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28K views 150 replies 25 participants last post by  gigem75 
#1 ·
Interesting failure. The vendor that sold me this pump (one of two) recalled it because he said the hole that holds the cotter pin that holds the relief spring was to low which would cause excessive oil pressure. I got it back and installed it in a new motor. I should have known something was up when the oil pressure gauge stayed pegged even when the oil was hot but silly me I figured it was the sending unit. I installed it with the 3 bolt tightening method and I could not detect any binding. I was just about to change the break in oil as I was approaching 1000 miles. 20w50
Any thoughts?
 

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#3 ·
As a builder of Oil pumps, I can't comment other than to say that high oil pressure did NOT cause that failure. There are 2 good 2L pumps currently being sold, BOTH built by one of Alfa's original pump builders. NEITHER are "cheap", and both are good. That said, much else of what is available is "none-too-good".
Don't take my word for it. Ask professional engine builders. (or ask Bill Gillham, Mike Besic and many others!)
 
#11 · (Edited)
As a builder of Oil pumps, I can't comment other than to say that high oil pressure did NOT cause that failure.
This begs the question of what did cause the abnormally high oil pressure. I have seen situations where the check valve sticks on an old pump, causing the cold oil pressure to be too high. But still high when hot? Perhaps it was just a bad sender.

the wear pattern makes me wonder not just about the alloy (brass not Bronze) but if the drive gear on the crank was put on backwards.??
In my limited experience, a gear installed backwards misses contacting the pump gear entirely. But maybe tolerances allow a backward drive gear to sometimes chew into the pump gear; still, in that circumstance, particularly with high oil pressure, I would expect the distributor timing to slip (e.g., the gears would skip teeth). I like the "cheap pump / bad alloy" theory.
 
#6 ·
Gordon Raymond will have a better answer but like every other engine part, with wear the tolerances just get too big.
Gordon’s pumps are not cheap either but worth every penny.
 
#7 ·
pumps

Factory pumps are pretty bullet proof, not so some of the aftermarket pumps.

Even with some wear on the aluminum bodies around the outside of the gears, they are going to pump adequate levels of pressure for the low volume required in an Alfa engine. Typically closing the amount of end play on the gears will improve efficiency. That is easily done by removing the studs from the bottom housing and removing a few thousandths from the surface.

Gigem75, where did you source that pump? At Atlanta for the "Mity" Malcom, the owner of Apex Racing, had a similar failure of a new pump sourced from Spruel, on Sharon`s Giulietta SZ that they maintain. This was a new engine and she only got in 2 laps...
But the wear pattern makes me wonder not just about the alloy (brass not Bronze) but if the drive gear on the crank was put on backwards.??
 
#8 ·
I'm just glad I had a Wix oil filter on. In all my years this is the first time I've pulled a pan with the motor in the car. First oil pump failure too. I can see slivers of bronze on the drive gear and on the sides of the front cover by the gear. My plan is to wash down with solvent from up top and get the remains out that way.
 
#9 ·
The pump came from the same place as your friend's oil pump. The motor was fresh with less than a thousand miles on it. Ahhh shucks, now you're messing with me Richard. You did get me to check though I'll give you that. :)
 
#10 ·
I did the same thing to an original pump in a 1600 motor. In my case, I think it was a result of improper installation. The pump went on after the front cover was attached. It was difficult to feel for binding. The most recent motor I assembled, I installed the pump on the front cover first.

Jim
San Antonio, TX
 
#12 ·
And remember the original vendor recalled the pump because the relief valve retainer hole was in the wrong place! That certainly would cause the pressure to remain too high. Then tells the customer don't worry, I don't sell those anymore!
Who else here got one of these?
And our pump rebuilder expert knows who makes the good pumps and who makes/sells the bad ones and will not say.....
I can't imagine how this is good for the community.
 
#19 · (Edited)
And remember the original vendor recalled the pump because the relief valve retainer hole was in the wrong place! That certainly would cause the pressure to remain too high.
Oops, I had forgotten about that. OK, that explains the high oil pressure.

gigem75 said:
I thought Richard was talking about the drive gear on the crank. Since it can't be installed backwards on the crank (it can but I doubt it would even start)....
Right, that was my point about the gears not even touching if the one on the crankshaft is installed backward. Distributor won't turn, engine won't start, so no damage done.

