HD7GB won’t stay running
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=207979
Printed Date: 19 Oct 2025 at 7:20pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: HD7GB won’t stay running
Posted By: Tiger Joe
Subject: HD7GB won’t stay running
Date Posted: 28 Aug 2025 at 5:47pm
Dad has a HD7GB crawler loader. Had the big 3500 6 cyl turbo diesel.
We rebuilt motor in 2013 and machine has run good since.
This week, he starts it after about 10 min dies. Will start and dies within seconds.
So first we change fuel filters. In process find line from tank was split. Thought that was our issue.
New filters and line on, runs for about 10 min again and then dies.
Searching online seems like this is a relatively common problem with Roosamaster injection pumps- which this has. They clog the check valve? Which overpressurizes pump shuts it down
So plan is to blow out return line and remove/clean check valve. Dumb question- where is the check valve? Is it just the fitting in pump where return line connects?
|
Replies:
Posted By: DMiller
Date Posted: 28 Aug 2025 at 6:10pm
|
The return fitting atop the Top Cover of the pump. Remove the line and remove the fitting to inspect then clean, then in some not too distant period of time ready yourself to remove said pump for the coupling replacement internally.
|
Posted By: Tiger Joe
Date Posted: 31 Aug 2025 at 9:20am
Got it running. So looks like someone has been in this before- no check valve on top of pump.
Found return line plugged. Again, this appears to be modified from original, it’s metal line that wraps around engine, then turns into rubber hose- then back to original metal somewhere under cab. That hose failed. I was able to blow it out. We are just going to make an entire new hose and put a new valve on the bottom of the tank also.
|
Posted By: SteveM C/IL
Date Posted: 02 Sep 2025 at 12:00pm
|
Sounds like the elastomer governor ring is crumbling. To plug return with check valve missing it must be really bad. Do yourself a favor and line up timing marks in window and pull pump for a rebuild. Otherwise you're pi$$ing in the wind.
|
|