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vac pump oil line leak


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I took my vacuum pump & power steering pump off as a unit to seal the PS pump reservoir leak.  The oil line is leaking where it connects to the vac pump.  There is a threaded piece that screws into the pump itself then the oil line connects to that piece.  I put oil resistant piece on the threads that screw into the pump.  It looks like the leak is where the nut for the oil line threads onto that piece.

 

Am I missing an o-ring or something?  It looks like it is supposed to be a mechanical seal with metal surface to metal surface but is is a large leak.  Removing the line and making sure everything was clean didn't help.  Any ideas on how to stop it? 

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The fitting that threads into the vac pump came off when I unscrewed the line.  I put pipe dope on it just because and don't think that connection is leaking.  The connection to the actual line looks like other oil fittings where the male end is rounded and fits into a cupped female side.  I can't see where any o-ring fits but I'm laying in the gravel on my back so it's not like I have a good view. 

 

I took it apart and reinstalled again and it still leaks so something is obviously wrong.

 

here's the fitting https://www.ebay.com/itm/1998-2002-DODGE-RAM-24V-CUMMINS-DIESEL-VACUUM-PUMP-OIL-FEED-LINE-BLOCK-FITTING/122896104694?hash=item1c9d2dbcf6:g:OzkAAOSwTO9aTmCz&vxp=mtr

 

here's the line.  https://www.genosgarage.com/product/ram-cummins-vacuum-pump-to-block-oil-line-3934396/engine-replacement-parts-2

 

Doesn't look like it should leak.  It's raining tomorrow.  I'll look more on Tue but am open to any info.

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Is that not an o ring on one side of the fitting? Hose connection is flared fitting and should not need anything to seal it as long as the matting surfaces are in good shape. Good chance the pump needs re sealing. I just did mine a few months ago, don't believe I messed with that fitting either, but it is dry now.

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16 minutes ago, dripley said:

Is that not an o ring on one side of the fitting? Hose connection is flared fitting and should not need anything to seal it as long as the matting surfaces are in good shape. Good chance the pump needs re sealing. I just did mine a few months ago, don't believe I messed with that fitting either, but it is dry now.

I can't tell from the pic what is on the one side of the fitting.  Pump was resealed previously and is not leaking any place besides the oil line.  Rain looks like it is holding off tomorrow so I'll be able to pull at least the end of the line off and examine.

 

I may call Cummins in Nashville and have them tell me what the sealing mechanism is.

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What I think I've learned is that the connector going into the pump has "NPTF" threads which are the same specs as NPT EXCEPT that NTPF has "interference" threads and seal dry.  I didn't find any specific information that says sealant will prevent them from working but lots of info especially "machinist's forums" say sealant is not needed.

 

The connection to the hose is a "JIC" fitting and also is not supposed to need sealant.

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Looks to me like an oring on one side and jic on the other. Make sure it's not cross threaded or something like that and both metal surfaces make contact, so once tight you shouldn't be able to wiggle metal line. Could be something wrong with mating surface too, they sell copper washers that are deformed to fit in jic to help it seal. 

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I found it at O'Reillys of all places for $3 and change.  Edelmann PN 148420

 

https://www.oreillyauto.com/detail/edelmann-3479/hardware---fasteners-16585/brass-fittings-16690/pipe-thread-fittings-18437/edelmann-1-8-inch-flared-fitting/148420/4290480

 

The Cummins part is upwards of $10.

 

I "think" the threads are "NPTF".  "F" is a fuel designation and allows for a "dry seal".  I'll know tomorrow if it works.  Some machinist's threads said that these fittings are not necessarily reuseable because  the NPTF threads compress to seal.

Here's the specs from O'Reilly's.

 

  • Warranty:  1 Year Limited Warranty
  • Unit of Measure:  Each
  • UPC:  #21597601500
  • Thread Size:  1/8 Inch
  • Tube Size (In):  1/4 Inch

Applications for this product

  • Select a vehicle to see vehicle applications.
  • Detailed Description

    Male Connector - 1/4 Inch Tube (7/16-20) Male SAE Thread X 1/8 Inch Male Pipe Thread; SAE 45 Degree Flared Fitting; Male Connector - 1/4" Tube (7/16-20) Male SAE Thread x 1/8" Male Pipe Thread

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