Aluminum heads leaking coolant!

http://www.crankshaftcoalition.com/wiki/Head_gasket

"Though aluminum is lighter than cast iron, it expands twice as fast. This quicker cycle of expansion and contraction stresses head gaskets. To handle this, a non-stick coating is often applied to the gasket, like Teflon or molybdenum.

Many OEMs are using graphite head gaskets on iron blocks with aluminum heads to help compensate for different coefficients of expansion between the two differing metals. Graphite head gaskets may have multiple types of coatings in different areas to facilitate sealing (silicone) and expansion (Teflon/molybdenum).

With iron heads, a product can be applied for the opposite effect. Silicone, Viton, or other fluoroelastomer sealants are applied to increase the pressure between the iron heads and the iron block."

 

leaking aluminum heads

I don't think I'm getting what the problem is here. The heads have to be flat (surface 'em) and smooth, the block has to be clean and smooth, the fasteners have to be clean and good, and assemble everything with a good Fel-pro gasket that was designed for aluminum/cast combo and torque as per factory spec. End of story. There are endless race cars that make more cylinder pressure than any street car that work just fine and are sealed right up. Copper coat and stuff like that is old OLD news and no longer applies!

 

The copper sealant was recommended in Rocky Rotella's "How to build a Pontiac V-8."
Many people have followed his recommendations and have done well with it. But my heads and block are iron.

 

leaking

coppercoat is for steel shim head gaskets ONLY and who uses them? Like I said OLD SCHOOL and not good school.

 

Well I kind of solved the issue with a bottle of block seal. I hated to do it but I have tried everything else.
After two sets of head gaskets changed, I still was leaking water from the area between the heads and the block. The block seal worked.
I know I have a flat set of heads and the block was decked just a couple of hours of use ago. Something else was the culprit and the block seal fixed it.
I wonder if there was a small leak on the valve seats or the casting of the heads?
I think I'm going to go with some copper gaskets and the coppercoat sealant. I just made two very nice passes(10:89 and a 10:92 at 124 / 128 MPH respectively!) at woodburn today and the engine is running alright and tight. Temperature never got over 200 degrees and no water in the oil.
I still don't know what the issue could be so keep those opinions coming and maybe we'll solve this one.
Thanks.
Dave

 

I didn't catch what heads you were using but I have a few things to look at should this pop up again. 1st you said you are using aluminum heads on an Iron block? If they are old castings one thing you may want to look at the next time the heads are off is the water jacket holes around the deck of the heads fluid running across unlike metals can generate an electrical current that just eats up aluminum. If that's true the block needs to be grounded better Ford and others have TSBs on this issue. If coolant is getting out of the engine and not into the oil then clearly it's not a cylinder sealing problem this suggests to me that there is the possibility of cylinder head twist, or there is the possibility of a trapped air pocket causing a localized area of extreme heat. If Block Seal fixed it than the rise would have been very small. Aluminum is known for twist it's quite often these heads will measure flat but when you mill them or surface them they will show themselves as being twisted. A V8 head contrary to apparent popular belief can have up to .004" inch of warp end to end and up to .002" warp intake to exhaust side of the head and still be considered "acceptable for use" This case however sounds much more like an electrolysis issue, the head was installed twisted (I didn't catch what all you did), or there was trapped air in the head that allowed for localized superheating. Also depending on what gasket you use sometimes heads can be surfaced too smooth. If it's your common blue stripe type gasket then the surface finish needs to be in common English a little rough. If it's a shim, copper, or MLS gasket it needs to be glass smooth and I don't care what people say always always always use some kind of spray on or very lightly coat shim, copper, or MLS gaskets with copper coat. I prefer the spray because it goes on real thin but can save your day if there happens to be any little imperfection at play. I can't tell you how often we've had stoooopid problems because customers can't keep stuff clean. Some little sliver of something is all it takes to lift a head off a motor .002"-.003" and cause a water leak when you use shim, copper, or MLS gaskets and the MLS gaskets can trap stuff between the layers if the gasket isn't kept clean that'll drive you nuts. As far as the valve seats being eaten out that is also a good possibility for aluminum heads but there would be coolant in the oil and it would have shown up in a pressure test. I'd say if this kicks up again pull the head buy some bolts double check the block for straight (they're usually pretty close) make sure the coolant passages look good and healthy on both the block and the heads and have your local machinist (or you if you happen to be one) lightly surface those heads again with some blue layout die on them just to make sure there's no high spots. One last thing make sure that it's not an intake leak that's just running around the base of the head till it drips off. Water seems to go everywhere when it leaks and Intake gaskets are a far more likely culprit especially when any real amount of material has been removed from the heads and block. They need to be milled for correction that or the intake sides of the heads then you must and I mean MUST use silicone on the valley rails or when you torque down the intake it WILL distort and leak. That's all I've got off the top of my head. Hope that helps.

