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Low oil pressure

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#1 mjay OFFLINE  



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Posted July 10, 2011 - 02:01 PM

My Deere 455 has a problem with oil pressure. it is a 3 cylinder yanmar.

When it is warm the oil light comes on when you drop it below about 1/3 throttle.

I have changed the swtich, so it must actually have low pressure.

Does anyone know of any common fault, or quick ideas? Does anyone know if there is a pickup screen in the sump? I think I can get the sump off without taking the engine out so I could do that.

The clock only has 1000 hours on it (actually it rolled over a couple of days ago). I cant believe there is alot of wear on it. It does have a bit of blowby, so maybe it has been clocked?

It is currently doing alot of hours as we are mid season and with all the rain the grass is growing fast! I cant strip it down until the winter, but I dont want it to go bang before!

#2 olcowhand ONLINE  


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Posted July 10, 2011 - 02:14 PM

Jim, I hope it's not wear for sure! It will have a pickup screen I'm sure, so that's the 1st thing to check. If that checks out OK, then it's time to pull the oil pump & check clearances, PLUS the pressure regulator valve in the pump may be sticking & not seating fully. I am assuming the regulator valve is a part of the pump. Never been inside a Yanmar to know for sure.

#3 mikebramel OFFLINE  


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Posted July 10, 2011 - 02:38 PM

If youre running 15-40 Rotella I would step up to 30W

#4 hammerdwn20 OFFLINE  



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Posted July 10, 2011 - 06:33 PM

Are you the original owner? keep up with oil changes? If not you could have some sludge build up.
get a cheap oil pressure gauge and hook it up. You need some numbers to go.

#5 mjay OFFLINE  



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Posted July 12, 2011 - 01:09 PM

Hi Mike, its got 10W30 in it at the moment. I have no idea what JD specify. It does it regardless of if the temperature is in the 90s or in the 60s.
Hammer, no, it has been owned by a council, then on a large private estate. I have no idea of the history. But it hasnt done alot of hours.

Dan, thats my thinking too. I will look into the pump and relief valve.
Sounds like it'll be an allnighter some time to pull the sump off. The belts in the vaccum need replacing too so I'll do it at the same time.

Thanks for your input, I'll let you know how it goes when I get round to it.

#6 Endo OFFLINE  



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Posted January 23, 2012 - 04:21 PM

Wondering if you found a resolution to this? Thanks to this thread I found this site and hopefully resolved a similar problem I had. Not to thread jack but I will give a little synopsis of the issue I had and fixed. Purchased a diesel 455 two seasons ago and after the first time I ran it for a long duration on a 80+ degree day my oil light started flickering at idle. The motor ran nice and quiet and had put several hours on it so figured it was just a switch. So after replacing switch still had issue. Checked with a true gauge and found very low pressure. It was only about 5-psi from idle to full throttle. So, after checking local dealerships found very few that had any experience with this motor and that potential rebuilds would run in the 1500-dollar range. My bright idea was to install a new oil pump. Not difficult but not an hour project either. Still low oil pressure. So disgusted, but still loving the mower, figured run it till it blew or find someone familiar with the motor. Never did find anyone but decided to check the regulator that is behind the filter. Low and behold a small piece of metal (flashing?) was holding open the bypass. Clean, inspect, and reinstall. now holding a consistent 45-psi!!!!

So, thanks for starting this thread and getting me motivated to do the research.

Hope your fix ended up this simple.
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