Loose Intake Manifold Bolts

EWM1 · February 28, 2009

I am looking for opinions. I have been noticing a small rough idle on my 07 NBS 5.3l. I checked the torque on my intake manifold bolts and found that they were only torqued to 35 in/lbs. It has been this way from the factory. I currently have 15k miles on the truck and was wondering if I can just torque the intake properly (44 in/lbs first pass, 89 in/lbs second pass) or do I need to have the gaskets changed? Any help would be appreciated. Thanks.

Zembonez · February 28, 2009

I am looking for opinions. I have been noticing a small rough idle on my 07 NBS 5.3l. I checked the torque on my intake manifold bolts and found that they were only torqued to 35 in/lbs. It has been this way from the factory. I currently have 15k miles on the truck and was wondering if I can just torque the intake properly (44 in/lbs first pass, 89 in/lbs second pass) or do I need to have the gaskets changed? Any help would be appreciated. Thanks.

You should be able to re-torque them but I'd confirm that they are actually out of spec for sure before doing so. Even at a lower torque, I can't see how they would cause your run issue. An actual intake leak would probably trip a CEL and store a code. Good luck with it.

pennzoil29 · February 28, 2009

I know my truck is a lot older, but you could try removing the oil fill cap while the truck is running. Put the palm of your hand against it, and if it suck's your hand, then I'd assume you have a intake leak.

EWM1 · February 28, 2009

I know my truck is a lot older, but you could try removing the oil fill cap while the truck is running. Put the palm of your hand against it, and if it suck's your hand, then I'd assume you have a intake leak.

Thanks so far. I checked the torque with a calibrated torque wrench that goes from 0-150 in/lbs. At 35 in/lbs, the bolts started to move.

Why is there suction at the oil fill tube when there is an intake leak?

pennzoil29 · February 28, 2009

I know my truck is a lot older, but you could try removing the oil fill cap while the truck is running. Put the palm of your hand against it, and if it suck's your hand, then I'd assume you have a intake leak.

Thanks so far. I checked the torque with a calibrated torque wrench that goes from 0-150 in/lbs. At 35 in/lbs, the bolts started to move.

Why is there suction at the oil fill tube when there is an intake leak?

I honestly can't answer that. It was an old trick showed to me years ago. That is how I knew my intake gaskets took a crap on me for the second time. Good luck.