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6 Bolt Front Cover

Posted by 1cleangsx, Aug 6, 2020

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  1. 1cleangsx

    1cleangsx Proven Member

    388
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    Cheyenne, Wyoming
    A3E96BDF-487C-4C08-BBBD-833705FCC84A.jpeg 76E0126F-D60D-4266-9AFA-5B7863F1DC61.jpeg 82F6A785-86A7-44FA-8B21-F65AF568B81E.jpeg FE8A76FD-6CB3-4FA3-A84C-18942B7F553A.jpeg 93766BCF-1673-4445-9852-2C19FAA0949C.jpeg 7FF0A1D6-25ED-437B-A162-2DC9B16BDBA6.jpeg 59AFA072-2F62-40D9-A855-8119F3EDDCBB.jpeg Alright guys I’m looking for opinions, I know everybody has one LOL, I’m still collecting parts for my build, but I’m currently in a dilemma with a pretty important part, the front cover/oil pump. I’m going to be running a bsek with the oem stub shaft, from what I’ve read the straight cut gears and stub shaft are the winning combo, okay cool, the straight cut oil gears are no longer available new, luckily my dsm is the best year EVER. The 1990, haters say what you want, call it a bastard LOL, this bastard came with a oil cooler from the factory, the strongest gearset according to many, and oh yeah I guess it ALSO came with straight cut oil pump gears which are discontinued but apparently the only ones recommended for a stub shaft and high rpm reliability. Didn’t I mention my car is a 90? Lol, anyways, on my last stock motor rebuild I ran the helical gears in an acl pump and they still look great, however that motor had balance shafts and this new motor won’t, so I dug out my original [email protected] front cover, straight cut gears and all, took some pics and wondering what you guys would do, obviously I’d like to reuse my discontinued gears, but should I reuse the cover? I’ve watched the Jafro video and he basically recommends just buying new, as it’s the heart of the engine, I agree but I’ve read there are 2 different 6 bolt covers, one for straight cut and one for helical, is this true? I’d love to buy a new one from stm tuned but not if the clearances will be off with my old gears, any help Is greatly appreciated:thumb:
     

    Street Build 2K  11

    1990 Mitsubishi Eclipse GSX
    13.2 @ 104.64 · 1G DSM
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  2. Dericsh

    Dericsh Supporting Member

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    Pearl River, Louisiana
    I managed to get one of the last sets of gears by pure accident, I don’t normally get lucky like that. If you would like any sort of measurement to compare yours to new let me know, that way you can decide if you want to purchase a new cover or not. For the $300+ they cost, I think yours looks as good as any used one would tho.
     

    Street Build 388  2

    1991 Mitsubishi Eclipse GST
    fwd · manual · 1G DSM
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  3. Kryndon

    Kryndon Proven Member

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    You can measure the tolerances all you want but to me, those surfaces look too worn and I can see a substantial groove where the bigger gear rides. Also the driven gear's bore looks very pitted and scratched. I'd at least try to find a less worn pump, even if it was with helical gears.
     

    Street Build 4K  13

    1997 Eagle Talon TSi AWD
    13.43 @ 99.7 · 2G DSM
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  4. 1cleangsx

    1cleangsx Proven Member

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    Those parts have 130k on them LOL, I’ll buy a new oem case, I guess I’m worried tho if I have to run the helical gears should I run a race shaft?
     

    Street Build 2K  11

    1990 Mitsubishi Eclipse GSX
    13.2 @ 104.64 · 1G DSM
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  5. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    Independence, Kansas
    I run the ACL pumps FWIW. I take them apart and inspect, clean, reassemble with assembly lube and do the BSE usually. I run 90 lbs oil pressure in a pull to 8500 and she settles to 17 at idle hot. No balance shafts, no OFH port, oil squirters, oil passage mod, tear drop mod and Kiggly HLA.
    When I was young, the man I worked for would take domestic oil pumps to a piece of glass with 2000 grit sandpaper and smooth their covers until no grooves were in them. They were just plates that were flat so it was easy. If the pump has scoring, it really needs replaced. They are the heart of the motor so they need to be in top notch shape. These are just my experiences Jeremy.
     

    Street Build 5K  29

    1992 Eagle Talon TSi AWD
    14.74 @ 117.04 · 1G DSM

    2K  15

    1990 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    936  18

    1967 Chevrolet Camaro RS
    rwd · automatic · Misc Vehicles

    Street Build 1K  7

    1998 Eagle Talon TSi
    fwd · manual · 2G DSM

    Street Build 6K  15  25

    1990 Eagle Talon TSi AWD
    13.620 @ 108.460 · 1G DSM
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  6. miguelmcv

    miguelmcv Supporting Member

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    Those grooves looks deep for an oil pump, I would replace it with a new oneor even a used one with no scratches.
     

    Street Build 847  1

    1997 Eagle Talon TSi AWD
    awd · automatic · 2G DSM

    3K  0

    1995 Mitsubishi Eclipse GST
    manual · 2G DSM
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  7. Vegas Smith

    Vegas Smith Proven Member

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    Houston, Texas
    I believe there is only a difference between 6 and 7 bolt, not straight vs helical. I bought a Hyundai front cover for significantly less and have been happy with it. Many people run the Hyundai with great success, but it's up to you.
     

