Cracked cylinder head. Stitching pins and new seats

[Wlhequipment]

Hi folks,
First post here. My name is Pete, I live near Denver CO, and I own a one-man shop where I work on mostly construction machinery. I am posting this to solicit opinions (I know they’re out there). I have a gray market Mitsubishi D1800 tractor with a KE95 engine. The head is cracked. I can get a replacement (rebuilt even) head, at a cost of about a grand. That’s my safety net. I have an old Bridgeport knee mill also. I am planning on attempting a fix on the head. A pic of the crack is my avatar. I can’t tell if the valve seats are pressed in or molded in as part of the casting. Either way, my plan is to cut the seats out, fix the crack with stitching pins, and install new seats. I thought about welding / brazing the crack, but I don’t want to warp or crack the head. I’ve never done this kind of work on a head, so I’m open to suggestions on what tooling / pilot to use etc. Thanks for any input!

 

[gbent]

Rebuilt head for a grand? Buy it.

 

[Garwood]

Not a chance in hell you can fix that without welding. And by welding I mean you bring the whole casting up to plastic temp and TIG weld it with cast iron filler, then you remachine everything. That will cost around $500 in my area.

How much coolant does it consume? If it's tolerable then check the deck and valve seats and run it. There are millions of engines out there running for long productive lives with cracks through the valve seats like that.

Every 6.2/6.5 Chev diesel and every 6.0 Powerstroke has heads cracked like that.

 

[pan60]

i have done and do do a bit of this knd of work.
if it was here i would look for a head or weld it up.

 

[michiganbuck]

an experienced head shop will dowel a crack if they think the crack will not grow to cause further problems. Cracks like to grow if it is an Iron head.
A used head might be found for lower than a grand. A grand for a rebuilt head is not a bad price.
You might take it to a head shop to get a quote--if it is in a problem area they likely won't touch it.

 

[johnc]

I did some time in an automotive machine shop back in the '80s and pinned a few heads. While it worked, what I remember is that after the pins were in place, it took a fair amount of peening with an air hammer to get the head to pass a pressure-test. The area between the seats might be extra tricky to pin as you would have some serious pin overlap.

A quick check online shows that you will probably drop $100-150 for the pins/special tap, not to mention what you will spend on a piloted seat cutter, valve cutting tools, pressure testing rig, etc.

While I applaud your ambition, I would say your chance of success would be fairly slim.

My recommendation would be to buy the rebuilt head or have yours welded. 40 years ago, we used William's Cylinder Head (now Midwest Cylinder Head) in Nevada IA, they did great work then. It might be worth a phone call to see what they would charge. Or maybe there is someone in the Denver area that does similar work.

 

[Garwood]

I looked up your head and it seems it's a rare one with limited support. The one outfit selling rebuilt heads is probably farming that work out. They don't look like a rebuilder, more of a parts seller.

DCW - Diesel Cast Welding | Diesel Cast West

www.dieselcastwelding.com

These guys are near me. They do amazing work and I wouldn't be surprised if they were the ones who repair the cracked heads for the other outfit that sells them. I would give Diesel Cast Welding a call and see what they would charge to weld yours up and get a quote for them doing the whole job.

I've had them weld up hard to find cast iron heads and blocks as well as re-fit lost maincaps and do the main line and deck on a large diesel engine. Their work is top notch. They have a very large capacity machine shop and know their stuff. The welding is very reasonable. Their machinework charges are about double the rate of smaller shops.

 

[john.k]

The small diesels usually crack in the swirl chambers ,with crack involving valve seats.......these are impossible to fix .........ive seen thousands spent on crack repairs for diesel heads that failed in a few hours running...........and yes ,some big engine heads (Carerpillar ,GM) are remanuf on an industrial scale ,the process is way beyond a small (or large) shop.

 

[Wlhequipment]

All good points folks thanks for all the input. There’s a lot of knowledge floating around here, that’s obvious. Thanks I’ve never welded cast iron before because of the pre-heating and slow cooling and high possibility of a crack, etc. I’m reading about a TIG filler rod that melts at a lower temp than normal for cast. They’re saying you can TIG a piece of cast without pre / post heating. Is this a new thing? Is it more like brazing?

 

[michiganbuck]

We had a journeyman blacksmith Bobby Dudah who could weld Cast Iron. He told me that you have to melt it past the crack and then build it back up. He had an old fire blanket and a bucket of ashes for slow cooling different jobs. That guy should have written a book on welding and straightening.

 

[cg285]

i recently picked up some of this rod but have not yet had the opportunity to try it

Home - EZ Weld TIG Wire

ezweldtigwire.com

advertised as preheat not nec

 

[Wlhequipment]

i recently picked up some of this rod but have not yet had the opportunity to try it

Home - EZ Weld TIG Wire

ezweldtigwire.com

advertised as preheat not nec

Yep! That’s the stuff I was looking at.

 

[magneticanomaly]

IMO special rod cannot eliminate the need for preheat, because you are still melting into the cast iron, which needs to cool slowly in order not to self-harden and/or crack.
Preheat also limits warping of the whole casting.

 

[gbent]

There is a big difference between fastening cast iron back together and producing a durable, pressure tight weld in a area where the parent metal failed.

 

[Servicar rider]

I tried the EZ WELD on some exhaust manifolds and it didn't work near as well as the Youtube videos claimed! I've had better luck using soft iron baling wire from the farm store. The EZ weld cracked when it cooled.

 

[GregSY]

I'm sure some cast iron repairs last and work well. But I'm also sure a lot don't. The expense of putting an engine together, and the risk of having to start all over again, dissuades me from repairing cast iron. I know there are some blocks and heads out there that can't be replaced...but I haven't encountered one yet.

 

[Garwood]

All good points folks thanks for all the input. There’s a lot of knowledge floating around here, that’s obvious. Thanks I’ve never welded cast iron before because of the pre-heating and slow cooling and high possibility of a crack, etc. I’m reading about a TIG filler rod that melts at a lower temp than normal for cast. They’re saying you can TIG a piece of cast without pre / post heating. Is this a new thing? Is it more like brazing?

You are really going the wrong direction here. You cannot repair that head. Not possible unless you have tribal knowledge of the process and a huge capital investment in the equipment and skill to use it. There are a select few companies that can repair that head and it will probably last awhile, then crack again.

The question still remains- What was wrong with the head? Why did you pull it? Using coolant? Overpressurized coolant system?

If it was running, the smart option is to patch it together and run it. Throwing money and time at a 30 year old 20HP tractor makes no sense at all.

 

[GregSY]

"Throwing money and time at a 30 year old 20HP tractor makes no sense at all."

I agree...but if the tractor were otherwise in good shape it would be worth fixing (properly). The price of a new 20HP tractor is 'high', and so is the price a good used one.

Plus, the new tractors are sorta garbage in their own right.....computers and emissions controls. A tractor that can be repaired has value; a 2022 tractor 30 years from now will most likely cost far, far more to repair than it's worth.

 

[john.k]

The catch with all the theories is .......a sound casting cracked in use......what chance does a weld repair have of survival...........cracked heads are par for the course with swirl chamber engines due to the steep temperature gradients and resultant high stresses in the casting...........the only swirl chamber head that is durable is the Caterpillar with a screw in chamber .

 

[BT Fabrication]

buy the rebuild, the crack will always come back to bite you later on.