Zero oil pressure

Discussion in 'Fox 5.0 Mustang Tech' started by slow5ohgt, Nov 24, 2012.


  1. slow5ohgt

    slow5ohgt Member

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    Decided to start a new thread since my other thread was poor performance related.

    To recap, after a long series of small fixes, lots of cursing, and roughly three bottles of scotch, I got my 89 gt running correctly. First successful teat drive was night before Thanksgiving. Drove 50 miles to inlaws for Thanksgiving on Thursday morning and lost oil pressure less than a mile from their house. Abandoned the car in a cracker barrel parking lot and trailered it home tonight.

    Once i got it in the garage i pulled the distributor and found the pump shaft broken in half. I can see both pieces through distributor hole. My plan is to use a magnet to pull them out, then install a new shaft and use a priming tool to spin pump with a drill. If it doesn't have any excessive resistance and it produces oil pressure I will reinstall and test drive. Does anybody see any flaws in that plan or suggest any extra steps?

    Sent from my SAMSUNG-SGH-I717 using Tapatalk 2
  2. ratio411

    ratio411 Founding Member

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    The top of the shaft will have a ring on it to prevent it from being pulled up through the top.

    Being broken in half might allow it to come out one of the top openings, I have never had one break in half.
    Give it a try, but DON'T expect it to come up through the small hole. You might manipulate it to a larger opening.

    The real thing I'd worry about is why it broke.
    There is a reason, and you have to figure that out or nothing will change.


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  3. srtthis

    srtthis the guy doing it does every local racers rear end

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    what he said... you wont be able to pull old shaft out or put new shaft in...
    other then that you can use a 1/4" drill hex shaft for a primer...
    as for why it broke. the stock one is a 1/4" hex shaft and its pretty much a POS..
  4. slow5ohgt

    slow5ohgt Member

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    Couldn't the ring just be removed so that it can be installed from the top like an oldschool 302?

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  5. ratio411

    ratio411 Founding Member

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    Agreed, however even the stocker doesn't break for no reason.
  6. mikestang63

    mikestang63 Mustang Master

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    Something went wrong or it was defective. Did the top piece that broke off have the ring on it? If not, I don't see how how you get t out that hole when it is designed not to. The ring is machined into the shaft.

    Here is a picture of the stock one

    [​IMG]

    Here is a chrome moly FRPP shaft that is stronger than the stock one I use instead of the stock one.

    [​IMG]
  7. slow5ohgt

    slow5ohgt Member

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    *UPDATE*

    Ok, I started tearing into it tonight. After about 30 minutes of trying to pull the peices out the top (I almost got them) I said screw it and started removing the pan. Took about 45 minutes to get the pan loose. A note for anyone who comes across this post in the future, you can get the pan loose and drop it onto the crossmember far enough to work with the shaft and pump if you remove the rack. I did not have to remove motor mounts to do this. Once pan was dropped I removed the shaft peices and snaked the new shaft into place. The ring that is on the new shaft is not machined, its just a pressure fit ring, so prior to installing i slid it down the shaft a bit, slid shaft into place and dropped into oil pump, then used a heavy duty pick to push ring upwards while holding shaft with pliars, locking shaft into place. Pump spins freely via drill with shaft in place. Reinstalled distributor and locked it down. In the morning I will reinstall pan and rack, fill with oil, and test oil pressure. I will report back with results tomorrow. Thank you for all the support so far. By the way, the old shaft is pretty mangled, looks like a pair of drill bits. Im not sure if its coincidence, but i did an oil change the night before this failure and went with a heavier oil, which I suppose in theory could have increased stress on the old shaft to cause this failure.
  8. Bullitt95

    Bullitt95 Active Member

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    I hope for your sake that you've solved the problem but for the oil pump shaft to get twisted far enough to look like a drill bit, I suspect that a small solid fragment got through the oil pump pickup screen and wedged itself between the oil pump gears.
    Although yours seem to be spinning freely, I'd take a look inside in case that fragment is still there but lying loose ready to wedge itself again.
    ratio411 likes this.
  9. slow5ohgt

    slow5ohgt Member

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    In about to go get stated on it again. I'm going to run a magnet through the pan and see what i get because i agree with you. It seems odd.

