Allis Chalmers HD 21 Dozer torque converter proble
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=207495
Printed Date: 01 Sep 2025 at 11:16am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Allis Chalmers HD 21 Dozer torque converter proble
Posted By: Shaun
Subject: Allis Chalmers HD 21 Dozer torque converter proble
Date Posted: 17 Jul 2025 at 5:56pm
|
I have an early 50s Allis Chalmers HD 21 Dozer with a torque converter issue. The torque converter is the old style which uses diesel for its fluid. The Dozer was working good until parked for several years runs great now but has no push power at all barely moves back and forth under its own weight. I have changed the fuel filters and I know the fuel in the tank is good and clean. If anybody has any ideas of where I can start I would really appreciate it I have looked on the Forum for other postings I am having trouble finding the mentioned restrictor to make the fuel pressure in the torque converter stay above 30 PSI I do not have a fuel pressure gauge if I can share some pictures with someone who can maybe give me a hand locating what I'm looking for I would really appreciate it. Thanks.
|
Replies:
Posted By: gemdozer
Date Posted: 17 Jul 2025 at 7:36pm
|
I am not sure but when these machine ben long time park the fuel tank have to be 75% full for good working. AM NOT A EXPERT
|
Posted By: Shaun
Date Posted: 17 Jul 2025 at 8:14pm
|
Thank you very much I will try throwing a few more Jerry cans in it and see what happens if it makes a difference
|
Posted By: Shaun
Date Posted: 18 Jul 2025 at 10:56pm
|
Hey guys I tried more diesel and didn't make any difference. When I used to operate the tractor I could be crawling along pushing a load and lift the blade at the end of a hard push while still moving no problem. Now it doesn't barely want to crawl and the blade only lifts when clutch is engaged but not in gear. I should also tell you that it is an old cable lift blade using the rear winch. Any help would be much appreciated
|
Posted By: CAL(KS)
Date Posted: 26 Jul 2025 at 3:42pm
make sure you have fuel pressure! any air intrusion or loss of diesel in the converter makes a big difference. on my hd20 it runs about 60 lbs. my 20 uses a separate cooler for the fuel, but i think 21s were built into the radiator. follow the converter cooling tubes up to the radiator and the restrictor should be in the fuel return line near the cooling pack, but really only need to bother with it if you have excess pressure. sounds like you have very little or none. if fuel has leaked out you need to have the clutch engaged and engine running for a couple minutes before the converter will refill. your symptoms say low pressure. cable control on rear of machine is also driven by converter so it will affect movement
-------------
Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20
Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15
|
Posted By: Shaun
Date Posted: 26 Jul 2025 at 4:59pm
|
Yes it does definitely have low pressure I was able to locate a gauge and the needle isn't coming out of the red it is staying seated pretty much at the bottom the gauge is leading between what appears to be the injection pump and the Bell house for the torque converter. does anybody by chance have an idea about where I would start diagnosing why I have no pressure yet the engine is getting sufficient fuel pressure to run at full RPM?
|
Posted By: Shaun
Date Posted: 26 Jul 2025 at 5:00pm
|
And this does have a separate cooler for the diesel off to the side of the radiator for the coolant in the engine
|
Posted By: CAL(KS)
Date Posted: 28 Jul 2025 at 10:26am
the engine will run on low pressure to the injection pump but not move with the converter. here is my 2 cents. start by double check fuel flow from tank they can get plugged/partially at the outlet, condition of filters? could be nearly plugged, fuel flow at transfer pump inlet, should run out when disconnected. transfer pump could be worn out. rubber seal rings at fuel line connections can cause air intrusion especially if filters arnt flowing well. good luck
-------------
Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20
Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15
|
Posted By: HD6 Merv
Date Posted: 28 Jul 2025 at 12:11pm
|
probably got air trapped in converter as well. Which will give you all the problems your having. I know 15A D8s which use a similar system need air bleeding out of them. Your going to have to follow fuel pipes from charge pump to converter and loosen them make sure you have a good flow of fuel to converter, and then out of it. They sometimes have a bleed tap on top of converter. You really need to get a service manuel for it to help yourself. This applys to anyone who owns machinery
-------------
tits tyres and tracks
they all cost you money
|
|