MTFCA Forum

Best way seal a cracked block still good but had water left in it and cracked between rad and s/n
I've used block seal in the past any other ideas
Thanks in advance

Bottom of water jacket or?? a picture would help.

I am not going to say anything…

I've had good success with Belzona 2 part epoxy - was told it was approved by Caterpillar for block repair by my long-time diesel mechanic friend - rather pricey but I did one rather large water jacket repair in the rear of a '26-'27 block over 10 years ago and it's still holding.

As long as the crack is not going through into the crankcase or cylinder wall use the crack repair as suggested.
Using just the old stand by JB Weld can last for years too but if there is something better use it. Several improved epoxies have been developed.

Hi Bob,
That's a bad place to make a repair because it can be misconstrued as tampering with the S/N. I have a block that had several cracks ( the car
is registered with the engine # ) so there was little options I opened the ends & the crack with a small ball end Dremel so the opening was
smaller on the outside than in the crack, filled with JB Weld then covered with a aluminum plate. ( I don't think that a plate will be easy in
your situation ) It has held for years. There is many products better than JB Weld one that comes to mind is Devcon. Drilling & pinning is a good
option but is not a DIY thing and needs an expensive professional to do it. Good luck.
Craig.

Steve the Belzona 1111 is awesome but grab your wallet it’s close to $400 last I needed some a few years back. The Belzona products differ based on application need.
The are made for major heat, pressure & liquid contact. These products are used in industry with a record of success when used as directed.

I used JB Weld, the original not the quick stuff with embedded window screen and it held up well. The secret is a thick application.

Without seeing exactly what/where the issue is, any type of suggestion (-especially from those who don't have professional first-hand experience!! ) that anyone gives is just a WAG. If it is determined that welding is a viable option, we use a product named MuggyWeld to repair cracks in vintage engines and cast iron components. Not the only product that can be used to weld cracks in cast iron, but definitely one of the better rated ones IMO.

Yes John, it is rather pricey but makes a hell of a repair ! I purchased the "small" kit a number of years ago & keep it sealed & in my heated office.

Steve if you have dealt with the open valve blocks you know they are thin, especially in the galley between 2 & 3 cylinders, the area looking through the inlet hole in the block. Generally extremely pitted from corrosion & thin. The high temp Belzona 1813 adds layers and smooths the surface out and prevents corrosion sealing the block basically for life.

The general way to repair any cast iron crack is to first, drill a small hole at the end of the crack so it does not spread. Then take a Dremel tool equipped with a metal cutting disc and starting in the middle of the crack, cut a V on each side of the crack with the Deepest part of the V being in the center of the crack. Do not go through. Clean thoroughly of all oil and dirt. You can then repair in whichever way you choose. Filling the V with cast iron weld is the best if you can find an old welder experienced in welding cast iron, or you can fill with a good epoxy putty. I have always preferred Aluminum Devcon 10610, 2 part, 4:1 ratio putty (4 parts putty : 1 part activator). You can get it from McMaster Carr (www.McMaster.com). Somewhat expensive but not nearly as expensive as the Belzona. Jim Patrick

I work for Caterpillar at the Large Engine Center. We do not use Belzona to repair cracks. We only use it as a filler for voids in the surface of a casting.

Another good product that is now available is Lock-N-Stitch. We do use their repair inserts on threaded holes on our big blocks.

When I worked in the aftermarket, I used Irontight pins to repair cracks.

Scott C how does this product work with heat? Always learning especially if it’s less costly with equal quality.
On a side note have you ever used their blind inserts? I’m heading into that direction with a block I have. Best John

John: if you are asking about Lock n Stitch blind inserts they work great. I use them all the time. Their regular inserts are great too.
But they are not cheap to get into. Tooling is expensive as well as inserts. But they are top of the line. Dan

We do not use it very often. We only use it on exterior surfaces like oil pan rails and end faces where there is not much heat transfer and only to fil voids. Most of those kinds of defects actually get welded. We machine damaged features and plug, or sleeve them also, then machine them to print. All repairs are done under Engineering approval. Then the part is deviated to only certain applications or reman.

Yes, I have installed the Lock-N-Stitch blind and open hole inserts. I have done both types of inserts. The ones with the flange at the surface and the ones with out. The flanged ones are more difficult to deal with. I have to get the counterbore tools reground to the right diameter, or there will be a void around it. When done properly it is hard to see the repair. Thier thread is proprietary with reverse tapered threads. The angle of the threads will actually hold 2 pieces of material together, making it a very good method for crack repairs. That being said the taps are fragile and the flutes will break off. Another thing to is they have a rough, finish and bottom tap for most sizes. I have had to have the bottom tap ground shorter to get the threads to the bottom because of the long lead on that tapered thread. I hope this answers your question.

Thanks all
I've used jb weld then follow up with K seal probly what I'll do this time as well
I get a pic next time I near the shop
Thanks for the replies

Another option to consider might be Marine Tex. It was used my GM to repair Vega blocks in the 70s. It was even machinable on block head gasket surfaces. More expensive than JB, less than Belzona.

Nv Bob wrote: ↑

Sun Nov 19, 2023 10:50 pm

Best way seal a cracked block still good but had water left in it and cracked between rad and s/n
I've used block seal in the past any other ideas
Thanks in advance

You mean a permanent repair like metal stitching? Yes we can do it. Without the silly putty.

I metal stitched a Willys Jeep block with a 6" crack through the freeze plug in 1973. Still going strong and never leaked.

Please describe what metal stitching is. Is it something an amateur can do or is it something that only a machinist in a machine shop, with specialized tools, can do. Thank you. Jim Patrick

It was explained to me (in an autoshop class I took) that it involves first drilling the ends of the crack, then drill and tap overlapping holes along the crack, installing a threaded rod in each one,leaving a small amount above the level of the existing metal, peening the exposed metal over. I was also told you have to do them one at a time so you're overlapping the threaded holes (eg like stitching it together)...

Of course now I want to hear from the professionals to see if I understood them correctly. It doesn't seem particularly difficult (until you break a tap in the hole!) but it does sound tedious, and if you get it wrong it still leaks...

Here is the nickel tour of using the Lock-N-Stitch pins to fix a crack as I have done it. I am not an expert and will welcome any tips or corrections from those who are better experienced.

First drill a series of holes along the length of the crack using the Lock-N-Stitch spacer. This first set of holes are for every other pin. Next counter sink part way into the holes to provide a shoulder for the pin to snug up against. Then tap the holes. Screw a stitching pin into every other hole and supply enough torque to twist off top of the pin. Here you have to be careful because if the cast iron is too thin where the crack is you likely won’t have enough threads engaged with the pin to withstand the torquing and you’ll end up stripping the threads. If that scenario seems like what you’ll be up against, snug the pins as much as you dare and then use a small cutting wheel to cut off the upper part of the pin. Now insert pins into the leftover holes. Grind the top of the pins close to the surface of the cast iron, but not all the way. You want some material for peening later.

Now start the process over by drilling, counter sinking, tapping, and inserting pins in all the spaces between the first set of holes. This is where the overlapping process of the repair takes place. Grind the new pins as before and peen the whole length of the repair to squish the top of the pins against the surface. Finally grind what is left down to the cast iron to smooth out the repair. A pressure test is always a good idea when you are done for peace of mind.

Here are a few pictures to help visualize the process. They show the first set of pins being installed.

Rich C.