(800) 853-2651
SHOP NOW

Rebuilt 8N, Low Oil Pressure <10

I

Irish_Jake

Member
For anyone still paying attention to my rebuild saga - I finally got my tractor running again (cam gear was incorrectly drilled) after a ton of testing and dinking around with it. It's running pretty well now, with a couple of exceptions, the most important of which is oil pressure.

After I first got it running my pressure started at ~20psi but then dropped to basically 0 after it warmed up. I checked the oil and realized what I should have realized before I started it up - when my timing was off and airflow through my engine was going in reverse, I pushed a bunch of fuel and coolant into the oil pan. Oil was thinned way out and sludgey. So I drained the pan, gave it a bit of a flush with some clean junk oil, and then filled it back up with fresh 10-40 and a new filter.

With fresh oil I'm getting 15psi at start, quickly dropping below 10psi and then when the tractor warms up going all the way down to 5psi. I've run it a few circles around the yard to get it warmed up, and those numbers seem consistent. I have double checked that my oil bypass spring is in place.

I did rebuild the oil pump with fresh gears during my rebuild, and although it's been a year+ since I did that now so I don't remember in detail, I recall it meeting spec at the time.

What's my most likely culprit here? Oil pump? Sludge from my bad batch of oil?


On another note - I'm getting some missing / popping from the engine. Not enough that it's a completely missing cylinder, but a miss every second or two. I did get to see how far a distributor coil can shoot it's innards a month ago when I left the key on after testing, going to say it's a good guess my points are in rough shape after that which could lead to missing?
 
Jake,I told you about your camshaft gear causing your cam to be out of time early on,but you seemed not willing to except that.Then you continued on and on with other things that just wasted your time.
Now on to your oil pressure problem.
Did you have the crankshaft turned at a machine shop?
Did you just put new bearings on the old crankshaft with out checking it?
Did you check the camshaft journals and the block for excessive ware?
Did you check the thickness of the new oil pump gears as many of the new gears are found to be to narrow?
Is the oil pump cover plate worn?
Is the oil pump housing worn?
Did you plasti gauge the rod and main bearings and what clearance did they have?
 
(quoted from post at 17:31:18 06/15/19) Jake,I told you about your camshaft gear causing your cam to be out of time early on,but you seemed not willing to except that.Then you continued on and on with other things that just wasted your time.
Now on to your oil pressure problem.
Click to expand...

Wasn't ignoring that at all Den - just limited on the time I have to put into the tractor, and didn't properly understand the way that the valve relationship to the #1 piston was being described. My answers to your questions are going to line up with the opinion of me you've formed, but here they are -

Did you have the crankshaft turned at a machine shop? - No
Did you just put new bearings on the old crankshaft with out checking it? Yes
Did you check the camshaft journals and the block for excessive ware? Yes, not excessively worn, internals were in reasonably good shape (valves and springs were the biggest issue before rebuild)
Did you check the thickness of the new oil pump gears as many of the new gears are found to be to narrow? Yes, in fact I originally ordered the wrong size gears so had to re-order and measured carefully.
Is the oil pump cover plate worn? No
Is the oil pump housing worn? No
Did you plasti gauge the rod and main bearings and what clearance did they have? I did not.
 
Jake,You say,Did you plasti gauge the rod and main bearings and what clearance did they have? I did not.
Well that is the first place I would look for loss of oil pressure.
Too much bearing clearance in the rod and main bearings.
Second thing would be the oil pump gears,not the 9/16" - 3/4" difference but some replacement gears are too narrow in thousands of an inch,manufactured wrong.Also worn or improperly fitted oil pump bushings.
 
So my next step then is to drop the pan and check those. Oil pump I can check with a micrometer. Plasti gauge is new to me, any good links?
 
(quoted from post at 19:21:31 06/15/19) For anyone still paying attention to my rebuild saga - I finally got my tractor running again (cam gear was incorrectly drilled) after a ton of testing and dinking around with it. It's running pretty well now, with a couple of exceptions, the most important of which is oil pressure.

