Leaking cylinder sleeve

[Jean C.]

One cylinder in my 327 block (number match '64) was sleeved prior to my owning the car. It is now has a slight leak at the base of the sleeve where the sleeve meets the cast iron. Block was sealed off with water in it, 20# of air applied and small bubbles appear at the base of sleeve. Machine shop is apprehensive about boring out the sleeve to replace it because of not knowing the original problem requiring the sleeve. May destroy the block! Using a block sealant material has been suggested as a possible fix (no guarantee). Has anyone had experience with such a fix and what brand/type sealant was used? Thanks.
Charlie

[Joe L.]

Re: Leaking cylinder sleeve

Charlie----

I'm afraid that you have a VERY tough problem on your hands here. There are only 2 reasons that the condition that you describe could occur. These are:

1) The cylinder originally sleeved suffered from a VERY bad crack. Usually, a cylinder sleeve will adequately repair most cracked cylinder walls. However, if the crack is very bad, "open", or if the crack in the parent block material extends below the the bottom of the sleeve, it may not;

2) When the cylinder was originally sleeved, the overbore necessary got into a "wet" situation. In other words, the block may have suffered from enough original coreshift that the sleeve overbore went through to the waterjacket. Wet sleeves are good but, unfortunately, ONLY for engines originally so-designed (e.g. many HD diesel engines), NOT for repair of an original non-sleeved engine. For this sort of repair, the sleeve has to be a "dry" one.

It's very possible that all this was known when the block was originally sleeved. However, trying to preserve the "added value" which "matching numbers" confers to many folks, the owner may have instructed the machine shop to go ahead with the repair. Perhaps, even, the idea was to keep it going long enough to sell the car with the original engine without really being concerned about long term durability.

I hate to tell you this, but there is a very good chance that this block is irrepairable and is, consequently, scrap metal. I think that your machine shop is VERY wise to have told you "the way it is". In other words, any further attempt to repair the condition will result in the total destruction of the block. On the other hand, if what I expect is true, then you don't really have a lot to lose. Of course, I could be wrong.

One thing that you could do is this; have the engine rebuilt as-is (i.e. with the leaking sleeve). Then, after installation in the car is complete and the cooling system is filled, add SIX GM #3624621 cooling tabs. This is a heavy duty cooling system sealer which GM requires for installation in cooling systems of, even, new cars when the coolant is re-newed. These tabs have been around for ages, though, and have stood the "test of time". This MAY solve the problem. Of course, it's a great gamble since you, undoubtedly, are going to have to put considerable money from this point of the rebuild forward. If this fix works, then it represents a great investment. If it doesn't, then you've "thrown good money after bad".

[Clem Z.]

Re: Leaking cylinder sleeve

since the leak is at the bottom of the cyl were it will see no cyl pressure most good "block sealers" should work. i have had good luck with "moroso ceramic seal". i believe that it is still in their catalog.

[Craig S.]

Re: Leaking cylinder sleeve

Charlie - Joe and Clem have great advice. I went through a resleeve on my 66 427/425 block last fall, due to an original sleeve crawling down in the bore. Apparently, back in the time when my block was sleeved, it was frequently thought that friction alone would suffice in keeping sleeves from moving. The correct process is a good step sleeve operation, usually with the step at the bottom of the bore. It sounds like your block is like mine, with the sleeve going full length in the bore, all the way through to the crankcase. In my case, I sonic checked the block AFTER the machine shop cut the old sleeve out, and found the thrust faces still had in excess of 0.260-0.315 wall thickness, and the side faces of the cylinder had around 0.160 remaining. My original sleeve was 0.093 wall thickness, I opted for a high grade Darton top step sleeve, similar to the style used in aluminum blocks. This allowed the stepping to be controlled on the deck area, with the bottom area floating through the block as the original sleeve did. While Darton will custom machine and build a sleeve to any specs, the tool up is quite expensive, and it would have run about $200 for the sleeve and setup. I opted for the standard 0.125" wall thickness sleeve since I could get it without special setup from Darton, and they even cut to length for an additional $25. When the machine shop bored the block for the new Darton sleeve, He commented on the high quality of this sleeve and how true it was, he used the Darton suggested interference spec of around 0.001 press fit (was different than a normal non stepped sleeve). My block had two cracks in the outboard thrust face, probably from a rod break, the cracks were well up in the bore, not at all near the crankcase. Even with all the meat in this block, the cores on the 427 at the bottom end near the crankcase valley on the inward sides between the cylinders "dip" in slightly, I noted this by looking with a bright light through a core plug. With the overbore to install the thicker Darton sleeve, one tiny spot cut through to wet, about the size of a pencil lead. It was well up from the crankcase, about 1.5" or so, and the machinist used JB weld in this area and in the cracked areas prior to pressing the sleeve, and the wet JB pushed through the small hole as viewed through the core plug. He was very satisfied this would be no issue at all, since it was so far up the bore from the crankcase and the JB pushed through. Obioulsly, there was still extensive meat everywhere else from the sonic testing. My point is, if you do have the sleeve cut out, rememeber, you will have to go larger in the sleeve at least some to cleanup the original cut wall so it is true and you obtain a good press on the new sleeve. This will aggrevate whatever is going on in a wet area with more wet exposed. However, my machinist showed me a vintage 427 block with a chunk broken out, completely through, that he was going to sleeve. He indicated that using the block cement usually would solve these problems, but KEY was that you don't have block breakage down near the bottom of the block core near the crankcase, and if there is at least 1" of good solid block in that area, dry sleeves work well even with some pretty serious breakage above. I my case I was lucky and really only had the two small cracks to contend with, and the small wet spot when machining for the thicker wall sleeve. I would try Clem's suggestion with the cement first, before even considering the machine operation. If it fails, you can always cut the sleeve out later to evaluate what you really have going on. Best of luck!....and a well done sleeve is nothing to be scared of, the sleeve is superior to the actual block casting for strenth and durability.

Check out the Darton link below....good luck!...Craig




Darton Sleeves

[William C.]

Re: Leaking cylinder sleeve

Most shops that build Super-Stock Drag racing engines use a process that uses an epoxy to "fill" the block to provide added stiffness to the bores. a small amount of that material set into the lower area of the block should fix your problem without additional machining if all else fails.

[Clem Z.]

Re: Leaking cylinder sleeve

if you use the "block filler" which is expanding grout make sure you rehone the cyls because the grout can distort them as it expands.

[Mike M.]

Re: Leaking cylinder sleeve

clem: can one use standard, run of the mill ceramic tile grout or is it preferable to get the Speed shop varity ? thanks, mike

[Clem Z.]

Re: Leaking cylinder sleeve

run of the mill grout shrinks when it hardens and the stuff they use expands when it hardens. the "block filler" is also available from moroso at your local speed shop.

[Mike M.]

Re: Leaking cylinder sleeve

thanks clem. the old maryland cheapskate was trying to say a buck. mike

[Clem Z.]

how do you get you wife to do that?

save a buck.