Cracked Block

[Reginald West]

Need a few opinions. My stage 2 off center block cracked between the last 2 freeze plugs on the passenager side. I have been told of 2 ways to fix it .The first consists of stop drilling the crack and pinning the crack then using block sealer in the cooling system.The second method consists of filling the block up past the freeze plugs with a Hard Block Sealer (almost looks like cement) this may cause some heating problems. Anybody got any experence with these repair methods?


REG

 

[John Wilde]

I am sorry about your luck Reg.
If money were no object I would say go TA.

 

[Reginald West]

I hear you John. I would love to go to the TA Block but with the money I have in this block I have to milk it for all I can.

REG

 

[John Wilde]

What does Kenny want you to do?

 

[Reginald West]

Fill it with the Hard Block Compound. But then its a drag motor only of course i don't drive it on the street but once in a blue moon anyway.

 

[John Wilde]

I have seen some SBC guys drive half filled blocks on the street.
I have never spoken to someone that has done that with the V-6.
You could always try a see if your cooling system can handle it.
Do you have an electric water pump that you can run with the motor off?

Good Luck man, if anyone deserves a 9 second time slip it is you!

 

[Mac in SD]

Hey, Reggie, have you talked to Neal? He might have some insights for you, having been through the same thing. Is it a 3.8 block? What a bite in the balls.

 

[KendallF]

Originally posted by Mac in SD
Hey, Reggie, have you talked to Neal? He might have some insights for you, having been through the same thing. Is it a 3.8 block? What a bite in the balls.

Well, I have Neal's cracked block sitting in my car as my mockup block...if that tells you anything. I am planning to eventually give it a partial hard block fill and run it that way. It has the additional complication of having two cracked cylinders that have to be sleeved. I would hard block it past the crack point and run it.

 

[750H.P.V6]

Reg,

I hate to tell you this but the prospects for your block are limited at best. Having been where you are and having it to do all over again I would opt for the hard block. If the crack in the block goes from one freeze plug hole to the other it's on it's way out.

You can try to pin the crack but from my own experience I will tell you it will continue by cracking on the other side of the freeze plug hole and running forward and aft respectively. If you run it long enough (I did) the block will crack in the #4 cylinder horizontally approx 1/2 " below the deck surface then it's all over.

This is why I gave my old block to Kendall to use for his engine mock up. Just fill it up with the hard block and see if you can get another season out of the thing.

Neal

 

[ijames]

Why not do both? Stop drill both ends of the crack, weld, and then hardblok at least up past the crack? Or try the first, then hardblok if the crack comes back.

 

[The Radius Kid]

I would try drilling both ends of the crack with a center drill[60 degree],groove the crack and braze it all up.
Should hold nicely if the brazing is done right.

 

[Reginald West]

Thanks for all the input guys. I think I will go with Hard Block Ideal and try to run it 2 more seasons. As of today I making plans to buy an A L Block but its going to take a while to put the money togather.By the way this was 4.1 block that cracked.


REG

 

[QuickWrench]

I haven't had this experience [yet] with a Buick block, but have encountered the same thing with a Dart BBC block that cracked in a juiced Nova I used to run. After a violent N20 backfire, the block cracked between the freeze plugs on the right side of the block. Not a wide-open split, but a stress fracture.

After some convincing, our machinist set the block up in his CNC mill on its side, passenger side up. Using 3 steps of progressively-larger diameter/deeper ball-milling, he was able to irrigate the crack and provide a valley in the iron which we were able to have welded.

After re-honing cylinders 2,4,6,8, we ran the block on the street and ~20 track passes for another year without problems. No block filler.

 

[750H.P.V6]

Guy's,

There have been some pretty good ideas thrown out so far and I considered most of them myself when I was in the same position as Reg.

Here are some of the problems we came up with, first off you can't stop drill the crack because it runs horizontally between the 2 freeze plug holes. Mistakenly I thought the freeze plug holes themselves would act like giant stop drill holes and the crack wouldn't progress. This isn't the case.

We also tried to weld repair my block twice. Keep in mind the only proper way to weld cast iron is in to heat the part in a furnace and use a high nickle alloy rod. The problem with this is that the block distorts somewhat and all the machine work needs to be checked and re done as necessary.

We tried to "cold" weld my block. This is a B.S. concept whereby you weld a very smal amount then peen the weld once it cools to stress relieve it then weld a little more etc. The results were marginal at best and I wouldn't recommend trying it. Brazing might work and since the braze material is fairly flexible it may hold up.

Back to the idea of Hard Block. I didn't go this route and just kicked the block to the curb once it split a cylinder. I know Bill at Champion runs hard block in his engine and say he really suffers no ill effects in regards to cooling. There is still water circulation at the top of the block and thru the heads and that's where the heat is. BTW, there is a 4.1 liter Stage I block in the classifieds too.

Neal

 

[The Radius Kid]

To be honest,we've been using brazing instead of weld on cast iron for years in industrial app's.
Yup,we can do weld on cast iron,but the brazing always seems to hold.
That's on some very highly stressed parts.
Go figure.
Probably has to do with the lack of molecular alteration due to welding.

 

[NJTurbo]

Reg,

That really sucks you just do not seem to get a break anywhere

I would sniff around for another block Good Luck

 

[Reginald West]

Yea if was not for bad luck I would'nt have any at all. What to hell its only time and money and fortunately I still have a little of both left

 

[GARY HARVEY]

The "CRACK" Problem

There is a outfit here in Houston, that takes up a city block and all they do is repair broken cast iron. I was given the cooks tour and noticed a continuous
heat source being applied, where the area in question, stayed cherry red while a propriatory cast rod was employed to fill the ground out crack. After all this, the block goes to heat treat after it has been thru the machine process to recut the necessary surfaces. If this sounds like something that may interest you, let me know and I'll get you the needed info so you can give them a call. The guy that runs the place is "Red" and he only fixes things he can guarantee. Most all of the work they do is on large stuff and it comes in from all over the world. Note: this won't cost you an arm and leg and you may be able to send a picture or two and not have to ship the block...

 

[turbodave231]

Neal,

What is causing the cracks between the freeze plugs? Is the stress from the motor mounts causing this cracking? Would a mid-plate eliminate the cracking? I don't want to have the same problem.

Dave

 

[750H.P.V6]

Dave,

That is a good question. I've pondered this myself. Personally I think the block twists and distorts to some extent and over time this will manifest itself as a crack between the freeze plugs. The harder the block is run and the longer it's in service the more likely this becomes. 3.8 blocks are much more likely to crack than 4.1's also.

Personally my 3.8 Stage II block was a short block that came from John Gallinas SSDX car. No way of knowing what it had been subjected to. I believe that at the time he was running this particular motor he wasn't running a mid motor plate. I'm sure all those trans brake launches at high boost couldn't have helped any.

I would say that running a motor plate is a good idea in any high H.P. application. If I could come up with a good way to do this in my street car I would. Maybe I can talk Paul Ferry into making something with urethane bushings so it's not completely solid. Who knows? If you are going for more of a race car application I'd go with a motor plate.

Neal