Hail Mary pass on 8N low oil pressure?

My '49 front mount starts and runs pretty well, but the oil pressure drops to an indicated zero when hot. I've been using it some, and haven't thrown a rod yet.

It seems to be the consensus on here that replacing the oil pressure relief valve (it's really old, maybe original) won't help, right? Should I forget about that? Or maybe, like my maternal grandfather would say, "It can't hoit" to replace it before tearing into the engine??

Thanks, boys.
 
How old is the oil pressure gauge that you have?

What weight oil are you using?

Have you pulled the OPBV to inspect it and it's spring. stretch the spring and see if it helps any. and yes, the flat spot on the nose is normal.
 
If you're not running 20-50 oil, try it. It can't hoit. In my humble opinion, stretching the relief valve spring will just make higher pressure when cold, but not so much when hot.
 
Oil pressure is a result of bearing clearances.
The oil pressure relief valve keeps it from getting too high.

No, it can't "hoit" to try stretching it, unless you break it.
Zero $$ to try otherwise.

I would also second trying another gauge. A known good one.
If you have an 80 PSI gauge, try a 50 PSI gauge for more accuracy.

What is the cold oil pressure and how long does that last?
 
How long has it been since the engine was rebuilt/overhauled? Is the oil level up to the required level cold? A worn engine will show up as low oil pressure as it gets hot. When the engine is started from a cold stance, like setting overnight, at idle, does the oil pressure gauge read up between 30-40 PSI? As the engine gets hot, does the pressure gauge begin dropping? If so, there' probably nothing wrong with the gauge and it is functioning normal. Now work the tractor some, then park in neutral at idle and observe where the oil pressure reads. When oil pressure gauge starts showing 10 PSI or less, hot, at idle, it is time to be concerned about a badly worn engine and doing a rebuild. When running for a few hours at low PSI, chances are you are using/burning up oil. Lt tractor set for a several hours and get cold then check oil level. Chances are it will be down or very low. Just my opinion, based on experience. I pushed my '48 8N for 3-4 hours one year to mow grass with a severely worn engine. I'd be at 5 PSI, at idle when done, and would need to add more oil the next time out. I finally rebuilt everything before I did any major damage.

Tim *PloughNman*(MI)
 
"Forever" since the last rebuild!

Using straight 30 weight oil, with a bunch of Lucas oil additive!

On a warm day, it will run maybe 20 minutes before the oil pressure gets too low.

I sure hope that maybe it is the oil pump rather than bearing clearances (I know I'm probably dreaming) because I would like to try removing and repairing the original oil pump so maybe I could bolt it back on without having to do a line bore.
 
It's almost certainly bearing clearances.

That said, try 20W50 oil when you next change it. Maybe straight 40W if you can find it and are not in a cold climate area. Forget about the snake oil.

If all else is OK, you will likely get by for years.

At what RPM does the hot oil pressure go below 5 PSIG?

Dean
 
I would like to try removing and repairing the original oil pump

Unfortunately, besides truing up the "cover" if grooved or warped there really isn't much you can do to actually "rebuild" your oil pump.

If you can get a quality new set of gears and accurately rebush it, that may help SOME, but that still doesn't resolve the fact that when the bushing wears the gear wears into the housing, making a greater clearance for oil to "slip" by, even with new gears.

Unfortunately.

And what a DUMB design to make a wear item part of a main bearing cap!
 
In retrospect, one cannot argue with your analysis.

That said, Ford sold millions of engines with similar designs and made enormous amounts of money doing so.

Historically, technology was changing VERY rapidly in the 1920s-1930s when the Ford flathead was designed. NO ONE expected that Ford 9N tractors would continue to be used 10 or 20 years after they were designed and sold. NO ONE.

The fact that such machines continue to be used 80 or so years after first design is testament to a monumentally successful design project.

Is there anyone, anywhere who believes that ANY design from Apple, Samsung, pick a company, will remain useful 10 years from now, let alone 80?

Dean

Dean
 
Thats right Bob dumb idea my 43 holds 30 startup and 20 warm. My 2- 52s is 40+ start up 20 warm I have never put a wrench on
any of them except for a water pump and reg maint. Maybe the dumb idea original guages are lying. You and that Texas Cowboy should start a N bashing forum. I would write Ford and tell them your dumb oil pump only lasted 60+ years.
 
(quoted from post at 01:27:40 08/10/18) Thats right Bob dumb idea my 43 holds 30 startup and 20 warm. My 2- 52s is 40+ start up 20 warm I have never put a wrench on
any of them except for a water pump and reg maint. Maybe the dumb idea original guages are lying. You and that Texas Cowboy should start a N bashing forum. I would write Ford and tell them your dumb oil pump only lasted 60+ years.

Come on LB play nice.
 
(quoted from post at 04:27:40 08/10/18) Thats right Bob dumb idea my 43 holds 30 startup and 20 warm. My 2- 52s is 40+ start up 20 warm I have never put a wrench on
any of them except for a water pump and reg maint. Maybe the dumb idea original guages are lying. You and that Texas Cowboy should start a N bashing forum. I would write Ford and tell them your dumb oil pump only lasted 60+ years.

Ford engineering did a lot of things right with the N-series but the engine oil pump was not one of them. To this day problems with them continue to plague owners and the difficulty/expense of replacing them when they wear out (and large numbers of them have) is central to that issue. The next generation engine (134 CID) was a vast improvement and the redesigned oil pump is just one of a shopping list of bad ideas Ford corrected with the NAA. Acknowledging bad design choices is not N-bashing - it's simply stating the "obvious".

TOH
 

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