Fluid Dampener Inspection
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=187624
Printed Date: 01 Apr 2026 at 5:06pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Fluid Dampener Inspection
Posted By: CrestonM
Subject: Fluid Dampener Inspection
Date Posted: 12 Apr 2022 at 9:29am
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How does one go about checking the viscous fluid dampener on a 7080, 8070, etc.? Since I’ve got my 7080 in the shop for hydraulic work, I thought it might be a good time to check or replace it. Hour meter stopped at 9,000 hrs but I don’t know the history of the engine. Second question is where to get a new dampener? I see them online for the smaller 7000 series but not the 7080. Thanks! |
Replies:
Posted By: DrAllis
Date Posted: 12 Apr 2022 at 5:52pm
| I've only experienced two bad fluid dampers on tractors. One was a 7080 and the other a 7580. The 7580 had welded up alternator and A/C brackets and then finally a failure of the engine oil pump mounting bracket. So, I think it had been operated quite some time with a bad damper. We had to replace the crankshaft, line bore the block and resize all connecting rods from the sudden lack of oil pressure. We got the engine back together and it sounded like all the timing gears were bad at 2500-2550 RPM's no load. Above or below that sweet spot everything was quiet. Removed the damper and the noise remained. Installed a new damper and the noise was gone. This customer apparently never noticed this rattling noise and paid a heavy price with a catastrophic failure. The 7080 customer noticed the same exact noise and we replaced the damper before his had engine troubles. I've heard of N-5/6 combines throwing the A/C belt on a regular basis and this is what the problem was...a bad damper. |
Posted By: MACK
Date Posted: 12 Apr 2022 at 8:57pm
| Dr. is right. If you cannot keep AC belt on, replace the dampener. MACK |
Posted By: SteveM C/IL
Date Posted: 13 Apr 2022 at 9:55am
| I contend there is no way to check a fluid damper. I put new on my 8070 last year after sleeve oring went to leaking at 700 hrs past O/H. Couldn't find a cause so went with that. Hole in new one is like .015 oversize so wobbled out of round running. The right amount of masking tape wrapped on hub and spins straight.Creston there seems to be no listing for new from any mfg. Might be NLA at AGCO. Mine was NOS from Wa. Had a conversation with folks at Vibratech and they have one "Allis Chalmers" but it's not the 426. It's a 4-71 Detroit but I think the demensions are the same. GOOD LUCK |
Posted By: CrestonM
Date Posted: 13 Apr 2022 at 1:16pm
| Interesting. Thanks guys, I guess I’ll leave it be. I haven’t had any vibration or noise issues, and no belts getting thrown. |
Posted By: DMiller
Date Posted: 13 Apr 2022 at 6:27pm
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Just dealt with this on the Cat I just overhauled. Cummins has similar views where at around 600-900,000 miles the viscous fluid gel in the dampers starts solidifying, Heat, tension of fluid in motion, and just time kill them. Calculate engine hours to miles at 55-58 miles per 1 hour time, Idling and slow RPM hard work is as bad. Over 9000 hours is over 500,000 road miles. The old hard rubber dampeners were easier to diagnose as the rubber would harden and lose elasticity allowing the outer ring to move.
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Posted By: MikeKroupa
Date Posted: 15 Apr 2022 at 8:50am
| I'm pretty sure the fluid dampener used on the 3750. 670HI is the same part number as a 4-71 DD. My 7080 has over 9k hours and is still original. If in doubt I'd replace it. |
Posted By: Ron(AB)
Date Posted: 15 Apr 2022 at 8:57am
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The AC belt was getting thrown on my 8070. It had under 4000 hrs at the time. I got a new damper thru Agco and the problem was solved. ------------- 405, 7000, 7050, 8050, 8070, L3, 2300 & 2600 disk |
Posted By: CrestonM
Date Posted: 15 Apr 2022 at 11:03pm
| I guess I’ll just keep an eye out for vibration and thrown belts. I might call Agco and price a dampener just to see. |
Posted By: SteveM C/IL
Date Posted: 16 Apr 2022 at 8:37am
Be sitting down when you do....
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CrestonM wrote:Posted By: cowkicker
Date Posted: 16 Apr 2022 at 9:49am
| I guess I just found out why my 8070 keeps throwing a/c belts! Is the damper from a 7080 the same as the 8070? How much of the front of the tractor has to be removed to change it? |
Posted By: SteveM C/IL
Date Posted: 16 Apr 2022 at 9:18pm
| It's your lucky day.....just reach in through the rt side with side panel off and you can get to all 6 bolts (5/8 wrench) and unbolt it and wiggle it off the hub. Don't have to remove anything else. Belts are behind it. DON"T keep running it! Bad things will happen. |
Posted By: DrAllis
Date Posted: 16 Apr 2022 at 9:26pm
| Get as rough as you want with the old one. DO NOT drop/dent or get rough with the new one or it will be junk. There is a close fitting donut inside surrounded with a thick silicone liquid. If it cannot float freely, because of damage to the outer case, it won't work. |