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Engine/Transmission (1994 - 1998) I think my vaccum pump went out.

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I was backing up a trailor today and as I held slight pressure on my brakes they went from good pedal to hard (no power assist).



I test drove it and after the first pump of the pedal they get a hard feel like theres no pressure there.



I can start my truck with the brakes held and under normal conditions the pedal would get soft after engine start. Now the pedal stays that hard feel.



So what does this mean?
 
what year truck? Do a signature so we are better able to help. Its either a vacum leak or bad pump unless you have hydro boost brakes which started in 97.
 
Vacuum assist loss is "normal" on '94-'96 trucks when using the brakes a lot at idle. The pump just can't keep up with the demand, it's probably the reason DC switched over to hydro assist. You can either wait for the vacuum to catch up, run up your rpms or add additional vacuum storage. A small vacuum tank and a some hose connected to any of the truck's vacuum lines will probably set you back less than $30. Vacuum tanks are available options with many aftermarket cruise controls for cheap and can be bought separately.

You might also have a vacuum leak if the problem occurs all the time, most common place is the line to the cruise control under the drivers side battery.
 
Hydro Boost Upgrade

Who has converted the vacuum brake booster to Hydro Boost? At the price I hear for a vacuum pump, it might be cheaper to by the electric vacuum pump and convert to Hydro Boost if the original vacuum pump fails. What about cost? Same master cylinder? Junkyard items? Thanks in advance.



Ronco
 
Ronco, I've wondered the same thing. Output of my pump seems low. (wonder if that's why the brake light is almost always lit)



With the engine off, if I pump the pedal til it's hard and start the engine, it takes about 6 to 8 seconds for the pedal to fall to normal height.
 
I guess my first step should be checking for a leak somewhere. Any hints on how to check everything? Maybe disconnect everything and close the system with a guage and add things one by one?
 
Pressurize the system with air at low pressure. Then spray things with soapy water. That will check everything but the vacuum brake booster. I don't have my service manual handy, but I think it has a check procedure for the brake booster vacuum.
 
I'm almost positive I did a search of this topic within the last 2 months and found a pretty good discussion on it. It led me to this TSB. I was having similar problems, with the brake light coming on more frequently as time went on, and found that the 11/32" vacuum hose coming off the pump had been softened by fuel/oil and was actually collapsing. I replaced the hose and checkvalve just recently and haven't experienced a loss in brake boost pressure or the brake light coming on, since. Just a thought.



TSB 05-11-99 Models: 1994-1996 (BR/BE) Ram Trucks



NOTE: This bulletin applies to vehicles equipped with the 5. 9L Cummins diesel engine.



Discussion:



A revised power brake booster check valve P/N 05011393AA has been released for service. The new check valve replaces performance has been improved by changing the flapper style check valve to a spring loaded style check valve. The spring loaded style check valve performance is superior especially in vehicles that utilize mechanical vacuum pumps to provide the vacuum source to operate the brake booster. Part number 05011393AA should be used anytime the power brake booster check valve is serviced on the subject model vehicles.



The new part should be used when the vacuum check valve on diesel models are serviced.
 
46mech, the TSB you speak of was a recall on '94-'96 trucks that also came with a seven year warranty on the entire vacuum system.
 
Warrany Extension for Vacuum Components on 1995-1996 Diesel Rams





From: J&L Warranty Newsletter May 1999

Regarding: Warranty Bulletin D-97-10 May 1997



Extension of affected vacuum operated components on 1995 & 1996 Ram Trucks with 5. 9L diesel engine.



The warranty extension on these vehicles applies to quite a long list of LOP'S. The coverage was extended to 7 years and no mileage limitaion.











Recall # 720

. Vacuum Check Valve Revised June, 1997



IMPORTANT DEALER SERVICE INSTRUCTIONS



See also NHTSA Recall Notice 98V068



--------------------------------------------------------------------------------







DEALER SERVICE INSTRUCTIONS Safety Recall #720



Vacuum Check Valve Revised June, 1997 , Please remove and. discard all prior recall notifications (mailed to dealers in May, 1997) from your files and replace it with this revised procedure.



models:



This service requirement applies only to 1995 and 1996 model year Dodge Ram (BR) trucks equipped with a 5. 9L diesel engine ("C" in the 8th VIN position) built from July 40, 1995 (MDH 071014) through July 1, 1996 (MDH 070114).



problem:



The power brake booster vacuum hose on the above listed vehicles, may deteriorate due to oil contamination from the vacuum pump. If this occurs, the vacuum supply to the power brake booster may be restricted and could cause a loss of power assist during repeated quick brake applications. in addition, the oil contamination may cause other vacuum operated components to malfunction, such as the speed control servo, the heater/air conditioning vacuum controls and the 4X4 front axle and transfer case vacuum controls. To prevent this condition, a check valve must be installed on the engine vacuum pump and the brake booster vacuum hose must be replaced.



