12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

Vacuum Problems!

Old Aug 27, 2011 | 09:52 PM
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Default Vacuum Problems!

I am having vacuum problems, I think its the vacuum pump/power steering pump seal. I have some oil leaking from that area so I am hoping that is the source of my problems. Does anyone know what type of pressure I should be seeing out of the vacuum pump? I am seeing 20psi currently but I can only run one vacuum line and have it work. If I plug in the 4 wheel drive actuator and the vacuum line to the heater control neither will work but if i only have one plugged I have enough vacuum to operate that part.
 
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Old Aug 27, 2011 | 10:59 PM
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Old Aug 28, 2011 | 12:54 AM
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Default Vacuum Problems!

Sounds like a small leak to me check all your vac lines and also is there cruise control on your truck? In my 24 valve the cruise is also powered by vac
 
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Old Aug 28, 2011 | 01:43 AM
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Originally Posted by BACONBITSFORU
Sounds like a small leak to me
Yep, look for the leak(s). There's a bad piece of tubing or loose connection in there somewhere...
 
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Old Aug 28, 2011 | 02:17 AM
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I found a "manifold" of sorts underneath the cowl on mine that had a vacuum cap that was dry rotted and leaking. I would look at stuff like that.
 
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Old Aug 29, 2011 | 12:49 PM
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All my vacuum lines are holding pressure that's why I am thinking it's the pump seal. I checked the T in the lines. I hope it's just the seal which is $11 @ cummins
 
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Old Sep 3, 2011 | 11:24 AM
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I replaced the seals in the vacuum pump, I am now getting 30psi of vacuum from the pump, does anyone know what type of psi should be coming from the vacuum pump?

once i got everything re assembled my brakes are acting up, I didn't touch any brake lines does anyone know if the power steering line effects the brake master cylinder ?
 
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Old Sep 3, 2011 | 11:58 AM
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I thought they started the hydra-boost brakes on the 2nd gens? If so, vacuum would have nothing to do with the brakes. In any case, 30 Hg (not psi!) would seem an exceedingly healthy vacuum, if that is in fact what you are measuring - which I doubt.

Sumpin' don't sound right, I'm not getting it....

Let's hope we don't have some vacuum and brake lines switched around somewhere!
 
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Old Sep 3, 2011 | 05:10 PM
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Yeah 30" Hg is pretty damn good. And to answer your question, yes, the power steering line does affect the brakes. It's used with the hyrdaboost "power brakes."
 
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Old Sep 5, 2011 | 11:56 PM
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sorry about the PSI- HG confusion, I haven't done much with vacuum stuff.
 
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