7080 - looking for advice
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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=204806
Printed Date: 29 Jul 2025 at 4:00am
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Topic: 7080 - looking for advice
Posted By: dnel45
Subject: 7080 - looking for advice
Date Posted: 03 Jan 2025 at 7:48pm
Have an 81’ 7080, good shape, 4500 original hours. Never been apart. Starting to think about rod bearings and main bearings. Pull oil samples every year, saying no metals in sample yet. I assume we should pull oil pan as a first step to check? I have little motor experience, anyone have a step by step guide? Is the Shop manual a good reference for rod bearings? Still our main workhorse gets about 120 hours per year.  
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Replies:
Posted By: DrAllis
Date Posted: 03 Jan 2025 at 8:08pm
| If the oil samples are fine, WHY would you want to open it up to do anything ??? The oil sampling is looking at things inside without doing so. |
Posted By: dnel45
Date Posted: 03 Jan 2025 at 8:12pm
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Everyone says 4500-5000 hours max on 7080 rod bearings? Quite a few posts on here saying that. Looking for opinions, I’d rather not open it up. Just wait for oil sample to show some wear? |
Posted By: DrAllis
Date Posted: 03 Jan 2025 at 8:37pm
| If you use the same oil analysis service, they are like your Doctor. They will tell you when something looks questionable. Main and rod bearing life is dependent on how many gallons per hour the engine uses (load), how frequent the oil and filters are changed and the quality of the oil and lastly clean air to breathe. If you've ever been around a poor old N-6 Gleaner with worn out helical bars and the boost gauge always at 20 psi for hrs on end, the rod bearings wear out much faster. |
Posted By: Mikez
Date Posted: 03 Jan 2025 at 8:45pm
| That’s a nice looking tractor you have |
Posted By: dnel45
Date Posted: 03 Jan 2025 at 9:03pm
| Thanks Dr, we are very religious on all filter and oil changes. 100-150 hours max. Annual oil samples and it’s always had A/C or Agco filters and Rotella 15w-40. Will keep an eye on samples for changes. |
Posted By: im4racin
Date Posted: 03 Jan 2025 at 9:07pm
| I would be more concerned about rod bolts and damper condition |
Posted By: dnel45
Date Posted: 03 Jan 2025 at 9:32pm
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Looking up info on the dampers, I’m 90% sure mine is original. I found a thread on here discussing dampers on 8070s and replacing them with a vibratech damper for a 4-71 Detroit. Would this be the same for the 7080? https://www.allischalmers.com/forum/front-crank-dampener-for-a-8070_topic193124_page3.html" rel="nofollow - https://www.allischalmers.com/forum/front-crank-dampener-for-a-8070_topic193124_page3.html |
Posted By: DrAllis
Date Posted: 03 Jan 2025 at 10:28pm
| Yes. |
Posted By: Mikez
Date Posted: 04 Jan 2025 at 12:24am
| I’m curious. 8070 and 7080 have different part numbers. What was different on the originals |
Posted By: DrAllis
Date Posted: 04 Jan 2025 at 5:51am
| Shouldn't be anything different between 7080/7580/8070/4W220/N-5 and 6 /R-5 and 6. Surely from 1974 to 1985 there could have been and probably was a p/n and vender change, but they all interchange. |
Posted By: DrAllis
Date Posted: 04 Jan 2025 at 6:01am
| A true story. I met this man in 1979 when he was about 60 years old. He was meticulous with his fleet of A-C equipment. He had a 68 or 69 series 2 D-21 that had a complete 7040 engine in it. The story goes when the D-21 was about 7 or 8 years old it had 1500 or so hours on it. In his ongoing efforts to be thee best A-C tractor caretaker that ever lived, he had his local mechanic drop the oil pan to "check" the rods and main bearings. The experienced mechanic did what was requested and reused the connecting rod bolts, of which there was an update to a better bolt at that time. The tractor ran about 20 hrs and pitched a rod right out thru the side of the block. So, the moral of the story is this......if there ain't a real good reason to be concerned, why set oneself up for a POSSIBLE failure ??? especially if you aren't skilled at doing such a thing !! If there was a real reason, that's different. |
Posted By: DSeries4
Date Posted: 04 Jan 2025 at 8:50am
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I have to agree with the Dr. If it does not have a problem, why would you open it up? Everything you are doing is keeping it healthy: frequent oil changes, oil analyses, etc. The engine will let you know when it has a problem. If you are only putting on 150 hours per year, you should be good for quite a long time. With little motor experience, I would rather let an experienced mechanic look after it should a problem arise.
------------- '49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '61 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080 |
Posted By: NEVER green
Date Posted: 04 Jan 2025 at 9:38am
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Pulled rods and mains on 8050 at 6800 hrs, looked like new except for few light scratches. The 8050 and 7080 came with bypass filters, makes a world of difference. ------------- 2-8050 1-7080 6080 D-19 modelE & A 7040 R50 |
Posted By: tbran
Date Posted: 04 Jan 2025 at 2:06pm
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Agree with Doc, however IF you ever pull the pan and replace brgs if the count goes up - always use the AGCO rod bolts - they are from ARP - none better. Must follow the instruction sheet for torque procedure.. ------------- When told "it's not the money,it's the principle", remember, it's always the money.. |
Posted By: MrSnerdly
Date Posted: 04 Jan 2025 at 3:08pm
| No advice on the bearings but that is about as sharp of a 7080 as I've ever seen. |
Posted By: SteveM C/IL
Date Posted: 04 Jan 2025 at 4:22pm
| If you replace mains the new uppers will have slots for piston cooling from the mains. You will loose some oil pressure. I would only replace lowers if possible. The fix from the smart people is to pull crank and drive tiny steel balls in main saddle. The block is already dilled. |
Posted By: DrAllis
Date Posted: 04 Jan 2025 at 4:43pm
| I would imagine that tractor still has the 4-ring pistons and piston cooling is thru the main bearings. Only the very last few months of 1981 did any 7000 series engine get the newer pistons and piston cooling design. When "brass" starts rising in the oil samples, that would indicate rod/main bearings are getting thin. |
Posted By: dnel45
Date Posted: 04 Jan 2025 at 7:09pm
| Dr- Serial number on this 7080 is 41st from the last one made. Would this have the updated pistons? |
Posted By: SteveM C/IL
Date Posted: 04 Jan 2025 at 7:09pm
| Duh, I was thinking 8070..... |
Posted By: DrAllis
Date Posted: 04 Jan 2025 at 7:37pm
| You'd have to use the engine s/n and look on AGCO parts website to figure that out. |