If the vacuum pump on an involved vehicle has been replaced previously, the replacement pump may have an internal check valve. The threaded vacuum hose nipple on pumps with an internal check valve have a larger hex head and a larger thread size. Therefore, the recall external check valve will not fit, and is no required on these vehicles. However, the vacuum hose assembly must be replaced.



The torque specification for the new check valve has been reduced to 200 in-lbs (23 N-m). Disregard the reference to 38 ft-lbs listed in the parts package instruction sheet.



Service Procedure:



A. Inspect for Vacuum Check Valve:



1. Inspect the engine vacuum pump for the existence of an internal vacuum check valve (Figure 1) or an external vacuum check valve (Figure 2).



NOTE: If the vacuum pump on an involved vehicle has been replaced previously, the replacement pump mav have an internal check valve. The threaded vacuum hose nipple on pumps with an internal check valve have a larger hex head and a larger thread size. Therefore, the recall external check valve will not fit, and is not required, on these vehicles. However, the vacuum hose assembly must be replaced.











2. If an external vacuum check valve is already installed (Figure 2), return the vehicle to the owner. No further action is necessary.



If the vacuum check valve is not present and the nipple hex head size is 14 mrn (Figure 1), continue with Section B.



If the vacuum check valve is not present and the nipple hex head size is 22 mm (Figure 1), the pump has an internal check valve. Replace only the vacuum hose assembly per the instructions in Section B.



B. Install Vacuum Check Valve and/or Vacuum Hose Assembly:



1. Disconnect the 1/8" HVAC vacuum line from the tee in the vacuum hose that runs between the vacuum pump and the brake booster (Figure 2).



2. Remove and discard the vacuum hose that runs between the vacuum pump and the brake booster (Figure 2).



3. For vehicles with a 14 mm pump nipple hex head size: Remove and discard the vacuum hose nipple from the vacuum pump.



CAUTION: DO NOT remove the 22 mm nipple (if equipped). The internal check valve components will become dislodged.



4. For vehicles with a 14 mm pump nipple hex head size: Install the provided check valve on to the vacuum pump. Tighten the check valve to 200 in-lbs (23 N-m) (Figure 2).



5. Install the supplied hose clamps on the ends of the provided vacuum hose assembly.



6. Install the hose assembly on to the vacuum pump nipple and the brake booster nipple such that the vacuum tee in the center of the assembly points upward (Figure 2). Secure the hose assembly to the vacuum pump and brake booster nipples with the hose clamps installed previously.



NOTE: The vacuum hose assembly must be routed above the power steering hoses.



7. Secure the vacuum hose assembly to the engine wiring harness near the rear of the fuel injection pump with the provided tie strap (Figure 2).



8. Connect the 1/8' HVAC vacuum line to the hose assembly tee.



Completion Report and Reimbursment:



Claims for vehicles which have been serviced must be submitted on the DIAL System. Claims submitted will be used by Chrysler to record recall service completions and provide dealer payments.



Use one of the following labor operation numbers and time allowances:



Labor Op # Time Allowamce

Inspect vacuum check valve 09720181 0. 2 Hr

Inspect and install vacuum check valve

and/or replace vacuum hose assembly 09720182 0. 3 Hr



Add the cost of the recall parts package plus applicable dealer allowance to your claim.



NOTE: Any other vacuum operated components must be diagnosed and repaired according to the appropriate service procedures and a separate warranty claim must be filed for reimbursement.



Note: See the Warranty Administration Manual, Recall Claim Processing Section for complete recall claim processing instructions.



Additional notes:



Effective immediately all repairs on involved vehicles are to be performed according to this Recall Notification. The Labor Operation Number for TSB 24-16-96 is being canceled. Vehicles that have already had this repair performed, as determined from our warranty records, have been excluded from this notification.



7 Year/Unlimited Mileage Vacuum Operated Component Warranty:



Vehicles involved in this recall also have a 7 year warranty (with Unlimited mileage) on all affected vacuum operated components such as the power brake booster, the speed control servo, the heater and air conditioning vacuum controls, and on 4X4 vehicles, the front axle and transfer case vacuum controls. If any conditions covered by the extended warranty are found, now or in the future, dealers are to correct these conditions free of charge. Refer to Warranty Bulletin D-97-10 to be issued in late May, 1 997 for specific details of coverage. Parts for any of the covered components should be ordered through the normal means. Parts Packages: Each involved dealer, to whom vehicles in the recall were invoiced, will receive enough Check Valve Packages to service about 50% of those vehicles.
 
Well, I guess I was in the dark about it because I never got a notice for that recall. I looked thru my maintenance records to make sure. Go figure! The 8th digit of the VIN did match the recall, but maybe I didn't get the recall 'cause my truck was built in May. But the check valve that the TSB calls to replace is the plastic one that is plugged into the power booster, not the one on the pump. What gives with that?

Interesting... ..... I guess I'll check to see if the nipple on the pump has a 14mm or 22mm hex head. Thanks for that info. That's what is so good about the TDR. :)
 
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