After I first got it running my pressure started at ~20psi but then dropped to basically 0 after it warmed up. I checked the oil and realized what I should have realized before I started it up - when my timing was off and airflow through my engine was going in reverse, I pushed a bunch of fuel and coolant into the oil pan. Oil was thinned way out and sludgey. So I drained the pan, gave it a bit of a flush with some clean junk oil, and then filled it back up with fresh 10-40 and a new filter.

With fresh oil I'm getting 15psi at start, quickly dropping below 10psi and then when the tractor warms up going all the way down to 5psi. I've run it a few circles around the yard to get it warmed up, and those numbers seem consistent. I have double checked that my oil bypass spring is in place.

I did rebuild the oil pump with fresh gears during my rebuild, and although it's been a year+ since I did that now so I don't remember in detail, I recall it meeting spec at the time.

What's my most likely culprit here? Oil pump? Sludge from my bad batch of oil?


On another note - I'm getting some missing / popping from the engine. Not enough that it's a completely missing cylinder, but a miss every second or two. I did get to see how far a distributor coil can shoot it's innards a month ago when I left the key on after testing, going to say it's a good guess my points are in rough shape after that which could lead to missing?
Click to expand...

Possibilities:

1) Bearing oil clearances are excessive.

2) You got some of the junk oil pump gears currently on the market.

TOH
 
(quoted from post at 21:43:48 06/15/19) I'll be honest, I'm going to be pretty miffed if I got hit by a junk cam gear and oil pump gears.
Click to expand...

What was the face width of the gears you installed? Need a measurement good to +/- .001 to be useful.

TOH
 
If it helps at all with diagnosing - and I'm still planning on dropping the oil pan in the morning - I just did another start and cold it was at 15psi mid-throttle, 20 throttled up, and spiked to 25 as I throttled down. Only ran it long enough to see if the headlights I just wired were brighter with the tractor on, but slightly different numbers / behavior than I was seeing earlier.
 
INFO:
As per pictures:

I'm a Recent owner 1945 2-N:

Bob...Retired Power Engineer.....

cvphoto26425.jpg


cvphoto26426.jpg


cvphoto26427.jpg


cvphoto26428.jpg


cvphoto26429.jpg


cvphoto26430.jpg


cvphoto26431.jpg
 
Hi Jake, I remember your saga of the cam gear problem. I read your post twice, and have a question. How does incorrect cam shaft timing push coolant into the oil pan? If you really had coolant in the oil, you have other problems with that block.
 

Combo was a bad gasket on the manifold.

Anyone have the specs for the oil pump gears handy? I see the shaft specs, but not the gear specs.
 
(quoted from post at 09:34:00 06/17/19)
Combo was a bad gasket on the manifold.

Anyone have the specs for the oil pump gears handy? I see the shaft specs, but not the gear specs.
Click to expand...

What specs do you need? I have posted full gear specifications in the past if you search the archives. As far as face width goes it is .563/.562 for the narrow gears and .725/.724 for the wide ones. I am expecting an APN6600B kit I just purchased from Just 8N's when the mail gets here this afternoon. Wonder what slot in the roulette wheel it lands in....

TOH
 
(quoted from post at 06:34:00 06/17/19)
Combo was a bad gasket on the manifold.

Anyone have the specs for the oil pump gears handy? I see the shaft specs, but not the gear specs.
Click to expand...

My suggestion is to check the easy part first, as it is the most likely in my opinion - the oil pump. The aftermarket parts we get now from the land-of-almost-right will infuriate the average mechanic. These old N's are very forgiving, but they do have their limits. Check for wear around the edges of the pump where the gears turn as well as any scoring on the top cover. The top cover can be re-smoothed (tough to do correctly), but any wear on the sides of the inside of the pump warrants a new pump. Measure the gears. Replace the shaft bushing and ream with the CORRECT tool (I got lucky and obtained a real Ford Model A oil bushing jig/cutter).

Also - oil pressure gauges are known to be inaccurate as well...

