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Caterpillar 112 diesel motor grader, fuel in oil

Printed From: Unofficial Allis
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=194283
Printed Date: 28 Apr 2024 at 8:31pm
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Topic: Caterpillar 112 diesel motor grader, fuel in oil

Posted By: Clay
Subject: Caterpillar 112 diesel motor grader, fuel in oil
Date Posted: 27 Mar 2023 at 11:30pm

I was asked to get an old Cat 112 grader running.

This machine has not been used for at least 10 or 20 years.

Checked the engine oil and found the level very high on the dip stick. Stick says to check oil with engine running. The oil was very runny. It has diesel contamination.

Drained some of the oil down to what is thought to be a running level.

No antifreeze evidence, when the plug was first pulled. Radiator still had antifreeze. This was good news.

This engine had the pony motor replaced with a 12 volt starter.

Installed one of the batteries from my AC 180.

Injector lines were cracked to help bleed any air in the system.

Opened the compression release, cracked the throttle, pushed the starter button.

Pulled the starter engage lever and the engine cranked. Oil pressure began to build within 20 seconds. Fuel was pumping from all four injector lines.

Retightened the fuel injector lines.

Started the engine.

Amazingly, the engine ran smoothly. It is not a smoker.

Did not run up to full throttle because of the condition of the oil. Only ran for a minute before shutting down. Did not want to take any chances.

Before changing and filter, I would to figure out how the diesel fuel is getting into the crankcase.

Replies:

Posted By: Lars(wi)
Date Posted: 28 Mar 2023 at 5:11am

If memory serves, depending on the model engine, more than likely a leaking seal on the drive side of the fuel pump. Also excessive idling can cause this also. My money is on a leaking seal, thats probably the reason it was parked.

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I tried to follow the science, but it was not there. I then followed the money, and that’s where I found the science.

Posted By: fjdrill
Date Posted: 28 Mar 2023 at 7:05am

I'm with Lars. Fuel tanks above engine. Be sure and check levels of gear boxes. especially the ones below the floorboards that send power up.

Posted By: Ray54
Date Posted: 28 Mar 2023 at 10:16am

Yes it is transfer pump seals, most of the old Cat engines used big o rings. When you get it apart it will look like a square ring, but they all started as a o ring.

Antique Caterpillar Machinery Owners Club website will get you all the details you need. They finally have a library of parts and service manuals, but you have join to get access to them I think. But a lot of times someone will share screen shots of the pages you need. And with a bit of luck you can search and find where it has been explained before. Or maybe the owner has books?Or is willing buy the books. So far Cat has been good to have most all parts for the more popular machines from the 1950's. But it is starting change.

Posted By: HudCo
Date Posted: 01 Apr 2023 at 9:28pm

i was after some d6 c parts this last fall a lot more of stuff is nos

Posted By: 55allis
Date Posted: 20 Oct 2023 at 6:39pm

I just fix that on one I just got a couple of months back!!
There’s a #318 O-ring between the pump and the fuel filter that goes flat and needs replaced every 50 years (cat didn’t think they’d last that long).

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1955 AC WD45 diesel with D262 repower, 1949 AC WD45