# Exhaust Manifold Bolt Coolant Leak



## bdamsp (Apr 8, 2017)

I have coolant leaking from the rear bolt on the passenger side exhaust manifold, does this mean a cracked head?


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## PontiacJim (Dec 29, 2012)

bdamsp said:


> I have coolant leaking from the rear bolt on the passenger side exhaust manifold, does this mean a cracked head?


Perhaps not, and this is my guess. What year head? Casting digits on the center exhaust port? Some of the Pontiac heads, like the 1973 7K3 heads do not have a hole drilled for one of the rear bolts. Not a problem if using the cast iron exhaust manifolds. It is however a problem if using headers as you need both bolts to tighten headers up and keep them from leaking.

Some will drill and tap a hole in the head where this bolt should go. If this is done, I believe it will run into the water jacket. If this was done and it did hit the water jacket, you would need to use a sealant on the bolt threads.

Not saying you do not have a cracked head, but this is not a common thing and I have never heard of a Pontiac head cracking, but I suppose anything can happen given the right circumstances. Is it possible that the water is somehow coming from a leaking head gasket or even one of the freeze plugs found on the end of the head?


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## bdamsp (Apr 8, 2017)

Thanks for feedback. The head is a '68 #16 HO, cast in Oct of '67. I installed new cast iron Pontiac repo headers from Ames. These only allow the rear-most bolt to be installed on the number 8 exhaust port. The header has been on the car for 3 years with low-mile usage, and just started to leak while in storage this winter.


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## PontiacJim (Dec 29, 2012)

bdamsp said:


> Thanks for feedback. The head is a '68 #16 HO, cast in Oct of '67. I installed new cast iron Pontiac repo headers from Ames. These only allow the rear-most bolt to be installed on the number 8 exhaust port. The header has been on the car for 3 years with low-mile usage, and just started to leak while in storage this winter.




OK, standard bolt pattern, so someone adding the bolt hole is not the answer. Is it possible that the single bolt used was too long and it bottomed out inside the bolt hole? This could possibly crack the head.

You are sure it is coming from the bolt? Can you take any pics and post them? The leak may be coming from somewhere else and traveling, simply collecting at that point. I suppose the only way to know 100% is going to be to pull that exhaust manifold and look if you don't find any other sources of the leak.


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## bdamsp (Apr 8, 2017)

Here is a video, it is upside down as that is the way I took it on my phone and could not find a way to rotate it. I appreciate the help.


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## HP11 (Apr 11, 2009)

If you ever have the need to rotate a video again this site is useful:
https://rotatemyvideo.net/


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## Lemans guy (Oct 14, 2014)

Hard to tell the source with the engine running. A smoke test with the engine off may give you a better chance of pinpointing it before you start ripping things off. Any shop can do that, drain a little coolant down below the level of the leak and smoke the coolant passages, also you can smoke the exhaust. If that helps you pinpoint it.

An intake manifold gasket can leak and drip down to where you think the leak is. Another method you can do yourself is get a small bottle of coolant system dye at the auto parts store and put in in the radiator, run the engine let it go thru good, a black light will show up the fluorescent dye.

If it is a bad intake manifold gasket, then you can zero in. Or whatever, a bolt etc. Like Pontiac Jim, light driving does not sound like a cracked head, but those gaskets will leak after many years....


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