2N Oil Pressure momentary drop

7080316 · Oct 29, 2014

So I bought a 6ft finish mower and after replacing the coil had a good time mowing. I was about an hour into mowing I glanced down at the oil pressure gauge and was shocked to see it either 0 or really close. I instantly put in the clutch, engine revs up without load, I go to push the kill switch and the oil pressure jumps right back to 10lbs where it had been constant since warming up. At this point I am thinking it was a fluke so some sort so I turn around to make one last pass on the way back to put the tractor in the shop. I get 30feet and the oil pressure reads 0 ish again. same thing happens.. This time, I disengage the PTO and put it in 3rd gear and went straight to the shop. I checked the oil and it was at the bottom of run, so I will be adding some, but that shouldn't be low enough to cause a loss of oil pressure.

I recently changed the gauge. The old gauge would always show pressure immediately, sometimes while cranking. The new gauge from time to time takes a second or 2 to show pressure.

So my questions are.

Is there anything inside the engine that could cause this?
If it were a bearing spinning, I would think the oil pressure wouldn't come back. I mean what are the odds that it lines back up after spinning..

Is it more likely that my new gauge is faulty?

Should I be asking any other questions?

Jeff

HCooke · Oct 29, 2014

"Is there anything inside the engine that could
cause this?"

Loose oil pick up tube. Low oil level.

"I recently changed the gauge. The old gauge
would always show pressure immediately,
sometimes while cranking. The new gauge from
time to time takes a second or 2 to show
pressure."

Put the old gauge back on and see what happens.

10psi at hot working rpms is not a good sign.

Royse · Oct 29, 2014

What did your old gauge read at working temp? Same?
If the two read the same at working temp I would suspect
a problem other than the gauge. Unfortunately.

souNdguy · Oct 30, 2014

if oil is low, very low.. that may be it. .. i'dd add some oil and see if you get oil out the gauge line at startup immediately.

if not, i'd change the oil and see if that pickup tube was loose.

you can always hose off the oil pan and drain plug and use a clean catch basin and reuse the oil if it is new.

L.B, · Oct 30, 2014

Im with the others. But might try this first. Take
off your oil lines blow them out and put them back on and start it up. You may have a
piece of crud in them. If your lucky that may
solve your problem.

lha · Oct 30, 2014

I agree with HCooke,that seems low for working oil
pressure at speed. My mostly wornout 9n hot idles at
about 15,but goes up to about 35 at working speed
when hot,cutting,plowing etc. lha

Bob · Oct 30, 2014

NOT a chance of that happening.

The line to the gauge ain't gonna momentary clog, and if the line to the filter were to momentarily clog, oil pressure would go UP, rather than down.

L.B, · Oct 31, 2014

Bob your are wrong. I have told people to do this on this forum many time. I was right twice, check the archives-then post and tell me your wrong.

R Geiger · Oct 31, 2014

Both of my 8ns will show a drop in OP if the level is low and I am going down hill. Sucking air!

Bob · Oct 31, 2014

L. B., the 2N has a BYPASS filter that bleeds off a part of the flow from the oil pump and "wastes" it from the pressurized lube system, dumping it either directly back into the crankcase, or back into the crankcase through the governor.

It does not return to the pressurized oil gallery.

So, any flow through the filter can only REDUCE oil pressure in the main oil gallery.

HOW would you explain bleeding off a portion of the flow from the oil gallery can INCREASE flow, and hence, pressure, to the bearings?

7080316 · Oct 31, 2014

To me this all sounds like good advice. I am going to drain the oil in a clean pan and then cut the filter open to check for debris in the oil and filter and check the lines for restrictions. Oil is relatively fresh, guessing 10hrs or less since oil change. If I find no metal flakes I am going to assume the gauge is faulty and buy another one, I have had new gauges that are bad or go bad quickly. Learned my lesson after changing a perfectly good engine a few years ago.... I'll just say I felt like a complete idiot, but my trike had a new engine and a spare with low miles so it could have been worse...

I will still have low oil pressure, but I am going to just put some heavier oil in to make it last till the snow is blowing. Only need to finish mowing the yards and the orchard since we are going to have a hard freeze tomorrow night..

I called a local tractor salvage yard today to check on engine availability, and he said I am better off buying his kit for $375 (seems like a good price to me, I pay more for a kit on my chevy 4.3L v6 and the LS1 engines I use in the trikes) that includes everything minus machine work if needed. So this winter I am going to zero time the engine and change the clutch and trans seals and take a look at the Sherman since the handle seems a bit wobbly. The wobble makes me wonder if I have a bushing or two that are in need of replacement..

As always, I appreciate any advice anyone has to offer. Been reading through my FO-4 and am getting more and more excited about the tinkering that is to come...

Jeff

L.B, · Oct 31, 2014

Ok Im talking about jumpy gauge, the route to the gauge is a dead end you could crimp that line and the relief would not be effected that is not why I told him to clean lines they could have crud headed to the gauge on next start up. The jumpy ga could be a broken ga and not telling you anything about what is really going on. After re-reading these post again I think we are talking 2 different things. Once the oil hits the gauge it is there to stay it becomes a liquid rod taken out of the circulation/ equation. You dont get new or different oil till next start up so any crud that is in the lines could find its way to the gauge line and cause a gauge problem. Small stuff that could affect a ga will go there marry way in the sys and cause no effect to the relief. You are talking about the relief behind the 15/16 plug were one can prime the oil pump?