    Street Build 4K  4

    1993 Eagle Talon TSi AWD
    awd · manual · 1G DSM
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  8. jakelandry

    jakelandry Proven Member

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    In all my days of frequenting the forum, I have never heard of Motor damage or inadequate oiling resulting from reusing a worn case or from a high mileage case in general. I’m not defending worn cases here as I have always put a new OEM one on when refreshing a motor, but i’d love to hear a technical explanation why the grooving is such a bad thing and how it can make a motor fail.
     

    4K  0

    1995 Mitsubishi Eclipse GSX
    11.410 @ 125.490 · 2G DSM
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  9. miguelmcv

    miguelmcv Supporting Member

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    Fresno, California
    Grooves in the oil pump area is more like grooves on the crank journal, that’s extra room where the oil pressure can escape, if the groove is very minimal, it can be trusted but not recomendable.

    The more recomendable way to check is, check for clearance between the case surface and the gears itself to see if there is not much clearance, otherwise it will fail sooner or later.
     

    Street Build 847  1

    1997 Eagle Talon TSi AWD
    awd · automatic · 2G DSM

    3K  0

    1995 Mitsubishi Eclipse GST
    manual · 2G DSM
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  10. TK's9d2TSi

    TK's9d2TSi Supporting Member

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    Cincinnati, Ohio
    The front case and the gears don't look bad at all. I'd replace the inner case but not sure if it can be swapped from one to another. I don't see why you can't since they're not machine together.

    Take a look in here where the driven gear rides. I’d bet is worn uneven

    6885937D-3DB6-4D63-BEAC-DFC6C95351FD.jpeg
     
    Last edited by a moderator: Aug 8, 2020

    524  3

    2000 Jeep Cherokee Sport - Classic
    awd · automatic · Misc Vehicles

    553  4

    93 Civic 4 Door -sold-
    fwd · manual · Misc Vehicles

    Street Build 3K  5

    1992 Eagle Talon TSi AWD
    12.2 @ 120 · 1G DSM
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  11. talon749

    talon749 Proven Member

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    Chillicothe, Illinois

    200  1

    1991 Mitsubishi Eclipse GST
    fwd · manual · 1G DSM

    310  0

    1995 Eagle Talon N/T
    manual · 2G DSM
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  12. Kryndon

    Kryndon Proven Member

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    Bulgaria, Europe
    Alright here's a basic rundown of how exactly this thing works and why it can wreck motors (and not only DSMs, Skylines too!).

    The oil pump we have on our motors is a twin gear type pump. It's really simple, with a main drive gear and a smaller driven gear. It works in unison with the pressure relief valve on across the front cover. There's a reason why Jafro said in his video that the pump itself doesn't produce oil pressure on its own, but rather that's the job of the relief valve and the condition of the pump and all other components.

    The pump gears spin, producing oil flow. The oil then starts to travel to all other areas in the engine where you need lubrication, but the first stop is the pressure relief valve, before the oil filter. The pressure relief valve has been designed to maintain a position which, based on engine RPM, provides the most optimal oil pressure that our engines need to stay healthy. It does so by moving in or out (aided by a stiff spring), essentially acting like a thumb over the garden hose, but not quite. This is also why the factory oil pressure gauge is fitted right after that relief valve, so it can monitor the work of the relief valve and pump.

    Now take a look at this figure:
    unnamed.jpg

    It's a simplified example of what the gear oil pump is. But it outlines the very critical point that I was trying to make earlier and the point which Jafro also mentioned and decided his old pump was junk.
    The majority of the oil flow moves along the outer edges of the pump housing and continues on to the relief valve. The pump has been designed with a specific flow potential at given RPMs if it's still within tolerance/spec. As soon as you get wear either on the gear teeth, the gear faces or the surfaces which the gears ride against, you get an increased volume of unwanted oil flow, or in other words, oil flow which the pump and pressure relief valve were not designed to run with. That's why the manual has a maximum wear on the gear teeth to side clearance as well as gear faces to pump housing surface. (And although you can't technically put a feeler gauge in those grooves for example, you can usually apply the same fingernail scratch test that you would in other situations where bearings and oil come into play.)

    If you exceed those limits, either by wear from dirty or improper oils, or by having the grooves we can see in the above pics, you essentially change the oil flow and volume going through the pump. Thus, the relief valve will take the oil pressure out of the optimal range, which can lead to premature engine wear due to oil starvation in certain parts.
     

    Street Build 4K  13

    1997 Eagle Talon TSi AWD
    13.43 @ 99.7 · 2G DSM
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  13. 1cleangsx

    1cleangsx Proven Member

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    Cheyenne, Wyoming
    Very informative! I appreciate all the responses, I’ll definitely just buy a new cover with the gears and inspect/measure clearances as Marty suggested, is anybody out there running the gsc race shaft with the helical gears?
     

    Street Build 2K  11

    1990 Mitsubishi Eclipse GSX
    13.2 @ 104.64 · 1G DSM
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  14. bastarddsm

    bastarddsm Proven Member

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    Mendota, Illinois
    Lay a piece of 400grit wet/dry on glass. wd40 and run that part around in fig8's for a bit and see what it looks like. If it was easy to get a new pump I would, but I'd not throw that a way. Might come a day when that's all you have. I've never fretted about the straight vs helical nonsense. My car goes 10k often, been 11 when a trans broke. has a stub shaft.
     

    Showcar Build 6K  1

    1991 Eagle Talon N/T
    9.805 @ 144.00 · 1G DSM
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