Overly above idle condition

Tiny
HOTRODZ
  • MEMBER
  • 1981 PONTIAC TRANS AM
  • V8
  • 2WD
  • AUTOMATIC
  • 65,000 MILES
Can a blown head gasket produce an overly above idle condition on a 1981 Pontiac Firebird TransAM Turbo V8 301 CID 4.9 Lt. Eng?

All Vacuum Hoses connected or unused ports capped off.

Carb Air screws adjusted and the car ran fine for 3 hours.

Shortly after replenishing 134A Freon to the A/C, it returned to overly above idle condition as prior to carb. Adj. I then noticed oil in the radiator; However, no water on the oil dipstick.

The car had sit to rest for five consecutive years.
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Sunday, January 16th, 2011 AT 5:18 PM

2 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
No, a headgasket won't cause that to happen. Check to make sure the idle break solenoid is working properly. Also, since the vehicle sat, check to make sure the choke isn't moving around on the carb while running. As far as the oil in the radiator, make sure it is motor oil and not trans fluid. The cooler may have rotted through. If coolant gets into the trans, it will destroy it.
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Sunday, January 16th, 2011 AT 7:08 PM
Tiny
HOTRODZ
  • MEMBER
Hi Jacobandnickolas, fortunately, I hadn't poured coolant on the radiator as of yet since I was still in the process of flushing it after having had replaced the timing chain, timing cover and water pump.

Thanks to your advice, I went ahead and isolated the cooler section off the radiator, capped off the bottom radiator line thread and applied a bit of compressed air through the upper end and noticed air bubbles inside the radiator which proved your theory correct.

I have continued flushing the radiator, thus becoming oil free.

I drained the transmission fluid and inspected the trans oil pan
with no apparent water mix.

As far as the above idle condition, after it reaches normal operating temperature, the idle feels normal; however, there are instances that while accelerating either at cruising or short stop, it accelarates above normal by itself and by sudden quick pushing and deppressing the accelerator pedal it releases from above idle back to normal.

You had mentioned the possibility of the choke being moving around inside the carburator.

If that's the case? What may be causing that and what should I observe and adjust or replace accordingly?

Prior to this, I cleaned out the carb, installed the lean mixture screw repair kit and the carb repair kit and replaced the secondary Choke Pull Off.
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Tuesday, February 1st, 2011 AT 6:57 PM

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