That being said, these low RPM Ns will run fine on any pressure that registers.

Good luck,
Dan
 
So real talk - I'm set up to wrench on engines, but I'm not a machinist and I'm not set up for honing, reaming, or grinding for the oil pump, crankshaft, or cylinders. Because of that I went with the assumptions that if the new parts fit and met clearances, I'd be good to go. When I rebuild the oil pump in particular I didn't hone it, I just press fit the gear/shaft.

Knowing that, and knowing that the tractor does run (albeit with low oil pressure) what's my best option going forward, with the given that I'm checking the oil pump gear size asap (just got it out late last night).

- Rebuild oil pump again as needed, hunt down specialized tools needed.

- Send out oil pump to be rebuilt by someone who's set up to do it.

- Take the tractor to someone locally who can both rebuild the pump, check all the fit and fitment on the crankshaft/pistons/etc. and adjust as needed, and just bite the cost.

What would you all advise?[/list]
 

Checking pump wear is as easy as looking at it, and putting a feeler between the body of the pump and the gears - no specialized tools required. Remove the plain gear and leave the one with the shaft in place - grab the gear and try to wiggle it back and forth. Does it move? Yes = bad, slightly = bad, but may be usable with lower oil oil pressure, no wiggle but spins easily = awesome! No complex tools for that test either. If it does wiggle, the options are a new pump ($$), find the right tools (luck), or find someone who has the right tools and can ream a new bushing in for you correctly.

Hope that helps,
Dan
 
There's no wiggle on the drive gear - it was a tight press fit. It also spins freely now that it's in place, no excessive drag. Only thing I didn't do was make sure it's centered with the proper tool Will check with a feeler gauge tonight on clearance.
 
(quoted from post at 15:09:36 06/17/19) There's no wiggle on the drive gear - it was a tight press fit. It also spins freely now that it's in place, no excessive drag. Only thing I didn't do was make sure it's centered with the proper tool Will check with a feeler gauge tonight on clearance.
Click to expand...

A loose shaft fit to the bushing will not cause low oil pressure. It will cause the gear to wobble and with time damage the housing. And in time that will cost significant $$$ to fix.

If you have the "bad" pump gears the excessive clearance will be on the end of the gear - not between the tips and the housing. To check that you will need a micrometer. Pull the driven (loose) gear and measure the width. Narrow gears are .563/.562 - wide gears are .725/.724. If they are more than thousandth or two narrow they will cause bypassing and reduced oil pressure.

There is no reason to live with low oil pressure on a rebuilt engine. If done correctly you will get 30+ PSI @ 1500 RPM when hot. The bearings don't care what the pressure is as long as they get enough volume to keep them filled under load but you will lose the oil spray that lubricates the cylinders. The pistons, rings, and sleeves will care.

TOH

PS> Just got an APN6600B kit from Just 8N's. Unbranded but based on the packaging I believe it to be a Tisco kit and the gears measure .724+.
 
(quoted from post at 15:09:36 06/17/19) There's no wiggle on the drive gear - it was a tight press fit. It also spins freely now that it's in place, no excessive drag. Only thing I didn't do was make sure it's centered with the proper tool Will check with a feeler gauge tonight on clearance.
Click to expand...

Try this again - banned words filter seems to have killed it in Modern view.

A loose shaft fit to the bushing will not cause low oil pressure. It will cause the gear to wobble and with time damage the housing. And in time that will cost significant $$$ to fix.

If you have the "bad" pump gears the excessive clearance will be on the end of the gear - not between the tips and the housing. To check that you will need a micrometer. Pull the driven (loose) gear and measure the width. Narrow gears are .563/.562 - wide gears are .725/.724. If they are more than thousandth or two narrow they will cause bypassing and reduced oil pressure.
There is no reason to live with low oil pressure on a rebuilt engine. If done correctly you will get 30+ PSI @ 1500 RPM when hot. The bearings don't care what the pressure is as long as they get enough volume to keep them filled under load but you will lose the oil spray that lubricates the cylinders. The pistons, rings, and sleeves will care.

