Excessive backflow of PCV emissions into the air cleaner

Tiny
TERRITORYGIRL
  • MEMBER
  • 1990 FORD F-350
  • 5.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 90,000 MILES
Burning pcv emissions into the air cleaner, fills up cab, dark smoke behind the rig. Excessive blowby on the air cleaner side of the pcv. For some reason to much pressure somewhere in the engine.
Tuesday, March 11th, 2014 AT 2:40 PM

2 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check to see that the pcv is actually working as it's the breather not the pcv. The hose or the valve can be blocked and should have intake vacuum. Then check compression with a leak down test. Also check to see if cylinder head drain back holes are blocked.
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Tuesday, March 11th, 2014 AT 3:05 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 46,565 POSTS
It sounds like a problem I had in the shop the other day, The truck was two years newer but had the exact symptoms you describe. Once disassembled, the engine had a broken top piston ring allowing the engine to fill with excess pressure. (It would cause the same problem if the piston is cracked.) Is the engine making any noise?

Best, Ken
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Tuesday, March 11th, 2014 AT 4:59 PM

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