.... or he was talking about the drive gear on the oil pump being installed backwards or upside down really by the manufacturer.
Got it. The gear on the oil pump may have been upside-down.
 
#13 ·
Even with some wear on the aluminum bodies around the outside of the gears, they are going to pump adequate levels of pressure for the low volume required in an Alfa engine. Typically closing the amount of end play on the gears will improve efficiency. That is easily done by removing the studs from the bottom housing and removing a few thousandths from the surface.
I followed that advice from Richard when I rebuilt my motor 5 years ago and it has very good oil pressure. Jim K describes the same method in his book.

They don't make 'em like they used to :frown2:
 
#14 · (Edited)
I thought Richard was talking about the drive gear on the crank. Since it can't be installed backwards on the crank (it can but I doubt it would even start) he was either pulling my leg or he was talking about the drive gear on the oil pump being installed backwards or upside down really by the manufacturer. The installing on the front cover first is suspect to me. Would it get by the slinger? It's diameter is almost as big as the OD of the front seal. Either way the factory method is to tighten the three mounting bolts gradually in sequence all the while checking for binding which is the way I do it. My final check is to move the oil pump shaft with a large screwdriver back and forth using the lash between the crank gear and the gear on the oil pump. It's not much but enough to get a feel for any binding.
 
#16 · (Edited)
On some aftermarket pumps sent me, the relief valve upper body cylinder appears drilled with a wood auger! This DOES cause the piston to freeze in that cylinder as it might catch against a ridge or groove in the cylinder, causing high pressure.
As a rule with most Alfa parts that move or might cause whatever "system" failure, Brian's comment is 100% correct..."It sounds like the bottom line is, if it's going in the engine, don't pinch pennies."
 
#17 ·
It is more than a case of pinching pennies. It is often a case of installing a part that was designed without the knowledge of the original design specs and/or manufactured by a company that does not have an adequate quality assurance program. Failure of such parts is not uncommon.
 
#18 ·
I checked the play in the pump shaft on the other motor with the same pump and I pulled that motor just in time. A LOT of lash. Fortunately I had built "the one" with Alfaholics forged pistons, balanced crank, etc, windage tray, 30 deg big intake valves, RJ cams, MSD Streetfire ignition, 123 Bluetooth, Kent valve springs, and ported head where I went easy on the exhaust porting that was ready to go. BTW if anyone gets the Alfaholics forged pistons you will need to narrow the small end down to 21.99 mm so the small end will fit into the piston. A little tidbit they don't tell you on the website. But it's all good now and I'm very satisfied with the parts. Oh and a new oil pump from Classic Alfa. I also used their "race" timing chains and got the best fit ever on the lower one.
 
#20 ·
With the benefit of 20/20 hindsight I now know what the whirring sound is that I heard. At first I thought it was the spica belt cogs since it sounded like a fast bicycle with playing cards taped to the fender. I never could track it down and pretty much ignored it. Now I know it was the oil pump. I also compared the spring to a stock factory pump and it is about 7mm shorter and has fewer coils. It also feels stiffer but can't say how much. Bottom line is that if you hear something that sounds like cards on a bicycle and you just put a new oil pump in that was cheaper than average (under 200) stop!
 
#21 ·
Pump gears

I thought Richard was talking about the drive gear on the crank. Since it can't be installed backwards on the crank (it can but I doubt it would even start) he was either pulling my leg or he was talking about the drive gear on the oil pump being installed backwards or upside down really by the manufacturer.
I was not being facetious, your wear pattern would indicate either
mis- alignment of the gears, improper contact (small diameter of the oil pump gear) or softer alloy or material of the gear. As well the surface angle of gears must be the exact same so that there is a perfectly even contact pattern on both gears.
 
#23 ·
It is often a case of installing a part that was designed without the knowledge of the original design specs and/or manufactured by a company that does not have an adequate quality assurance program. Failure of such parts is not uncommon.
[/QUOTE]


This is why they're called "pattern parts" I suppose. The difference is one of apparent quality versus actual quality.
 
