426 /301
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=199538
Printed Date: 24 Sep 2024 at 3:23am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 426 /301
Posted By: JPG AUSTRALIA
Subject: 426 /301
Date Posted: 29 Jan 2024 at 6:53am
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Question for the gurus , the 301 motors nearly always need rebuilding because of liner cavitation/electrolysis ,how often do the 426 get cavitation/liner pitting water in pan problems.? I haven’t seen as many allis motors as some, but out of all my time fixing stuff i have only come accross 426 motors with conrod out of the block as there main issue.
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Replies:
Posted By: DrAllis
Date Posted: 29 Jan 2024 at 9:14am
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When either engine has a coolant filter (that is maintained) or the correct "pink" heavy-duty diesel coolant, neither have a problem. 301's are MORE likely to have issues with only two sleeve Orings. I have never seen a 426 do it, but have been told they can, again due to poor maintenance.
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Posted By: JPG AUSTRALIA
Date Posted: 29 Jan 2024 at 5:24pm
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Thanks doc, i have never come across a 426 with a liner pitting problem ,interesting that you havent either. Have Seen the 516 motors pitted badly . I only use fleetgaurd DCA4 coolant,and have done for over 20 years,does a good job.
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Posted By: Acguywill
Date Posted: 29 Jan 2024 at 7:41pm
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What is it that causes the pitting? Is it time, the cycle of heating and cooling or something else? I have engines with 20 year old coolant in them but they are not used very much maybe 50 hours a year. They do have filters and I replace them occasionally but really don't know what is happening inside the engine. I remember rusty looking antifreeze in engines when I was a kid but never see that now even with it being 20 years old.
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Posted By: tbran
Date Posted: 29 Jan 2024 at 8:20pm
Cavitational erosion or electrolysis is the general term. Wet sleeve engines suffer from sleeve vibration at the bottom. The vibration causes tiny 'bubbles' or cavitation that contact the sleeves or originate from the sleeves. Now pistons/rings move up and down at high speeds and cause and slight electric charge. As the air pockets contact the sleeve there is a micro 'lightning strike' as each air gap leaves or contacts the sleeve. This moves molecules of metal from the surface of the sleeve - thus the 'pitting'. Keeping the coolant at a PH of 7 will make H2O a non conductor and mostly eliminate the issue of electrolysis. Cavitation erosion will still occur but takes longer in this environment.. The SISU or Agco Engine has a sleeve mid mount point that virtually eliminates the sleeve vibration and exponentially reduces electrolysis. I have listened to and read theories for decades and on this issue - this is our take - some say the electrical part is false - to which I ask then why does the pitting only take place where the sleeves are closest between the liners and less on the outside ends? . I have noticed the higher the HP and RPM the faster the pitting occurs. as in 7020's and 7080's.
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When told "it's not the money,it's the principle", remember, it's always the money..
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Posted By: Oldwrench
Date Posted: 30 Jan 2024 at 7:14pm
So I'm just curious. Is cavitation and pitting not really a problem on lower power, low RPM diesels (think old Cats and such). Is it just more modern larger diesels at higher stress levels?
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Posted By: DrAllis
Date Posted: 30 Jan 2024 at 10:13pm
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Some engines more likely to have trouble than others. Direct injection engines. More injection timing. More HP output per cubic inch. More RPM's. The cooling system is thee most neglected system on any diesel engine. Using the correct type coolant will see to it the problem NEVER arises.
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Posted By: Kevin in WA
Date Posted: 31 Jan 2024 at 9:54am
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The 426 engine has much thicker sleeves which seems to help with the vibration, also the orings have a thicker cross section and seem to compress more when installing, of the engines i have worked on over the years i can only think of one 426 engine that was leaking coolant into the oil, but I have seen dozens of 301's leak, but like Doc says if a 301 has the proper maintenance they are fine.
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Posted By: RedHeeler79
Date Posted: 31 Jan 2024 at 12:20pm
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As Dr Allis pointed out, cooling system maintenance is key. Speaking from experience with Caterpillar, Cummins and Detroit heavy truck engines, the use of red extended life coolant rather than conventional green ethylene glycol, is the single biggest prevention tool against liner pitting and cavitation. Upon tearing down an engine that has used ELC it’s whole life, I have (rarely) seen minor cylinder liner pitting, but never catastrophic damage. With conventional green coolant, a whole other story…. You’ll still have liner (sleeve) seals fail and put water in the basement after years of service sometimes, but again, not as often. Only bad thing is, the red ELC doesn’t seem to make your oil as milky and sludgy when it’s leaking into and mixing with engine oil, so it’s more difficult to spot the problem happening as compared to conventional coolant….
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Posted By: cjarosz
Date Posted: 31 Jan 2024 at 7:11pm
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I’ve been thinking about this for a little bit as well I just had my xt overhauled a couple years ago and they put green back in it and I’m thinking it’s time to change it anyway but if I refill it with the new stuff will what is left in the block hurt to mix? I figured I’d drain radiator and block as best I can but there is always a little left and I know that there are some combinations that will not work any ideas
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Posted By: RedHeeler79
Date Posted: 31 Jan 2024 at 7:26pm
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I personally wouldn’t worry too much about a small amount, but you could flush it once or twice with plain water before refilling. If there is a drain cock or pipe plug in the lower portion of the block and/ or oil cooler, remove it to get the most of the old stuff out first before putting it back in and refilling with new coolant.
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