Welding engine block

[Cutlass]

My BJ8 block has a repaired crack extending the entire length of the water jacket, just below the head mating surface. I've received mixed advice concerning attempting to repair this crack. Some say no repair is worth trying, and advise getting a replacement block. Does anyone have actual experience with having cracks like this repaired? Is it cost effective? Reliable? Thanks.

 

[Keoke]

Cutlass, If I understand this correctly.The block was previously repaired,Welded,but the repair has opened up again.This being the case it is difficult to conventionally weld over previously welded cracks and get a reliable fix. But, if you can find a professional"TIG" welder experienced in welding engine blocks he may be able to fix it.However, I think peace of mind probably requires replacing the block-FWIW---Keoke

 

[Cutlass]

Sorry about the confusion. The prior weld appeared to be with epoxy, such as JB Weld. The crack was stop drilled, then widened with a burr, then filled with epoxy. It stopped most of the leaking, but not all, and surely was not a permanent fix.

 

[Keoke]

I Know JB Weld claims it can fix cracked blocks I have viewed this claim with skepticism even though I use the material frequently.For this case the epoxy can be burned out with a torch ,given a very good cleaning of the crack's surfaces and properly welded.Make certain the stop drilling is far enough away from the end of the crack to stop it and the welders are experienced with block repair. Peace of mind is still invoked-FWIW---Keoke

 

[Randy Forbes]

[ QUOTE ]
Sorry about the confusion. The prior weld appeared to be with epoxy, such as JB Weld. The crack was stop drilled, then widened with a burr, then filled with epoxy. It stopped most of the leaking, but not all, and surely was not a permanent fix.

[/ QUOTE ]

In that case, you have two (2) options repairing your block. TIG welding, as stated and stitching the crack with tapered/overlapping brass plugs.

As the stitching is a cold process, it would be my first choice and has a proven history of success.

I wish I could tell you more about the TIG vs. cast iron process, but I only learned GTAW last month at the Lincoln Motorsports Welding School. I do know that the higher the carbon content in the subject, the more important pre heating/post cooling is.

 

[Skip & Lynne]

Well guys you have finally hit upon something in my area of engineering. Cutlass the most important thing to remember is not to get the block to hot or it will distort the head mating surface beyond use. I don`t recomend TIG for cast iron it is great for other things but cast iron isn`t one of them. This block can be welded using SMAW or stick welding as it is called. Go to the welding supply house and get about 1 lb of 3/32 Nirod 55. Some folks use 310-15 stainless but it has a high coefficient of expansion and will crack again right at the toe of the weld. I have welded many castings using the Nirod 55 or just ask the supply house for a cast iron rod. It is a NiCrFE alloy similar to Inconel. Drill a stop hole about 1/8 inch at the end of the crack at each end. Clean the crack as clean as you can get it use a power wire brush and get it spotless if you can; no paint or grease at all. Use about 75 amps on DC reverse polarity and take a torch and preheat the crack to about 250 deg. (Get a 250 temp stick from the welding house). Weld in short sections of about 4 to 6 inches at a time going from the stop holes to the center of the crack and keep it warm but not to hot. It is not nearly as hard as it sounds. Don`t let it cool to quickly after you weld it cover it with a layer of rags or old blankets several inches thick and leave it alone for a couple of hours. You can have it liquid penetrant checked afterward if you like to be sure of no defects. By all means don`t throw it away. Skip

 

[Cutlass]

Thanks, Skip. While I do weld, stick, mig and tig, I haven't tried cast iron welding, and am hesitant to do so for the first time with this block. My alternatives are to get some junk heads to practice on, or to find and experienced welder in my area,which is Atlanta, Georgia, or elsewhere if necessary. Guess my main question is whether welding a crack such as this is really a viable alternative to replacing the block. You seem to believe that it is, and thanks for the advice. Know anyone around here that does this for a living and will stand behind their work? Thanks again.

 

[Healey 100]

I had a Buick block with a similar crack repaired successfully using a cold process. Some sort of threaded anchors are inserted into drilled holes along the crack. It is all filed off smoothly in the end, and I could barely see it. I have heard of doing the same thing with sheet metal screws.

A crusty retired machinist that I know well frequently brazes cracked castings. He tells me he has had very mixed results with this process, sometimes the casting is lost when it's over. He uses a big oven to preheat the casting with a window through it to do the brazing.

Since your crack is in the water jacket, I would not give up on the epoxy route so quickly. Using fiberglass with resin and perhaps some sheet metal to beef up the area around the crack might do the job for you. It is not clear to me how much they widened the crack to put in the JB Weld. If the crack is not too wide, I think JB weld or some other epoxy could definitely do the job if you clean and cure it properly.

Good luck, take your time before putting welding or brazing rod on that block.

 

[Skip & Lynne]

I live in Savannah and get to Atlanta on business every 3 or 4 months. Skip

 

[bighly]

A new block would be my vote.

 

[Skip & Lynne]

If you get another block I will buy the cracked one. Skip

 

[Keoke]

Cutlass, Just give Skip the cracked one---Keoke /ubbthreads/images/graemlins/laugh.gif

 

[Cutlass]

Thanks again. Skip, I'm not in much of a hurry on this, as I'm just now ready to send the chassis out for stripping, and this will be a multi year effort. So if you plan to be in town, let me know. I'd like someone with some experience to take a look at the engine. In the meantime, I'll explore the market for a replacement block. I'd like to keep the old one if it's really the right thing to do, for it's somewhat of a known, if imperfect, quantity. The engine was running when I got the car. Anyway, my e-mail is jma@jmalawfirm.com. Yeah, I'm a lawyer. But I was a car nut long before that.

 

[Skip & Lynne]

Cutlass I would be glad to weld it for you if you like as well. Skip

 

[Cutlass]

Thanks. I've got a Miller Syncrowave 185. That good enough? And I'd be happy to pay for the effort. Or should I bring the block to you?

 

[piman]

Hello all,
I believe that the options are the cost of locating a replacement bock (plus possible machining - I would doubt that a 'new' block is available) versus the proven methods of welding or stitching. I personally would have no long term faith in chemical repairs.

Alec

 

[Skip & Lynne]

Cutlass you have a good machine just clean it up really good and get some cast iron rods and weld her up. I should be in Atlanta in the next few months I would be glad to give you a hand. Skip