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Oddmanout84

L6 Oil pump differences

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I've dealt with three L28 engine teardowns over the past couple years, so I have three oil pumps that I've removed from them. In addition, shortly after I bought my Z in California years ago I purchased a "high pressure performance oil pump" upgrade from MSA in order to make sure the car was ready to drive across the states to CT. However when I used the on base auto shop I decided I was too chicken to try installing it. Maybe a good thing. That engine had a lot of grit in it when pulled (and half of a 3M sanding disc from god knows where).

 

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Years later and with a bit more experience on the car, I swapped this MSA pump onto the turbo motor Airjockie sold me in order to freshen it up a bit. Less than a year from then, my motor broke down. After inspecting it, my grinded thrust bearing told me that I *might* have been running low on oil pressure, or maybe the grade I used was too thin. So I read my Datsun books and various sources on the internet and found that there were three (?) different oil pumps? The turbo automatic received the highest volume pump, since it had the addition of a turbocharger AND an oil cooler to deal with. Information was a bit spotty and some of it contradictory on the other pumps so I decided before I risk another motor I should at the very least inspect all the pumps I had. Also, while it is "known" that the H4 pump is the OEM high volume pump, the documentation on the aftermarket (typical auto parts supplier brand) is pretty scarce. Usually, the pump housing has a cast number in it which denotes which version it is. However Nissan uses one lettering system and all the aftermarket versions (the ones you're likely to get through a parts supplier) use a completely different one. In essence, I wanted to make sure that there was a little more information available for anyone who has one of these brand pumps, so there was less wondering if the pump they just bought at autozone was just a re badged "???" pump or a wrong part.

 

Here are my findings.

 

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All pumps and internal components will stay in THIS order, left to right, for all following photos. Besides external markings and dirtiness, all pumps appear to have the same housing dimensions.

 

Now we start to see differences.

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’78 L28 pump housing as pulled from my original engine.

 

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L28ET pump pulled from my turbo swap engine

 

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MSA “High performance oil pumpâ€, made by Paraut. As you can see, the bottom of the casing has different markings than the other K1-marked pump in the next picture. The yellow box shown earlier is what it came in, and as labeled states that it is actually a 280zx turbo (Manual trans) replacement pump (tricky).

 

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The other K1 pump, pulled from the other ’81 280zx Turbo engine I have. I don't know who manufactured it, but I assume its another Paraut.

 

 

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These are the sleeves in which the rotors slide into and turn with in order to pump the oil. The only one visibly different is the one on the far left, which is from the ’78 L28. It is about a couple mm shorter. The housing is machined less to fit this accordingly. Also, the aftermarket pumps have additional alignment markings. I measured the inside of each one, and the two aftermarket parts on the right are a few thousandths of an inch wider than the Nissan pumps.

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Pump rotors. Same differences in length, but also the Nissan rotors are pinned to their shafts, instead of just pressed like the aftermarkets.

 

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Pressure relief valve “pistonsâ€. The two aftermarket pistons have slightly longer “nipplesâ€, I’m guessing for increased pressure.

 

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Pressure relief springs. Note the one on the far right is the longest. Also, both aftermarket springs seemed noticeably stiffer.

 

That’s about it for the differences noted, but here is an extra.

 

Also, it appears that the KA24E (SOHC) engine from the 240sx uses the same pump as the L28ET Automatic. I haven't gotten my hands on one though.

 

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D.L. Potter adjustable high pressure relief valve springs and shims. You add/subtract shims from the pressure relief plug on the bottom to change oil pressure. I displayed the two springs (meant to be used in tandem one inside the other) next to the ’78 L28 H 28 spring. They’re a lot shorter, and stiffer. I got the kit from ebay for $10. Unfortunately, it looks like they’re no longer available, unless you find them elsewhere. Mr. Potter passed away from what I gathered…

 

 

That’s about all the information I have. I essentially wrote this because I couldn’t find comprehensive enough information anywhere else. Especially not the kind with pretty pictures! So I made my own. Feel free to add in anything you have. You can also donate me a Kameari/Tomei pump if you’re feeling generous. I’m curious to see what differences they have inside. :P

 

 

 

Links:

 

Here is a link I found with someone doing an inspection similar to what I did, only he is comparing two original Nissan pumps: http://forums.hybridz.org/index.php/topic/79476-high-flow-oil-pump/

 

http://forums.hybridz.org/index.php?showtopic=61680

http://forums.hybridz.org/index.php/topic/88729-truth-on-l6-oil-pumps/

Edited by Oddmanout84

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The reason most auto parts places price the Turbo/Auto pump cheaper than the 'standard' is because the KA24 still used it! It's a current production part.

 

The rotor length dictates physical flow capability. The relief valve spring pressure dictates pressure delivered as long as the pump capacity can exceed the leakdown from the bearings in the engine.

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The reason most auto parts places price the Turbo/Auto pump cheaper than the 'standard' is because the KA24 still used it! It's a current production part.

 

The rotor length dictates physical flow capability. The relief valve spring pressure dictates pressure delivered as long as the pump capacity can exceed the leakdown from the bearings in the engine.

 

 

That is interesting, Tony. I had been afraid before to buy one of those from Autozone for the fear of getting the wrong thing. MSA seems to be in opposite land in that respect, because their turbo/auto pumps are 3 TIMES as expensive as the standards on their site ($224!!!!!)

 

I'll probably end up using the aftermarket turbo/auto pump on the far right of the pictures, since its still in immaculate condition. Still deciding if I'm going to install the Don Potter kit when I build the motor or after I break it in.

Edited by Oddmanout84

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The Melling M111 is a common turbo upgrade oil pump.... I think the Melling turbo replacement is the Melling M90 for the turbo - the M111 is the KA replacement with higher output IIRC....

 

The M111 is the turbo one, 40mm rotor ( more flow ), I just got mine today

 

http://forums.hybridz.org/index.php/topic/88729-truth-on-l6-oil-pumps/page__p__843819#entry843819

 

Nigel

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post-2090-011198400 1302150228_thumb.jpg

Edited by Noddle

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The M111 is the turbo one, 40mm rotor ( more flow ), I just got mine today

 

http://forums.hybridz.org/index.php/topic/88729-truth-on-l6-oil-pumps/page__p__843819?do=findComment&comment=843819

 

Nigel

Update to an old thread...

The KA24 pump is the Melling M152 - same rotor as the M111, and the pressure relief appears to be set at 70psi.

 

Just installed one of these, and it's working fine.  I'm now getting ~18psi at 900 rpm idle and 170 degF 10W-30 oil...

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Another update to this old thread, since I looked and couldn't find this anywhere.

I just got a Hitachi OUP0016 'turbo' oil pump from Rockauto. 

The pump itself is marked K11 - no other marks, not even a Hitachi logo.

But I opened it up and the rotor is indeed 40mm. 

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I have 2 oil pumps (one on the car & spare). They have been both swapped around a couple of times so I can't remember which came with the engine. Its an F54 block.  One is labeled H 18 and the other H 6. Both have the same logo as on the H 28 & H 4 pictured in the first post.

 

Does anyone know what oil pumps these are stock on? 

 

I'm looking to increase oil flow to the head on a hunch that I have not enough flow up there.

 

Thanks.

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