N1 Oil Pump - Epic Fail

[Duncan]

...so far only killed 1 x N1 and i suspect it ate turbo bearing anyway....

spot on.

I don't buy this story that n1 pumps are death traps. I reckon people are just going to the broken pump and not the actual cause of the failure (ie what went through it and killed it).

I've had an n1 pump break but I'm sure it was a symptom not the problem.

I guess the splined gear pumps may solve the symptom (much more tolerant to crap in the oil)....but if there is something wrong in the motor it will just move to the next point of failure instead of the oil pump, probably a big end bearing

BTW I also ran a heap of bearing through a nitto pump lately. I can't confirm how they last in race use, but this pump has been through 2 major bearing failures and is still working fine.

[T04GTR]

lol @ sig..

what needs to be done is just a simple square spline drive inner gear.

basicly have a designe that would be durable if made of nylon. them make of steel. the material doesnt have to be an exotic hardened 4340 etc etc.

the things ive noticed on gm oil pump and also on the ford pump is that the gears themselves are free to float whithin the housing. ie there is no fixed position of the rotors.

just the alignment of the ports. this freedom of movement wound take stresses away from the inner gear...which would be otherwise fixed in the hosing...

[shanef]

lol @ sig..

what needs to be done is just a simple square spline drive inner gear.

basicly have a designe that would be durable if made of nylon. them make of steel. the material doesnt have to be an exotic hardened 4340 etc etc.

the things ive noticed on gm oil pump and also on the ford pump is that the gears themselves are free to float whithin the housing. ie there is no fixed position of the rotors.

just the alignment of the ports. this freedom of movement wound take stresses away from the inner gear...which would be otherwise fixed in the hosing...

that would require a total new housing being made though wouldnt it dave? as the gears in the gtr pumps are made to work with the internal design of the housing they sit in.

Saying that, the rb25/26 pump gears are like a free floating design already, as in the outer gear is centralized by a shelf in the housing and the inner gear rotates freely inside the outer gear. The rb30 pumps have a second shelf between the 2 gears which keeps both central about each other.

Like this:

RB26 left RB30 right

RB30

See the inner gear on the RB30 pump has a locating hub. Also the outer gear has a similar locating shelf. The RB26 pump is flat in the centre and the outer gear is only aligned by the outer shelf.

[RB30 Ceffy]

I really like to read these threads!

One thing that someone brought up a while ago was the clearance on the OD on the crank drive and the ID on the pump drive. What anyone can do and realize such a simple problem that doesn't get brought up very often is that the milling on the flats of the JUN collar in relationship to the N1 pump drive. That problem is that I can stick a 20ga wire between the flats. Call me crazy but the problem seems to lie on the drive to pump clearance. I took a jun collar and a n1 pump and the drive rattles inside the pump like a mad woman. I believe that the smashing of rev limiters more so the harsher ones like the BeeR and the PFC is enough rattling force to smash the pump after some time. Some are lucky and last forever and some that smash quickly.

In my experiences: Ive smashed a regular pump once in the past on one of my own engines. It was a factory crank with a full drive. "Was from 94 v-spec GTR". I am not sure if the factory drive on that specific crank has the same clearance issues as the Jun collar but my guess is that it does. Also just a hunch that the CA18 and SR20's do not have this clearance issue on the flats. I have also seen my friends N1 pump smash on it's 4th pull on the dyno after a fresh build. I dont trust the engine builder of that specific engine so I cant say much but from what I gathered up was a result of hitting limiter at 8400rpm on a pfc and a heap of bad luck. Again, loose as a goose drive in a N1 pump.

It was just the flats on the jun collar that do not have the proper clearance to the N1 pump.

Who makes a collar that has the proper clearance cuz I will either buy one from whoever or make my own? Its not rocket science. I dont have any problems with the N1 pump at all. I believe that with a proper crank drive they should do what they were engineered to do. I have built a few RB26's now equipped with N1 pumps and factory R33 cranks and none of them have smashed yet and I did use one for drifting and it did see limiter action often with a factory rom. I still think it is a gamble without a proper drive to pump clearance of .001 thou.

Just my opinion from what I have seen. Let me know what you guys think.