7080316 · Nov 1, 2014

Well I think I found the issue... Decided I would go ahead and drain the oil and dissect the filter tonight, still away after taking the boys trick or treating... Had a great first Halloween trick or treat with my 4y/o and 2 y/o, Gotta love small towns.

Anyways, I am not sure if I am angry, embarrassed, irate, relieved or scared..... After I drained the oil and filter cup and pulled the filter, I started cleaning up the bolts, nuts, plugs etc, and I found THIS laying in the drain plug...

Upon Inspection of the filter element. I found no trace of anything. It was completely clean no metallic debris. So I guess I lucked out.

New oil and filter, heavier weight, Throttle set in center of travel, oil psi reads 55psi when cold and 20 when hot on Ford original gauge and 18psi on cheap sunpro autozone gauge. Leaning towards trusting the ford gauge.. Oil pressure is achieved instantly on engine firing. I checked the line to the gauge, opened it up and watched it slowly pee some oil off, let it pee till my new oil came through, I am assuming that it should be a gentle flow.

During this time while I was waiting to get the engine warm I decided to clean up the oil fill breather. I had a large funnel with a thick lint free rag shoved down it to let it breath, but not be open... When I opened it up, I found a material I am guessing is like steel wool. Am I right? If I am going to replace it, does anyone see any issue with finding some steel wool of similar texture?

This situation reminds me of college. We had this instructor who was a miserable human being that would find the most impossible ways to cause the aircraft engines to have issues. Packy (10 years later, I still can't figure out why he was called that), would do everything from a golf ball in the intake manifold, marbles in the air cleaner, water in the oil (air cooled engines), removed valve springs, disconnected throttle cables, removed oil pressure lines, crimped oil pressure lines, cylinder jugs shimmed out to make valves not operate, and my favorite was a constant speed prop that pushed backwards. We'd have a set time to figure out the issue, fix the issue, and have the engine running at perfect operating parameters. He said he did it to make us better diagnosticians, but I have always figured he was just some sort of evil devil worshiper who wanted us to go crazy trying to find the problems that could almost never happen on an airworthy aircraft..

So the question I have today is does anyone see anything I am missing, other than the screen on the drain plug?

Jeff

JMOR · Nov 1, 2014

(quoted from post at 05:44:50 11/01/14) Well I think I found the issue... Decided I would go ahead and drain the oil and dissect the filter tonight, still away after taking the boys trick or treating... Had a great first Halloween trick or treat with my 4y/o and 2 y/o, Gotta love small towns.

Anyways, I am not sure if I am angry, embarrassed, irate, relieved or scared..... After I drained the oil and filter cup and pulled the filter, I started cleaning up the bolts, nuts, plugs etc, and I found THIS laying in the drain plug...

Upon Inspection of the filter element. I found no trace of anything. It was completely clean no metallic debris. So I guess I lucked out.

New oil and filter, heavier weight, Throttle set in center of travel, oil psi reads 55psi when cold and 20 when hot on Ford original gauge and 18psi on cheap sunpro autozone gauge. Leaning towards trusting the ford gauge.. Oil pressure is achieved instantly on engine firing. I checked the line to the gauge, opened it up and watched it slowly pee some oil off, let it pee till my new oil came through, I am assuming that it should be a gentle flow.

During this time while I was waiting to get the engine warm I decided to clean up the oil fill breather. I had a large funnel with a thick lint free rag shoved down it to let it breath, but not be open... When I opened it up, I found a material I am guessing is like steel wool. Am I right? If I am going to replace it, does anyone see any issue with finding some steel wool of similar texture?

This situation reminds me of college. We had this instructor who was a miserable human being that would find the most impossible ways to cause the aircraft engines to have issues. Packy (10 years later, I still can't figure out why he was called that), would do everything from a golf ball in the intake manifold, marbles in the air cleaner, water in the oil (air cooled engines), removed valve springs, disconnected throttle cables, removed oil pressure lines, crimped oil pressure lines, cylinder jugs shimmed out to make valves not operate, and my favorite was a constant speed prop that pushed backwards. We'd have a set time to figure out the issue, fix the issue, and have the engine running at perfect operating parameters. He said he did it to make us better diagnosticians, but I have always figured he was just some sort of evil devil worshiper who wanted us to go crazy trying to find the problems that could almost never happen on an airworthy aircraft..

So the question I have today is does anyone see anything I am missing, other than the screen on the drain plug?

Jeff

.........and perhaps a failure to remove the foil seals from oil bottles. :wink:

R Geiger · Nov 1, 2014

No steel wool, it will rust.

this site sells the correct mesh filters for it!

2N Oil Pressure momentary drop

7080316

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HCooke

Well-known Member

Royse

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souNdguy

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L.B,

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lha

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Bob

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L.B,

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R Geiger

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Bob

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7080316

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L.B,

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7080316

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JMOR

Well-known Member

R Geiger

Well-known Member

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