# ford 8n showing oil pressure at start but then zero out



## Redmapleleaf (Sep 18, 2021)

Hi all,

I bought a ford 8n (1952) tractor a few months ago. It had some problem running initially but since I figured out the problems and fix the cab and distributor, then it has been working excellently. It always start on the first push and it can run all day without any issue. The only thing I have noticed is that the oil gauge only show compression (around 20psi) at the beginning when the engine started. Then after that it would stay flat at 0 (the same thing goes for the amp meter). All the gauges look new on this tractor when I bought it. Would anyone know what is the problem with my gauge meters?

Thank you for your help.


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## sixbales (May 18, 2011)

Your oil pressure should be at least 30-40 psi, maybe 20 psi at idle. I wouldn't run your engine any more with zero pressure... you'll ruin the engine. First of all, ascertain that the oil pressure gauge and sending unit are functioning correctly.

Do you have a shop/repair manual for your tractor? You are going to have to drop the oil pan and scrutinize inside to determine why the oil pressure goes to zero. You are dealing with a 70 year old tractor.

With an 8N, you will have to slide the front axle forward to get to the oil pan bolts up front. I've got a Ford 3600 and it requires sliding the front axle forward. Complicates a simple job.

There's quite a bit of information on the internet regarding 8N's with low oil pressure. It would be good for you to read through these posts to garner all the possibilities.


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## Redmapleleaf (Sep 18, 2021)

sixbales said:


> Your oil pressure should be at least 30-40 psi, maybe 20 psi at idle. I wouldn't run your engine any more with zero pressure... you'll ruin the engine. First of all, ascertain that the oil pressure gauge and sending unit are functioning correctly.
> 
> Do you have a shop/repair manual for your tractor? You are going to have to drop the oil pan and scrutinize inside to determine why the oil pressure goes to zero. You are dealing with a 70 year old tractor.
> 
> ...


How do I test the sending unit and the gauge for problems? If the oil system is having a problem pumping oil, wouldn't my engine be toasted by now? I have been running it like this for a few month now.


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## HarveyW (Sep 15, 2014)




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## Redmapleleaf (Sep 18, 2021)

HarveyW said:


>


So I disconnected the oil gauge and started the tractor. I can see plenty of oil came out of the oil line. I reconnected the oil line to the gauge and see that the pressure hold steady at about 20 psi. After a while of working, the gauge again went down to 0 psi during idling. Then if I throttle up to about 3/4 then it registered 15 psi. I still don't know what the problem is. Again this tractor run very well over several months now in this condition. Should I be worry about it?


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## HarveyW (Sep 15, 2014)

As the the old adage goes: You can pay now, or PAY later....


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## Joe.S.AK (Nov 26, 2020)

"Red". disconnecting the oil line simply shows that there is SOME SORT of oil pressure/flow, but it doesn't show anything about actual pressure. Now, if you had done the 'ole thumb over the garden hose thing to see it squirt a little then that might have helped with understanding more about the pressure and back pressure 'stuff'. There can be "flow" at 1 PSI but without pressure oil aint-a-gonn'a flow enough to do the job.

First though, common sense might point to deciding if your gauge is shot or not. Spend a couple of bucks for a cheap TSC or even a car parts store simple oil pressure gauge. Remove the line at the old gauge (again) and hook up the unmounted brand new gauge to the dangling fitting. If the new gauge shows proper pressures then it's just a problem with the old gauge. If the new gauge shows the same low pressure conditions then it's probably the oil pump and you have an inexpensive, spare, back-up, diagnostic gauge to put in the Ol'e tool box (yeah - it's OK to pamper your self a little with a spare). If you're at that decision point (both gauges working the same) it's either open heart surgery or maybe a little medication ((heavier weight oil)).

In these old tractors oil is pretty much oil. Henry only had straight, mineral weight oils and so that is what he was forced to use. If he had recommended the then plentiful bear grease for lubricating those grease fittings then .......... 

We have a better selection of oils, greases and such now so why not use them? If Henry had a selection of multi-weight oils, silicone spray and even internet most certainly he certainly would-a used them, just like we work with "High Mileage Engines" in our cars today, it is possible (totally up to you of course) to do an occasional, careful, upgrade or two. 

I know that some of our frustrated racing gear head associates might cry "Foul!" but they should just, maybe, turn their attention to race cars and stay away from the practicalities of 'ole tractors.

Just my thoughts on this situation - and I have been powerfully wrong before ................

- Joe -

One other thing - I DON"T KNOW if these old 4 bangers have an oil 'pressure regulator valve' or not --- but maybe, just maybe ---. Something to look at over the winter.


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## Redmapleleaf (Sep 18, 2021)

Joe.S.AK said:


> "Red". disconnecting the oil line simply shows that there is SOME SORT of oil pressure/flow, but it doesn't show anything about pressure. Now, if you had done the 'ole thumb over the garden hose thing to see it squirt a little then that might have helped with pressure and back pressure conditions.
> 
> First though, common sense might point to deciding if your gauge is shot or not. Spend a couple of bucks for a cheap TSC or even a car parts store simple oil pressure gauge. Remove the line at the old gauge (again) and hook up the unmounted brand new gauge to the dangling fitting. If the new gauge shows proper pressures then it's just a problem with the old gauge. If the new gauge shows the same low pressure conditions then it's probably the oil pump and you have an inexpensive, spare, back-up, diagnostic gauge to put in the Ol'e tool box (yeah - it's OK to pamper your self a little with a spare). If you're at that decision point (both gauges working the same) it's either open heart surgery or maybe a little medication ((heavier weight oil)).
> 
> ...


Thanks Joe, I read in another forum and someone there had his oil pressure as low as 10 and he had been running it like that for years. So I am a bit less concern about toasting the engine now. As the winter is fast approaching here in the north east and with a large part of the homestead project not done yet, i really don't have the stomach to take the engine apart to try fixing it at this time ...


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## Joe.S.AK (Nov 26, 2020)

I feel your pain, Leaf, been there and have the faded and ill fitting tee shirt, too. 

Keep an eye on that oil level and really keep monitoring that gauge. I would really be concerned if the 'now usual' pressure were to drop, even a relatively little bit. 

Next time you swing through TSC or Pep Boys check out the $ for just a gauge - since you're there, anyway.  

Also, of course, keep the Ol' Walkman turned down to listen for that 'OMG Ticking Sound". With my luck, that other guy on the other forum would turn out to be stone deaf. 

All the best of fortune to you! - Joe -


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