Also, I think why we see so many stories of N1 failures is because of the issue on the flats of the jun collars and for the simple reason that everyone can afford an N1 pump and therefor having more stories. Not many people have the coin to buy fancy pumps so not many people have the chance to post horror stories. Plus, in canada, the people here that buy fancy pumps are people that dont drive their cars to hard and that have lots of money to spend on their cars. The people that do drive their cars hard are the drifters and they can only afford the N1 pumps as they spend their money on tires. I could only gather that lil bit of info up from what I read up on the canadian forums but it could conclude why we hear N1 bashing and not so much of it with the other pumps.

hehe

[GTRsean]

lol @ sig..

what needs to be done is just a simple square spline drive inner gear.

basicly have a designe that would be durable if made of nylon. them make of steel. the material doesnt have to be an exotic hardened 4340 etc etc.

the things ive noticed on gm oil pump and also on the ford pump is that the gears themselves are free to float whithin the housing. ie there is no fixed position of the rotors.

just the alignment of the ports. this freedom of movement wound take stresses away from the inner gear...which would be otherwise fixed in the hosing...

Nizpro actually had billet replacement gears made for the barra 6's as they had a few engines break stock pump gears too....

[MrStabby]

I really like to read these threads!

One thing that someone brought up a while ago was the clearance on the OD on the crank drive and the ID on the pump drive. What anyone can do and realize such a simple problem that doesn't get brought up very often is that the milling on the flats of the JUN collar in relationship to the N1 pump drive. That problem is that I can stick a 20ga wire between the flats. Call me crazy but the problem seems to lie on the drive to pump clearance.

I dont know anything about engine building but that makes a lot of sense to me. A loose fit will mean the crank is hammering the pump on the leading and trailing sides of the flat when on the limiter. The worse the fit, the smaller the area over which the force is delivered (think about the angles). If the area is small enough the stress becomes enough to plastically deform the gear, it work hardens and is made thinner until a crack develops and it dies.

From a previous photo, you can see the force is only being transferred over a small area indicating a loose fit. So yeah, getting the clearance right is critical to ensure the stress doesnt get up to the gear materials plastic limit. And IIRC fatigue can occur below the plastic limit.

[Marko R1]

^ i agree, a bit above my head but it makes sense if the tolerance is out hence the damage as per above pic

[proengines]

Ideally, A fit with almost no clearance would be good but unfortunately you need to take into account manufacturing tolerances when the block and oil pump are made. The main tunnels and the inner gear centreline will never be perfectly concentric which is why they need the clearance they have. Saying that, they are very close. My opinion, the N1 pump suffers from a brittle material compounded by a relatively thin wall section on the inner gear. The same drive style is used on SR20's, FJ20's, CA18's all EJ Subarus, 4AG toyotas and a lot more.

There isn't excessive clearance on an RB pump, photo below of a std RB gear sitting over one of my collars.

[bigmikespec]

It has less to do with tolerance and more to do with the fact it is a s**t design!

[RB30 Ceffy]

Ideally, A fit with almost no clearance would be good but unfortunately you need to take into account manufacturing tolerances when the block and oil pump are made. The main tunnels and the inner gear centreline will never be perfectly concentric which is why they need the clearance they have. Saying that, they are very close. My opinion, the N1 pump suffers from a brittle material compounded by a relatively thin wall section on the inner gear. The same drive style is used on SR20's, FJ20's, CA18's all EJ Subarus, 4AG toyotas and a lot more.

There isn't excessive clearance on an RB pump, photo below of a std RB gear sitting over one of my collars.

Fair enough. Your collar looks to fit right. What I was referring to was much more of a clearance issue on the flats. I have a crank in my garage fitted with a jun collar and I have a new N1 pump kicking around. In the next day I will see if it is possible to take a picture if I just throw the pump on back-words over the crank. I think you guys need to see how ridicules and obvious the problem is.

That being said, the pump that I smashed with a 33 crank had obvious proof just like the picture you supplied us with. on each corner of the flats has wear markings. If the drive and pump had proper clearance there would be no smashing going on and the wear marking we all see on these smashed pumps would show minimal wear or none at all.

