Ever seen a GPW engine cracked on top of the head?

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
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42cargo
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Ever seen a GPW engine cracked on top of the head?

Post by 42cargo » Tue Apr 17, 2018 4:02 pm

Hi all,

Thought you might find this of interest. I'm familiar with many of the usual places a GPW block cracks, but I don't know that I've seen them break like this around the head bolts and valve seats:

Image

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This engine, which is an early '45, was running when I bought it and I'm thinking it's worth putting back together and see if it runs without any issues. Worst-case scenario is if it fails, I'll have the spare '44 block that's correctly dated for my December '44 GPW bored, stitched, and time-serted to bring it back to life.

Anyone run into this before? Any ideas as to the cause?

Thanks,

John
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Re: Ever seen a GPW engine cracked on top of the head?

Post by artificer » Tue Apr 17, 2018 10:56 pm

Cracks around the head studs are not so common & can be caused by torquing the head studs into the engine block when they are meant to be fitted with sealant & just over finger tight.
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Re: Ever seen a GPW engine cracked on top of the head?

Post by nick peters » Wed Apr 18, 2018 12:22 am

John
Luc's spot on. I 've seen those same cracks on gpw engines a few times myself. Was worried the first time but the Engine ran without any problems. Got to say they were all on engines that had the heads bolted on. Don't recall seeing the cracks on later engines fitted with studs.
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Re: Ever seen a GPW engine cracked on top of the head?

Post by 42cargo » Wed Apr 18, 2018 6:18 am

Thanks for all your input. This bolsters my initial thought of putting it back together and running it. If problems develop at a later date, I'll go over to plan B.

Will post updates on this thread for those who might be interested: http://g503.com/forums/viewtopic.php?f=144&t=295942

Sincerely,

John
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Original F-marked bracket to hold battery in place and one J-bolt
Original F-marked front bumper

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Re: Ever seen a GPW engine cracked on top of the head?

Post by dpcd67 » Wed Apr 18, 2018 8:01 am

Now, when I have that, (common on GPWs as I assume Ford's casting house was taking some shortcuts), I always put thread inserts in the stud holes, and install hardened seats in the valve seats. Maybe not necessary but then I know nothing bad will ever happen to it. It's in the machine shop anyway.
Last one I did needed valve seats anyway as they had been ground too much.
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Re: Ever seen a GPW engine cracked on top of the head?

Post by OldPappy » Wed Apr 18, 2018 9:43 am

Maybe a bit off topic, but the mention above of bolts being used rather than studs answers a question I had about the engine I bought a few weeks ago. It is a WW2 engine, with head bolts rather than studs, and I was wondering whether that was original. Maybe, maybe not?

All of the other Jeeps I have owned have been post war, so the bolts struck me as odd.
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Re: Ever seen a GPW engine cracked on top of the head?

Post by 42cargo » Wed Apr 18, 2018 10:06 am

What’s the date on your block? GPWs transitioned from bolts to studs in Nov/Dec ‘44 as best I know.
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Re: Ever seen a GPW engine cracked on top of the head?

Post by harve » Thu Apr 19, 2018 4:37 am

Overheating the engine over the years will also cause those cracks. you’ll be fine after rebuild

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Re: Ever seen a GPW engine cracked on top of the head?

Post by harve » Thu Apr 19, 2018 4:39 am

Put a bad ass Copper Head gasket on it , you’ll be good to go

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Re: Ever seen a GPW engine cracked on top of the head?

Post by Ben Dover » Thu Apr 19, 2018 5:26 am

Depends on how many used Jeep engine blocks one has inspected. These cracks are quite common, especially on Jeep engines that have been driven while overheated.
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