#28 ·
We know of two that failed after a short time and both were installed by individuals who have built a few Alfa motors so things done by the manufacturer almost certainly caused the failure. Incorrect material of construction was a contributing factor. I wonder if these pumps were made on a special order from the vendor of the two failed ones or if they have a wider distribution.
 
#29 ·
In this case, it is likely that excess outside axial clearance caused the failure. There are 2 axial clearances in these pumps, interrelated. Internally, gear top to upper body flange, and externally, upper body tower bush to bronze gear bottom. There is a build tolerance as mass production of ORIGINAL FACTORY pumps components varied a bit and that was designed into factory clearances. However, too much clearance here allows the bronze gear to move up-and-down against the hardened steel gear, resulting in the hourglass wear-THROUGH seen. I've had many other pumps with soft brass gears that show the beginnings of this wear pattern.
Ed. They have a wider distribution. Our vendors often do not know the quality of aftermarket parts unless failures are reported. They are NOT manufacturers, component testers or engineers. They are trying to fill a demand. This is complicated by good components, used in incorrect applications. A good 2L oil pump for a slower speed FI engine, used in a faster running 1600 with Webers, does not last long. This is an application mis-match, rather than "bad" pump.
All the above, my opinions from my own personal experiences.
 
#30 ·
A good 2L oil pump for a slower speed FI engine, used in a faster running 1600 with Webers, does not last long. This is an application mis-match, rather than "bad" pump.
What is different in the design of 1600 and 2L pumps that enables one to run faster than the other?
Catalogo Rapido Ricambi shows the same pump 105.14.06.013.01 for all 1300, 1600, 1750 and 2000 engines.
 
#33 ·
#31 · (Edited)
Hi Ed,
The 2L pumps use straight cut gear sets, designed to carry more oil volume at lower engine speeds. They also feature a stepped (3 size) main shaft bottom end for machine hydraulic assembly rather than hydraulic assembly gauged by hand. While a decent performance pump can be built from a 2L straight cut gear pump, it may be more time consuming and have a shorter service life than a pump built from a 9 tooth helical pump core.
Here is what happens. With the straight cut gear set, both gears have the same size gear bore to be interchangeable. Not so with helical pumps, where the idler gear has a larger bore. To get the same O.D. tooth size to carry more volume with straight cut (SC), the gears have longer teeth, and a smaller hub. The first photo below shows a drive gear with a fracture at the gear tooth root from a gear loading failure at 7500 rpm. This partly due to the smaller gear bore (less material) partly a stress fracture from machining stress risers, and the pressure of the interference fit on the main shaft. Next pictures are the stepped main shaft on the (SC) pump. Following pictures show that the shaft tip galled in the pump bottom bush, wearing the bush oval and allowing the bottom of the drive gear to move to -0- radial clearance with shaft flex, chewing into the gear bore. This caused the shaft to first twist (red mark) then snap off at the through pin on the drive gear. All this happens as oil trapped between gear teeth at high rpm cannot escape quickly enough, causing excessive gear loading as both gears try to move away from one another. While this is happening, the smaller diameter idler pin in the SC gear pump tilts away from the drive gear and main shaft, reducing the upper radial clearance to -0- as that gear cuts into the gear bore. Examine some dead SC pumps for confirmation.
The helical pumps (H) use a larger diameter idler pin, with better support in the pump bottom. Main shaft is single diameter, full length, so loading on the shaft tip in the pump bottom boss is reduced. Shaft flex is also reduced as the full diameter shaft is stiffer than the stepped shaft. Finally the helical gears do not push directly away from one another as much, with oil trapped between teeth, at high rpm. The 9 teeth will carry less oil volume than the same OD 9 tooth SC gear, but handle higher speeds better, without damage. Experimentally, we ran a race, double steel helical geared pump at 6,000 rpm for about 2 minutes. This is 12,000 rpm engine speed. We stood FAR away. It did get warm, not hot. Disassembled, there was no measurable clearance changes from the initial build. I will not repeat this test, as it was a bit frightening.
All this aside, the QUALITY 2L pumps are perfect for intended (FI engine) use. The standard 31 mm gear version works just fine with 20-50 mineral base oil, the "tall-gear" version was designed for use with much lighter weight oil or synthetic, and is also fine used as designed. Both these pumps were intended for ~5500 rpm maximum engine speeds. Higher speeds cause earlier pump failures.
 

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