head gasket not sealing

C

cjc56

Senior Member
I am having trouble getting a head gasket to seal around #7 cyl of my 57 312. I have tried 2 times to get one to seal and both are leaking around the 7 cyl. Before I tried it this last time I took the block and the head to the machine shop. They decked the block but the head was okay. We thought that the head getting decked would fix the problem but it did not. By the way, both sides of the block were decked and the right side (1234) sealed just fine. When I installed it this last time I made sure that the gasket(felpro) was positioned correctly. I torqued the bolts in 3 steps, 55,65,75 final. And I used the order of fastening shown in the manual. When the gasket did not seal I even removed the rocker arms, exhaust manifold and torqued While hot to 75lbs agian. Still no luck. Does anyone have any suggestion before I pull out what hair I have left!!!!!!!!!!!!!!
 
Was the head or block ever checked for cracks ? Is it possible the freeze plug or temp sending unit on the intake side of the head (behind the intake gasket) is leaking and running down to the head gasket area on the outside ?

Sal
 
It is difficult to see where the leak is coming from but it looks to be around the rim of the cylinder closest to the exhaust manifold. The top rim of the cylinder in that area shows water was entering the cylinder from 4 to 8 oclock if you are looking at the block from the left side of the car. Not sure if I mentioned it before but this leaky cylinder is on the left side. Both the block and the cylinder were pressure test before I put them back together. I am sure that the cylinder is not cracked. Nothing is leaking and running down on the outside.
 
I would still think cracked head under exhaust.you said 4-8 if this right it would I think make sense as this would be where it would pool due to angle of block.I know they pressure tested but I have seen virgins give birth LOL.this applies to crack at top of block as well.do they offer magnalfuxing?
 
Just a thought, do you have the head bolts in the correct position? Of the upper head bolts, two are longer and should be positioned on the ends of the heads where the dowel pins are. If not they will be too long for the bolt holes and bottom out before they clamp the head.
 
Maybe you have a short head bolt hole. Run a thread chasser or tap down, and try to measure how far down they go. You may need to shorten one bolt by .060, or add a flat washer.
 
Did you have hard seats installed? Were they pressure checked after that? Sometime you cut into water putting a seat in. They always leak and you'll never find it without a pressure check. I have never seen anything to fix that other then another head.
 
Yes I did have hardened seats put in but the head was pressure checked. In fact I watch them do it. Could there be any chance that the intake manifold could be leaking inside? When I took the intake off I checked the gasket area where the water flows from the intake to the heads and the gasket look like it sealed on both heads. Before I removed the heads I decided to run a quart of Blue Devil head gasket sealer to see what would happen. I have used this before for a quick fix and I have had some success. But even if it does not check the leak, it does leave a white deposit where ever there is a leak. It did not check the leak in this engine but there is no doubt that the leak is coming into the #7 cylinder, because a white deposit has been left on the top of the head above #7 cyl and around the rim of the cylinder. But I also notice that there are deposits in all the intake ports on both heads. These deposits could have formed from steam after the engine was stopped, but I thought it was abnormal.
 
Well I just got back from the machine shop where they pressure tested and magnafluxed the head and found no cracks. The shop also inspected the head gasket and said that they did not think the gasket leaked. I am at a real lose as to what to do. I am wondering if the Blue devil sealer did its job and stopped the leak(where ever it was) but the water in the engine that entered before, simply settled to the bottom of the oil pan. Then the next morning when I started it up the oil quickly mixed with water. I think it might be worth a head gasket and intake gasket to try it again and see what happens. Any suggestions are welcome
 
Double check that the head bolts are not bottoming out in their holes. If these are the original grade six bolts, then they could be stretched and/or any decking and milling of the heads and decks has effectively shortened up the head bolt holes. Running a bottoming tap into all the head bolts holes could help in this instance.
 
This is a long shot. You don't say what casting number head you have, but if you are unlucky enough to have a 239 head, or maybe a 256 head, the 312 gasket will not seal between a water jacket hole and the cylinder bore. John
 
I do have ECZ-C heads and I have double checked the bolt depth. All check out.
I went ahaed and had both heads pressure tested and both check out OK. They magnaflux and found no cracks. Does anyone know if a head could have a crack on the inside but yet pass both of these test?
 
if they pulled the valves as they should to magnaflux the likely spot would have been in the exhaust valve pocket.that would apply to pressure test as well.over the years I have had cracks in exhaust pocket that did not show until the were hot.but I think magnaflux should show even small crack.it seems they are trying to solve your problem unless they are saying that they did it to appease you hoping you will go away or get another head as they may not have done these things.not to say they did not just strange that if these were done properly it should have found crack.
 
Since this leak is hiding and I can find it, I have decided to pull the engine. Since the only thing left in the car was the rad and block is only 1 hour job. I plan to take the oil pan off and pressurize the water system and see if I can find where the leak is. I plan to reuse the head gaskets that I took off for this test. I don't want to spring for a new set just for this test. I will use a little sealer around the water holes to be sure it seals. Also before I only tightened the head bolts to 75 max. Some one told me to go ahead and try for the manual suggestion of 90lbs. What do you think? I have done 90 before without trouble.
 
If you have done 90 with those same bolts, that may be your problem! You have stretched the bolts! At 90 you are taking a chance on pulling the threads out of the block. I would not do it, and would not use any kind of sealant either. Blobbing sealant on just makes places for leaks! Think film thickness.
 
no problem reusing the head gaskets.you dont need any goo.i have no idea what your problem is.you dont happen to have an old head around that you could try.
 
You could try switching the heads side for side. If the leak then moves to cylinder #2, then the problem is the head. If it remains in #7, it is a block issue. John.
 
Thanks Hoosier, Didn't think of that. Anyway I think I found my problem. After hooking up the engine to house water pressure, water begin flowing out of the spark plug hole for #7. Not sure if I mentioned this before but this Block had sleeves put in in before. But before I rebuilt the engine I had two different machine shops check them out and they checked out ok. I let the water run for a while in hopes that the leaking water would leave some tale tale sign of the leak. When I pulled the head I found small rust deposits around the outside edge of the sleeve, where the top edge of the sleeve meets the block. I yeas the sleeve must have opened up after the engine got hot. Not sure what to do next. May just need to look for another block.
 
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