G Head Observation
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=205238
Printed Date: 12 Mar 2025 at 6:03am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: G Head Observation
Posted By: ibleedorange
Subject: G Head Observation
Date Posted: 02 Feb 2025 at 1:48pm
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What do you think caused all the pock marks on the head? The piston looks good, but I'm sure they are not the originals. Only on 1 cylinder. Also found a little piece of 5/16" bolt with a offset hole in it lodged in one of the cooling ports. Most likely from an easy out, but what was it doing in there?   ------------- Tractors; If it runs, use it. Motorcycles: Ride em like today is your last day. |
Replies:
Posted By: RedHeeler79
Date Posted: 02 Feb 2025 at 2:27pm
| Looks like that cylinder had water or coolant leaking into it, and sat that way for quite a while at some point in it’s long life. |
Posted By: ekjdm14
Date Posted: 02 Feb 2025 at 3:37pm
| Agreed, looks like corrosion damage from water. What piques my interest though is the "tree rings" pattern barely visible on that part of the head. How high up do the pistons sit in a G? Wouldn't imagine the compression ratio was that high that it'd be a corroded impression of a piston sitting at TDC for years, so I'm wondering if it let a rod loose one time and the piston kissed the head? |
Posted By: RedHeeler79
Date Posted: 02 Feb 2025 at 4:02pm
| The tree rings you’re seeing are marks from the cutter head on the surfacing machine at the machine shop. They used to leave a slight texture for gasket sealing, but with the newer MLS style gaskets they usually leave a more smooth, almost mirror like finish. —-on closer inspection, i see what you’re talking about, and it’s probably the area where the fire ring sealed against the head—- see that it follows around the combustion chamber |
Posted By: JoeM(GA)
Date Posted: 02 Feb 2025 at 6:06pm
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5/16 bolt piece was from a manifold stud into the water jacket someone was trying to get out ------------- Allis Express North Georgia 41 WC,48 UC Cane,7-G's, Ford 345C TLB |
Posted By: ekjdm14
Date Posted: 03 Feb 2025 at 7:12am
What I'm seeing is all through the pitted part of the head, not in line with the machining marks but perfectly concentric with where the bore would be & going all the way in to the center. That's why I thought maybe residue from a piston kissing it as the marks look just like the machine marks you see on the crown of a piston. Like I say, barely visible but just in the area where the piston could've touched. You can see it better in the close up shot, easily missed on the first photo.
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RedHeeler79 wrote:Posted By: RedHeeler79
Date Posted: 03 Feb 2025 at 12:26pm
| I see that now… it does look like the machine marks in a piston crown of a flat-top piston. Your theory may be right. I’m assuming a G engine is not a power crater piston since the combustion chamber is in the cyl head. Never taken one apart. Perhaps ever so slight contact? |