90 Pont. Firebird 305 TPI
Alright, so I have some oil on my intake manifold on my passenger side. I noticed some oil around the head of the intake manifold bolt closest to the oil leak. I suspect it runs through an oil jacket. I do remember some intake bolts having poor threads when I did my heads last summer. It is not a lot of oil.

Problem is, I'm having a hard time finding replacement bolts online anywhere. I looked at NAPA, Autozone, and Advanced Auto. Can anyone help here?


Also I noticed my oil level is lower than usual. I have never really had to worry about oil loss in my car. The car is at 208k miles now so I am okay with losing 1/2 quart every 3000 miles. I topped it off a few weeks ago and now I'm at MIN. on the dipstick. This is unusual for me. I pulled my PVC and saw oil in the hose. Is it possible my PCV is sticking? Replaced it approx. 10k miles ago.

 

If you are leaking oil through the intake manifold bolt, then tighten them down. They need to be torqued back down after a while, after any engine work you do.

 

Does the engine have unusually high crankcase pressure? You may need to do an engine flush, something like BG Compression restore. As far as the intake manifold bolts go, they are 3/8" x 16 thread. You can buy this size bolt in all lengths and head designs at any good hardware store. Forget the auto parts stores. They have minimal fastener selection. The hardware store is where they really stock fasteners. I found bolts there that were almost an exact copy of the factory bolts but with allen heads rather than torx. Length for the manifold can be anywhere from 1 1/2" to 1 3/4".

 

Thanks guys. I thought the bolts were metric... I'll see what I can find at tractor supply.


Also, how can I measure crankcase pressure? Would putting a gauge at the valve cover grommet that the PCV sits in be acceptable?

 

Generally I place the gauge adapter in the make up air opening on the opposite side from the PCV valve. Of course, I'm usually looking for excessive vacuum from a failed crankcase pressure regulator on various German or Asian engines. On early domestics, I usually just pull the PCV valve cap off the make up air opening, and look for excessive blow by gases from the opening while snapping the throttle.

On a healthy motor, there should be only a small amount of visible emissions from the crankcase in this test. If you hold your hand a few inches above the opening, you should feel a soft push of air. If you get a large amount of air with oil spray, you have excessive blow by. As I mentioned. BG's Compression Restore crankcase flush works very well. I know some use Sea Foam as well. An engine flush with something like this should help if the problem is just varnish build up in the ring lands. If crankcase pressure checks out okay, just reseal the valve covers.

EDIT: BTW, the TPI runner bolts are metric 8mmx1.25.

 

Half quart every 3000 miles is not that bad at all considering the mileage. You might need to remove the intake and redo your gasket if you took that off. The valve seals will leak oil into the cylinder and the easy way to check that is gun the throttle and check for a billow of smoke through the exhaust that kind of looks white when you let off the gas.

 

Pulled the PCV, some puffing at idle. My Vacuum/Pressure gauge didn't really pick up any pressure. Less than 1 psi. No oil splatter either. Will try it with snapping the throttle tomorrow.

I might run some of that through my engine anyway just to see if I get any results.

What do you mean reseal the valve covers?

 

Replace the gaskets. They are a silicone rubber gasket and they can get hard and crack up after so many years of duty.

 

Oh yeah, did that in September.

 

1986 TA mentioned oil leaking past the intake manifold bolts. Installing new bolts with Permatex Teflon Thread Sealant applied to the threads should prevent this.

 

I think this is where I messed up. I took a gamble and reused the bolts because I did not know any better. I did put sensor-safe sealant on them but the threads were poor on a couple.

Appreciate all the input.

 

I usually put RTV on the top few threads of each bolt on the intake manifold and then wipe them clean after I torque them down. Never had any issues. Always made great oil pressure too.

 

Is it possible to remove an intake bolt to reseal threads without removing intake plenum and runners