Cracked head question

[Bob from Northport]

Over the weekend, I cleaned and checked three standard heads from A engines. All three had a small crack running from the head stud hole to the water jacket hole adjacent to it on the drivers side hole directly opposite the distributor. The middle hole in the head. Any thoughts why these are all the same place, why they are cracking there??


Bob

[V4F]

it seems to be the common crack . seen many like that . very fixable ....

[Tom Wesenberg]

Many A's had and still have that common crack. I wouldn't worry about it You might have to use silicone around the stud hole to keep the coolant from seeping past the head nut.

[Drive Shaft Dave]

Dave Gerold posted a fix for this. Check the search function.

[BILL WILLIAMSON]

If it were mine, I'd just shop for a head WITHOUT a crack! Heads are plentiful & reasonably CHEEP. Why tempt FATE? FATE has TRICKY ways uf "GITTIN" you & yo' POCKETBOOK!! If you wuz a cheep old USED CAR DEALER, you WOULD put it on, along with 2 JARS of BARS-LEAKS!! Would you put on a tire or a tube, with jist a "LITTLE BITTY" crack in it???
Bill W.

[Dave in MN]

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Originally Posted by Drive Shaft Dave

Dave Gerold posted a fix for this. Check the search function.

I see there are varied opinions as to whether this common crack needs to be repaired. Opinions...to each his own...I respect that.

FWIW: If I did not have the ability or equipment to make this repair, I would not worry about a crack like this for my own car as I know how to seal it as others have described. That being said, I rebuild engines and when I sell someone a resurfaced head included with a longblock I make this repair. Why?
Couple reasons: 1) It only takes about 10 minutes to install and machine the guide while set up for surfacing the head. 2) The cost is under $6.00 for the guide and threadlock. 3) If the head were to go on my car...I'd fix it as described below. 4) If I was purchasing a rebuilt longblock, I'd expect a fix better than slathering the cracked area/stud and nut with a sealant. JMO!

Here is the fix posted early in 2013

The repair shown below solves the problem with coolant leaking around a head stud and nut from a cracked head. Repaired...they don't leak!

The repair involves installing a cast iron sleeve in the stud hole that has a crack that runs into the water jacket. The sleeve is made from a cast iron valve guide.

Here is the cast iron guide and tooling info to complete the cracked head repair.....

The cast iron guide I use is available from Engine Parts Warehouse and possibly other sources.
The guide is: SBI #1408591
Outside diameter: .5635"
Length: 4" (I would have chosen a shorter guide...but couldn't find one...)

The ream is sized to be .001" smaller than the outside diameter of the guide. I use one from Rock River Tool #246518
Size is 9/16" or .5625"

The drill bit used to prep the hole for the reamer is a 9/16" undersize that mic's at .560".

You can use any cast iron guide that has an outside diameter close to the size above. I chose this particular guide because it left a reasonable amount of the original cast iron in the head available to surround the guide and the required .5625 (9/16") reamer is readily available. Don't go to much larger or you may machine or break into the water jacket area. When choosing the components you will use, the important thing to keep in mind is that you should have about .001" interference fit. Note that the ream referenced above is .001" smaller than the guide. The guide I chose has a chamfered end to make it easier to install and to allow the Loctite to build between the guide and the head as it is pressed in place...a sharp edge would just wipe the Loctite from the surfaces. I use a Bridgeport but you could use a good drill press. I have a jig for surfacing heads and use it to support the head while making the repair. After leveling the head I locate the center of the hole being repaired, drill the hole and then ream the hole from the same "set-up". I lightly but completely coat the surface of the drilled hole and the guide with Blue Loctite Gel and press it in about an inch with the mills arbor and then finish driving it in place with a brass hammer leaving a bit of the guide protruding from each side of the head. After installing the guide, rough cut the excess on both sides with a cut off blade installed in an angle grinder. Carefully grind the gasket side flush knowing that the final surface will be cleaned up when the head is surfaced. (I always lightly surface the head after making these repairs but it would not be necessary if the head was straight and you don't mess it up when flushing the guide.) At this point the installed guide is drilled the same size as the original stud holes. The size of drill escapes me at the moment... just match the size to the original holes. After surfacing the head flat, it is removed from the jig and the head is clamped top side up to the bed and the top of the guide is milled/spot-faced flush to the boss. I have included a photo of the items needed for the repair, a photo of the installed guide and a micrometer showing the size of the undersize drill bit.
I often repair two locations in a head as the adjoining hole to the distributor often has a similar crack. The installed guide photos below show the repair prior to the head being surfaced.
Let me know if you have any questions.
Good Day!

[tbirdtbird]

they all crack there. Not really a problem. The fix above is nice but not needed.

Just use permatex #2 sealer and it will be fine. Put the sealer around the studs involved just before you drop the head on so that it becomes in contact with the nut on top.

Mine has run 20 yrs like this no problems

[BILL WILLIAMSON]

Originally Posted by tbirdtbird

they all crack there. Not really a problem. The fix above is nice but not needed.

Just use permatex #2 sealer and it will be fine. Put the sealer around the studs involved just before you drop the head on so that it becomes in contact with the nut on top.

Tbird,
Just thinking, "maybe" it would be better to coat the inside of the stud bore in the head with # 2 Permatex, otherwise, it might be scraped off the stud & get "piled" up on the head gasket??? "MAYBE" I WURRY too much???
Bill W.

[Growley bear]

Originally Posted by BILL WILLIAMSON

If it were mine, I'd just shop for a head WITHOUT a crack! Heads are plentiful & reasonably CHEEP. Why tempt FATE? FATE has TRICKY ways uf "GITTIN" you & yo' POCKETBOOK!! If you wuz a cheep old USED CAR DEALER, you WOULD put it on, along with 2 JARS of BARS-LEAKS!! Would you put on a tire or a tube, with jist a "LITTLE BITTY" crack in it???
Bill W.

I agree with Bill.
Chet

[Growley bear]

Seems to me that the fix is much more expensive and time consuming than a head with no cracks.
Chet

[crumbaa]

Thanks for reposting Dave, I have this issue and was not sure how far to go with the hole dia.to drill over and sleeve. Great info

[peters180a/170b]

Here is my guess why it cracks there>>> Some torque the head down without the dist. in place with ignition cable and clamp .Like me i torque the head down and then remove the head nut where the ignition clamp goes and then later place the dist, . ignition wire and clamp onto the head and its hard after to re-torque the head with my torque wrench [ dist, ear is in the way] so i just crank the head nut down with a flat wrench. Maybe that's why it cracks there???the head is now not torque in that place correctly...just my guess...so maybe i'll find out the correct way of doing it ...

[Tom Wesenberg]

I think if the head is torqued in just one pass it pulls down too much in the center and might add to the cracking problem. I would only torque by using 3 or 4 passes, such as 10, 25, 40, 55.

[tbirdtbird]

yep the dizzy is in the way. Use a crow's foot on your torque wrench to get around that problem.
But I suspect the crack is from thermal stress....overall expansion and contraction...