Crack in shortblock

[Basoline]

Hey all,

I found out that there's a 3" crack in my shortblock between the two freeze-plugs on the drivers-side. Looks like it's there for a long time because of the rust-buildup in that area.

A friend of mine, who works at a truck-shop (Scania), told me about a liquid sealant I could use to close the crack by mixing it with the cooling fluid.

Should I be worried or...thanks for the info.

It concerns a 383 from 65.

 

[Coronet 500]

This is something I would do as a last resort on a old beater car just to keep it going.There is the risk of plugging up things you don't want plugged up.I know on refrigeration systems the chemical reacts to oxygen and hardens as it leaves the system this makes future access impossible.I'm not sure how the liquid sealers work.

 

[wannadrag]

I had a small block chevy years ago that a bud forgot to drain before winter,frost plugs didnt move and split the block.Gave it to me,i cleaned the area very good a used a 2 part epoxy putty.I ended up running it a couple years and it never did leak.

 

[chrisd]

I sold things like for years at AutoZone. and because of the salary they paid, used them many times. I would strongly recommend taking the block in to have it welded at very least or replacing it. The liquid sealants are not made to last more than a season (if it can be stopped). I have heard of people using things like JB weld that is supposed to last longer, but still I would say weld it or replace it.

 

[69 Runner]

interestingly, there is a place here (that I pass all the time) that repairs diesel blocks. Haven't talked to them about what they charge, but one of these days I'm gonna stop and check the place out.

Don't know about any chemicals that will do what you want

 

[Basoline]

This is the product i'm talking about that they use in the machine-shop from the Scania garage:

http://www.tunap.com/en/ranges/automotive/products/p642.html

Block was rebuilt about 2000 miles ago. Not magnafluxed or blueprinted, just honed, cleaned and rebuilt with new(er) parts. This has nothing to do with frost or something like that because the crack was discovered when it was still not freezing...

I'm quite done with taking out engines...and, I don't have the money to rebuild the whole engine AGAIN...

 

[Cranky]

I product I hear is good is called Seal-Up.....Cargo brand. Need to flush the system of all antifreeze before using. From what I hear, the newer products are much better than the ones of yesterday.....

 

[Meep-Meep]

Being it's outside in the water jacket area it's not too big a deal, and I'm sure some sealants can fix it well enough, but the proper way is to use the lock stitch repair method. Basically you drill holes along the crack and install cast iron taper threaded plugs in an overlapping fashion. You also use a sealant while doing this. My buddy just fixed a set of 351C heads this way and no issues.

Here is a site that sells the stuff -

http://www.goodson.com/store/templa...?NID=406&SID=ce9216101f14af5d563f53e90e56ece2

 

[72Satellite440]

Id still be warry about this fast fix...I suggest JB weld also-

 

[q-ship]

Hey all,

I found out that there's a 3" crack in my shortblock between the two freeze-plugs on the drivers-side. Looks like it's there for a long time because of the rust-buildup in that area.

A friend of mine, who works at a truck-shop (Scania), told me about a liquid sealant I could use to close the crack by mixing it with the cooling fluid.

Should I be worried or...thanks for the info.

It concerns a 383 from 65.

What you describe was frequent enough that the factory redesigned the blocks with extra stiffening ribs in 69 or 70 (I forget which year).

It most commonly occurred in very cold climates, which I am guessing was due to the continued stress of expansion differentials of the engine heating from the inside out, while the outside was exceptionally cold/freezing.

The good news is that it doesn't cause any problems other than potential slight coolant loss, but I have heard of freeze plugs coming loose and popping out if it is not repaired.

The ideal method would be to have a welding shop run a bead down the crack, but I would be afraid that the weld would crack unless it was run extensively on both sides of the crack (for the same reason the stock block cracked). I have heard of JB weld, or silicone, used with perfect success.

The problem I see with an internal only sealant is that the expansion differential problem will crack the internal seal much easier than the original cast iron, so I doubt it would do anything other than "gum up" the cooling system.

Were it me, and keep in mind that I have never had the problem happen, so I am only offering a solution that I consider logical, .... I would clean the perimeters of the effected freeze plugs, and a 1/2 inch or more along the crack path. Use about 4 small dabs of JB weld around the diameter of the freeze plugs so that they can't pop out (not so much that you could not get the freeze plugs out if you ever need to replace them), Then about a 1/8th inch thick layer of "ultracopper" high temperature silicone along the crack path.

This should allow the block to expand as needed in any temperature differential, while keeping the freeze plugs from coming loose if the temperature differential is extreme.

A tube of Alumaseal in the coolant, along with the external repairs, should provide as long a life as a non cracked block. --- Keep in mind that most blocks that do this are never even discovered to have a problem till time for a rebuild, so the effects of the problem are quite minimal.

My opinion anyway. --- Good luck

 

[polkat]

You mentioned that it was rusty around the crack area, but is it actively leaking...can you see it leak?

