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oil through the pcv valve

Discussion in 'The Garage' started by poolcues, Jul 2, 2006.

  1. poolcues

    poolcues 1/2 ton status

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    i've got an 87 k10 350/700r4/208. upon acceleration from sitting at a stop light i get a cloud of smoke. at first i thought "new valve seals" would do the trick however i pulled the tbi unit to clean it, replace the injectors i noticed oil looked like it was coming through the pcv valve into the intake causing the smoke. could this be from a vacuum leak, valve seals being bad or ?. i did a search and found a lot of good info. but nothing exact. any ideas would be appreciated. i never did have the heads service yet.
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    usually its blowby...

    The PCV valve often sucks in excessive oil fumes from too much blowby past the piston rings....or because the "breather" that lets fresh air into the crankcase is clogged up,and it pulls air past the rings and anywhere else it can,bringing oil along with it..I see that a lot on cars and trucks with "hot rod" chrome valve covers with no provision for a breather filter..many have no baffle under the PVC valve hole too,which causes it to suck up oil more than usual...

    Valve stem seals missing or failing,and loose valve stem to guide clearence will cause a big puff of smoke upon starting,that dissapates rapidly,and the engine usually consumes little oil between changes..also while coasting downhill,especially if you downshift it,they will cause excessive smoking under those conditions..

    Blowby past the piston rings will make it smoke during acceleration ,or under a load, like climbing up a hill...sounds more like rings or piston problems than valve seals in your case...compression test is the next step--take readings "dry",then try adding a teaspoon of oil to each cylinder and test again..higher readings with oil means piston,rings,or cylinder wear...a "leakdown" test is another good way to pinpoint oil consumption causes,by using compressed air to charge up each cylinder and see where the "leakage" is coming from..:crazy:
     
  3. poolcues

    poolcues 1/2 ton status

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    i appreciate the input. i was hoping it would be something simple like the valve seals cause i'm not in the mood to pull the motor and go through it if need be!!:doah:
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    Fudge it!...

    Nearly every GM vehicle I've owned has well over 100 thousand on them,and all used a bit of oil between changes,(like a quart or two),and smoked upon startup or while accelerating,etc....I didn't fix many of them,just ran them until they blew,or swapped in better running motors from rotted hulks I'd buy cheap...

    Most of those engines ran sweet,they just smoked a bit..I'd just run 20W-50 oil in warmer weather,and add a can of Lucas oil treatment or "motor medic" ,"STP",or similar "oil thickener" to reduce oil consumption and smoking...you could do the same and avoid doing the work it'll need to fix it for quite some time...:crazy:
     
  5. poolcues

    poolcues 1/2 ton status

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    that sounds like some good advice and worth trying:D
     

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