~Couch

 

Na wrist pin clearance gets worse as the engine warms. Probably more like a collapsed piston. It's pretty common... BTW collapsed piston pin bores can wear more making it look like wrist pin clearance issues. Pin clearance can more than triple when the engine warms up. Just my .02

~Couch

 

Thanks for the block of info. It will take me a couple reads to make sure I got all of that.
In regards to cast aluminum: I have seen pin hole leaks from Edelbrock, brand new. Just the other day I saw someone post about their pin hole leak near the spark plug recess.

 

Unfortunately in the aftermarket even more so in this awesome economy it's getting very hard to find a foundry that can produce quality. At a recent conference we jumped on the guys at World for there Merlin heads because they make great power and really move air but they weigh 100 pounds more than stock heads so you typically loose in weight that you gain in power. It's the material they are using more than anything we call it pig iron. Low quality materials and poor craftsmanship are what you can expect for the duration at this point. It just costs too much to make quality stuff when you can't sell it for what it's worth. I imagine there are a lot of stories like this one floating around out there.

~Couch

 

What??? Has Mr. Edelbrock become senile?
I'd run through the torque sequence again, perhaps adding a few lbs for good measure.
Assuming flat surfaces and correct assembly the gasket should seal from the get go, I'll be happy to tell Mr. E to his face.
Did all the bolts feel right when tightening them? Holes clean?
Are these new heads? Porous castings?

 

Coolant leak

Ok I've had about all I can stand with these heads leaking. I've had the pair off twice now and added every type of sealant that they make and still the problem exists!!? They have been bench tested and pressure tested and whatever else I can think of. Come on guy! Do any of you have any ideas what this could be??

 

I like to do all my own work but I will get an assembly. I would hit the strip and nose around for a #1 aluminum tech and get a small block built. Absolute cleanliness is a must. Where were leaks again? What heads?

iarats

 

Bbf

Aaah! Big Block Ford! Take off your intake and remove the gaskets. Put it back on (no bolts) with just the end rails and shine a light from the back. This will show you the clearance and the angle between the head and the manifold. If it sits too high, you'll have to position it with feeler blades front and back to get it lower. The angle is the biggee. If it is out, you will NEVER get a good intake seal (water and oil). You will note your intake gaskets have a channel to leak water to the outside not into the engine. Fix it by machining intake (depending on what the intake is. They can be worth a fortune and you don't want to screw it up) or intake side of the heads. Measure Carefully!!! (measure twice, cut once). Eldenborks are cheap heads and poorly machined and can run some dough and heartache to straighten out all the issues (whatever Vic and co say about their magic manufacturing etc) including correct push rod length. seat movement, and just plain fit. Just a thought but very common on the FE because the intake manifold is sort of 'half the head'. Oh, and look carefully at P/rod to intake clearance. Check out the FE forum as well Good luck that's all I know

 

Thanks for the ideas guy but the engine is a 1971 Windsor 351 block stroked and bored. The heads are Edelbrock Victor Jr's and they have been off several times and are true and flat within 2 one thousandths of an inch. The block is also flat and true within 3 thousandths. I had the block magnifluxed to be sure it didn't have any cracks before I put it together too. The intake is a fabricated dual quad (Made before they made em at Edelbrock) but it is also square and true. I have used several types of head gaskets from Felpro and still I have small leaks!? I also tried my performer single carb intake with no better results. Everything is new and just to make sure, I even had the heads pressure tested and they were fine! Has anybody ever had this happen to them before? Because I haven't!! I have a lot of money tied up in this damn thing and would hate to trash the engine due to this damn leak. Do you think a copper gasket and some copper coat might help? I am at a loss for ideas here guys.

 

Many OEMs are using graphite head gaskets on iron blocks with aluminum heads to help compensate for different coefficients of expansion between the two differing metals. Graphite head gaskets may have multiple types of coatings in different areas to facilitate sealing (silicone) and expansion (Teflon/molybdenum).

If your heads seal at first and then leak you might have a need for the composite head gasket. If you could get a torque and turn spec that might help.

The head must be machined not surfaced.

How do you shut your engine down? What temp does it run at. Get a tester and see if exhaust gas goes into the water column.

"Most aluminum heads using a multi-layer steel (MLS) head gasket should have no more than 0.002-inch (0.05 mm) of total distortion (block plus head combined) in any direction."

Read more: http://www.importtuner.com/tech/impp_1007_cylinder_head_distortion_check/#ixzz2ZgnqRJw0

No more than .002. To me that means less is possible.
​