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1969 Camaro RS
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Discussion Starter #1
Hello Everyone,
I installed some 186 heads on my 327 engine for a minor upgrade and put a Z28 intake on as well. I did start the engine but I prime the oil pump to make sure oil was reaching the rockers. That’s was fine. Then next day I had antifreeze leaking from the heads. (See pictures) I pulled the valve covers and antifreeze was under both valve covers all over the heads and rocker arms. My question is do you think the heads are crack or the head gasket and intake gasket didn’t seal properly. I used Permatex Aviation sealer on the head and intake bolts with Victor Reinz gaskets. Bought the heads of eBay a while ago, so can’t return. Any suggestions, thanks.
 

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Hello Everyone,
I installed some 186 heads on my 327 engine for a minor upgrade and put a Z28 intake on as well. I did start the engine but I prime the oil pump to make sure oil was reaching the rockers. That’s was fine. Then next day I had antifreeze leaking from the heads. (See pictures) I pulled the valve covers and antifreeze was under both valve covers all over the heads and rocker arms. My question is do you think the heads are crack or the head gasket and intake gasket didn’t seal properly. I used Permatex Aviation sealer on the head and intake bolts with Victor Reinz gaskets. Bought the heads of eBay a while ago, so can’t return. Any suggestions, thanks.
I don't see any picture(s) to look at?

If anti-freeze was/is under the valve covers it could be coming from the head bolts, did you use thread sealer on the head bolt threads and were head bolt threads in the block cleaned properly before you assembled and torqued the head bolts?
 

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That sealer should have worked fine for you, but it still may be just leaks at the threads.

Only way is to pull the heads and have them checked.
I don't believe a poor seal at the intake would result in coolant under the valve covers.
 

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1969 Camaro RS
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Discussion Starter #4
I don't see any picture(s) to look at?

If anti-freeze was/is under the valve covers it could be coming from the head bolts, did you use thread sealer on the head bolt threads and were head bolt threads in the block cleaned properly before you assembled and torqued the head bolts?
Yes, I used thread sealer as mention above, everything was cleaned and torque to manufacture spec. Thanks.
 

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1969 Camaro RS
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Discussion Starter #5
That sealer should have worked fine for you, but it still may be just leaks at the threads.

Only way is to pull the heads and have them checked.
I don't believe a poor seal at the intake would result in coolant under the valve covers.
Thanks, I guess I will have take them to a machine shop.
 

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The rocker studs go into water also. Are the pressed? If so, pinned? Screw in? Were the spring seats cut down for more lift?
Should be able pressurize the cooling system with the covers off and see where it's coming from if it's on the top end.
 

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I can't think of any way a leaking intake gasket could allow anti-freeze to get under the valve covers.

I also can't think of any way a leaking head gasket could allow anti-freeze to get under the valve covers.

If it's not the head bolts leaking, the only other thing I can think of is a crack in the head so having them checked is probably the best way to proceed, or you could first try removing each head bolt, cleaning and then resealing and see that brings a different result.

How long did it run and did the cooling system get up to pressure when you later found anti-freeze under the valve covers?
 

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The rocker studs go into water also. Are the pressed? If so, pinned? Screw in? Were the spring seats cut down for more lift?
Should be able pressurize the cooling system with the covers off and see where it's coming from if it's on the top end.
X1 Great post ^^

The pressure test should be the next thing to do for sure.

Hopefully, it wasn't run long enough to do any damage.
 

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X1 Great post ^^

The pressure test should be the next thing to do for sure.

Hopefully, it wasn't run long enough to do any damage.
That's true, the rocker studs are also a possibility, agree the cooling system pressure test is the best way to proceed.
 

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Before you go pulling the heads - I would start with the simple things first. You mentioned the intake is new to you as well.

The pics show significant antifreeze around the rocker nuts. That could have splashed or came up through the pushrods.

You could very well have a intake coolant leak causing the antifreeze to drop into the lifter valley, pan and circulate.

Pull the intake, clean everything and put a steel straight edge on all the port surfaces of the heads and intake.

It looks like you have sealer on the intake manifold ports, with a quality intake gasket all you need is a few dabs of clear gasket cinch to hold the gasket in place - use the gasket dry.

Its entirely possible its the heads/seats/studs/ etc but I would start with verifying your intake is sealing properly
 

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If the heads end up coming off then have them pressure tested at a machine shop. My one 186 head casting was so weak that it was trash. I had a pin hole in the exhaust valve area and it could not be fixed. The whole head was rotted from driving.
 

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1969 Camaro RS
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Discussion Starter #12
I can't think of any way a leaking intake gasket could allow anti-freeze to get under the valve covers.

I also can't think of any way a leaking head gasket could allow anti-freeze to get under the valve covers.

If it's not the head bolts leaking, the only other thing I can think of is a crack in the head so having them checked is probably the best way to proceed, or you could first try removing each head bolt, cleaning and then resealing and see that brings a different result.

How long did it run and did the cooling system get up to pressure when you later found anti-freeze under the valve covers?
Car hasn't run, only prime the oil pump to verify oil was going to the rocker arms, the next day antifreeze was leaking from the valve covers.
 

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1969 Camaro RS
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Discussion Starter #13
The rocker studs go into water also. Are the pressed? If so, pinned? Screw in? Were the spring seats cut down for more lift?
Should be able pressurize the cooling system with the covers off and see where it's coming from if it's on the top end.
They are pressed in studs. I drained the antifreeze already and don't have a way to pressurize the cooling system.
 

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1969 Camaro RS
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Discussion Starter #14
Before you go pulling the heads - I would start with the simple things first. You mentioned the intake is new to you as well.

The pics show significant antifreeze around the rocker nuts. That could have splashed or came up through the pushrods.

You could very well have a intake coolant leak causing the antifreeze to drop into the lifter valley, pan and circulate.

Pull the intake, clean everything and put a steel straight edge on all the port surfaces of the heads and intake.

It looks like you have sealer on the intake manifold ports, with a quality intake gasket all you need is a few dabs of clear gasket cinch to hold the gasket in place - use the gasket dry.

Its entirely possible its the heads/seats/studs/ etc but I would start with verifying your intake is sealing properly
I think I will start with your suggestion first before trying anything else. Thanks.
 

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Discussion Starter #16
Is it possible, that when you pulled the old intake, antifreeze flowed out and into the lifter valley?
No, that did not happen.
 

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Was there any chance you had antifreeze in the oil pan when you primed the motor? If you say the engine never ran and all you did was prime the oil pump..could there have been antifreeze in the oil pan perhaps from when you pulled the old intake? Just guessing here.
 

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don't have a way to pressurize the cooling system.

Yes you do. All the chain parts stores carry a free-rent radiator and cooling system test kit.
 

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If you can't find an auto parts store locally that has a loaner to borrow as Steiner suggests, Harbor freight also sells a pressure test system that with one of their 20% off coupons is very reasonably priced. It's not Snap-On quality but it does get the job done.

I little time (and money if necessary) spent diagnosing the problem can save a lot of time and replacement parts money in the long run.
 

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Car hasn't run, only prime the oil pump to verify oil was going to the rocker arms, the next day antifreeze was leaking from the valve covers.
In your first post you said you did start it up, you meant to say did not start it. OK, when did you prime it, after the intake installation or before. And at what point did you add the coolant. trying to understand the sequence.
 
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