Loose intake bolts?

[Tom L.]

With the weather finally being so nice here in the north east, I decided to give my car a bath, run it for a bit and check the fluids so I could take it to work today.

While I had it running I noticed some oil around the intake gasket. I then shut it off amnd immidiately assumed it was the valve covers but they were tight. Next I checked the intake bolts and they were ALL loose. I was abe to get at least one turn on each.

The engine ran fine before and after, my question is, what would make this happen? And what may need to be done to prevent this from happening again?

BTW, I assume that the oil leaked at the end of last season and went un-noticed, it is a '72 LS-5, it was rebuilt prior to purchasing it a few years ago and I have never touched tose bolts before.

[Jack H.]

Re: Loose intake bolts?

The engine ran fine before and after, my question is, what would make this happen? And what may need to be done to prevent this from happening again?

Here are three guesses for why...

(1) Originally torqued to the wrong spec.
(2) Originally torqued in the wrong order.
(3) Originally torqued with the wrong method.

On #3, the typical method is to take each bolt up to HALF of its final torque spec following the bolt by blot sequence described. Then, making a second pass in the same sequence to arrive at the final torque spec. That allows each bolt to strain relieve itself properly...

[Joe L.]

Re: Loose intake bolts?

With the weather finally being so nice here in the north east, I decided to give my car a bath, run it for a bit and check the fluids so I could take it to work today.

While I had it running I noticed some oil around the intake gasket. I then shut it off amnd immidiately assumed it was the valve covers but they were tight. Next I checked the intake bolts and they were ALL loose. I was abe to get at least one turn on each.

The engine ran fine before and after, my question is, what would make this happen? And what may need to be done to prevent this from happening again?

BTW, I assume that the oil leaked at the end of last season and went un-noticed, it is a '72 LS-5, it was rebuilt prior to purchasing it a few years ago and I have never touched tose bolts before.

Lynn------


This is a very common problem with intake manifold bolts and, most especially, the bolts at the center locations on each side.

My recommendation is to remove all the intake manifold bolts and scrupulously clean them. Then, clean the threads in all the holes with a thread cleaning tap. Make sure that the holes that go through to the lifter valley are scrupulously clean and free from ANY oil or grease.

Apply Locktite 242 (blue) thread locking and sealing compound to the bolts and reinstall. Torque the bolts in the pattern described in the service manual. Use TWO complete rounds. The first to 1/2 the specified torque; the second to the full specified torque.