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Old 10th September 2008, 06:39   #1
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Angry Spark plug clearance on a Chevy Optra 1.6?

Hi guys,
Yesterday i had my spark plugs changed to bosch super. the preset air gap is 0.9mm and my manual says that i need 1.0~1.1mm. now my mechanic says that due to heat the preset air gap increases and it willl be 1.0mm once i start the car! is it true?
Also when he was changing the plugs we noticed that a little amount of engine oil was in number 3 chamber of the plug (not where the plugs ignite the inside combustion chamber, but where the cables go to reach the plug) he said that the TAPET COVER SEAL needs to be replaced and its not a big job and can be done later also. i would like to put it very precisely that very little amount of engine oil(around 1-2 ml) was found in it and he cleaned it and installed the plugs.
One more thing i would like to add is i have got my injectors cleaned at 17000kms(15 months back) and engine decabonised at 20000kms(12months back) now i'm at 30000kms do i have to get my throttle body cleaned and adjusted by removing it? i've also done engine flushing with changing the spark plugs.
by the way i'm having a chevy optra 1.6 .
please help me guys
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Old 10th September 2008, 09:50   #2
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Metal expands on heating and does not turn away, so the gap will decrease on your plugs. Get the seal changed and follow the service manual for the throttle body cleaning.
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Old 10th September 2008, 10:04   #3
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First of all the people who wrote the manual must have been aware of the fact that metal expands on heating. So they must have considered that.

Secondly, it's not only the tip that would expand. The whole spark plug assembly would expand so the end result may be a constant gap. I would say stick to the manual. You can also try driving it around and see if there's any difference for better and decide.
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Old 10th September 2008, 10:25   #4
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Thats what I meant, stick to the prescribed gap and dont add your margins.

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First of all the people who wrote the manual must have been aware of the fact that metal expands on heating. So they must have considered that.
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Old 10th September 2008, 10:27   #5
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Quote:
Originally Posted by mdesai_1981 View Post
Hi guys,
Yesterday i had my spark plugs changed to bosch super. the preset air gap is 0.9mm and my manual says that i need 1.0~1.1mm. now my mechanic says that due to heat the preset air gap increases and it willl be 1.0mm once i start the car! is it true?

Set to comp specified limits

Also when he was changing the plugs we noticed that a little amount of engine oil was in number 3 chamber of the plug (not where the plugs ignite the inside combustion chamber, but where the cables go to reach the plug) he said that the TAPET COVER SEAL needs to be replaced and its not a big job and can be done later also. i would like to put it very precisely that very little amount of engine oil(around 1-2 ml) was found in it and he cleaned it and installed the plugs.

he might be right, since the oil residue is on the outside

One more thing i would like to add is i have got my injectors cleaned at 17000kms(15 months back) and engine decabonised at 20000kms(12months back) now i'm at 30000kms do i have to get my throttle body cleaned and adjusted by removing it? i've also done engine flushing with changing the spark plugs.

Either you can use throttle body cleaner spray (2nd preference) OR do it the proper way by opening and cleaning the assembly. Get it done by A.S.S dont rely on local mechs for such jobs. they do tend to screw up big time
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