Welding a crack in a cast engine block???

Date 07-23-2011 05:51

I have a Cat dozer that has a small crack in the block.
A previous owner of it had been running water instead of antifreeze and ended up freezing it bad enough to push the freeze plugs out and crack the block.
He changed the freeze plugs and ran it for 5 years. When it gets hot, it will leak again and I would like to fix the little crack rather than pay $6,500 for a short block if the crack decides to spread during this wonderful heat wave we are all in right now.
Again, it's on a non stress part of the engine and has been running weekly for 5 years like this. Its on the side of the block, in the center, about an inch and a half long and runs horizontal.

Now to the question:

I have heard from the "old timers" around here that I can grind the crack out a little and weld it with a nickle rod. Does anyone have any experience with this type of repair or know if it that method will work? Since it is cast I was thinking it may need to be heated first and slowly allowed to cool after welding to keep it from cracking out more.
I obviously have no idea how to do this but think its worth a shot considering the alternative. Any help with this is greatly appreciated.

If I could ever get my copy of the Farm Code book it is probably in there under the chapter on aerospace and dirt track repair. :)

By DaveBoyer (*****)

Date 07-23-2011 07:11

This is the sort of thing that doesn't always work, but then again many have had luck with it. My Dad did one and it worked :surprised:

Most suggest that You don't preheat, weld a really small ammount and peen with a light ball peen hammer as the weld cools, then weld a litle more and peen, continue 'till You get it done. You want to be able to keep Your hand on it before You weld the next bit.

We have been strictly adhering to the Farm Code since 1959...

By commonarc (**)

Date 07-23-2011 08:23 Edited 07-23-2011 08:40

I've made numerous repairs on cast and this seems to work for me. try this:

1) Degrease as best as you can. Oil & grease are your enemy.
2) Grind out crack as deep as possible or practicable.
3) preheat area 3" or so around the weld area...just enough to take the chill out of it
4) Weld, pean, weld pean ...don't stop until it's filled.
5) Have torch ready to POST heat and warm it up good...too hot to touch if possible but nowhere near cherry red (300 F temp stick)
6) Pean one more time and either wrap tightly in insulation and tie with wire OR pack clean dry sand onto weld area (insulation) if possible.
7) Let it cool off and check for cracks. Sometimes you get horizontal surface cracks on the weld bead but otherwise the weld seems sound.
8) Don't give up if your first attempt fails. You may have to do this more than once.
9) Try a different type of cast rod if all else fails.

There are numerous new cast electrodes out there that produce much better weld quality than the old Ni-rod. I don't have the brand names handy. All are very expensive. Check with your local welding supply store.
Good luck

By 99205

Date 07-23-2011 13:37

Don't scrimp on the peaning he mentioned. Peaning and a slow cool down are critical.

By Superflux (****)

Date 07-23-2011 14:01

For slow cooling, the cat litter type floor dry works the best for sealing in the heat on odd shaped pieces. If not available, cat litter is the next best. The floor dry is lighter and a better insulator. For peening down in the groove, I like to use a well worn chipping hammer, or dull one to about 3/8" diameter and well rounded. The peening will stretch the new metal and counter the shrink effect when cooling.

By Rafter_G_Weldin (***)

Date 07-23-2011 18:13

JB WELD? worked on my ac system in my truck

By weldwade (***)

Date 07-23-2011 19:37

I repaired a block on a 789 Cat haul truck once with brass pins. Drilled the holes .003 under the pin dia and overlapped each hole to lock the pins in place. It is still running today. worked good. used red Loctite on each pin.

By nevadanick (**)

Date 07-23-2011 20:07

Caterpillar recomends the use of a product called belzona for temporary repairs, its a 2 part epoxy like jb weld only better. Ive seen cracked blocks fixed with it and last for years.

By weldwade (***)

Date 07-24-2011 00:40

Belzona is amazing!!! It is the absolute best product I have ever seen for conveyor belt repair. If their product for steel repair is anything like their belt epoxy I would use it no questions!

By rcwelding (***)

Date 07-24-2011 03:02

I saw this a while back.. It's a really cool process.. I think this is way better than welding and much safer..!!!!!

http://www.youtube.com/watch?v=Pq0wfU4ZaKk&feature=related

Roughly the same concept on this one too but different application..

http://www.youtube.com/watch?v=9XfTORBtcSE

RC

By DaveBoyer (*****)

Date 07-24-2011 05:05

http://www.locknstitch.com/AboutLocks.htm

These go across the crack to tie the sided together in non welded repairs. This particular product is a modern version of an old process.

By Northweldor (***)

Date 07-24-2011 11:39

Interesting link, Dave, and while I have used the old process of drilling, threading, spaced grub screws and stitching together with ni-rod or brass, I didn't know that this process had developed to this extent since the advent of CNC (complete with "trade" training!).

By rcwelding (***)

Date 07-24-2011 17:20

I was looking all over for that one Dave... I have seen it before but couldn't remember what it was called.. Thanks for posting..!!

RC

By FixaLinc (****)

Date 07-26-2011 01:39

Like others said JB weld or two part metal filler epoxy of other brands sold at machine shops. If not a long crack or getting bigger or cracked inside the JB weld can last for years. Use the regular 24 hour cure stuff not the quick 4 hour kind. Get it clean of grease and paint clean off with rubbing alcohol and slap lots of JB weld on. You can drill small holes at ends of the cracks to stop them and don't have to drill all the way through. Have repaired cracks in blocks and heads that way on irrigation engines on the stand with JB weld or nickel rod no preheat and both ways they ran for years like that. If you can preheat the area some but if only a small crack it shouldn't take much just lay 3/4 to 1" of rod let cool and peen then weld more till done.

http://jbweld.net/products/uses.php

Other way besides welding is lock n stick

http://www.locknstitch.com/castironwelding.htm

By sparkin (*)

Date 07-24-2011 00:43

Thanks for all the advise guys. I fixed an old Massey with a hole in the block a few years ago by riveting a piece of thin sheet on the inside of the block then filling the hole with JB weld. It worked, but it was an old Contentental motor and this one is priced like it is made from gold. Thanks for the remider to peen it, I completely forgot about that step as I haven't fooled with any cast in years. I just may use a combination of weld and sealer to make sure it takes. Maybe a little pepper in the radiator for good measure too. I'll let you know how it goes. Thanks again.

By mcostello (**)

Date 07-24-2011 02:41

I am surprised that no one suggested horse poo with Oats in them, old timey recipe or a joke on newby's can't tell from here, never used it......yet!

By Johnny Walker (***)

Date 07-24-2011 03:19

Rays cracked head service just up the road from columbus, indiana he can weld any thing

By Bob Garner (***)

Date 07-25-2011 16:12

The horse poo and oats are used to seal the interlock joints on sheet pile walls. We used it on the cofferdams for the new Dumbarton Bridge in CA.

By DaveBoyer (*****)

Date 07-26-2011 02:53

Horse poo WAS oats, just been through the horse, thats all :grin:

By Cumminsguy71 (*****)

Date 07-24-2011 09:46

I repaired an exhaust manifold not long ago. Drove car to my house, welded crack after shutting off, started the engine, repaired the a/c and then drove back to ladies house. Used plain ol' er70-s, figure it had lots of time to cool slowly. Maybe you could get the engine up to operating temp before the repair but with a crack I'm sure you'll want to stop the cracke, i.e, drilled holes. Good luck with the repair.