Welding cast iron is not very easy without a lot of prep, and the engine would have to be pulled, I think JB Weld is a good candidate here. Drain the block dry, clean the area, then clean the crack with degreaser, then acetone (the idea is to try and clean out the inside of the crack as much as possible (as JB Weld will peel off a greasy, dirty surface fairly quickly). Dry it completely dry. Then pack the crack with well mixed JB. Try to force it in with your fingers. Then place a bare, 100 watt light bulb about 3" from the crack and let it sit at least 24 hours. JB cures best with heat and the bulb will provide it.

JB Weld does not work well with exhaust manifolds, but I've used it for almost any other type of crack, and those engines are still running fine now.

 

[Basoline]

I didn't run the motor since a couple of weeks (say 4-5 weeks). So I have to check if i can see it leaking while running...I guess i won't because the heat of the motor will cause the engine-iron to expand and the crack will close (?).

I guess the crack was already there but we've had a period of extreme cold (12-14F) which is VERY cold for this area. That probably caused the crack to show.

Well, there's 4 possibilities to "solve" the problem:

1. use internal sealant
2. use JB Weld or something alike
3. weld
4. replace shortblock

Since i'm sick and tired of replacing engines, i'll start with 1...

 

[polish pete]

if your going to use an internal seal, i would try blue devil, i had a truck come into the shop which what looked to be a half inch hole where the head meets the block pouring coolant out. well my boss heard of this stuff and we tried it, crazy thing is, it worked and has been holding for 3-4 years already. all you need to do is follow the directions exactly.

 

[Cranky]

Welding cast iron today is much easier than it was just 10 years ago. Welding is advancing leaps and bounds and someone that knows what's going on and has a TIG machine can fix it with no problem. Hell, I'm just a novice TIG welder and was successful in my first attempt at fixing a cast aluminum intake! I credit the machine for that.....and a good teacher.

 

[Meep-Meep]

No matter what cast iron welding requires preheat and a slow cool down or it will crack. There is a nickel based filler rod to use with a stick welder but the best way to do it is to gas weld it with cast iron rod. Brazing also works but preheat is still mandatory. Very slow process. I suggest the lock stitch method as a proven permanent repair.

 

[pushrod]

Marine-Tex is the answer. This is a two part material that can be drilled tap and sanded, used originally on boat hulls and engines. Chamfer the crack before filling. We used this on a Chrysler marine block twenty years ago and it is still holding. It can be used on steel, cast iron or aluminium. I have also seen this used to repair chipped cylinder walls also with good success. It is not cheap but it does work.

 

[Cranky]

No matter what cast iron welding requires preheat and a slow cool down or it will crack. There is a nickel based filler rod to use with a stick welder but the best way to do it is to gas weld it with cast iron rod. Brazing also works but preheat is still mandatory. Very slow process. I suggest the lock stitch method as a proven permanent repair.

Yup, it's best to preheat and slow cool and that's not really hard to do but have you ever tried to TIG weld cast iron using aluminum bronze filler? In this case welding may not be the best answer but using one of the other fixes might be the way to go...

 

[Meep-Meep]

Yup, it's best to preheat and slow cool and that's not really hard to do but have you ever tried to TIG weld cast iron using aluminum bronze filler? In this case welding may not be the best answer but using one of the other fixes might be the way to go...

If you're using aluminum bronze filler then that sounds like TIG brazing to me. I have TIG brazed using silver solder and some precious metal furnace brazing alloys with good success but never on cast iron - yet. Will have to give that a try! I used to run a vacuum furnace at a national lab and got to play with all kinds of cool stuff (bad pun). How about brazing copper to graphite? Yep, done that!!

No problem with TIG brazing cast iron as far as I can see but I'm not a pro welder. Not long ago I gas welded cast iron using a special cast iron rod and that worked great! It's amazing how the rod just disappears into the base metal like butter on toast. I was repairing some 390 GT exhaust manifolds along with a side case from some tractor. I used a custom built BBQ that accommodated the size of my part to preheat and slow cool. Only thing with that method was fighting the smoke so I had a respirator on. Man the smoke made that a nasty job.

 

[Cranky]

I used to run a vacuum furnace at a national lab and got to play with all kinds of cool stuff (bad pun).

bad pun....got a good laugh from it tho lol. I'm kinda new to TIG welding and have mostly been learning on stainless and aluminum. And I've used my BBQ pit for other uses beside BBQ too lol. Mine is also 'custom' made by yours truly and is my first attempt but I'm not sure how custom it is. It's pretty simple unit and turned out pretty good......I think. I can cook without burning up stuff so I guess that's good lol. Btw, are you welding while the parts are in the pit??

 

[khryslerkid]

I had the same problem once with a '66 Ford 390. Used "Barrs Leak" (sp) and it worked for a couple of years but one day I found antifreeze while draining my oil. You don't know what kind of internal damage you might have.