Question about Vacuum Source for Power Brakes

Discussion in 'Diesel Tech' started by Jim, Oct 19, 2001.


  1. Jim

    Jim High Wheeler

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    I am getting a 1977 Diesel Scout Traveler tomorrow. It had a factory new
    turbo diesel installed about 40 k miles ago.

    The owner says the power brakes dont work because the manifold vacuum pump doesnt work for some unkown reason.

    My 80 Turbo Diesel uses the alternator as the vacuum pump. But this guy doesnt
    think the alternator on his Scout is this type.

    Does anyone know if some Diesel Scouts used some other kind of pump? In any case
    is there an electric pump that I could make work? Or a pulley type that installs easily in place of AC or ....?

    Also, this scout uses a vacuum source to shut off the motor. i.e. without it, one has to open the hood and manually shut it down for now. I suspect it will be easy to install a cable shut off which I prefer, am I correct in thinking this will be a relatively easy solution to the shut off?
    Jim
     
  2. John Donnelly

    John Donnelly Administrator Staff Member Administrator Moderator

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    VACUUM SOURCE

    Jim,

    Where did he get this engine from?

    Diesel Scouts only used the systems that your current Diesel has. All of this vacuum operated stuff is either custom or from a later model vehicle.

    As far as a vacuum pump goes, the electric pumps from a Chevrolet (ohh my fingers are burnt from typing that word!;) ) Cavalier usually seem to be the favorite. But, any vacuum pump is gonna be $$$, so be warned.

    I have the correct alternators, and pumps, get a look at his alternator, and see if there is a shaft sticking out of the back of it, odds are good that they just didn't install the pump, even the later model Hitachis with internal regulators still have the pump on the back, so I find it hard to believe that it doesn't work. My bet is the hose to the brake booster is no good or the check valve is inoperative if the pump is present.

    As far as making it "IHC correct" it should be easy, I can help you with that when the time comes.

    Keep on Dieselin',

    John Donnelly
     
  3. Jim

    Jim High Wheeler

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    I got the Scout, here's more info on the Vacuum Dilema

    Hey John,

    Thanks for the reply. Here's a long story that could be longer. I think there's a question or two in here somewhere.

    We had a nice flight down to Grass Valley. I picked up the Scout and drove it home. After an hour of driving, it occurred to me that I had payed way too much for the traveler. Too late to cry about that now.

    The alternator is the Hitachi. Same as the one on Diesel Daisy. There is no vacuum (or very little) produced by the pump on the back of the alt. and it is leaking oil a lot. I think there are other engine oil leaks on the driver side too but its dark and I wont be looking it over until tomorrow.

    I know there is an oil seal for the vacuum pump, do you know where I can get one? The alt. is charging fine, but something must be wrong with the pump. Do you have any suggestions on what I should do to diagnose it? It has a new master cylinder and power brake unit, so once I fix this oil leak and vacuum pump I should have good brakes and not so much oil consumption.

    Man I could use a few hours of Diesel Chat with you and Eldon sometime soon! This beastly Scout needs some attention and I dont know where to begin. That auto tranny is a dog, I cant wait to find a rust free Scout to put this nice looking diesel motor into.
     
  4. John Donnelly

    John Donnelly Administrator Staff Member Administrator Moderator

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    Vacuum pump update

    Jim,

    The seals and new vacuum vanes are available from JESCO, the whole kit is around $50.00 last I heard.

    This is easily rebuilt, and your manual gives you instructions on how to do it.

    I agree about the leaking causing what could be construed as oil consumption, and if the pump is leaking then it won't make good vacuum. Other leaks over there could be the oil pressure line to the vacuum pump, the return line to the vacuum pump, or both.
    The pressure line is a Nissan Item, and you can get the return line from them too, but a piece of high temp hydraulic hose works fine for the return line, and is far cheaper than the fancy molded hose that Nissan will sell you.

    I disagree about the Automatic being a total dog, sluggish, yes, dog, no. My mother drives a 4:10 axled 76 Diesel Traveler and it scoots just fine.

    I would bet that all of the linkage is not installed correctly as I explained to you in the email I sent you a week ago. If the Turbo boost sensing line is not rebent to clear the kickdown linkage, then the transmission will never shift correctly.