TOH

PS> Just got an APN6600B kit from Just 8 N's. Unbranded but based on the packaging I believe it to be a Tisco kit and the gears measure .724+.
 

Thanks! Was me that emailed you today as well. I'm assuming a caliper should be close enough for measuring? Otherwise I'll need to pick up a micrometer. I have the former, not the latter.
 
(quoted from post at 15:30:47 06/17/19)
Thanks! Was me that emailed you today as well. I'm assuming a caliper should be close enough for measuring? Otherwise I'll need to pick up a micrometer. I have the former, not the latter.
Click to expand...
No calipers, get a good micrometer!
 
(quoted from post at 17:30:47 06/17/19)
Thanks! Was me that emailed you today as well. I'm assuming a caliper should be close enough for measuring? Otherwise I'll need to pick up a micrometer. I have the former, not the latter.
Click to expand...

Got the email. A good quality caliper is accurate to +/- .001 and the "bad" gears are typically .007/.010 undersized so yes - that should be sufficient to make a determination.

TOH
 

Ok, measurements, taken with a calibrated caliper & feeler gauges -

Gear width on free gear - .724"

Clearance between driven / pressed gear teeth tip and housing, measured at both sides where gear teeth meet 'tighter' portion of the housing - ~.001"

I did notice though that my driven gear is sitting proud ~.010" from the housing, may need to be pressed on further? Corresponding to that I have some wear on the housing cover - http://dropshare.artisandm.com/Screen-Shot-2019-06-17-19-36-50.png

Thoughts?
 
(quoted from post at 19:44:07 06/17/19)
Ok, measurements, taken with a calibrated caliper & feeler gauges -

Gear width on free gear - .724"

Clearance between driven / pressed gear teeth tip and housing, measured at both sides where gear teeth meet 'tighter' portion of the housing - ~.001"

I did notice though that my driven gear is sitting proud ~.010" from the housing, may need to be pressed on further? Corresponding to that I have some wear on the housing cover - http://dropshare.artisandm.com/Screen-Shot-2019-06-17-19-36-50.png

Thoughts?
Click to expand...

Gear width sounds good but that one sitting high may cause a gap between the cover and the other gear. I'd press that on a bit tighter and clean up the cover and see what it does for the oil pressure.

TOH
 
Gear pressed further in, here's what I'm seeing now, with a video to make it easier to explain -

https://youtu.be/Yj9Ou65JR0o

Basically it's binding a little bit now, and the free gear seems to be inset vs the now flush driven gear. Is this expected behavior?
 
(quoted from post at 20:45:25 06/17/19) Gear pressed further in, here's what I'm seeing now, with a video to make it easier to explain -

https://youtu.be/Yj9Ou65JR0o

Basically it's binding a little bit now, and the free gear seems to be inset vs the now flush driven gear. Is this expected behavior?
Click to expand...

Actually that looks quite good. The driven gear lower than the driver gear would not concern me greatly. The difference seems quite small - you can lay a straight edge across the face of the housing and use a feeler gauge to measure the difference in clearance. Reason may be as simple as more wear on the bottom of the housing where the driven gear runs. As long as the end clearance between the cover and gears is In the .001/.003 range you are you should be good to go. The occassuonal catch is probably nothing more than a burr or bit of debris. Blow it out good with clean shop air then bolt it up and see what you get.

TOH
 

Great, thanks! Will check on that this evening.

So next step is plastigage before reassembling - do I need to do that at all the bearings, or just a sample at one?
 
(quoted from post at 09:08:22 06/18/19)
Great, thanks! Will check on that this evening.

So next step is plastigage before reassembling - do I need to do that at all the bearings, or just a sample at one?
Click to expand...
Do them all so you won't be wondering after the fact if it's still not right. If you find clearances that are .003 or more you can be pretty sure that is contributing to your problem.

TOH
 
(quoted from post at 06:20:34 06/18/19)
(quoted from post at 09:08:22 06/18/19)
Great, thanks! Will check on that this evening.

