Need advise on oil pressure!

[thetester]

Hey guys I have a 20 hp farmpro / jinma actually a 2420. I’ve been battling for a while!

I’ve resorted in a complete rebuild inside and out. Everything is brand new! Yes oil pump also.

When I first cranked it up I would get about 20ish lbs of oil pressure at a little above idle. When I reved the engine towards the upper end, I could reach about 40ish.

I’ve put about an hour on the thing to break it in and now all I can get topped out is 20 lbs. At idle it’s about 5-10!

I have no idea what this thing calls for as what the pressure should be at all.

To me this seems low but I don’t know.

I’ve attempted to dicker with the pressure regulator on the oil filter housing and I get no change no matter what I do.

Any advice ideas or is this just normal??

 

[Unclewillie]

Hey guys I have a 20 hp farmpro / jinma actually a 2420. I’ve been battling for a while!

I’ve resorted in a complete rebuild inside and out. Everything is brand new! Yes oil pump also.

When I first cranked it up I would get about 20ish lbs of oil pressure at a little above idle. When I reved the engine towards the upper end, I could reach about 40ish.

I’ve put about an hour on the thing to break it in and now all I can get topped out is 20 lbs. At idle it’s about 5-10!

I have no idea what this thing calls for as what the pressure should be at all.

To me this seems low but I don’t know.

I’ve attempted to dicker with the pressure regulator on the oil filter housing and I get no change no matter what I do.

Any advice ideas or is this just normal??

The oil pressure gage may be faulty or giving faulty reading , sometimes gunk gets on the end in the engine during rebuilding.

 

[Unclewillie]

I would think at cold start (80 degrees) it should read around 45 and drop to around 30 idle warmed up.

 

[Bob Rooks]

5 to 10 psi at idle on a warm engine is acceptable. 20 psi at high idle is about 10 psi less than I'd like to see.
What oil are you using?
Did you install a new/reground crankshaft with appropriate sized main and rod bearings?
Did you have cam reground, and with new bearings correctly oriented?

 

[thetester]

Well It’s a brand new mechanical gauge. I would hope it’s not that. Before I rebuild it and the main reason was low oil pressure.

It’s strange... I was also thinking it should hover at 40-45 then drop to about 30-35.

At real low idle it’s as low ad 5-10.

 

[thetester]

Any ideas on what to check and how to go about it??

 

[Bob Rooks]

Any ideas on what to check and how to go about it??

Did you Plasti-Gage any of your bearings?

 

[thetester]

It was a brand new standard crank. New cam new bearings. All brand new and no need to gage. Everything but the head and block is new.

 

[Cougsfan]

All brand new and no need to gage.

Not sure I'd buy into that philosophy. Did you replace/rebuild the oil pump? Does the oil pump have a pressure release that may be faulty?

 

[thetester]

Not sure I'd buy into that philosophy. Did you replace/rebuild the oil pump? Does the oil pump have a pressure release that may be faulty?

Yes brand new pump.

The pump is gear operated internal design. I’ve seen no sign of a relief made into it. The only thing I know that’s on this tractor is what I think to be a oil regulator in the form of a spring and ball bearing tensioned by a set screw.

It is located on the oil filter housing.

I am using mobile delvac 15w-40

 

[Bob Rooks]

Not sure I'd buy into that philosophy.

I don't buy into it either. If you didn't check it you did it wrong, so therein probably lies your answer.

 

[Bob Rooks]

The only thing I know that’s on this tractor is what I think to be a oil regulator in the form of a spring and ball bearing tensioned by a set screw. It is located on the oil filter housing.

That is the relief valve. That dumps excessive pressure to the sump. If you cranked down on that sucker and all you got was what you indicated, you have sloppy bearings, and that's all you'll ever get. Period.

 

[thetester]

These are images of rpm and pressure.

 

[thetester]

I don't buy into it either. If you didn't check it you did it wrong, so therein probably lies your answer.

No sir not to argue but on these Chinese tractors, what you buy is what you get. Not a lot you can do or say. It ain’t a Ford whereyou can just drop back by the parts house.

I own a machine shop as my business. I mic’d the crank and checked the bearings. I checked the side gap, ring gap, etc.

I cross checked it to the old crank and parts which only had 300 hours on.

They were damn close!

You can gripe all day but at the end ordering Chinese parts that only have a couple of sources in the states, THATS IT!

I’ve already said “to me it had low pressure before” that’s why I went through the machine.

 

[thetester]

These are images of rpm and pressure.

 

[pjbci]

Faulty oil filter? Its a long shot but worth a few bucks to rule it out. Faulty oil filter is fresh on my mind because it happend to me on my last oil change with a big caterpillar filter. Pressure normally ran 65psi. Changed oil/filter, it ran 40 psi. I put another new filter on and its back where it was before.

 

[Bob Rooks]

Faulty oil filter? Its a long shot but worth a few bucks to rule it out. Faulty oil filter is fresh on my mind because it happend to me on my last oil change with a big caterpillar filter. Pressure normally ran 65psi. Changed oil/filter, it ran 40 psi. I put another new filter on and its back where it was before.

Cat large bore master mechanic here. That makes absolutely no sense at all. The filters have no way of regulating/changing oil pressure whatsoever. They do have a built in bypass like all other filters, but that only opens when the oil is cold or when the filter media becomes plugged. What was the Cat part number on the filter?

 

[quicksandfarmer]

My Jinma is very sensitive to oil viscosity. If I don't use 15W40 it has trouble maintaining pressure. So the first thing I would check is that the oil is the right grade.

 

[pjbci]

Cat large bore master mechanic here. That makes absolutely no sense at all. The filters have no way of regulating/changing oil pressure whatsoever. They do have a built in bypass like all other filters, but that only opens when the oil is cold or when the filter media becomes plugged. What was the Cat part number on the filter?

Thats what Petebilt guy said too. I had (deleted back about april) before and after pics of pressure guage but they say impossible. I dunno what was up but they wanted to rebuild but I wanted to try it first. Try as you might but you will never convince me otherwise unless it happens again soon. Here’s the best I can do with pic of it installed on a C15 6NZ.

 

[TMGT]

Thats what Petebilt guy said too. I had (deleted back about april) before and after pics of pressure guage but they say impossible. I dunno what was up but they wanted to rebuild but I wanted to try it first. Try as you might but you will never convince me otherwise unless it happens again soon. Here’s the best I can do with pic of it installed on a C15 6NZ. View attachment 704073

I've run into the same problem with a WIX filter for the Honda on the zero turn. No gauge buy couldn't get low pressure light off, ended up putting old filter back on until I could get a replacment.
Cut the filter open but couldn't find any obvious problems with it.
I typically cut most of my filters open for inspection so familiar with what they should look like!

25yrs in the auto industry and first time I've ever had this issue, wish I had had a gauge to see exact pressure but it doesn't come on until its about 5psi I believe.