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  10. slow5ohgt

    slow5ohgt Member

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    Magnet came out fairly clean in pan, just typical break in material. I decided while i had the pan down i would remove oil pump and just inspect the internals. Its a good thing I did, the backside of the outer gear had a gouge in it where a peice of metal has gotten into it so even though it was spinning freely it would have locked up again. going to get a pump now and start the tedious task of installing it.
  11. mikestang63

    mikestang63 Mustang Master

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    I'm still concerned as to why the shaft twisted. My guess is something got by the screen in the pickup, got stuck in the oil pump gears and twisted the shaft. While you have it apart, check for restrictions in the oil pump pickup . Is this a recent build? I would stick a large magnet on the bottom of the pan in the sump area so that any future metal pieces dont get sucked up into the oil pump pickup. Are you replacing the oem shaft with another oem piece?

    Cut the filter in half and see if there is anything metal in there.
  12. slow5ohgt

    slow5ohgt Member

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    The metal that was in the pump looked to be a peice of metal from the gears themselves. The clearance on the OD of the larger gear was more than i would prefer. I checked the screen while the pan was down and it was clear. Also ran magnet through pan and even wiped pan out with rag to see what I got. Very minor dusting of metal in the fluid, but nothing more than what i would consider normal over time. The build is not fresh, Its a stock motor with 140k miles. Pump and shaft were both original. The replacement pump is a melling standard volume pump, I didnt go with the high volume pump because the motor doesnt need it. I have a 351 on a stand and plan to keep the 5.0 stock and just do a direct swap. The shaft im replacing with is also a stock shaft. The way I figured it if i put a hardened shaft in and something like this happened again, its just going to shear the pin on the bottom of the distributor and ill still be screwed, so i didnt see the point in shelling out the extra cash for a stock motor. I may be wrong about that, thats just my thoughts on it.

    Ive got the pump in and im putting the pan back up now. Then all thats left is to reinstall the rack, put oil in it, and crank it to see if the problem is fixed. Ill report back.

    *edit*
    Oh and regards the filter. The filter was installed on wed night, but when i swapped it, I did cut the old filter (the one that was on the car for 5 years while it was sitting in the previous owners driveway after he popped the freeze plugs) and it was clear of major debris.
  13. clement

    clement Founding Member

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    the first thing i would do is get away from cheap oil pumps, whether HV or not.
  14. slow5ohgt

    slow5ohgt Member

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    so in other words if i were to continue running this motor for years and years i should expect the same problem again in the future? I suppose thats a little more motivation to get my 351 build moving forward.
  15. clement

    clement Founding Member

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  16. slow5ohgt

    slow5ohgt Member

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    I didnt clarify my point very well on the 351. Im not building the 351 stock, its going to be a HCI build and WILL have hardened shaft, high volume pump, and aftermarket rotating assembly.

    Repair on the 302 is complete. Car has oil pressure again. When I first started it, all the lifters were stuck, presumably from being slammed shut when it lost oil pressure. I let it warm up to operating temp and then flogged the throttle a couple times and it popped them loose and motor quieted down. Test drove car for 20 minutes and all is well, pulls strong, no odd noises, no unusual fluctuations in oil pressure. Worst problem i ran into is i couldnt get the damn thing cranked because i had the dizzy 180 out. Finally clicked in my head what was wrong.

    Thank you guys for all the support as I tackled this.
  17. mikestang63

    mikestang63 Mustang Master

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    glad to hear everything is fixed. I'd say the standard volume melling pump will be fine on a relatively stock motor They last 100k miles from the factory. I agree in not going cheap on a poop boys unit.
  18. Exile

    Exile Active Member

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    It seems he is already using a good Melling oil pump. That and you can get that same base oil pump on Summit for half the price.
    http://www.summitracing.com/parts/mel-10687
  19. clement

    clement Founding Member

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    that is the standard volume race pump. since he didnt give a model # i am assuming he is running one of the $30 pumps.http://www.summitracing.com/parts/mel-m68/overview/make/ford

    google melling and powdered metal. notice i recommended the blue printed race pump. i can send you pics of a crank and rods after the powdered metal gears in one of the cheap pump came apart at 6000 rpm. i had to break a set of arp pro series rod bolts to get the rods off of the crank. is the pump i recommended double the price of a melling race pump, yeah. but since melling has started cutting corners to make more $ i now dont trust any melling that doesnt have steel gears and has also been blueprinted. to me $140 is cheap insurance after seeing $3000 worth of callies crank and crower rods toasted.
  20. ratio411

    ratio411 Founding Member

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    Maybe it's just me, but anytime I take down an oil pan, I replace the oil pump.
    It's cheap insurance, and you KNOW there is something wrong since the shaft broke.
    Why take a chance? Just put a new pump in since you went through all the trouble to drop the pan.

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