Farm Equipment - D15 oil pressure

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D15 oil pressure

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=208142
Printed Date: 11 Sep 2025 at 8:21am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: D15 oil pressure

Posted By: Dave (Mid-MI)
Subject: D15 oil pressure
Date Posted: 10 Sep 2025 at 8:41pm

My Series I D-15 has good oil pressure on startup but lower pressure once warmed up. When warm, the engine must be run 1/3 to 1/2 throttle to maintain pressure in the normal range on the gauge. I switched from SAE 30 oil to 15W-40 but saw no difference. Is this an indication of worn main or rod bearings? Cam bearings?

Replies:

Posted By: IBWD MIke
Date Posted: 11 Sep 2025 at 6:30am

The quickest, easiest way to help that is to add a quart of Lucas oil conditioner. Obviously this doesn't fix the problem but does help the pressure. Cam bearings are probably the issue.