Piston scoring D-21/210/220/7030 engines
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=209128
Printed Date: 15 Jan 2026 at 11:52am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Piston scoring D-21/210/220/7030 engines
Posted By: DrAllis
Subject: Piston scoring D-21/210/220/7030 engines
Date Posted: 27 Nov 2025 at 9:09pm
| Trying to finish up this customers knocking 220 engine. I've experienced this problem for I'd say 30 years off and on. It's always the engines that don't have piston cooling spraying oil from underneath to keep piston temps down that seem to do this. Replacement pistons and sleeves are parts that work fine in 7040's and bigger because they do have piston cooling, but the newer design piston/sleeves do not like being used in the old non-piston cooled engines. Unfortunately, the old piston/sleeve parts have been discontinued for a very looong time. All you can purchase now is the newer designed tighter fitting parts. The older engines used to spec piston skirt to cylinder sleeve clearance at .007". All the newer piston/sleeve kits are .003". Sometimes they work for years and then, just like this engine, you've got a mess to deal with. I've got a jig made to take my sleeves to a favorite machine shop and have (new or old) sleeves power honed out an extra .004" to alleviate this problem. It's an unfortunate event with no warning whatsoever. My advice is if you are overhauling one of these older non-piston cooled engines, you'd better loosen it up a little or you might get to do it again someday down the road. Pictures on the way. |
Replies:
Posted By: Calvin Schmidt
Date Posted: 28 Nov 2025 at 4:40pm
|
Thanks DR. I've heard of this before. Had this happen about 20 years ago while breaking in a fresh rebuilt D21 engine on the dyno at a moderate load. ------------- Nothing is impossible if it is properly financed |
Posted By: coggonobrien
Date Posted: 28 Nov 2025 at 8:07pm
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Posted By: DrAllis
Date Posted: 28 Nov 2025 at 11:39pm
| I got the 220 engine fired up today and it sounds fine, but was only ran for a couple of minutes as it was supper time. This engine has the later model crankshaft driven oil pump and deeper oil pan on it. The oil capacity should be 21 quarts. This tractor has passed thru how many owners and technicians over the years ?? Who knows ?? Anyway, there isn't a serial number tag on the engine block, so I'll have to try and determine by the chassis s/n if it had this newer oil pump or not from the factory. I did notice that the engine oil level dipstick had been modified by someone in the past. It has been made longer, which would cause you to NOT fill the engine to 21 quarts capacity. I think it's about an inch too long, so we've probably been maybe 2 gallons LOW on oil all these years?? So, I will be changing that for sure. It also (at some point) had new slotted -.010" rod bearing shells installed and they did not get the connecting rods turned around as was required with that change to updated parts. So, now that has been corrected. It now has the newest "ARP" brand connecting rod bolts installed and torqued to 85 ft lbs. All six new wrist pin bushings were needed as they should have been replaced when the engine was OH'd before sometime in its past. One more thing to be extremely careful of when installing sleeves in these engines. Obviously, you want to clean the block very well and dry fit the new sleeves without the Orings on them. They should go in easily and be able to rotate when installed fully in the block. Remove the sleeves, roll on the new Orings (two black on the top two grooves and orange in the bottom groove) and then with a pocket screwdriver go around each one to be sure nothing is rolled/twisted. Now, the next important part: wipe Mazola cooking oil lightly on each Oring with your finger. Also wipe the inside of the lower block bore too. Nothing excessive !! just a light coat on the rubber and in the block bore. Shove the sleeves in and bolt them down. Excessive lube between those Orings can cause things to squeeze the sleeve and when you've only got .003" skirt clearance, you cannot afford to have that happen. Maybe the snow storm won't be so bad tonite and I can get the front axle under it and get in a hr or so of run time tomorrow. We'll see !! |
Posted By: SteveM C/IL
Date Posted: 29 Nov 2025 at 12:08am
| I'm sure it wouldn't help if it was turned up some. Show me one that isn't. Mine got the mains jetted at OH with M&W's and turned to 170hp in early 2000's. Has around 1500hrs on it. So far so good. It's retired to batwing duty now. |
Posted By: DrAllis
Date Posted: 29 Nov 2025 at 12:47am
