Intake Manifold Exhaust Leak

[RFortuna]

My 73 convertible has a pretty loud exhaust leak. I asssumed it was an exhaust manifold gasket. I took it to the exhaust shop and they traced it to the intake manifold. There are four plugs, similar to tiny freeze plugs on the front and back of the intake manifold. I have never heard of this before, and I can't find any such part listed anywhere. They don't seem to be threaded either. Here are my questions.

1. Has anyone else come up against this? and how did you solve it?
2. Does anyone know what the replacement plug is called? and where could I get one.
3. Anybody know how to go about removal and replacement.

My Father suggested JB Weld liquid steele, and just replug it, but I wasn't thrilled about an incorrect repair that may alter the manifold permanently.

Thanks, Randy

[Smartin]

I'm fairly sure they are just freeze plugs...but don't know the size.

[centurion 455 ragtop]

It is all part of the Air Injection Reactor System (A.I.R) The A.I.R System reduces the hydrocarbons and carbon monoxide content of the exhaust gases by injecting air into the exhaust port of each cylinder. The oxygen in the air reacts with the hot exhaust gas, causing further combustion in the exhaust manifold before the gas enters the exhaust pipe.

The system consists of a belt driven air pump, divertor valve, check valve, special intake manifold and cylinder head assemblies and hoses connecting the various componets.

It is all listed on page 6F-154 in the 1973 Buick Service Manual.

In the photo I marked the four corners where I think you are talking about. If this is it then I would JB weld it up. It is not pressured, but if it is left open the car will run like crap with a vacuum leak. On my 73 I disconected the EGR system (up yours Al Gore) but I re-installed all the pollution devices to give it a stock look. Anyway I gutted the vanes from the air pump so it free wheels, and then under where the elbo pipe attached to the intake shown in photo (arrow pointing and it says A.I.R Intake) I placed a solid gasket blocking up the hole and then re-installed the pipe. This way it won't leak air. So in your case a quick easy way is to use JB weld if the leak is at those four air tube corners. Even if you still have the system hooked up once sealed it will be ok. You can always clean it up smooth and once painted it won't be noticed.

[Robroy]

It is all part of the Air Injection Reactor System (A.I.R)
Which year did Buick start with this?

My air pump is taken off by the way. It was in the trunk when I got the car.

[Smartin]

1972 was the beginning of it, and then in 1973, every Buick had it.

[Robroy]

I would have guessed 73, but now I know!

That system probably reduce the power the same way a generator or compressor do...

[Smartin]

It might a little bit, but the worst part about the system, is that it injects HOT air/exhaust gas back into the engine. That is what really robs the horsepower.

[Robroy]

Think I see your point, it has to do with that cold air gives you a better filling of the cylinders, more oxygen or something… am I right?

[Smartin]

Cold air is more dense, so there is more of it to burn. Cool fuel also has the same principle.

[Robroy]

Remember reading about water injection systems that people installed on their engines in the 80’s to get more HP. Always thought it sounded crazy but I think it had to do with this. It was often used on turbo charged engines

[The German]

Is that a reason why you prefer the ´71 Centurions, Adam, because they have more power ?
___________
Rolf

[The German]

Remember reading about water injection systems that people installed on their engines in the 80’s to get more HP. Always thought it sounded crazy but I think it had to do with this. It was often used on turbo charged engines

That´s right, Per, and I guess it will come again; just few weeks ago I read an article about that possibility! They told that with this system one could save gas and get higher milage per gallon !
_________________
Rolf

[Smartin]

Is that a reason why you prefer the ´71 Centurions, Adam, because they have more power ?
___________
Rolf


I just prefer the look of the front end on the 71's...plus, my first car was a 71 LeSabre.:beers:

[Robroy]

That´s right, Per, and I guess it will come again; just few weeks ago I read an article about that possibility! They told that with this system one could save gas and get higher milage per gallon !
_________________
Rolf

The never ending struggle to get higher milage per gallon! :rolleyes: :D

[RFortuna]

Thanks Everyone. Rick, Your diagram is right on. That's exactly where it's leaking. Thanks for the advice!

Randy