So next step is plastigage before reassembling - do I need to do that at all the bearings, or just a sample at one?
Click to expand...
Do them all so you won't be wondering after the fact if it's still not right. If you find clearances that are .003 or more you can be pretty sure that is contributing to your problem.

TOH
Click to expand...

I was hoping for the other answer - there's a lot of really nice lock wire work I'll be cutting off - but I'll do them all. :)
 
(quoted from post at 09:22:08 06/18/19)
(quoted from post at 06:20:34 06/18/19)
(quoted from post at 09:08:22 06/18/19)
Great, thanks! Will check on that this evening.

So next step is plastigage before reassembling - do I need to do that at all the bearings, or just a sample at one?
Click to expand...
Do them all so you won't be wondering after the fact if it's still not right. If you find clearances that are .003 or more you can be pretty sure that is contributing to your problem.

TOH
Click to expand...

I was hoping for the other answer - there's a lot of really nice lock wire work I'll be cutting off - but I'll do them all. :)
Click to expand...

Loctite and ditch the safety wire.

TOH
 

Loctite and ditch the safety wire...

My thoughts also... But the diagnostic approach to where he's at just plan chucks he's still in the hole hope'N and pray'N...

I have pizzed a bunch of time and money away hop'N and Pray'N...
His battle plan could have been determined before he dropped the pan :(....
 

Which it was, Hobo, just checking in as I go.

Main bearings clearanced at between .002 and .003, back on with loctite now and torqued to spec. New oil pan gasket arrives Thursday, so I'll get it back together then and see where it's at.
 
(quoted from post at 19:28:14 06/18/19)
Which it was, Hobo, just checking in as I go.

Main bearings clearanced at between .002 and .003, back on with loctite now and torqued to spec. New oil pan gasket arrives Thursday, so I'll get it back together then and see where it's at.
Click to expand...

Jake,What are the clearances of the rod bearings check them also,and did you pack the gears of the oil pump with grease or white lithium grease .
 

I'll check the rod bearing clearance tomorrow.

As far as grease - I did not, I plan on priming the pump with some gear oil before cranking.
 
(quoted from post at 22:28:14 06/18/19)
Which it was, Hobo, just checking in as I go.

Main bearings clearanced at between .002 and .003, back on with loctite now and torqued to spec. New oil pan gasket arrives Thursday, so I'll get it back together then and see where it's at.
Click to expand...

Assuming the plastigage number is accurate (big assumption) main bearing oil clearances are on the wide end of acceptable. Crankpin clearances next.

TOH
 
This site "YT" sells.....if you require ?????

Under size bearings as per below ...for your info:

Ford Rod Bearing Pair, .001 - For tractor models 8N, 9N, 2N. 1 Pair for one Rod. Order 4 for a complete engine. (Part No: 9N6211B-PAIR)


Bob...Retired Power Engineer...
 
Well, bad news. While torquing one of the crankshaft bearing nuts last night I snapped the stud. I'm fairly certain my torque wrench malfunctioned / wasn't clicking at the proper torque, and with a target torque of 110 ft/lbs, it doesn't take much more to snap it. Price of a cheap torque wrench and ignoring that 'this feels like more than it should' feeling.

Anyway, I don't have the time available this summer to split the tractor and pull the crank again, so I'm looking for a shop that can handle it properly. I have a couple to look up already, but if anyone has recommendations in West Michigan I'm open to them.
 
(quoted from post at 09:16:54 06/20/19) Well, bad news. While torquing one of the crankshaft bearing nuts last night I snapped the stud. I'm fairly certain my torque wrench malfunctioned / wasn't clicking at the proper torque, and with a target torque of 110 ft/lbs, it doesn't take much more to snap it. Price of a cheap torque wrench and ignoring that 'this feels like more than it should' feeling.

Anyway, I don't have the time available this summer to split the tractor and pull the crank again, so I'm looking for a shop that can handle it properly. I have a couple to look up already, but if anyone has recommendations in West Michigan I'm open to them.
Click to expand...

