More on oil pump gears

I just received an oil pump from a customer who reported that after he rebuilt it himself it still would not hold prime. Here is what I found. Based on the earlier discussion started by WeldingMan on the width of (some???) aftermarket gears I immediately checked the width of the gears he had installed. This is the 8N-6614 I removed from his pump:



I posted full specifications for the OEM gears in WeldingMan's thread and the correct face width is .724/.725. Here is one of about a dozen 8N-6614 gears I have removed from other pumps - they are all dead nutz on.



The difference in width is in excess of .010 and I am quite sure that is the cause of the losing prime problem. The pump has something in excess of .015 end clearance and after sitting a short while cannot produce enough vacuum to prime itself with the small amount of residual oil that remains in the pump. Next step is to see if I can find a supplier of replacement gears that are the proper width. If not this pump may go back to the customer with a set of the old gears I have here. My bet is that would fix the priming problem AND boost the pressure he was seeing.

TOH

PS> His pump also had pronounced scoring on the inside of the cover plate which only makes things worse. That will have to be ground out as well.

So the question is how did that .711" gear get into his pump? I wonder how many pumps left the factory like that?

And, how many new Ford tractor owners had their oil pumps repaired by whoever sold them the tractor? And were they repaired free of charge?

And, how did these tractors pass inspection at the factory if they would hold a prime? No one bothered to look at their oil pressure gauges?

(quoted from post at 20:59:50 10/10/17)
So the question is how did that .711" gear get into his pump? I wonder how many pumps left the factory like that?

And, how many new Ford tractor owners had their oil pumps repaired by whoever sold them the tractor? And were they repaired free of charge?

And, how did these tractors pass inspection at the factory if they would hold a prime? No one bothered to look at their oil pressure gauges?

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The .711 gear is an aftermarket replacement that came in an oil pump rebuild kit. The owner installed the gear - not the factory.

TOH

(quoted from post at 18:05:18 10/10/17)

(quoted from post at 20:59:50 10/10/17)
So the question is how did that .711" gear get into his pump? I wonder how many pumps left the factory like that?

And, how many new Ford tractor owners had their oil pumps repaired by whoever sold them the tractor? And were they repaired free of charge?

And, how did these tractors pass inspection at the factory if they would hold a prime? No one bothered to look at their oil pressure gauges?

Click to expand...

The .711 gear is an aftermarket replacement that came in an oil pump rebuild kit. The owner installed the gear - not the factory.

TOH

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Thanks for the info. It's something to be aware of when dealing with the oil pump. That's one of the things that makes this forum great. You learn a lot of stuff that you might just run across in the future. I have a whole bunch of copies of posts dealing with stuff like that in a "Tractor" folder on my computer. Every time I run across something like this, it gets saved in there for future reference. :wink:

That surprises me not a bit.

I gave up on aftermarket parts years ago.

Dean

In the 50s 60s 4 or 5 ??? 9/8N oil pumps were rebuilt every year at the dealership . Never did we replace the front main bearing cap. Never did we line bore a crank .Oil pumps were rebuilt when necessary .Kits came from Ford. The rebuild jig was there. A Ford dealership, cars and tractors, from the 20s to the late 80s. Seems the oil pressure problem came with the new kits , not built here!!

Mistake!! Never line bored a block..

Bingo, Wayne.

There once was a time, before foreign made aftermarket parts, when OEM service parts were quality made.

I avoid aftermarket parts like the plague.

Dean

TOH-
Just curious if this gear came like that from Cheena (most likely) or are there signs it may have been altered by whomever installed it because it was a tight fit and they simply didn't know about specs/tolerances and just wanted to get it in?

Tim Daley(MI)

(quoted from post at 06:41:55 10/11/17) TOH-
Just curious if this gear came like that from Cheena (most likely) or are there signs it may have been altered by whomever installed it because it was a tight fit and they simply didn't know about specs/tolerances and just wanted to get it in?

Tim Daley(MI)

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First let me apologize for the overly large images - they have been reduced - clear your browser cache to display the smaller ones.

The rebuild kit was purchased by the PO and I have no way of knowing what brand of kit or it's country of origin. To the best of my knowledge Steve Dabrowski was the first to identify this issue and that was at least a year ago. I've rebuilt a number of pumps since Steve's first report and this is the first one I have encountered. I'm hoping the issue is only with one supplier that can be identified and black listed.

