340 Engine Leaking Coolant from Valve Cover Bolt Hole

[Adams1stCuda]

Looking for some information or pointers with an issue I have never seen.  Have a fair amount of mechanical experience, but honestly, not a ton of time on classic year cars.  Bought my wife her childhood dream car, an e-body cuda (72 BS 340).  We have just got it home and though it 'runs' I am starting to go over it and make a punch list of the things I need to accomplish to get it safe and reliable.

So I noticed what looked to be signs of a leak under the valve cover on the e-manifold.  Noticed the valve cover screw was relatively loose and decided I was going to pull the cover for further inspection.  Loosened same bolt and before I even got it completely out of the hole, coolant was steadily oozing out...

Can only assume somehow it has intersected the coolant jacket, but has anyone else heard of this?  Anything else I should inspect or look into with this issue?

Bolt is on driver's side outer center.

[EDL94]

There should not be any coolant there. The only thing I can think of is a cracked head. Good luck, I hope its something other than that.

[Cuda Cody]

   I've never seen that.     Are you sure it's coolant?  Could it be oil that is leaking out?

[Adams1stCuda]

100% it was coolant...could clearly see color when it was leaking out and within a few seconds had enough to puddle on the garage floor.

[Roadman]

   Is it possibly coming from under the valve cover (gasket). ???  Either way I would pull the valve cover and inspect.   

[Shane Kelley]

I have messed with a bunch of 340's and I have never seen that. I don't recall a cooling passage being that close to the bolt hole. Maybe somebody got aggressive drilling it out at one time and drilled into the passage? Seems really odd. But if that is the case some thread tape will fix the leaking coolant issue if that is the only place your seeing it. Definitely need to pull valve cover and inspect.   

[anlauto]

More likely coming from the exhaust manifold bolt 

[Adams1stCuda]

More likely coming from the exhaust manifold bolt 

For sure not coming from the EM bolt.  Was coming from center VC bolt pictured running through the spark plug wire holder.  Pulled that bolt and coolant was running freely.

[anlauto]

If that's the case try thread sealant ?

[Adams1stCuda]

on a separate forum had one person say they have seen it once in a 340 where this happened without a cracked head due to a flaw during casting.  Looks like in any event I will be pulling VC and possibly head to investigate further.

[Shane Kelley]

on a separate forum had one person say they have seen it once in a 340 where this happened without a cracked head due to a flaw during casting.  Looks like in any event I will be pulling VC and possibly head to investigate further.

You might not need to pull the head. If you feel confident that's where it's coming from just wrap the bolt in Teflon tape or thread sealant. You just want to be sure it is sealed and not start leaking on the inside and getting in the oil.  Another thing would be use some sealant on a stud in that hole. Then you wouldn't have to deal with the coolant leaking when pulling the valve cover. The stud would be the safer route and more worry free. 

[Cuda Cody]

   Yes, there are sealant that will seal that up so you should not need to pull the head. 

[RUNCHARGER]

I agree: I would pull the valvecover however I would plan on running a stud in that hole with some sealant. Take a long thin screwdriver and see how far it goes down into the hole, it sounds like it got drilled out.

[Adams1stCuda]

Anyone have a recommendation on where to order a full set of studs for both covers?  Looked at a couple places and didn't see any.  Decided I am still going to pull the VC's, inspect, clean, and re-install.  Thanks for all the help.

[Brads70]

Go to your local industrial bolt supplier and get some stainless set screws, they come in various lengths. Liquid teflon then in position.