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4BD1T: Cracked Head--Where Do I Go From Here?

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11K views 30 replies 10 participants last post by  duffontap  
#1 ·
Hello everyone,

Know a few of you guys from over on IH8MUD, but it's my first time posting here.

I've been working on a '90 NPR 4BD1T that I hope to swap into my '77 FJ40; I've been focusing on the bottom end, but just started working on the head and now that it's shiny clean I can see it's cracked. :crybaby: The guy I bought it from sold it as a builder and the price made it worth the gamble. (The PO uses a newer NPR in his construction business and told me that cracked heads were common, but we both looked this head over closely and didn't see anything wrong.)

By now, the bottom end has been gone through and ready to reassemble, and I have other projects (I'm going to rebuild the injectors next) but this cracked head really throws a wrench in it. What are the chances that I will find a good head at a reasonable price? It seems more likely that I'll just have to buy another builder engine, and would be better off using the parts that had worn together--so I'm really reluctant to proceed with my bottom end rebuild, installing expensive new parts when I don't know if I'll be able to replace the head.

How would you proceed? JD
 
#2 ·
Where is the head cracked at? You could always try the unthinkable and buy a 4bd2 head(new ones are common now), injectors and convert it to a 4bd2t. People say the the parts will interchange from the 2 to a 1 and I couldn't see why it won't go the other way. Honestly I'd keep my eyes out for a replacement head or look into repairing yours if possible.

Matt
 
#7 ·
Thanks Erik! I might need that number.

I'm going to get a quote on a head from Isuzu so I can rule out that option.

Matt suggested "the unthinkable." A brand new head for $300ish is tempting, but I would also need injectors, and then the new pistons I have wouldn't work. I think I'm going to stick with the 1T for my application.

Would anyone be willing to try talking me into to getting some nickle welding rods and attempt to repair this one?? I'm usually up for a Hail Mary if it isn't too expensive.

Appreciate the support, gentlemen. Attached is a pic of the rig I'm building this for. Cheers, JD
 

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#11 ·
Thanks guys,

I've got a quote from the dealership: a bare head casting from Isuzu is $1,5xx.xx (I stopped listening after the 'fifteen hundred').

Waiting to hear back from Rudy.

Should mention that this 3rd cylinder piston was toast, and one of the valve stem guides was snapped off--I did not find the remains when I removed the valve.

Holy cripes that's a good one!
Whoa!

Never seen one crack there. :eek:
You may be wondering how I missed it? In my defense, it's a lot easier to see in a closeup pic with flash! I also didn't expect to see a crack on top so I probably didn't inspect the top as closely as I should have.
 
#9 ·
I would not be swapping from a 1T to 2T its kind of a step backwards, there are cheap 2T heads all over because they ALL crack. Cracks on the 1T are very uncommon especially in the spot yours is. Should be no issue rebuilding the good bottom end you have and using a different 1T head.

Also a swap from a 1T to 2T is not as simple as heads and injectors, there is injector lines, pump, pistons, intake manifold. So its not a cheap process unless you get a whole engine and at that point you are better off getting a 1T re builder engine.
 
#12 ·
If that was my engine I'd probably part it out (the IP alone will fetch a nice price) and just look for another runner. They can still be found for $1000 or less if you're patient.

That is unless you can source a good head for under $500.
 
#13 ·
#20 ·
My 1T was cracked on the #3 cylinder also, but in between the valve seats in the combustion chamber. Just a warning on the new Chinese 1T heads. The one I got from Rudy was not drilled for glowplugs. I don't know if it was a bad batch from the importer or not. Since I live in a colder climate I swapped it for a good used head that Rudy had. When I was looking for a replacement I discovered that used 1T heads are kind of hard to find.
 
#21 ·
Good to know, helix.

No word back from Rudy yet. I actually sent him an unrelated email last week and haven't heard back from that either; several phone calls during business hours went to voicemail, too. Perhaps they're swamped.

Not sure the Hail-Mary-weld-the-crack is a viable option, now. After a very careful inspection, it appears that the crack extends across the top, ends on one side of a freeze plug, starts back up on the other side and runs out somewhere between the push rod passages.
 
#25 ·
I've had good luck with Busbey's truck parts back east. I've had to buy some good used parts like cam and brackets and such and always got good parts at decent prices from them.

Don
 
#27 ·
Any reason why a 4BD1T out of a Link-Belt excavator wouldn't work? I'm in contact with a guy who will only sell the engine whole, but the price is within my budget. It's partly torn down and needs a rebuild but the seller says the head is good. Are there any relevant differences between the NPR version and the excavator version of the 4BD1T?