Prior to a day or two ago all I could do was check for excessive end clearance after the gears were installed. I now have hard OEM data on what the width right out of the box is supposed to be for the 8n-6614/8N-6610 gears. When I encounter a kit with undersize gears I will bring it to the attention of the distributor AND the company making them. I don't know if that will get things corrected or not but at .013/.014 undersize this gear is unusable garbage and I will not be buying anything from whoever makes them until the problem is fixed.

I also have the full specifications so getting good gears made is also a possibility. Purchasing a run of 1000 or so from a small gear shop would not be terribly expensive. Too bad the little one man shop I had been using went out of business - this would have been right up his alley.....

TOH

PS> It appears the 52-6610/52-6614 spur gears were also used in the 60 HP flathead V8. Apparently there were two versions - a 9 tooth gear (-B) and a 10 tooth gear (-A). I can't find any flathead V8 suppliers that list either one new but I have found folks selling good used ones for $150 a set....

(quoted from post at 00:16:21 10/11/17) In the 50s 60s 4 or 5 ??? 9/8N oil pumps were rebuilt every year at the dealership . Never did we replace the front main bearing cap. Never did we line bore a crank .Oil pumps were rebuilt when necessary .Kits came from Ford. The rebuild jig was there. A Ford dealership, cars and tractors, from the 20s to the late 80s. Seems the oil pressure problem came with the new kits , not built here!!

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Based on just the oil pump design history poor oil pressure has been a problem from day one. Ford didn't increase the oil pump displacement by 33% twelve years after the start of production just because they felt like it. Persistent and ongoing oil pressure problems dictated that design change.

In the 50's and 60's your dealership was working with relatively fresh engines and quality OEM service parts. Now fast forward almost 70 years and the picture is a lot different. The oil pumps have seen a lot more wear and OEM service parts are NLA. The decision to stop supplying service parts for the machine was the OEM's decision and overseas suppliers are now the only recourse. Without them there would be nada, zilch, zero, nothing, but a bunch of well worn 60+ year old salvage parts of questionable servicability.

Regardless of all of that, I can assure you that even if you could find a NOS Ford rebuild kit from the 50's or 60's it would not fix either of the two pumps shown below. The one with a chunk missing is obvious - you have to look closer at the other. That one was run for a long time with a badly worn drive gear bushing and the housing wall was badly hogged out by the wobbling drive gear. The only way to fix either of them is with a replacement cap (your choices today are used OEM or new overseas service part) , a rebuild kit (new overseas service part), or salvage parts of unknown origin and servicability. Regardless of which you choose a line hone of the block is going to be required when you fit the "new" pump. Old engines wear out and the older they get the more severe the wear problems become. That increased severity means the repairs needed become more extensive. Such is the reality of life :roll:

TOH

TOH, parts book says 60hp cars used both A and B . 9N 40 HP trucks used only -B gears.
Melling, Sealed Power and Federal Mogul sell the oil pump gears. I wonder if they are made offshore to looser standards too?

(quoted from post at 13:10:26 10/11/17) TOH, parts book says 60hp cars used both A and B . 9N 40 HP trucks used only -B gears.
Melling, Sealed Power and Federal Mogul sell the oil pump gears. I wonder if they are made offshore to looser standards too?

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Yes - I have now discovered a number of suppliers for new V8 oil pump gears and from what I have read it appears to me the -A and -B gears are interchangeable??? Based on the Ford numbering system the -A ten tooth gear would have been the original (1935 136 CID ??) design and the -B nine tooth gear a later revision. I would be surprised if any of the aftermarket gears are made in the USA.

Like I said - this one is the first one I have come across so hopefully we have a single outlier - either manufacturer or production run - of the bogus part and good gears are still available from higher quality producers. Word gets around and you can't stay in business long making internal engine service parts that simply don't work.

TOH

One of the biggest problems we run into with N oil pumps now is worn pump housings. We see a lot that had new gears installed without replacing the bushing or not sizing the bushing properly (too much clearance or not straight). It would be nice to find a way to install a different style pump and not have to replace the front main cap. What do you know about electric oil pumps?

