Construction and other equipment - HD7G loses lube pressure after 15 mins

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HD7G loses lube pressure after 15 mins

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=169747
Printed Date: 19 May 2025 at 3:16pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: HD7G loses lube pressure after 15 mins

Posted By: turboturtles
Subject: HD7G loses lube pressure after 15 mins
Date Posted: 03 Apr 2020 at 7:49am

I've got an HD7G that loses transmission lube pressure after running for about 15 mins.
I can kill the engine for approx 1 minute, and it will run for another 15.

It was worse, and would run 5 sit 5 before I went through all three screens and 3 trans filters, oil change. Haven't noticed anything large in any of the screens and filter (bearing material ect)

Been in contact with "Dmiller" on here, and hes helped me locate alot of hard to reach and see places. Super helpful.

Using AW32 oil in place of the 10W.

No visible leaks.

I'm a chemical operator by trade, all my intuition tells me the fluid is getting kind of vapor locked, because as soon as I kill the engine....it all runs back to the sump in short order and runs fine. Not a warm up /viscosity problem. Feels more like a floating restriction, or a check valve somewhere is stuck open or closed.

I searched the forum and a guy named DoctorCorey had an identical issue, but never replied on the thread about how he resolved it, I did see he sold his HD7G "ready to work" but he hasnt been active here for a couple years.

Replies:

Posted By: gemdozer
Date Posted: 03 Apr 2020 at 9:38am

You could try ATF oil or 10 standar oil no detergent