420 oil pressure

[johndeeregreg]

Hi, I recently got a 420 crawler, the first time I used it the oil pressure seemed to fade away so I changed the oil and filter, I put in 10w-30, just had a chance to try it again and the oil pressure still drops after it gets warmed up. When cold it'll be just on the low side of the green normal band at about any rpm but when it gets warmed up it barely stays above the stop line at full throttle. I have a new pressure gauge on it from Jerry trcka so I tend to trust the gauge. What's my next thing to try before tearing into the engine to check bearings? Is there a relief valve or pressure control valve I should check? The pump? Looking for things to try before going deeper into it than I have too.

 

[JIM MN]

You might try single weight heavier engine oil, 40 or 50? You can not take off the oil pan to check the oil pump. Oil pressure is adjustable at the oil pump with shims. Heavier oil and try

 

[johndeeregreg]

You might try single weight heavier engine oil, 40 or 50? You can not take off the oil pan to check the oil pump. Oil pressure is adjustable at the oil pump with shims. Heavier oil and try

OK, I'll get some heavier oil and give it a try.

 

[LandonT]

I got my 40 back from 'rebuild' because I thought I should leave the job to professionals. Came back with poor oil pressure.
1. Check that front seal is not blown (pretty big leak)
2. Replace the oil pump relief spring, it's not expensive or intrusive.
3a. You have to drop the pan, but check that oil pump bolts are tight. Mine were finger tight only, if that. This made a huge difference. You can inspect the pump gears for slop at this time.
3b. Check that the mesh intake to the oil pump is not clogged with sludge. Mine was filthy after the 'rebuild'

Hope this helps.

 

[JIM MN]

Remember, his 420 is a crawler?

 

[Jim.ME]

Remember, his 420 is a crawler?

I am pretty sure the oil pan can be removed from a JD 420C engine. What am I forgetting that would prevent removal? Don't say because of the belly pan; that is just something to be removed to get to the oil pan on a crawler.

 

[JOCCO]

Agree with others on pressure adjust first. BUT "the oil pressure still drops after it gets warmed up." many times means bad bearings.

 

[Lavoy]

Oil pan can be easily removed, not an issue.
Lavoy
www.jdcrawlers.com

 

[johndeeregreg]

I found some 50 weight engine oil and put it in for now, it raised the pressure but I haven't had a chance to run it for more than a couple minutes to see if it maintains pressure once warmed up good. I may end up just dropping the pan and checking things out, for peace of mind, once I get it in the shop this winter to address some other things.

 

[420C+VANBRUNT]

Oil pan easy to remove unless dozer frame is in the way. Also protective pan under oil pan has to come off