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6.1.  Testing One-Way Valves

6.1.1. Many vacuum operated circuits use in-line one-way valves to apply vacuum in one direction only. 

6.1.2. to test the function of the valve remove it from the circuit. Attach the Vs4021 vacuum tester (fig.7) and operate pump to apply vacuum. In one direction the  

 

valve should hold vacuum and in the opposite direction it should not.

6.2.  Testing electrically Operated Vacuum solenoids

6.2.1. Electrically operated vacuum solenoids are commonly used in control circuits for air conditioning/ventilation systems, emission control systems, idle step up 

 

systems etc. and testing the function of these when using the Vs4021 is extremely simple. 

6.2.2. locate the solenoid to be tested and remove the line that goes to the component being tested. connect the Vs4021 to the solenoid port (fig.8) and start    

 

the engine. With the system turned off there should be a zero gauge reading. now turn the system to the 'on' position and a gauge reading equal to the    

 

manifold vacuum should be observed, if no reading exists remove the vacuum supply line and test for manifold vacuum at this point. If the vacuum does    

 

exist this indicates that the solenoid is faulty or it is not receiving a 'switch on' voltage (use a multimeter to test this). If no vacuum exists trace the supply    

 

line back to the vacuum source checking for kinks and breaks.

6.3.  Testing Thermal Vacuum switches

6.3.1. there are many vacuum controlled circuits that must only operate when the engine reaches normal operating temperature. this is done using thermal  

 

 

switches that remain in an 'off’ position until a given temperature is reached. 

6.3.2. to test this type of switch, remove the vacuum supply line coming from the manifold to the switch and test for manifold vacuum. If this vacuum is correct refit  

 

the supply line to the thermal switch and remove the opposing line from the switch. Attach the Vs4021 vacuum tester to the port (fig.9) and start the  

 

 

engine. With a cold engine no reading should be noted. When the engine reaches normal operating temperature a manifold vacuum reading should be  

 

 

noted.

6.4.  Testing Vacuum Operated Heater Taps

6.4.1. climate control ventilation systems are becoming very common on newer vehicles and most of the systems use vacuum operated taps to control the heating  

 

modes. on the majority of makes and models, the system uses vacuum to turn the heater tap 'on'. 

6.4.2. to test these remove the supply line from the tap vacuum module and connect the Vs4021 vacuum tester (fig.10). With the engine at normal operating  

 

 

temperature locate and feel the heater return hose. With the heater tap in the 'off' position, this hose should be cold. now operate the vacuum pump to open  

 

the tap.the gauge reading must hold. If the tap is in working order, the return hose will begin to heat. If the hose does not begin to heat, this indicates that   

 

the tap is faulty.

6.5.  Testing Vacuum Operated Remote central locking systems

6.5.1. some makes and models use vacuum operated bellows mounted in each door to centrally lock and unlock the vehicles doors. these systems use either    

 

manifold vacuum stored in a reservoir for use when the engine is not running or an electrically driven vacuum pump which operates when the doors are    

 

locked or unlocked.

6.5.2. In either system, the Vs4021 vacuum tester is ideal for testing each individual door bellows. to do this, remove the door trims as required. remove the  

 

 

vacuum supply lines from the bellows and attach the Vs4021 vacuum tester (fig.11) and operate to apply vacuum to the bellows. Wait for 30 seconds, no    

 

drop on the gauge should be noted. If the bellows are found to be in order attach the vacuum supply line to the Vs4021 vacuum tester and operate  

 

 

system to test for vacuum supply. If the vacuum supply does not exist or is low trace back down the lines to the vacuum supply looking for kinks, restrictions  

 

or cracked lines. repair as required and retest.

6.6.  Testing Automatic Transmission Vacuum Operated Modulator Valves

6.6.1. Automatic transmissions are normally equipped with a vacuum operated modulator valve in order for the automatic transmission to detect engine loads and  

 

adjust shift points to suit. 

6.6.2. the Vs4021 vacuum tester can be used to test both that the modulation valve diaphragm is serviceable and also to simulate varying engine loads so  

 

 

modulator pressure readings can be recorded. to test the modulator valve diaphragm remove the vacuum supply line from the valve and attach the  

 

 

Vs4021 vacuum tester. operate the vacuum pump until approximately 15inHg is achieved and monitor the gauge reading for approximately 30 seconds.    

 

no vacuum drop should be noted.

6.6.3. to check modulator pressure readings attach a pressure gauge to the appropriate port on the transmission. remove the vacuum supply line from the  

 

 

modulator and attach the Vs4021 vacuum tester (fig.12). start and run the engine and apply vacuum pressures. Monitor readings and confirm that these    

 

are in conformance with manufacturer specifications.

  6.  ADDITIONAl VAcuuM sysTeMs

Original Language Version

© Jack sealey limited 

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Vs4021     Issue: 1 - 08/06/12

Summary of Contents for VS4021

Page 1: ...unction diagnostic tool used to test a variety of essential engine and associated functions including fuel ignition transmission and emissions Kit also includes reservoir hoses and adaptors for bleeding brake and clutch systems on cars commercials and motorcycles Brass bodied vacuum pump features large easy to read vacuum gauge calibrated in both inches and millimetres of mercury 1 safety instruct...

Page 2: ...readings shown below are only examples of what may be observed It is important to remember that it is the action of the needle rather than the actual reading that is more important Varying engine types will run different manifold vacuum pressures depending on camshaft profile valve overlap timing etc so an exact vacuum reading cannot be specified The main criteria is that the needle reading is bet...

Page 3: ...f this vacuum reading is not achieved or the vacuum drops off immediately with the engine shut down the fuel pump requires either overhaul or replacement 5 2 Carburettors 5 2 1 There are many different types of vacuum control systems used on carburettors Using the VS4021 vacuum tester kit allows quick and accurate testing of these systems Listed below are just two examples of tests that can be car...

Page 4: ... connect the VS4021 vacuum tester fig 10 With the engine at normal operating temperature locate and feel the heater return hose With the heater tap in the off position this hose should be cold Now operate the vacuum pump to open the tap The gauge reading must hold If the tap is in working order the return hose will begin to heat If the hose does not begin to heat this indicates that the tap is fau...

Page 5: ...h the appropriate size bleeding attachment to the bleed nipple on the brake calliper of the first wheel normally nearest to master brake fluid reservoir 7 3 4 Operate vacuum pump until approximately 21inHg vacuum is created 7 3 5 Apply copper grease to the brake bleeding nipples before and after the brake bleeding procedure to reduce the possibility of seized or broken nipples when the brakes are ...

Page 6: ...s from purchase date proof of which will be required for any claim INFORMATION For a copy of our latest catalogue and promotions call us on 01284 757525 and leave your full name and address including postcode 01284 757500 sales sealey co uk www sealey co uk 01284 703534 Web Sole UK Distributor Sealey Group Kempson Way Suffolk Business Park Bury St Edmunds Suffolk IP32 7AR fig 14 fig 15 Original La...

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