. Completely 1 way. Other pcv I tried out just now let's air through both ways. So confused
Old 10-19-17, 09:37 AM
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PCV is supposed to only work one way. Hot, thin, fuel diluted oil will blow by.

Change your oil as I posted earlier, do not overfill.
Old 10-19-17, 01:22 PM
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Originally Posted by Banzai-Racing
PCV is supposed to only work one way. Hot, thin, fuel diluted oil will blow by.

Change your oil as I posted earlier, do not overfill.
I hear you, but any oil hot is thin - it's all relative. Even a good 40 or 50 wt oil is like water at >250F. So I think something is not working properly.
Old 10-19-17, 02:13 PM
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Originally Posted by DaveW
I hear you, but any oil hot is thin - it's all relative. Even a good 40 or 50 wt oil is like water at >250F. So I think something is not working properly.
so I just changed. The oil to fresh 20w50 and oil filter. Drained out about 3.5 ..4 ish qt. And put in 3.5qt. Landed the stick at a little above half ways.
i have an dual oil coolers. And my fans work properly


i took it out for a short drive and a little 4 wot pull in first and second gear. So far there is no sign of leakage. Returning to the garage and checked underneath, my control arm is dry. It gets wet and dripping prior to the oil change.

and then I tried to free rev it .. no oil or mist


so strange ... I'm gonna drive it some more later just to confirm.

the oil haves about 3~4k semi hard miles. The entire duration on desert summer weather. 100f plus
Old 10-19-17, 08:05 PM
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Get a catch can
Old 10-21-17, 09:44 PM
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I would definitely install a catch can. How ever my real question is. It didn't need one for the pass 8 month when I drove it semi hard. Why all of a sudden it needs one ?
it litteraly started puking oil out of my stock BOV that's vented to atmosphere. And then some oil collected in the IC.
That's my primary inlet. I can see a little oil in There.
the shaft play is minimal, Just like 8 months ago when I had the wastegate ported.

if it's just a blown turbo then I can switch with a better unit and not run a catch can right ? I'm not trying to say I wont install one but rather I'll install one after knowing what the real issue is. Not to install one as a bandaid

i checked the pcv on the top nipple of the oil filler neck. It's working. Blow 1 way towards the manifold only.
Old 10-21-17, 10:03 PM
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Originally Posted by Banzai-Racing
If you are not using an oil catch can, then oil is dumped into the primary turbo inlet elbow whenever there is too much oil or too much pressure in the pan. Disconnect the hose that points down from the filler neck. Cap the nipple and go for a drive, if the BOV is not blowing any more oil then it is not the turbos. If you recently changed the oil and overfilled it, it will pump into the primary turbo.
Either way chances are that the IC has oil in it also.
i have not tried this yet so I'll go cap off the bottom nipple and try it. With it capped off. There's no vent under boost . Will this hurt anything ?
Old 10-22-17, 11:23 AM
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Originally Posted by kensin
if it's just a blown turbo then I can switch with a better unit and not run a catch can right ? I'm not trying to say I wont install one but rather I'll install one after knowing what the real issue is. Not to install one as a bandaid
A catch can is not a band-aid for a bad turbo, it catches the oil from the fill neck that gets pushed into the intake from excessive crankcase (for lack of a better term) pressure, i.e. blow-by. With forced induction, you can get blow-by regardless of the condition of your turbos, so it's not a band-aid for the turbos and it is my experience (with good turbos), that FDs produce blow-by with heavy use. If you are still getting oil in your intake (or BOV) after installing a catch can, it is probably the other source of oil, bad turbo oil seals.

I also recommend a baffled oil filler neck. After installing one, my blow-by reduced significantly. And remove your IC and check for oil as advised by Banzai. If your BOV is spewing oil, it is probably in your IC
Old 10-24-17, 12:33 AM
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Originally Posted by TomU
A catch can is not a band-aid for a bad turbo, it catches the oil from the fill neck that gets pushed into the intake from excessive crankcase (for lack of a better term) pressure, i.e. blow-by. With forced induction, you can get blow-by regardless of the condition of your turbos, so it's not a band-aid for the turbos and it is my experience (with good turbos), that FDs produce blow-by with heavy use. If you are still getting oil in your intake (or BOV) after installing a catch can, it is probably the other source of oil, bad turbo oil seals.

I also recommend a baffled oil filler neck. After installing one, my blow-by reduced significantly. And remove your IC and check for oil as advised by Banzai. If your BOV is spewing oil, it is probably in your IC

All that was collected inside the intercooler. So positive on blown turbo ? I let the car idle and the bov was getting wet and apon hard vacuum the oil amount gets worst . Tested with the filler neck tube to primary inlet unplug.

Last edited by kensin; 10-24-17 at 04:49 AM.
Old 10-24-17, 10:59 AM
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The stock pcv system in these cars works very poorly and easily becomes overwhelmed. The one way valve only vents when the car is off boost. Being that they are nearly always on boost, it doesn't work. So Mazda added another vent path that dumps oil into the primary turbo inlet. Genius idea. Remove the pcv and block off its port on the intake manifold. Then plumb a vented catch can in-line with the other hose that goes into the turbo inlet. This will allow the system to breathe and any oil that comes up the oil neck will fall into the catch can instead of going into the turbos. Also remove you intercooler and piping and degrease them of any oil. Drive the car and see if it clears up before deciding the turbos are bad. Also, are you really going that long between oil changes? I recommend 3000 miles at the very most. Ideally every 2000 miles. The oil gets diluted by gas and can't do its job if you wait too long.
Old 10-25-17, 03:24 PM
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If you are getting oil in your intake after disconnecting the source of blow-by (i.e. the line from the filler neck to the primary turbo), it's the only other source of oil and that's the turbos. The only other thing to possibly check is the oil drain from the tubos, but i doubt you have a problem there

Looks like it might be a good time to upgrade
Old 10-25-17, 06:23 PM
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Originally Posted by TomU
If you are getting oil in your intake after disconnecting the source of blow-by (i.e. the line from the filler neck to the primary turbo), it's the only other source of oil and that's the turbos. The only other thing to possibly check is the oil drain from the tubos, but i doubt you have a problem there

Looks like it might be a good time to upgrade
yup. Tubes are clean and did the disconnected primary inlet pipe. No change.
the Frankenstein turbo is on and going on a 1 hour test drive. Shortly. 99spec center piece and cartridge from 2 different twins. New boost pill new actuator since the old ones were filled with oil . Thanks guy for the help along the way




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