WD Engine Overhaul Kits
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=13932
Printed Date: 31 Oct 2025 at 3:39am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: WD Engine Overhaul Kits
Posted By: Osage_Orange
Subject: WD Engine Overhaul Kits
Date Posted: 15 Jun 2010 at 7:55pm
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I notice a couple of things about these kits: 1) Most go from 4" bore to 4-1/8" bore. Why? 2) Most include new pistons. Why not just use new liners same size as originals and re-use standard size pistons. Should save $.------------- Why is there never time to do it right the first time, but always time to go back and fix it? |
Replies:
Posted By: DrAllis
Date Posted: 15 Jun 2010 at 8:08pm
| Most pistons are worn out in the ring grooves.....too much up and down slop for the rings. |
Posted By: powertech84
Date Posted: 15 Jun 2010 at 8:10pm
| no replacement for displacement |
Posted By: mlpankey
Date Posted: 15 Jun 2010 at 8:24pm
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Also to add to dr. allis statements is after pistons have had several hours of run time on them they usually measure smaller than original so unless the sleeves are undersized to be bored and honed to the piston size your ring seal with just new drop in sleeves will suffer due to the sleeve wall to piston skirt increased clearance or piston slap. As power tech wrote also no replacement for displacement and more power is made from bore size than stroke because increased piston displacement increases airflow ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Dave(inMA)
Date Posted: 15 Jun 2010 at 9:24pm
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I'm confused about the piston shrinkage point. Won't this happen with new pistons as well? So after a few hours of run time the new pistons have shrunk, just like the old pistons already have shrunk? Or maybe it's too late in the evening!!!! ------------- WC, CA, D14, WD45 |
Posted By: mlpankey
Date Posted: 16 Jun 2010 at 1:30pm
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Are you thinking the old pistons shrinkage stops after first rebuild? once the material has been removed from the sleeve for a clearance on a new piston then it cant be added back for the shrinkage of old pistons and they are no guarantees 4 old pistons shrank the same amount. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Dave(inMA)
Date Posted: 16 Jun 2010 at 1:37pm
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ml, I'm trying to understand the notion of used pistons shrinking every time you put in new sleeves. Do they? If I put several sets of new sleeves into a block, would the original pistons shrink with each new sleeve install until they wouldn't function at all? Not saying that the pistons don't shrink - looking to get educated. ------------- WC, CA, D14, WD45 |
Posted By: Matt MN
Date Posted: 16 Jun 2010 at 2:16pm
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I would be thinking that the piston would wear the same as the sleeve they are both getting used the same amount. They are replaced as an assembly for that reason. ------------- Unless your are the lead horse the scenery never changes!! |
Posted By: mlpankey
Date Posted: 16 Jun 2010 at 4:56pm
All the new forged pistons I have measure dead on what they suppose to 4.125 ,4.310 ,4.625 after the pistons were run the arias 4.125 and the ross 4 .625 pistons both loss .010 . So if the sleeve is exactly 4.125 you allready have .010 skirt clearance but if the sleeve manufacturer had the sleeve honed with .010 thousandths four a true 4.125 sized piston then now you have .020. clearan ce. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Brian Jasper co. Ia
Date Posted: 16 Jun 2010 at 7:50pm
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.010 seems like a lot of wear. How many hours are you running to get that kind of wear? Makes me curious to see what the used pistons from my D262 compare to the new ones and what the new dimensions are supposed to be. ------------- "Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford |
Posted By: mlpankey
Date Posted: 16 Jun 2010 at 8:00pm
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about 5 seasons of tractor pulling. no wear marks or scoring .its just shrinkage kinda like men's do with 50 years or so of age. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Dave(inMA)
Date Posted: 16 Jun 2010 at 8:31pm
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ml, if you installed a set of used 4.115 (4.125 new less .010 shrinkage) in a new set of sleeves, would the pistons wear again by .010 to 4.005? What's causing them to wear - don't the rings make the contact with the sleeve wall? Thanks for your help! ------------- WC, CA, D14, WD45 |
Posted By: mlpankey
Date Posted: 16 Jun 2010 at 9:05pm
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Its not wear . Aluminum like anything else made up of molecules expands when heated and contracts when cooled. Like all metals it doesn't always go back to what it measured at 70 or 100 degrees when it goes through its 1200 or above cylinder temp back to ambient temperature cycle or cycles ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Dave(inMA)
Date Posted: 16 Jun 2010 at 9:18pm
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Thanks for the explanation. The graph of shrinkage vs cool/heat/cool cycles must drop off rapidly, else pistons would eventually shrink to nothing. ------------- WC, CA, D14, WD45 |
Posted By: mlpankey
Date Posted: 16 Jun 2010 at 9:33pm
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It does and they are some wear also that factors in I didn't mean to sound if wear has no effect. Realize also that forge pistons run more clearance cause manufacturers know the expansion rate. That's why some individuals don't like forged pistons because you can hear them slap in a engine especially if it has a quiet exhaust system. The best build is to number the piston to each hole bore each hole to the measurement of its assigned piston and hone to manufacturers clearance recommendations for the piston. ------------- people if they don't already know it you can't tell them. quote yogi berra |
Posted By: Brian Jasper co. Ia
Date Posted: 16 Jun 2010 at 10:26pm
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I understand what you're saying now. I'll bet the same pistons used in an engine that was only being worked at stock power demands probably wouldn't shrink near as much. ------------- "Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford |
Posted By: Dave(inMA)
Date Posted: 17 Jun 2010 at 6:17am
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Thanks, ml. Probably not too much an issue on my tractors that only get recreational use! ------------- WC, CA, D14, WD45 |
Posted By: mlpankey
Date Posted: 17 Jun 2010 at 7:06am
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Brian report back with what your findings are on the D17d old piston skirt measurements to the new piston . I know cast pistons dont require as much clearance as forged but it would be of interest to me to know the variation. Also I would like to leave this subject with this thought. I am in the parts buisness I have 5.00 a hour with commision on sales order takers not really but play along with the thoughts. I sell a particular brand of piston /sleeve combo .I know the piston manufactorer recommended clearance and the sleeves are bored and finished honed to that clearance. Now you call just wanting to buy the sleeves my order taker needs to buy her child some school clothes. She ships four sleeves that has excessive clearance to you due to you using a different and maybe worn or shranked used pistons. Which will greatly reduce the time between rebuild to next tear down. ------------- people if they don't already know it you can't tell them. quote yogi berra |