450C Leaking head or head gasket?

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nelstomlinson
430 crawler
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Location: Delta Junction, Alaska

450C Leaking head or head gasket?

Post by nelstomlinson » Tue Nov 27, 2018 4:41 pm

I have finally started putting my 450C loader engine back together. I put in new cylinders, with new orings and packings. I got the head bolted on with a new gasket, put the cooling system back together and started to pressure test it. When I pump up the pressure in the radiator there is a loud hissing from the back end of the head. When I stick fingers into the back pair of push rod holes the sound is muffled, so the leak must be somewhere in the block, at the back.

I ran out of time and energy, and haven't taken the head back off yet. Any thoughts on what I should look for when I get it off?

dtoots1
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Re: 450C Leaking head or head gasket?

Post by dtoots1 » Tue Nov 27, 2018 5:21 pm

did you use the copper head gasket spray sealer?

Jim B
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Re: 450C Leaking head or head gasket?

Post by Jim B » Tue Nov 27, 2018 5:55 pm

Did you check the protrusion of the new cylinder liners? If one is setting too high for some reason it might prevent the gasket from sealing properly. Did you have the head checked while it was off? Are the two alignment dowels in the block? Did you chase the threads of the head bolt holes in the block and clean them out good. I've seen bolts come up on torque and not be providing the right clamping force, because of bad threads or dirt in the holes. Just a few thoughts.

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gregjo1948
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Re: 450C Leaking head or head gasket?

Post by gregjo1948 » Fri Nov 30, 2018 5:20 am

Could it be a crack in the block between the cylinders?
JD 350B diesel 6way blade, Case 580B Loader/backhoe, Farmall 504 high crop w/ flail boom mower, International 404 , International 284 diesel w/belly mower, 1972 Ford F600 dump truck, Galion 3-5 roller, Allis Chalmers D17, 1620 Ford

nelstomlinson
430 crawler
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Joined: Wed May 29, 2013 11:03 am
Location: Delta Junction, Alaska

Re: 450C Leaking head or head gasket?

Post by nelstomlinson » Thu Dec 27, 2018 1:53 pm

Sorry about disappearing immediately after I posted that question. Got busy at work and at home. Thanks for all the replies.

Yes, I did use the copper spray on the head gasket. I was able to get the head back off last weekend and there was a nice, even pattern of copper on the top of the block and on the bottom of the head, so I think it did seat well.

I checked the cylinder liner protrusion with a feeler gauge before I torqued the head down. It was in spec.
The alignment dowels are in the block.

I did NOT chase the threads in the bolt holes in the block. Oops. I'll do that. Some of the bolts were seriously crudded up, so that is a real possibility.

If that doesn't solve the issue, I'll take the head up to Fairbanks to be magnafluxed on my next trip up there.

nelstomlinson
430 crawler
430 crawler
Posts: 60
Joined: Wed May 29, 2013 11:03 am
Location: Delta Junction, Alaska

Re: 450C Leaking head or head gasket?

Post by nelstomlinson » Fri May 29, 2020 1:58 pm

After delaying way too long, I took the head to a machine shop in Fairbanks and learned that it was not cracked, but was warped. The shop milled it flat, ground the valves, and I reassembled the engine. It is staying sealed and runs fine. I've put a couple of hours on the rebuild and all is well so far!

Now I need to adjust the clutch and replace the right steering brake, since it only turns left.

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