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Cummins 5.9 oil leak from new vacuum pump gasket??

Camshawn

Senior Member
Joined
Jan 25, 2017
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585
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Langley BC
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retired
In my pickup, replaced the power steering pump and Vacuum pump due to an oil drip from the seal between the two. New gasket on cleaned surfaces between the gear case and the vacuum pump, bolts tight and I am getting an leak from the flange through the gasket on the bottom side. Any advise? Silicone or form a gasket between the gasket and the flanges? The bolts are tight.
Cam
 

Truck Shop

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Dec 7, 2015
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The only sealer I would use is NAPA The Right Stuff and a thin amount at that. Or you could use Indian Head and never take it apart again.
 

Camshawn

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Langley BC
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Thank you all for your replies. I will pull the vacuum pump again this morning to make sure there is not a piece of crap on the face or a fold in the gasket that I missed, then off to Napa to get some sealer. Nothing fresh here at home. I will try to get one of the ones recommended above. Cam
 

Engineer44

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Nov 30, 2017
Messages
60
Location
Portland
Permatex Ultra Black Maximum Oil Resistance is the best stuff I’ve used. Just be sure the parts to be joined are perfectly clean/oil free. I wipe the surfaces with Brrakleen until the cloth shows no discoloring. I’ve sealed some difficult to seal joints years ago and they are still bone dry.
 

Ben Witter

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Apr 3, 2013
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On the outside
What year Dodge? If you thoroughly cleaned both surfaces and there were no defects you should not need any sealer. Did you replace them with new or used parts? If you cleaned them did you use a powered surface prep disc and possibly remove too much material from the timing case? The seal on the vacuum pump is easily replaced with a $20-30 kit
 

Camshawn

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Jan 25, 2017
Messages
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Langley BC
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Truck is a 96 with 260,000 km. The gasket kit for the pump is $110 can$. The aluminum case and insert need to separate to replace the seal. An hour tapping, pressing ect and the 2 would not come apart so a new pump was purchased for $600. There is also some scoring inside the “chamber” from the vanes, probably not enough to cause a problem but....260k. With the cost of a new computer controlled truck and the places we go, I would like to keep this one another 10 years. The only rust is at the bottom of the passenger side fender. I am just going out now to pull it apart again and see if I can spot the root cause of the oil leak. Cam
 

Ben Witter

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Apr 3, 2013
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On the outside
https://www.ebay.ca/itm/Vacuum-Pump...687835?hash=item4d9913b6db:g:ZqoAAOSwyNtdPwOq
https://www.ebay.ca/itm/Cummins-Gen...462896?hash=item23d111d7f0:g:nqUAAOSwKsdbYytF

Seal kits are cheap. The seal retainer just needs some persuasion with a decent sized hammer. But you have already gone down the road you have chosen.

If it is leaking there is either debris left on the surface or the surface is not true. If you are going to use RTV or gasket maker I would just toss the gasket and use the sealant alone.
 

Camshawn

Senior Member
Joined
Jan 25, 2017
Messages
585
Location
Langley BC
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retired
Thanks for the links. I never think of buying parts on line. I found a little thread damage on the new gasket from the bottom bolt. I reinstalled the old gasket(also 10 thousands thicker) and the leak is gone. The only good thing was none of the bolts had any corrosion on the threads. I pulled the pump combination back enough to slip out the gasket, wipe everything clean and get the old gasket back in with the hoses still attached.
Thanks for all the tips. Cam
 
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