The 4200 uses torque to yield head bolts and they can snap off in the block.

I'll detail how I have removed them with NO breakage.

Once you have all the other parts off to get at the big head bolts:

1) using a 1/2" breaker bar/10mm hex bit - loosen each bolt until the first TICK this is like 1/16 of a rotation - stop.
If the bolt will not budge - don't force it.

2) using a piece of 1" steel round bar as a punch and a 5 pound hammer - smack each bolt head 2-3 times.

3) using a 1/2" breaker bar/10mm hex bit - try to loosen the bolt - usually it will only turn a tiny bit more.

4) repeat step 2

5) repeat steps 3 & 4 about 3 times.

6) 1 at a time try undoing the bolt - some will come loose other will need more smacks.

Once you have a full turn on the bolt it should come out.

Main thing is to 'feel" what the bolt is doing - just don't yank on it. Some bolts will need to be run back near tight and then loosened off.

Patience pays off here.

Excellent post. I use the same method in the machine shop with clamp down studs and nuts. Some times you get some fine shavings in the threads, and when they start to bind up I give the nut a good rap. Adds just the right amount of clearance between the thread faces to finish removal.

Sometimes I wonder if the underlying engineering on these 21st century power plants even included tear-down/rebuild considerations. Under warranty a failed engine is swapped in the service bay with a replacement from a crate. The failed unit 'may' be disassembled for root-cause analysis of failure - but never rebuilt . . .

I totally agree with Stock 49. My father told me that in the 30s-40s that engine overhauls were common 35-45 thousand miles wasn’t unusual. Now it doesn’t happen much at all. When I started working on semi trucks in 1979 engines were overhauled at 500,000 miles max. That was with a set of bearings rolled in at 250k. When I retired in 2016 engines went over 1,000,000 miles with nothing but a couple of water pumps and maybe a injector or 2. Most big trucks are like cars now, by the time the engine is junk, the rest of the truck is too. Jay

Considering that the 4200 uses replaceable dry sleeves the short block can be rebuilt many times with minimal machining.

Not arguing the ultimate serviceability of the platform here.

It just seems that the design engineers didn't give much (if any) thought to disassembly - given the finesse/patience required to coax the head bolts out . . .

They were more concerned with getting equal clamp load on the head bolt to prevent warranty head gasket issues.

By the way the stock head gasket is a MLS like a cometic.

I broke a bunch on my rebuild. Tried the whacking and impact hammer method...no success; although admittedly did not do it to the level of detail above. Just cranked them out after no success; ended up with 7 broken.

Irwin left hand drill bits took them right out. No ez outs needed.
amazon # 30520.

They came out so easy if I was to do it again I would just crank them out right from the beginning.

Just an added data point for all.