I'd be more inclined to think the stud has experienced metallurgical degradation over time and failed before the torque was actually reached.

Good luck with your rebuild and please let us know what the shop finds after inspection - particularly what you have in the way of instrument measured oil clearances.

TOH
 

Certainly could be either - it felt like it was too much torque, but could definitely have been fatigue in the metal. It was the 3rd time I've torqued them during this rebuild, and that's quite a bit of torque.

I'll post an update - plan is to find someone who can check all the crank and rod bearings and double check my cylinder clearances as well and adjust all as needed. If the tractor has to be split again and I'm going to pay someone, might as well check it all.

Thanks for the help TOH, I appreciate it.
 
(quoted from post at 12:57:39 06/20/19)
Certainly could be either - it felt like it was too much torque, but could definitely have been fatigue in the metal. It was the 3rd time I've torqued them during this rebuild, and that's quite a bit of torque.

I'll post an update - plan is to find someone who can check all the crank and rod bearings and double check my cylinder clearances as well and adjust all as needed. If the tractor has to be split again and I'm going to pay someone, might as well check it all.

Thanks for the help TOH, I appreciate it.
Click to expand...

You are quite welcome. I'd suggest you make sure whoever you get to work on the engine will do a through inspection and report the results to you. Some low dollar shops simply take the engine in, give it a cursory inspection, grind the crank, and throw a new set of undersize bearings into it without actually checking the clearances during fitting. That generally works if everything else (e.g big end and main bearing housing bores) are at or near factory specifications. On a 70 year old engine there is a very good chance those bores will be oversize and/or out of round and require resizing if you want to get reliable oil clearances. You will of course pay more for the services of the better shops....

TOH
 
If the tractor has to be split again and I'm going to pay someone, might as well check it all.
Click to expand...

This is the downfall of the little N's , that is paying someone competent to work on these tractors quickly cost more than the whole tractor is worth , while finding someone to do it inexpensively costs twice as much in the long run .
 
(quoted from post at 22:25:55 06/20/19) Totally agree with Ken(Ark)....


Bob...Owner...1945 Ford 2-N..
Click to expand...

The 8N is an OLD machine that had a LONG run due to its low purchase price and modest maintenance cost. It's now an aging machine with all of the expensive aches and pains that come with advanced age. It can't compete with newer used machines with low purchase and maintenance costs. As a working tractor time has caught up with it. Far more cost effective to buy something newer and with more features than fix the old Ford. And with millions made it is way too common to have much value as a collectible classic. It is now a nostalgia item with a price tag that exceeds its tangible value. The good news is that price tag is still well within reach for people like me that have a real sentimental attachment to them. The bad news is people like me are aging right along with the tractor and when we are gone that niche market of nostalgia buyers is going to get even smaller.

TOH
 
If it helps I'm in my 30's, and have a sentimental attachment to these tractors. My second tractor (not the one I'm working on now) belonged to my grandfather, and has sat in a garage, not running, for the 35 years since he passed. Plan on doing a nice restoration on that one someday, after learning on this one.

Also spent yesterday talking to half the old-timers in Michigan before ending up with the name of a machine shop just down the street from me that should be able to help with my engine.
 
You must log in or register to reply here.

Similar threads

B
8N no oil pressure
2
Replies
38
Views
2K
Eman85
E
H
8n shift rail leaking oil
Replies
5
Views
282
Hidude
H
C
ford2n 1942 no oil pressure
Replies
15
Views
2K
TheOldHokie
TheOldHokie
G
1943 2N no oil pressure
Replies
17
Views
773
Tim PloughNman Daley RIP
T
C
  • Question
1950 8N overheating in hello oil pressure
Replies
7
Views
427
Eman85
E
Tractor Parts Tractor Manuals

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Copyright © 1997-2024 Yesterday's Tractor Co.

All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.

Yesterday's Tractors - Antique Tractor Headquarters
Website Accessibility Policy

Back
Top