Water leak was at the back right corner of the intake/head sealing surface. The dye was only found in that area of the valley directly under the water port of the head. The new head went on last weekend and then let sealants cure for 24 hours before refilling with coolant.

Just finished a brief pressure test and with very little pressure I dribbled out 1 tablespoon of fresh coolant out the the oil drain plug. That means a fourth failure without having to go through the trouble of starting the engine. Can't see the point in doing it over for the fifth time. Maybe I should throw the heads away since that sealing surface hasn't been replaced like the intake. Something has to come to a head since it has now been two years since on the road. Looking great in the driveway isn't good enough yet options are running out for a cure.

 

Mike, was that a different head or was it (the head) pressure checked? I wonder if it is a crack or ? in the upper part of the block in the valley.

 

Not a different head just the originals checked and rebuilt. I'm quite sure the seal between the head/intake surface is not happening especially in the back right corner. The engine seemed to leak a little water very slowly over the week just sitting there. To make sure my eyes weren't fooling me when looking into the radiator I did a quick pressure check. Got a tablespoon after pumping air in while quickly sealing with my hand. Crude but it demonstrated what I needed to know. Imagine the system pressurized with a cap?

Now the question is if I am motivated enough to go at it again or just leave the redone truck sitting for some time. The problem is that it blocks the Mustang and Cougar in the garage and those are fine running cars that haven't been driven since Jan. 1st. If attempted one more time then this time I guess I will need to accurately measure all four corners with feeler gauges and see if material has to be removed to get them all perfectly equal as far as clearance. Or get a new engine.

 

I've been following this post from the beginning and can only say I'm sorry that you have had this must trouble. I see why your frustration level must be through the ceiling. I have fought a few projects in my lifetime were the only real solution was dynamite. Take a break if you can for a little while before tackling it again if thats what you chose to do.

Have you ever put a straight edge across the intake side?

Possible the head was surfaced unevenly front to rear?

After torquing the manifold I usually go back and hit each bolt again to the final torque value, have tried retorquing it?

 

WOW!!!!! Kudos to you. That intake would have found its way to the middle of the alley. I was however thinking why you didn't put an aluminum intake on it.
You have a great deal of sticktoitiveness about you. I do hope you resolve the issue.

 

I want my square bore manifold for my square bore Autolites.

 

Well I confirmed where my leak is coming from. Since I didn't start the engine it was easier to trace it. The two leaks are at the interface between the intake and the head front water port. Both leaked and put a little water in the heads which flowed back. Also some in the valley area that also flowed back. Now how to solve this as it looks as though the back interface is sealing. Another clue was water condensation on #1 and 5 rockers while #4 and 8 were dry. Sealant was around all water ports but didn't matter up front.

 

I would be suspicious of the heads intake surface, it seems to be the only thing that has not changed. Was the intake surface of the head checked for flat and straight? You can mill a small amount without getting into alignment problems. What gaskets for the intake? I have had the best luck with standard Fel-Pro or Victor replacements. You definitely do not want the 1247 Fel-Pro, they are a known problem for street engines.

 

Next Saturday the intake will come off and cleaned up. Then both intakes will be placed on a dry gasket to check clearances at the corners. We'll see...

 

I noticed I didn't pull one of the intake gaskets off the intake I did the third try/failure on. The engine did run for maybe 10 minutes before stopping so the gasket was in great shape. In fact such great shape it could be usable again. Why? There are no compression marks on the gasket from either the head or intake sealing surfaces. The gasket is 0.065 in thickness and had no compression marks around the ports. Obviously my clearance is too great on the sides for a gasket to seal. The 1247-S3 was used based on Barry @ Survival Motorsports recommendation for a street engine. I did try a non steel shim gasket and found that it did squirm

 

<p>How well does the intake line up with the heads? Is it possible the head's intake surface was milled so far that the bolt holes in the intake don't allow the intake to sit low enough to seal against the heads?</p><p>The top of the intake and head where the valve cover sits, do they line up or is the intake a lot lower (or higher) than the head?</p>

 

The intake surface of the heads was not milled at all. The four corners where the head and intake meet was also not out of the norms at all.

 

Have you put a straight edge across both the head and manifold surfaces?

Bolts bottoming out in the heads?

 

Clarification on my prior post, the Fel-Pro 1247-S3 is fine for a street engine, the standard 1247 is not.
It really sounds and looks like something is not allowing the intake to sit down all the way or the bolts are too long and bottoming out before the gasket is compressed.

 

Never considered the bolts to be an issue since they are original to the engine. Will know more on Saturday when the intake is removed and I can check side clearance both bare and with gasket set in place. With it bare I am making the assumption that the mating surfaces should meet uniformly and have little gap since the end seals aren't in. From my last recollection it was anything but the last time.