3B and vacum

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I've got an '81 BJ42 thats in alot of pieces. Lots of questions but right now I need to know about vacum and how it is used and stored(?). There is a vacum tank bolted to the left frame rail under the drivers seat. Is this tank used to store vacum? I read somewhere that diesels don't make vacum at the intake like gassers do. My friend,he had an old ford p/u with a diesel,says that is not true. I realise that there is a vacum pump on the back of the alternator. What other function does it perfom,there are steel braided lines down to the block beside the oil filter.
Anyway any and all help will be apreciated.
Thanks Caveman
 

Greg_B

 
 
 
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The steel braided lines are the oil supply and return lines to the alternator. Yes, on your 1981 BJ42 the vacum pump off the back of the alt supplies vacum to the brakes for boost assist. The canister on the framerail stores vacum, for multiple brake applications. A diesel does not create vacum, as it is unthrottled, as compared to a gasser.

hth's

gb
 
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Tapage

Club 4X4 Panamá
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In my case my vaccumm reservoir is in the drivers fender on the engine bay. Is a little botle, but separate vaccum to brakes and assist clutch.
 
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tlcruiserman said:
Greg is correct (like normal :) )Here is a picture of the alternator on an 84' BJ42:


Cheers,

Michael
Not trying to hyjack but is that the factory mount for the PS pump ?
 
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smcruisin said:
Looks like it. My ps bracket is from a 84 BJ60 (3B). It bolts right up to the 3B in my 81 BJ42.
Thanks< I will be looking mine is cobbled together down below the Alt.
 
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I looked at mine & I think...

it's located under the right hand side using the the frame brackets that support an F-series exhaust/cat converter. By the way, I have an 81 BJ42

SDC
 

cruiser_guy

 
 
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Mallred, you'll want to be careful as the PS altenator is slightly different from a non-power steering altenator. I can't remember which works with which but one way doesn't give enough swing to get the belt on and then tighten it.
 

crushers

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the old style coarse splines non-PS unit has the tightening tab too far inbound toward the block and you can ot clear the PS pump...
 
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the vacuum is the same as a petrol engine, its just that that vacuum directly controls the fuel regulation, so tapping the intake 'fold for vacuum could make for some interesting driving.

sam
 

Greg_B

 
 
 
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s79bj40 said:
the vacuum is the same as a petrol engine, its just that that vacuum directly controls the fuel regulation, so tapping the intake 'fold for vacuum could make for some interesting driving.sam
Could your explain this please. Remember, we are not including comment on the heathen throttle body butterfly pressure/vacum diaphram fuel control on the 3B...

:D

gb
 

cruiser_guy

 
 
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Greg_B said:
Could your explain this please. Remember, we are not including comment on the heathen throttle body butterfly pressure/vacum diaphram fuel control on the 3B...

:D

gb
Yes please! It's an interesting concept since all of us have never seen vacuum on a diesel like we can on a gasser!!
 
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sorry i didn't realise thottle body/butterfly valve assemblies were a taboo topic. I henceforth retract said comment... diesels now do not have manifold vacuum, its a figment of my imagination.

carry on.
 

cruiser_guy

 
 
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s79bj40 said:
sorry i didn't realise thottle body/butterfly valve assemblies were a taboo topic. I henceforth retract said comment... diesels now do not have manifold vacuum, its a figment of my imagination.

carry on.
Please, nothing is taboo, it's just that we have not seen the source of vacuum present on a deisel in the same way as it is present on a gasser. If you have seen different, please let us know!
 
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Buddy Blew It

I asked my ford( turns out it was a Chevy diesel- oops) diesel p/u friend about the vacum etc. and he admitted he blew it. He asked his HD mechanic daughters boyfriend about about it and he said the Chevy made vacum from a hydrolic pump(ps pump ?) He got rid of that truck along time ago.
thanks
 
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I have been pondering this Vacum ? on Diesels, There must be some or a NA engine woud not get any air for combustion, Why does it have less than a gasser? the 4 cycles on a diesel are the same just the diesels use compression for ignition instead of spark on a gas eng. A fuel injected gas engine has vacum, I am a little confused.

Myrle
 
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