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420A 420a now starts but still smokes and idles high

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jhunfiyell

Proven Member
69
0
Dec 12, 2012
williamstown, New_Jersey
i was able to revive the car back after replacing seals, head gasket, and new belts and the whole nine. basicaly, a upper engine rebuild. Now i have gotten my car to start and it idles around 1 rpm to 2, and stays constant at 1 at startup but when accelerating it slowly idles down from 2 to 1 hesitantly. i also having white smoke coming, but the mechanic said thats because it still has some oil left from the last time i drove it. and i just got it back to work yesterday, but when i accelerate and press on the gas, the car blows out smoke everytime i press the gas.. Need help. what else can i do
 
Any oil or coolant in the cylinders after the repair would have burned off within seconds. I'd suspect the recently replaced head gasket, or possibly a cracked head or cylinder. You could perform a leak down test (found here) to verify the source of the leak.

The high idle is usually from a vacuum leak after the throttle body, but could also be from a tight throttle cable or improperly adjusted throttle stop.
 
also, how about the rings? i heard piston rings, and im sorta afraid. what compression am i looking for ?

i also heard that, my headbolts might not have been torqued properly. because i was using a manual torque wrench. where it has the gauge, and what not.
 
On the 420a engine I believe service limit is 100 psi and standard compression is 170-225. There also shouldn't be more than 10% (or 15-20psi) difference between cylinders. But a compression test will only tell you if a cylinder is damaged, not why. A leak down test will help determine whether it's the head gasket or pistons rings.

For the head bolts, all that matters is that you torqued the bolts in steps and with the proper sequence. What kind of torque wrench you use doesn't matter so long as it's accurate.
 
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Sometimes the intake manifold is not torqued down in sequence or the gasket moved upon install. What kind of throttle body gasket did you use? 420A's are prone to blow-by with high miles. Do you have oil in your intake pipe ever? Like Wes said a leak down and compression test will get you in the right direction.
 
Could be a badly seated valve stem seal. Ive just had a brand new one go on mine, managed 500 miles before going
 
also, i realize that my engine, where the hg is placed ,i see smoke comng out in between, and the intake as well.. i feel like theres a small gap in the gaskets. also. it now smokes upon accelerating, during idle it calmed down from what i see. but thats just me. gotta take another look.
 
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