Oil is being sucked into the upper intake manifold from the PCV valve, causing the engine to blow out blue/gray smoke upon startup and heavy acceleration.
92 GT
347 Stroker
Edelbrock Performer Intake
Roush Iron Heads
High volume oil pump
All stock emissions gear attached and working except running O/R H-pipe with no cats
Built the stroker motor about 15 years ago and always had more oil consumption than with the stock motor. Being a 347 I expected a little more consumption and didn't worry about it, just kept the pan full. Haven't driven it much over the past 5 years but it always ran strong, just smoked a little upon startup and heavy acceleration and leaked some oil. Been getting it back into top shape and started fixing all the areas oil was leaking; valve covers were the main problem but also had a little oil around the PCV location. Checked everything - the PCV valve was fine but didn't fit properly in the grommet and the mesh screen below was missing. Installed a new screen, proper sized grommet, new PCV, and new hose to upper intake. Also during this time I replaced several vacuum hoses that had gotten loose over the years. Good news is that it no longer leaks oil. Bad news is that it now burns oil like crazy.
Traced the problem back to the PCV location. Oil is being sucked into the intake from the PCV, pulled into the back 4 intake runners, fouling plugs #3,4,7&8, creating the smoke, and making me really mad.
I've been reading through the forums for ideas and found two threads that seem to contain the most pertinent information.
I tried the method of splitting the hose for two PCVs before bringing into the intake, to hopefully slow down the amount of oil getting to the top (see link below, has pictures) but unfortunately it didn't seem to make any difference.
https://www.stangnet.com/mustang-fo...ke-via-pcv-solved-really.886733/#post-8924767
As a test I left the dual PCV contraption on but removed the line going to the intake. I capped the intake hose but left the hose going to the PCVs open. Started it up and no smoke. Drove it hard, revved it up, etc., and no smoke. No oil is coming out of the open hose either. Car is running better than ever with no oil leaking and no smoke at all. Haven't pulled the plenum to confirm no oil and only checked #8 plug, which was now a nice tan color. However, with the hose to the PCV left open I don't see this as a permanent fix.
Read another thread (see link below) that suggested running a relief hose from the driver's side valve cover to the PCV / intake hose to reduce the amount of pressure to the PCV and still pull out crankcase gases. Sounds like a valid option but before digging through eBay for valve covers or cutting into mine (yikes), I would like more input.
https://www.stangnet.com/mustang-forums/threads/oil-in-upper-intake-from-pcv-hose.701999/
I have not run a compression test yet but by the way it drives with the hose off, it feels 100% with no misses, no hiccups, nothing...idle is even excellent. Hoping for a simple solution to fix this for good.
92 GT
347 Stroker
Edelbrock Performer Intake
Roush Iron Heads
High volume oil pump
All stock emissions gear attached and working except running O/R H-pipe with no cats
Built the stroker motor about 15 years ago and always had more oil consumption than with the stock motor. Being a 347 I expected a little more consumption and didn't worry about it, just kept the pan full. Haven't driven it much over the past 5 years but it always ran strong, just smoked a little upon startup and heavy acceleration and leaked some oil. Been getting it back into top shape and started fixing all the areas oil was leaking; valve covers were the main problem but also had a little oil around the PCV location. Checked everything - the PCV valve was fine but didn't fit properly in the grommet and the mesh screen below was missing. Installed a new screen, proper sized grommet, new PCV, and new hose to upper intake. Also during this time I replaced several vacuum hoses that had gotten loose over the years. Good news is that it no longer leaks oil. Bad news is that it now burns oil like crazy.
Traced the problem back to the PCV location. Oil is being sucked into the intake from the PCV, pulled into the back 4 intake runners, fouling plugs #3,4,7&8, creating the smoke, and making me really mad.
I've been reading through the forums for ideas and found two threads that seem to contain the most pertinent information.
I tried the method of splitting the hose for two PCVs before bringing into the intake, to hopefully slow down the amount of oil getting to the top (see link below, has pictures) but unfortunately it didn't seem to make any difference.
https://www.stangnet.com/mustang-fo...ke-via-pcv-solved-really.886733/#post-8924767
As a test I left the dual PCV contraption on but removed the line going to the intake. I capped the intake hose but left the hose going to the PCVs open. Started it up and no smoke. Drove it hard, revved it up, etc., and no smoke. No oil is coming out of the open hose either. Car is running better than ever with no oil leaking and no smoke at all. Haven't pulled the plenum to confirm no oil and only checked #8 plug, which was now a nice tan color. However, with the hose to the PCV left open I don't see this as a permanent fix.
Read another thread (see link below) that suggested running a relief hose from the driver's side valve cover to the PCV / intake hose to reduce the amount of pressure to the PCV and still pull out crankcase gases. Sounds like a valid option but before digging through eBay for valve covers or cutting into mine (yikes), I would like more input.
https://www.stangnet.com/mustang-forums/threads/oil-in-upper-intake-from-pcv-hose.701999/
I have not run a compression test yet but by the way it drives with the hose off, it feels 100% with no misses, no hiccups, nothing...idle is even excellent. Hoping for a simple solution to fix this for good.