    You will also have no "passing gear" as they call it, I refer to it as "part throttle downshift" which is more accurate in my mind.

    What gears do the axles have? If they are 3:73, then acceleration should be accepable, not in the realm of a T-19 equipped Diesel Scout but acceptable.

    3:54 axle ratios are kind of tall for the first gear in the 727 automatic, but they will work too.

    I agree with most that the 727 behind the Diesel was not one of IHC's better moves, but let me tell you, it is awesome off-road.

    As far as chat, not sure when Bill will get that going again, maybe setting up a Schedule for an ICQ chat might be in order from my end in the interim. Maybe Thursdays at the usual time? I will post a poll.

    Keep on Dieselin',

    John Donnelly
     
  5. Jim

    Jim High Wheeler

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    New Diesel with Problems

    Thanks for the reply.

    I think there must be something wrong with the tranny or the motor.

    The tags on both axles read 4.09 so I expect the acceleration should be good. I checked the kickdown linkage, it looks good. I cant seem to tell where the oil is leaking on the driver's side. But I think I will just pull the pump off and inspect it and the hoses.

    I noticed that the Engine compartment was getting very hot during the day and on hills. It runs a lot smoother when cold or cool. Dont know what this could be.

    It also has a wierd vibration that comes and goes, I think it could be the tranny mount. Sometimes It feels like Im driving on those little bumps they put on the edge of some highways to wake the driver up. I guess I should also check out the front bearings and ujoints etc...
     
  6. John Donnelly

    John Donnelly Administrator Staff Member Administrator Moderator

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    The tags on both axles read 4.09 so I expect the acceleration should be good. I checked the kickdown linkage, it looks good. I cant seem to tell where the oil is leaking on the driver's side. But I think I will just pull the pump off and inspect it and the hoses.

    Looks can be deceiving.

    Is the spring that attaches to the firewall located at the left rear corner of the engine on the drivers side connected to the linkage? If it is, is the linkage up against the Turbo Boost sensing line that runs from the turbocharger to the injector pump? If it is, and the line hasn't been relocated, the transmission will not shift properly.

    Also the linkage rod on the passengers side that connects to the rack lever has to be 14.70 inches long. This is measured from the centerline of the adjustment block at the rear of the motor to the ball-stud at the injector pump. This is the first dimension that must be checked, and if improper, reset before troubleshooting further.

    Also, the throttle cable should have a measurement of .310" from the plastic stop on the cable to the front edge of the bracket that it mounts to. If this measurement isn't correct you won't get full throttle when you floor it.

    If these measurements are set, or corrected to what was previously mentioned, then with the accelerator depressed fully, the rack on the injector pump should be "full throttle" or "wide open". If it isn't, adjust the ACCELERATOR CABLE until you achieve this.

    Note that none of this will help unless the kickdown spring is present and not blocked by the turbocharger sensing line.

    As far as the leak goes, my bet is the seals on the vacuum pump are shot. That or when the engine was swapped someone used a wrench on the wrong part of the pressure line fitting to the vacuum pump, and stripped it from the hose.

    As far as the vibrations, how good are the tires and when was the last time they were balanced?

    The engine runs hot on hills...... no thermostat, or inoperative thermostat. A common SD33 abuse. Check to see if the thermostat is present, and if it is, see if it works by putting it in some hot water and recording the temperature that it opens at. Never use a thermostat hotter than 180 degrees if you have to replace it.

    Let us know your findings.

    Keep on Dieselin',

    John Donnelly
     
  7. Jim

    Jim High Wheeler

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    Great Info

    I will look into these linkage dimensions this week while Im doing the other maintenance items. Did you get those numbers from a manual? Or are you going by the set up on one of your scouts?

    PS this traveler has a 33 gallon tank on it. Just noticed that this morning.
     
  8. John Donnelly

    John Donnelly Administrator Staff Member Administrator Moderator

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    Jim,

    All that information came straight from the transmission section of the Scout II XLC manual.

    All information was validated on a 76' Traveler Diesel with an SD33T retro-fit that I service.

    Keep on Dieselin',

    John Donnelly
     

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