| I've thought of a couple of other things too that could contribute to this problem : A muffler versus a straight pipe. A straight pipe might be enough of a benefit (100 degrees pyro temp cooler ) to offset altering HP upwards a bit. The fan belts on the D-21/210/220 were those da** shoestring width sized belts that had to be kept very tight or there was a reduction in fan/water pump speed at full throttle, especially when the tin pulley on the fan got worn. It makes sense that 180 degree coolant temps would have to be better than running right on the edge of the red when it comes to piston skirt diameters. Lastly, your M & W's probably are a little looser fit than .003". For sure there's less blow-by with their top ring design and that would make for a cooler piston too, wouldn't ya think ?? |
Posted By: Mikez
Date Posted: 29 Nov 2025 at 7:34am
| This should be put in knowledge section |
Posted By: Lynn Marshall
Date Posted: 29 Nov 2025 at 10:32am
| Do you think that the scoring starts around the o-ring area? Our shop worked on an early 7030 one time that would score the pistons on a break in pull on the dyno. I didn't personally work on it and I remember that it was turned up to 180 horsepower. I think that it did that twice before we talked to someone higher up and they suggested removing the top o-ring on the sleeve. My memory fades, but I think that fixed it. Question, were the 426 engines always a three o-ring design or did the early ones just use two on the sleeves? |
Posted By: Michael V (NM)
Date Posted: 29 Nov 2025 at 11:14am
|
I'm for sure following this thread, because I have a 220 that needs a complete rebuild. needs an injection pump rebuild also,,planning on turning it +12-15%,, jus for playing mostly,, as long as I have it,, it will never see long days of hard work Hey DR.,, is there a way to get a sleeve/piston/overhaul set from you that has been honed the +.004??
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Posted By: DrAllis
Date Posted: 29 Nov 2025 at 11:24am
| Old original Gen One 426's I know were only two Orings. One black on top and one orange on the bottom just like the 301. You find that out on the first OH. Personally, I've only ever seen three Oring replacement sleeves and I'm sure a 7030 probably was just that. Remember, the 7030 engine developed 12 to 15 more flywheel HP right off the bat compared to a 220 engine, because of chassis/hydraulic loads. I too know of a very early 7030 that went thru two OH's in the first 24 to 36 months of its life due to scored pistons. It had an intercooler installed and turned up a bit. I don't remember if the muffler was on it or not. I didn't work on it either time but was aware of its issues. |
Posted By: DrAllis
Date Posted: 29 Nov 2025 at 11:30am
| That could be done. Or you could get your own kit of choice and just send me six sleeves and one piston and I can have them oversized for you. I'd suggest checking the clearance first to verify they are in that .003" to .0035" range to warrant doing it. My guy charged me $50 bucks each I believe. |
Posted By: DrAllis
Date Posted: 15 Jan 2026 at 8:17am
| Update to this subject: This particular 220 tractor got finished and driven 30 miles home on a nice Saturday (I think) the week after Thanksgiving. All is well at this point. Ten days ago, I had another 220 brought to me with a slight knock in the engine and coolant in the oil. I feel pretty strongly that we have another scored piston scenario with it too. I don't know the history on the tractor or engine, but maybe in a couple of weeks I'll have a chance to get into it to verify my suspicions as to what's actually going on. Finally, on the same subject, last night a friend of mine called me and was telling me of a restored 220 in his neighborhood that has right at 500 hrs on an engine OH that was being used on a forage chopper and now suddenly has coolant in the oil. It has since been parked for some time because of this. The owner thinks that an Oring was cut when a new sleeve was installed. I am wagering, once again, tight skirt pistons and sleeves and maybe some warm operating temps and once again, a scored piston or maybe more than one. In 50 years, I've never seen a cut sleeve O-ring at OH time, as there are three Orings to cut. But I sure have seen scored pistons that fry the sleeve Orings and dump coolant in the oil. I don't know if I'll get that engine to repair or not, but we will see how things go. |
Posted By: SteveM C/IL
Date Posted: 15 Jan 2026 at 9:10am
| The guy who OH'd my 220 warned me to let engine get up to temp before loading it or it could experience "4 corner score". Have no idea what clearance the M&W's were made with. He worked at a Deere dealership in the early days and said they experienced this problem on new 4020's when dynoing them before delivery. Must be something to it..... |
Posted By: DrAllis
Date Posted: 15 Jan 2026 at 9:37am
| I suppose that could be the aluminum piston was growing fatter and faster than the sleeve was until up to full operating temps. |