Car running really choppy, sounds like a miss

Tiny
MUNCHP3
  • MEMBER
  • 1999 CADILLAC STS
  • V8
  • FWD
  • AUTOMATIC
  • 199,850 MILES
I have just purchased this vehicle, supposibly the motor was replaced and only has approx
75,000 on it. I ran a compression test thinking blown head gasket but came back with decent compression all the way around. Also have noticed there seems to be a oil leak that I thought was coming from the head but maybe the valve cover. What else can I check that would cause this car to run really hit and miss and chug while idling. Also bad smell from the exhaust, excessive white smoke, as well as antifreeze in my oil. Also have replaced plugs and wires.
Sunday, March 15th, 2015 AT 2:31 PM

3 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If you have antifreeze in oil and white smoke it's probably a head gasket. If your compression had any cylinder that was 20% difference then it's no good. Scan for codes too
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Sunday, March 15th, 2015 AT 3:51 PM
Tiny
MUNCHP3
  • MEMBER
  • 2 POSTS
Is there something special that I need to do to these heads to change the head gasket? Ive been told that there is something inpaticukar that needs to be done on these cadillacs.
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Sunday, March 15th, 2015 AT 4:12 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It's not the heads sometimes the head studs pull out of the block
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Sunday, March 15th, 2015 AT 4:37 PM

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