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Discussion Starter · #1 ·
A little over a year and a half ago I relied on the members here to get me through the task of changing out the exhaust manifold seal on my '77 Skybird. I have not been able to drive the car much since then. Now my life is more simple and I have time to deal with this issue.

Ever since putting the Intake Manifold back on my Skybird it has been emitting the white vapor out of the exhaust. Pools of water do appear under the exhaust pipes. The radiator level does go down over time. I have had to put water in it three times over the last 18 or so months. Please keep in mind that I have only put about 150 miles on her since then and have only had her out of the garage 4 times.

I believe I torqued the manifold bolts incorrectly and this is where the water is coming from. I'm about to tackle this and want the input from this community. I used an old Craftsman Torque Wrench, Analog, and I believe the gauge on it had been damaged over the years and it is not accurate anymore. I did torque it to the correct number, according to the wrench, and in the correct order. Will the pan gasket need to be changed too? Is the issue one of the Intake Manifold Gaskets? No water in oil. Car runs GREAT. I just do not remember it ever doing this before I had to take the top of the engine apart.

It will continue to emit water vapor from the exhaust after idling a long time. I assume the pipes are so hot its evaporating the water.

1977 Pontiac Firebird "Skybird"

350 Pontiac w/ the arched Pontiac Manifold

5.7 liter


15,109 Posts
Water in the exhaust can be totally normal. When gasoline (which is composed of carbon and hydrogen) is burned, the hydrogen combines with the oxygen in the air and forms water. As it leaves the cylinder it is in vapor form (steam). When it hits cold exhaust pipes, it condenses, puddles and pools causing corrosion. The residual water vapor will become visible as a white cloud as it exits the end of the exhaust pipe and condenses in the cold air. On a cold day this can continue until the engine is put under load, heating the exhaust system.

But your ongoing loss of coolant may indicate a problem. Typically, the white cloud coming out of the tailpipe will have a "sweet" smell if it contains ethylene glycol ("anti freeze"). If you get that smell, you either have a bad intake manifold gasket, a blown head gasket, or a crack in the cylinder wall or head.

Have you done a pressure test on the radiator to determine if there are any leaks in the cooling system? Have you inspected the spark plugs to determine if one or more appear exceptionally clean - a common indicator of coolant in the combustion chamber?

2,125 Posts
(No water in oil. Car runs GREAT. I just do not remember it ever doing this before)

I got nothing

1,013 Posts
Im leaning towards a Bad Head Gasket...

Which can allow very minute amounts to seep through gasket before it is totally blown out like an exhaust gasket...

Another important fact is there are a couple of routine questions...

When one is not standing there looking at the vehicle while its acting up...

Here is a run down of what I think and look at.

1) Car just started up? (temp outside and humidity also make differences...)

2) Does it stop after less than 2 minutes? Once car and parts are all same temp.

3) Is there Oil in Water?

4) Is there Water in Oil? Is there any pressure in Oil or water system like radiator blowing out massive amounts of water...(like Blow By)...

5) Is it on one side or both? If only on one side then I start really thinking Gasket but also Cracked or warped head.

From my past of blowing a few engines....out of 11, I lost 6 due to over heating and poor radiators and cooling systems...The others were mainly from bearing wash out since I used to way over carb...

Did have one Cam break and fall into connecting rods...not good...

I am going to say with a shot in the dark its a Gasket, and sitting may have allowed rust to beat the gasket...

Now thats if the white smoke is only coming off one side...When heads are off you need to also have heads re worked, and checked on Plane...I dont mean fly up then start checking parts...

I mean

Good luck bud.

This was to help others that may be newer or reading, this in now way suggest the OP needs or even wants

I re read the post and also wondered if there was a change in the intake or just gaskets, could be a gasket seal issue there also...

If say five minutes after running up the road and up to max op temp it is still doing it you have an issue.

If just upon start up and then as parts warm up it slows then stops, Im leaning toward...You live where its cold and its normal...

Now with Water loss, that could be an unrelated issue like not having a reservoir. or it could all be balled up...
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