# reason for oil pump failure



## R33 GTR N1 (Oct 31, 2006)

Hi all whats the main reason for oil pump failure and is there anything to do to prevent this from happening. Also how often do people change the bottom end bearings 

manythanks


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## mattysupra (Oct 31, 2008)

From what i can work out (been researching this) is harmonics. A damper like ATI etc will sort this issue. 

Other failers could be related to crap in the oil. 

There is poor contact on older cranks between the oil pump and the crank. Not sure if this causes them to fail tho as teh crank/pump would have to wear so they spin inside each other.


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## AlexH (Aug 17, 2008)

also a good point of pump failure is lack of oil it's self, typicaly on the drag strip.
you launch it hard, all the oil shoots to the rear of the sump and the oil pick up is at the front of the sump, so no oil gets collected by the pump, then BANG!!!!!


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## geoffree (May 16, 2010)

There's a huge thread on SAU, especially the number of N1 pumps that let go. Not a lot of meat in the N1's outer gear due to it's profile.
Apart from the drive problem on early GTR cranks, there's heaps of theories.
However everyone agrees that banging away on the limiter is a sure recipe for a failure, and this can only be due to crank end float.


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## mattysupra (Oct 31, 2008)

geoffree said:


> There's a huge thread on SAU, especially the number of N1 pumps that let go. Not a lot of meat in the N1's outer gear due to it's profile.
> Apart from the drive problem on early GTR cranks, there's heaps of theories.
> However everyone agrees that banging away on the limiter is a sure recipe for a failure, and this can only be due to crank end float.




Who in there right mind would sit on the rev limiter? 

YouTube - top rpm playing around


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## R33 GTR N1 (Oct 31, 2006)

how to wreck your car lol


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## Bigman (Apr 8, 2010)

i was speaking to someone yesturday about this issue, he gave me a few pointers in order to prevent this happening, a oil restrictor in the block, a sump extension and try not to go over 9000rpm!!


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## geoffree (May 16, 2010)

Perhaps not using the correct term, rev limiter as in max rpm.
I'm talking about the 5-6000rpm launch control which you pre-set, sit there banging away until the clutch dump.
Oil pump doesn't like that.


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## mattysupra (Oct 31, 2008)

geoffree said:


> Perhaps not using the correct term, rev limiter as in max rpm.
> I'm talking about the 5-6000rpm launch control which you pre-set, sit there banging away until the clutch dump.
> Oil pump doesn't like that.



Why does this damage the pump? Surely if it can damage the pump in would distroy the bearings? 

Even more so would it not damage the A/F sensors / exhaust temp sensors that are ceramic filled and only need a slight knock to damage? 


I know that harmonics can damage the n1 pumps and thats why they are sold to be used with a harmonic dampner i belive? 

O and just add, the poor crank contact is a issue for 32 cranks only is it not? Doesnt the 33/34 have a wider oil pump drive machined on the crank. Wasn't the N1 pump designed to work with a 33/34 crank or a 32 crank with a adapter to give a wider drive? 

Also people do say that the N1 pumps fail but on what percentage? 

Nearly all skyline owners have a standard or N1 pump and very few have a Jun/tomie etc. there are maybe 15-20 people with N1 pump failer and a hell of alot more standard pump failer (which i would guess most standard pumps that have failed have many miles on them) but if you compare these numbers in a percentage to other pump failers i dont think the N1 pump is as bad as people make out. 

For instance, lets say 5000 N1 pumps have been sold and we know of 20 that have failed, does that work out that we have around 0.4 % out of 100 % fail? If so i think that is very low! 

(im guessing numbers sold and how many have failed from info i have gathered from other posts SUA etc)


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## Austrian GTR (Oct 28, 2008)

mattysupra said:


> O and just add, the poor crank contact is a issue for 32 cranks only is it not? Doesnt the 33/34 have a wider oil pump drive machined on the crank. Wasn't the N1 pump designed to work with a 33/34 crank or a 32 crank with a adapter to give a wider drive?


