Oil Pressure Drop

Hi,

I need some advise if possible

I have owned my little 135 for 2 years now and have recently been having problems with the oil pressure dropping when hot. The engine has been running fine and I have been topping and saw benching since I have had it with a fairly constant oil pressure.

I had an engine oil leak from the bell housing so split the tractor, replaced the clutch, clutch release bearing, clutch fork, split crank seal, gearbox input seals, flywheel starter ring, injector seals, leak off seals, new engine and gearbox oil, new oil filter, couple of fuel pipes and all new gauges. Only to find that it was still leaking when we put it all back together! So front axle off, sump off and new gasket set on the sump, oil leak all fixed.

I have run the tractor for 10-11 hours now and have noticed as soon as the temperature gets up the oil pressure drops. On one gauge it is dropping until it rests on the pin, on a second gauge it drops just into the red.

I have run Mig wire all the way down the gauge tube to the block to make sure it is clear, I have changed the oil to a good 10W40 and done an oil flush by running it for 2 hours and then draining again. Tonight I'm going to see if it does any better with a fixed grade 40 oil and maybe a new oil filter

Can anyone think of anything else I could have done to effect the oil pressure? or could the bottom end bearings or oil pump have worn in a matter of hours?!

Thanks
Karl

are you using MF filters not some cheap filters
I also run shell rotella 15w40 diesel oil, have much better oil pressure.

worth a try before you completely rebuild it again.

What engine do have?

The filter I had on there with good pressure was a cheapo one that I picked up just for temporary use, ended up being a year. The one fitted now is an Agriline filter

The engine is the AD3.153

I meant AD3.152

Does the engine knock any when the oil pressure is low? At normal operating speed the oil pressure should be around 30 to 60 psi. I run Shell Rotella 15w40 oil, and my tractor has 10 psi at idle when hot with no knocking (has 30 psi hot at working rpms). I plan on dropping the oil pan, and looking at the bearings, and oil pump on mine over the winter.

I know it's not easy to check ,but I had the oil pump relief spring to break on a 230 and cause it to lose oil pressure at idle,the tractor was less than 2 years old but it didn't do any damage as the old girl is still runs today

No, No notable knock when the pressure gets low, although the engine idles at 900rpm so is quite loud to start with! My gauge doesn't have PSI readout, just a green and two red sections.

I just remembered that we pulled off the rocker cover when we changed the clutch. We adjusted the tappet clearances, replaced the breather tube and put a new rocker cover gasket on, I cant see what that could have done though

I filled it up with a single grade 40W oil and put a new filter on it but it still dropped to just above the red after an hour at 1400rpm.

I had a friend borrow it with the PTO saw for a couple of hours. He had it after the clutch/injector/rocker cover work and before I changed the sump seal. He happened to mention that the fuel gauge was broken when he brought it back, so I would have thought he would have mentioned no oil pressure! Unfortunately he doesn't remember.

It certainly makes me think that whatever I have done I have done it when I took the sump off, Maybe knocked the pickup pipe to the pump? It might be a small enough gap to let thick oil pass but let air in when it is thinner?!

I guess I will have to take the sump back off when the shed is clear