It may be so that Nissan could have changed the contractors to build these pumps? In any mass production there is no guarantee unless the drives/or cranks are built to suit the pumps in the same house. I think its just a big simple mistake that nissan made. Maybe the old N1 pumps fit the drives better and the new ones that are now built in new shops by different contractors have the flats on the pump machined too deep.

I would like to hear what some of you engine builders have to say about this. I know you must know about it but keeping the secret to yourselves??? HAHA

The one statistic I would really like to know is for all the N1 pump failures how many of those had loose fitting collar to pump and how many look tight like the one pictures just above here. I believe the answer would show some of you guys that the pumps are not all that bad. But who knows right??? lol

[RB30 Ceffy]

Also, couldn't there be a drive built to suit the entire pump? Looks like there is still a few mm in length the drives could use to fill the whole pump. Im sure that could always help unless the front seal on the pump interfere with that somehow???

[RB30 Ceffy]

sorry for the triple post.

I just went to the garage to take that pic of the looseness of the N1 pump on the jun collar. I couldnt get a picture of it as the pump cant go on back-words so I cant take a picture and I couldnt unbolt the N1 pump to throw the drive on because one of the screws was on so hard I couldn't get it off. Anyways, when I throw the N1 pump on I can feel the looseness! Very obvious! But since I couldnt get a picture of it I pulled apart a 26 pump to throw the drive on the crank fitted with the jun collar. Feels just as loose as the N1 did so i grabbed a clearance tool and sure enough it was at .012!!!!!! OMG. Way too much! haha. So that is .006 tho of an inch when it should be at .001 tho of an inch. I can post a pic later if you guys want the proof of the tool slipped inside on one of the flats between the oil pump and jun collar.

Now, since the N1 pump and the std 26 pump have the same clearance on the pump I would say the collar is at fault. I dont have a std R33 crank to see if the std drive is the same size as the jun collars but from this and in my opinion the jun collars are no good no matter what unless the jun pump has a snug fit which it should being the same company.

Who makes a drive that fits the N1 pump PROPERLY? I would like to buy one or two.

Edited September 14, 2009 by RB30 Ceffy

[GT-RZ]

The tolerance issues are in the air. that's why people started making there own collars a long time ago. But tolerances are not the only issues with the pump. various problems exist and the main ones being material and design. End of the day a tooth design will be superior and hopefully using a matching material.

lots of collars fit right, infact almost every aftermarket machined one from aus i have seen is machined with good tolerances. Lewisengines here in SA are a nice fit. that does not mean i will be happy using an n1 pump after what i'v seen. Rather get some insurance.

[NYTSKY]

There are some tricks to tuning to make it easier as well on the pump.

My ECU cuts one cylinder at a time every 50rpm from 7700rpm, very easy on the engine and pump.

[T04GTR]

not a loose fit when its sitting still. but spin it to 6k on a limiter or get some harmonics happening the whole shooting match flexes on the flats and fatigues..

[RB30 Ceffy]

The tolerance issues are in the air. that's why people started making there own collars a long time ago. But tolerances are not the only issues with the pump. various problems exist and the main ones being material and design. End of the day a tooth design will be superior and hopefully using a matching material.

lots of collars fit right, infact almost every aftermarket machined one from aus i have seen is machined with good tolerances. Lewisengines here in SA are a nice fit. that does not mean i will be happy using an n1 pump after what i'v seen. Rather get some insurance.

I agree. I think the clearances tho is a good place to start and does drastically reduce the chances of failure. As we can see in the picture with the big crack on the flat. I am happy to see a tooth design built.

My ECU cuts one cylinder at a time every 50rpm from 7700rpm, very easy on the engine and pump.

Good idea! But how is this for smashing the limiter? This any good for the drifters? or is there a big of a lag when that hits?

not a loose fit when its sitting still. but spin it to 6k on a limiter or get some harmonics happening the whole shooting match flexes on the flats and fatigues..

Exactly.

[NYTSKY]

The limiter is not that harsh popping sound, more like a humming bird

[T04GTR]

yes, but the crank isnt going round and round in a smooth manner rather back and forth really fast.

[T04GTR]

this is what breaks the oil pump.

a good read on whats happening :crankshaft harmonics

[MrStabby]

That correlates with the "a good harmonic balancer will save your oil pump" theory i've heard stated on here.