Late model BNR32 (think from 2/93 on :nervous do also have the wider oil pump drive


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## R.I.P.S NZ (May 7, 2004)

geoffree said:


> However everyone agrees that banging away on the limiter is a sure recipe for a failure, and this can only be due to crank end float.


What do you mean by the last part?


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## jap power (Jun 19, 2010)

yep the guy is right stay away from 9000rpm their is nothing realy ther m8 ,plus get your sump converted ,and oil restrictors and a ati damper if you can and maybe a head draining kit and the set the rev to 8,300rpm and only give the car heavy foot treatment when the engine reaches perfect running temp and also if you havent got a turbo timer let the engine idle for a min before you switch off this is the way to do you best in terms of engine health and the bearing will last hopfully


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## geoffree (May 16, 2010)

R.I.P.S NZ said:


> What do you mean by the last part?


I was waiting for comment and that's my farmer theory, feel free to disagree.
Crank end float V's oil pump clearance is something nobody looks too hard at as the oilpump drive gear is designed free to move on the crank, and from memory Nissan's crank end float is smaller than the pump clearance. 
I think at big loads, it's not as free as one would think, and it grabs.
Note how the JZ engines have a spline not 2-flats like the Rb's.
My idea developed after having to rebuild my excavator's hydraulic pumps. They drive straight from the flywheel via a spline onto the triple gang hydraulic pumps. Only 200hp but loads of crank end float and despite the spline drive, it pushes the guts out of the pumps. Each pump element is splined to the next and yet they still transmit crank end float. 
Had to make up a composite rubber flex drive with the centre splined.


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## Darren-mac (May 13, 2009)

What about bee R limiters, are they sore on anything bottom end?


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## GT-R Glenn (Nov 9, 2002)

()Q([email protected])_$$)([email protected][email protected]##$$!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

FFS


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## mattysupra (Oct 31, 2008)

geoffree said:


> I was waiting for comment and that's my farmer theory, feel free to disagree.
> Crank end float V's oil pump clearance is something nobody looks too hard at as the oilpump drive gear is designed free to move on the crank, and from memory Nissan's crank end float is smaller than the pump clearance.
> I think at big loads, it's not as free as one would think, and it grabs.
> Note how the JZ engines have a spline not 2-flats like the Rb's.
> ...



I sort of understand your idea if the pump is worn already and the end float is pusing aginst the worn ridge created by poor contact on early 32 cranks. 

But end float dont all of a sudden happen, the oil pump and the gradule wear that may end up with end float on the crank should wear itself into the pump drive i guess. 

However, if you have alot of crank end float then i think you may have other issues.


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## R.I.P.S NZ (May 7, 2004)

geoffree said:


> I was waiting for comment and that's my farmer theory, feel free to disagree.
> Crank end float V's oil pump clearance is something nobody looks too hard at as the oilpump drive gear is designed free to move on the crank, and from memory Nissan's crank end float is smaller than the pump clearance.
> I think at big loads, it's not as free as one would think, and it grabs.
> Note how the JZ engines have a spline not 2-flats like the Rb's.
> ...


Interesting theory.

Crank end float in an RB is suppose to be around 0.005".

I have test fitted oil pumps without the gasket which is aprox 0.020" thick and there is still alot of clearance so in operation the crank would have to come forward a huge amount before you'd run out of drive flats and start putting forward load on the inner pump gear, by then you'd have a sump full of thrust washer material and far bigger issues to deal with.

I havn't seen oil pumps with the housings chewed out from forward load but I have seen the backing plate have marks from the crank when the rear thrusts are all but gone, the failiers everyone goes on about are the inner gear cracking from rotational loadings as far as I am aware.

Do you suggest that the crank comming forward a very small amount, over a long period of time, as the thrusts slowly wear, tries to make the back edge/step of the witness marks on the drive work on the inner gear causing the forward loading? and how does the forward loading cause the inner gear to crank and all without putting any witness marks on the front of the oil pump housing?

Interesting to discuss.......

Rob


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