2LT head cracked, sleeved, can this work? (1 Viewer)

[Fantom]

Got confirmation, head is dead. It's done. Never mind. Unless someone has an older style 2LT head I can use.




was going to post this up on Toyotadiesel.com but keep having issues posting pics there.
I gutted the 2LT I acquired and as mentioned earlier I found cracks in the block from a rebuild gone bad. I now have the head off and I found cracks in the usual spots but it clearly looks like it's been sleeved. The head has been rebuilt, it's stamped SA HEADS on the back, the valve seats on the exhaust are clearly inserts (little punch marks on the sides). The intake ones are slightly raised and not the factory cut ins into the head. Now I have no clue if the cracks happened before or after sleeving.
They seem to stop at the sleeve and not continue further up the walls.
Are there any chambers there, between the intake an exhaust ports? Or just a solid wall?
There doesn't look like there is enough thickness to actually have anything there. If that's the case, and it passes a pressure test, this should be fine, or not?

 

[raboyto2]

It doesnt matter that the crack cant continue into the valve seat. The damage is done. Bellow the crack is a coolant passage. Here is a cross section of the cylinder head to get an idea :

What I do find interesting is that all 4 are cracked but there is no visible pitting in any of the cylinders. From every picture I've seen, it looks like the crack 4,3,2,1 and you can see the pitting progress slowly depending on how long the crack has been there.

 

[Fantom]

Well the engine was rebuilt not long ago, and as far as I know the head did not blow. I drove it, it drove well and had no issues. It did not blow white or pressurize the coolant. The only reason why I found this and had the head off was because the block was damaged and had cracks from a bad rebuild.
As far as I know, it might not have penetrated.
I thought about tig welding the area between the ports if I can't sell the parts, bolt it all together and see how long it lasts.
Thanks for the photo, good insight there. So the little indent on the bottom of the photo, with the crack, is the same area? seems to be leading into an idiotically placed chamber almost intended to fail by design. I'm surprised since there is actually very little room between the 2 chambers.
If I sell everything and don't tig weld it for the fun, I'll set it up on the bandsaw and cut through mine, just to study it deeper.

 

[lostmarbles]

Thanks for posting this pic Raboyto2. (Someone's obviously gone to a lot of trouble to show the extent of the crack and grinding alloy is a pain in the butt because it tends to clog the cutting wheels .)



Is this a 2LT head too?

I'm more used to seeing cast iron heads on B-series and H-series engines.

But I'm pretty sure the crack in your pic is in the same "between-the-valve-seats location" as Fantom's.

Interesting.

Would you have a photo of the same head showing the same crack while the head was still in one piece?

 

[Fantom]

So I just finished talking to some of my contacts, and there are old school guys that know how to fix this to better than what it was. They would heat the entire head, evenly in an oven, to 800F, then oxy weld/braze with a cast steel filler. They would even guarantee the work. Only problem is finding anyone who can still do this.

 

[Wheelingnoob]

So I just finished talking to some of my contacts, and there are old school guys that know how to fix this to better than what it was. They would heat the entire head, evenly in an oven, to 800F, then oxy weld/braze with a cast steel filler. They would even guarantee the work. Only problem is finding anyone who can still do this.

I have heard of this and seen it done, the guy I use to know that did it passed away about 5 years ago. I would try contacting machine shops and see if they know of anyone. The old guy I saw do it was a black smith by trade.

 

[gerg]

Something like this, although its a tad hotter than 800f me thinks.

 

[Fantom]

Yes, something along those lines. I contacted Heads Unlimited here in BC, they said they could do it but recommended I just get another head because the repair has also failed on these. What does that tell you about this stupidly designed head.
They didn't even bother quoting me for the repair.
There is supposedly another place in the Vancouver area that deals with industrial engines that might be able to do it but at this point is pretty clear it isn't worth the hassle.

 

[BC40]

Not concerned with the steel valve seats and precups getting loose from shrinking the weld area?

 

[Fantom]

No, because the entire head is heated evenly to such a high temperature that the "welded" area would be basically the same. That's also the reason why in most cases you wouldn't have to worry about it cracking beside the weld, bonding with the surface or annealing it.

 

[Wheelingnoob]

Not concerned with the steel valve seats and precups getting loose from shrinking the weld area?

The guy I saw do it removed the valve seats before it was done. He got it glowing like the picture Gerg posted, welded it then cooled it over about 14 hours...very slowly. After it was cooled he then machined the welded area and inserted new valve seats.

 

[Wheelingnoob]

No, because the entire head is heated evenly to such a high temperature that the "welded" area would be basically the same. That's also the reason why in most cases you wouldn't have to worry about it cracking beside the weld, bonding with the surface or annealing it.

Well that would save a bunch of time. The old timer I saw do it seemed to always remove them, not sure why I never questioned him he seemed to know his stuff.

 

[gerg]

OK so die grind the crack open a bit, get some stainless wire for your mig and wrap a bbq in alum foil and crank the heat. Chuck that baby in there and get it red and lay down some weld in there. I got my bbq above 1100F once. I bet I could do it again. Now that would be fun I tells ya.
g

 

[Fantom]

OK so die grind the crack open a bit, get some stainless wire for your mig and wrap a bbq in alum foil and crank the heat. Chuck that baby in there and get it red and lay down some weld in there. I got my bbq above 1100F once. I bet I could do it again. Now that would be fun I tells ya.
g

Yes, that might work but you can't use stainless wire because stainless won't expand and contract at the same rate as cast iron. It will just crack on the side of the weld then.Your better bet would be a nickel steel filler or something closer to the cast composition. I wouldn't mig it, tig or oxy, like the old school guys, but essentially it could be tried.