Hard starting Perkins when warm.
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=171576
Printed Date: 25 Aug 2025 at 12:14am Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Hard starting Perkins when warm.
Posted By: Dean (West MI)
Subject: Hard starting Perkins when warm.
Date Posted: 28 May 2020 at 7:25pm
Working on a JCB 1550 backhoe with a turbo Perkins engine. I believe it's a Perkins 4.236.
I know this backhoe has seen lots of hours. The owner ran it out of diesel and could not get it started.
I replaced the lift pump and fuelshut off solenoid and blew out the fuel line coming from the tank. The line from the tank was severely plugged up. After bleeding the system, I still couldn't get it started. I found a can of ether in the cab, apparently the owner had been using it to try to start it.
I gave it a slight mist of ether and nothing. It took a direct, short shot into the intake before it would start. Once it started it ran great. However, it won't restart when hot. It will start no issues when it's cold, even without using the intake heater. But will not start hot.
I noticed when I shut it off hot and immediately try to restart, it hardly blows smoke. After about an hour, it will smoke while trying to start, but still will not start. Only after it's completely cold will it start.
Any ideas?
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Replies:
Posted By: MattLF9
Date Posted: 28 May 2020 at 7:50pm
Lucas CAV pump? Worn hydraulic head and rotor in the pump. You are looking at a new pump.
------------- A little CQB never hurt anybody.
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Posted By: MACK
Date Posted: 28 May 2020 at 8:59pm
Or delivery valve not seating or broken spring. MACK
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Posted By: Dean (West MI)
Date Posted: 31 May 2020 at 1:54pm
MattLF9 wrote:
Lucas CAV pump? Worn hydraulic head and rotor in the pump. You are looking at a new pump.  | Yes! It is a Lucas CAV pump. Thank you for the reply. This really helps me to narrow it down.
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Posted By: Dean (West MI)
Date Posted: 31 May 2020 at 1:55pm
MACK wrote:
Or delivery valve not seating or broken spring. MACK |
Thanks Mack, this is where I'll start at. Hopefully it's something m minor like a broken spring.
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Posted By: injpumpEd
Date Posted: 31 May 2020 at 2:59pm
The head in the pump is likely shot. The CAV DPA seems to be the one most prone to wearing the head, compared to a Roosa DB. There is no delivery valve in a DPA.
------------- 210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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