1974 450b low oil pressure

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Mlofton
MC crawler
MC crawler
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Joined: Wed Jul 06, 2022 7:02 pm

1974 450b low oil pressure

Post by Mlofton » Mon Jul 25, 2022 5:27 pm

Recently purchased a 74 450b turbo crawler / loader with unknown hours to use on the farm. Have a manual oil pressure gauge, oil pressure starts out pegging the gauge roughly 100psi. Once warm, it has 20psi at max rpm. We have added a few shims per the service manual. Before it wasn’t getting that high. My question is, manual says it should be 50psi +~
Engine runs good. What are the common oil pressure issues on these engines? I’m at the point of pulling the front cover and oil pan. I’m just trolling hoping for good news. I have read the balance shafts give a lot of issues, but then seen some say it was just a bad oil pump. I’m ready to repair whatever it is. Just looking for advice before tearing it down.

I have already had the fuel pump rebuilt, replaced the injectors, replaced the right side steering clutch abs the seat.

Any advice would be greatly appreciated.

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LeonardL
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Re: 1974 450b low oil pressure

Post by LeonardL » Wed Jul 27, 2022 6:47 pm

Since you say this engine runs good, the first thing I would do is get another gauge and double check the original gauge. Fluid gauges can go bad the same as the electric ones will. Your oil pressure on an old engine will vary some from cold to hot. But after it is hot I always like to see at least 20 to 30 psi and it carries that the entire time it's running. As long as it carries some decent pressure you should be okay. If it falls off to 15 or less then you have some sort of an issue. I have been inside a bunch of these older Deere engines and I have only ever seen one bad oil pump. Maybe I was lucky who knows. What I found the most on these old engines are bad bearings. Especially the main bearings. Check it with a known good gauge first is my recommendation.
40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.

Mlofton
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Joined: Wed Jul 06, 2022 7:02 pm

Re: 1974 450b low oil pressure

Post by Mlofton » Thu Jul 28, 2022 1:12 am

Thank you for the reply, I have verified with a good oil pressure gauge and it is in fact accurate. I do plan on taking the pan off and checking the bearings and pump regardless.
Out of curiosity, when you say you’ve seen bad main bearings. Where the bearings spun or just worn to the point it was causing pressure issues. Was the repair having the crank tuned during a full overhaul?

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LeonardL
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Re: 1974 450b low oil pressure

Post by LeonardL » Thu Jul 28, 2022 7:55 am

The cases I was referring to in reference to your issue were bearings that were worn badly and causing low oil pressure. Which in turn ended up being full overhauls. These were engines with a boat load of hours on them and a couple of them came from units that were in very poor working conditions. Lots of dust, sand, dirt and then coupled with poor maintenance.

I have seen a couple of engines where a main bearing had spun. I've seen more rod bearings spun than main bearings. Most however were very high hour units with more than 10K hours on the engine. Usually if they get to that point they need everything anyway. So an overhaul or total replacement are the only fix. I have had cranks turned or polished but again it depends on the individual engine. Usually on a well maintained engine these Deere cranks are pretty good about staying true. A person just needs to Mic them to be sure.

You may very well have a bad pump or some issue with the pump. I have seen them get loose and then not function properly. But for me anyway it was very rare that the pump itself was bad. They're just about bullet proof. Pulling your pan and checking things out is a good and smart start. Good luck!! :D
40 plus years working on JD 350s, 400Gs, 450s and other equipment both Ag and Construction.

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