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Discussion Starter #1
So i bought a 6bt vacuum pump and power steering pump assembly. Does anyone know if i can use the drive gear on the 6BT pump or do i need to exchange it with the one off of my stock pump? I just want to know before i go through all the trouble of changing the drive gear.

They look to be the same diameter, though i haven't mic'ed them. The cut looks the same as well, though the 6bt gear is thinner than the 4bt.
 

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I'd say you'll be better off swapping it so the original gear goes back in.
 

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Discussion Starter #4
I'd say you'll be better off swapping it so the original gear goes back in.
I don't really have the tools to do it so that's why i ask. If it's no different, like a few have said then i would rather not change it.

I tried to pull it off with a 2-jaw puller with little success. Even if i get it off,i need a way to press it back on. I was going to take it somewhere to get it done which is even more of a pain and $$$ that seems to be unnecessary.

right now i have 2 yesses, 1 no, and a maybe....
 

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It probably doesn't matter, like crewcab says, you should be fine.
 

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I did the reverse procedure. I installed a 4BT power steering pump on a 1993 6BT to eliminate the vacuum pump. The width of the gear is not as important as the gears tooth pitch. I think you should be just fine in using it.
 

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Discussion Starter #7
cool, i think i'm just going to use it the way it is. thanks for the help.
 

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I don't really have the tools to do it so that's why i ask. If it's no different, like a few have said then i would rather not change it.

I tried to pull it off with a 2-jaw puller with little success. Even if i get it off,i need a way to press it back on. I was going to take it somewhere to get it done which is even more of a pain and $$$ that seems to be unnecessary.

right now i have 2 yesses, 1 no, and a maybe....
You don't need any special tools to get the gear off the vacuum/pwr steering assy.

You'll need to make a "pin", place the pin in the shaft, tighten a bolt against it to draw the gear/eccentric/bearing off the shaft.

I qoute the "pin" dimensions from the FSM: Make a pin from 8mm or .312 hardened drill rod or a 10.9 or SAE Grade 8 capscrew. The Pin is 2 inches in length or 50.8mm

I had a note in my manual; 2 3/4 inch bolt, 1" o.d. washer and square nut. I believe those items came with the reman pwr steering pump I swapped in after resealing the vacuum pump unit. I reinstalled the gear etc by hand with a ratchet and combination wrench, slowly pressed it back on there with a bolt. And a shop vice. And it was a major PITA. And swearing was involved... But I completed the task and it has many, many miles on it now.
 

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I have a 6bt vacuum pump and i've slapped it on my 4bt...however...where the heck does that oil line attach to on the engine? am i missing something?
 

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I have a 6bt vacuum pump and i've slapped it on my 4bt...however...where the heck does that oil line attach to on the engine? am i missing something?
the oil line connects to a fitting on the side of the block
where the oil passage runs, some engines have a t-fitting
the top side goes to the injection pump and then the bottom
of the t fitting runs to the vac pump.
I'm not sure if all the cummins engines have this fitting or not
their is two or three ports in this side of the block in a row.
they have allen head plugs in the ones that are not used.
hope this helps.
if you need me to I can take some pics of the fitting on my engine
and post them for you.:idea:
 

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I have a 6bt vacuum pump and i've slapped it on my 4bt...however...where the heck does that oil line attach to on the engine? am i missing something?
On the 4bt you have (2) 1/8 NPT plugs one is right under the injection pump and the other is right infornt of the lift pump.Both are in the web of the block .

The 4b never had the T fitting ,only P pump 4b ,6b.

Scott
 

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my 4bt has one

On the 4bt you have (2) 1/8 NPT plugs one is right under the injection pump and the other is right infornt of the lift pump.Both are in the web of the block .

The 4b never had the T fitting ,only P pump 6b.

Scott
don't mean to argue but my 4bt has a T-fitting in the side of the block
can take a picture if you like:D
but mine does have a p-pump on it.bouncebounce
 

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Thanks for the info. Take pics please! also, if the hole on the block is female tread and the oil line is also female thread, what male/male fitting do i need?
 

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Once again you have a P pump !


Scott
Ya but you didn't say that to start with you edited your post after I
said mine had one you said 4b's didn't have just 6b-pump.:jester:

just givin you a hard time I've read a lot of you posts and you have
a lot of good information.

just like to have a little good clean fun now and thenbounce
 

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Ya but you didn't say that to start with you edited your post after I
said mine had one you said 4b's didn't have just 6b-pump.:jester:

just givin you a hard time I've read a lot of you posts and you have
a lot of good information.

just like to have a little good clean fun now and thenbounce
The reason I said that is because only 2% 4b had the P pump.:eek:
 

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found a place to put the oil line. Napa made me a really awesome longer oil line to reach it, and a really nice fitting to put the line in the block! thanks for the help!
 

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On the 4bt you have (2) 1/8 NPT plugs one is right under the injection pump and the other is right infornt of the lift pump.Both are in the web of the block .

The 4b never had the T fitting ,only P pump 4b ,6b.

Scott


Thanks for the info. Been a long time since I looked at the engine, but these are Studs rather than NPT Plugs on my particular engine. Location is correct though. Thanks again.
 

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You should also consider making a support bracket for this long assembly. I read somewhere on a web site for rebuilding these pumps that you can crack the housing if you leave off the bracket that connects one of the fasteners holding the two pumps together to the engine. I bought my combo pump unit from a guy that was parting out a 6BT. He gave me the support mount and told me it connects to the injection pump support. Well, it did not exactly fit like that on my 4BT, so I bolted it to the vac/PS pumps, cut it down a little and tack-welded it to the IP support bar with a piece of 3/8" square stock in between the two for the correct spacing. Remove the combo pump and complete the welding and the re-install the assembly.
 

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