Mark

(quoted from post at 14:03:31 10/11/17) One of the biggest problems we run into with N oil pumps now is worn pump housings. We see a lot that had new gears installed without replacing the bushing or not sizing the bushing properly (too much clearance or not straight). It would be nice to find a way to install a different style pump and not have to replace the front main cap. What do you know about electric oil pumps?

Mark

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Exactly - seeng more that are worn or damaged beyond repair. Often the result of a botched rebuild - the cracked on in my picture for example :shock:

Odd you should ask about electric pumps. I just spent a scant hour or so yesterday looking at electric oil pumps but didn't find anything that looked promising. I didn't look long or hard so there may be something somewhere that would get the job done. Might even be able to convert to a full flow filtering system in the process :idea:

What if any experience have you had with the new replacement caps/pumps? I'm tempted to buy one just to QC it....

TOH

(quoted from post at 11:21:45 10/11/17)

(quoted from post at 14:03:31 10/11/17) One of the biggest problems we run into with N oil pumps now is worn pump housings. We see a lot that had new gears installed without replacing the bushing or not sizing the bushing properly (too much clearance or not straight). It would be nice to find a way to install a different style pump and not have to replace the front main cap. What do you know about electric oil pumps?

Mark

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Exactly - seeng more that are worn or damaged beyond repair. Often the result of a botched rebuild - the cracked on in my picture for example :shock:

Odd you should ask about electric pumps. I just spent a scant hour or so yesterday looking at electric oil pumps but didn't find anything that looked promising. I didn't look long or hard so there may be something somewhere that would get the job done. Might even be able to convert to a full flow filtering system in the process :idea:

What if any experience have you had with the new replacement caps/pumps? I'm tempted to buy one just to QC it....

TOH

Click to expand...

We haven't installed one yet but I see it coming that we will need to try one unless we can come up with another pump system. I've done a little research on electric pumps as well but haven't found anything. If you think of anything that might work I would be very interested in hearing about it.

Mark

I totally agree. I buy nothing but OEM parts and lubricants. Many times the cost difference is minimal between "OEM" and "will fit" parts.

The discussion earlier in this thread about the way the teeth seal at the contact faces, rather than
the bottom of the gullet got me to thinking if it would be possible to make gear sets with a larger
outside diameter and bore the old pump housings oversize.

I don't have the knowledge to determine if it would work, but it makes sense that the gears could be
made .020 or .030 oversize on the OD if the tooth shape and gullet depth could be worked out. That
would allow most housings to be salvaged.

This would not be a cheap solution, but it may be cheaper than buying all new parts and line boring.
With the proper tooling, it could be set up on a dedicated machine that isn't CNC, or program a CNC.

(quoted from post at 13:06:45 10/12/17) The discussion earlier in this thread about the way the teeth seal at the contact faces, rather than
the bottom of the gullet got me to thinking if it would be possible to make gear sets with a larger
outside diameter and bore the old pump housings oversize.

I don't have the knowledge to determine if it would work, but it makes sense that the gears could be
made .020 or .030 oversize on the OD if the tooth shape and gullet depth could be worked out. That
would allow most housings to be salvaged.

This would not be a cheap solution, but it may be cheaper than buying all new parts and line boring.
With the proper tooling, it could be set up on a dedicated machine that isn't CNC, or program a CNC.

Click to expand...

At first blush that sounded interesting. But upon further thought that would increase the pitch diameter of the gears and require widening the center spacing. There may be a tooth form modification/workaround for that problem but it's beyond my knowledge level.

TOH

When you started talking about the oil pumps, I remembered this thread and my adventure. Worst worn out oil pump...ever...you said.

http://forums.yesterdaystractors.com/viewtopic.php?t=1187362&highlight=oil+pump :shock:

Since this is the exact same issue I am
going through, what supplier's currently
have the proper rebuild kits with gears
that are "Not" udersized ? Thanks

(quoted from post at 16:31:03 11/12/17) Since this is the exact same issue I am
going through, what supplier's currently
have the proper rebuild kits with gears
that are "Not" udersized ? Thanks

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Read here:

Bubba strkes again(or even more on oil pump gears)

TOH

Okay I see that it's from Just 8N's a Respectable vendor. I have a question specific to this part from a different supplier because it is sold as being American made https://www.external_link/FDS381-oil-pump-repair-kit. At least according to the book catalog. Any thoughts as to wether or not it truly is ?? Thanks