Construction and other equipment - 840 AC WHEEL LOADER

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840 AC WHEEL LOADER

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=27087
Printed Date: 15 Jul 2025 at 3:36am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: 840 AC WHEEL LOADER

Posted By: DAFF
Subject: 840 AC WHEEL LOADER
Date Posted: 10 Mar 2011 at 5:14pm

I have been looking to buy a 1970ish AC wheel loader. Everything on the loader seems A1 but the trans. The pressure on the guage is pegged and it will not move untill it warms up to normal operating temps. It seems to be intermittent too. If you turn off the machine and listen for hydraulic fluid draining and restart it everthing will work for a time but the thrans seems to get hot faster than normal. When working the trans will not slip and operates good then will not operate at all for a time untill you turn the loader off.

The pressure guage seems to be all over the pplace while working too. So what do you think ??? I am thinking there is an issue with the selector where the cable linkage goes into the trans. Something is out of sinc or a broken spring???

The fluid has been drained and no burnt smell or metal filings and is toped up to normal levels.

I do not want to get into a machine which needs extensive trans work.

Replies:

Posted By: wfmurray
Date Posted: 10 Mar 2011 at 8:34pm

Change the filters.

Posted By: DAFF
Date Posted: 10 Mar 2011 at 10:18pm

Not sure if the owner changed them allready??? I will have a look the next time I go look at the loader. Could it be that simple?? I feel the issue is small but at the same time not exactly sure. I would hate to buy a money pit!!!

I think I am going to go with my gut and buy the loader. Is $4000 too much?? Everything else seems rock solid, engine has been rebuilt and only 8100 hrs on the unit.

Posted By: Dean/MN
Date Posted: 11 Mar 2011 at 10:47am

$4000 for it is a good buy if the trans and all the pins are reasonably tight. A Cat that vintage would go for 20k plus.

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HD16,917H,185,7050,8030FWA,8050FWA

Posted By: DAFF
Date Posted: 13 Mar 2011 at 7:04am

Making an offer today will keep you posted on how it goes. After talking to some people I think the trouble is directly related to flow. Is the trans cooler in the radiator or external on this machine. I was wondering if it might be pluged up??? The previous owner has changed and cleaned the main screen on the drain plug. Are there any filters which might of been missed??

Posted By: DAFF
Date Posted: 14 Mar 2011 at 7:01pm

Got her for $3800 !!!! Tomorrow begins the battle. All I hope for is an EZ victory!!! At least cost effective. Will keep everyone up to date!!

Posted By: woodbutch
Date Posted: 14 Mar 2011 at 10:35pm

let's see your new toy!

Posted By: DAFF
Date Posted: 18 Mar 2011 at 9:12am

Did some work to the loader over the past few days. Started off by inspecting the fluids and checking the filters. To my surprise the filter on the pressure relief valve was broken sending metal into the trans. The filter had some little medal flakes but nothing too crazy...

Decided to tear into the pump and valve body sommore looking for the broken parts of the filter. At this point I thought for sure they were in the trans scattered in every orfice. To my surprise they all collected in layers at the power valve, thus blocking 95% of the fluid flow. After rebuilding the springs and totally cleaning the valve body I re installed the pump but to have still no motion. In face it is worse than before. This made so sence to me so off it came again seareching for the issue. Took everthing appart again and everything was perfect !!!! So what went wrong????

Just as I was about to give up I see a small circular spring on the top of the trans. Ah ha I thought !!! Turns out to be a seal between the pump and the input shaft without it the pump will not prime.. So here I await for the seal, will be here later this morning. Going to install and hope everthing is A oK. Cross your fingers !!!!

Posted By: DAFF
Date Posted: 18 Mar 2011 at 9:56pm

Seal installed ... still no go!!!! Thought to myself what if the fluid is too low. No it can't be that the previous owner just did a complete drain and fill. Well decided to do some digging on how the fluid is measured. 4 gals later and what do you know, my shop has a new opening where the wheel loader sat. It is perfect!!! Even the 3 speeds work.

All said and done it was an $4500 investment!!!

Posted By: rayfromTX
Date Posted: 19 Mar 2011 at 6:01am

That is great. Way to stay after it and get it figured out. That's what I love about old stuff.