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Briggs & Stratton classic 450 series, Maintenance Manual

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Briggs & Stratton classic 450 series Maintenance Manual Download Page 20

Engine Model:

  

 

Briggs & Stratton 
Classic,  
450  and 500 Series  
 
                                          

 

                         

 

 

Page 

20 of 32 B&S Classic, 450 and 500 Series Selfhelp 

Guide 2011, Issue 1.0 

7  Pull Cord Not Pulling or Snatching Back 

 

QUICK TROUBLESHOOTING GUIDE:
Problem:

 

Likely Cause:

Solution:

Pull cord will not 
pull

 

 
 
 

•

 

OPC not engaged

 

•

 

Grass caught between 
the  blade and the deck

 

•

 

“Hydraulic lock”

 

•

 

Hold OPC in (see A)

 

•

 

Remove grass from the 
blade (see B)

 

•

 

Remove oil from cylinder 
(see C)

 

 

Cord snatches 
back

 

•

 

Blade rotation is impeded

•

 

Blade is unbalanced or 
damaged

•

 

Free blade (See D)

 

•

 

(See E) and refer to dealer

 

 

A: 

The OPC lever must be held fully in to the main handle before the pull cord 
can be pulled and the engine can run.  If the OPC lever is fully engaged and 
the cord will only pull out 4” or so, see 

C

 below.   

 

B: 

Remove the grassbox.  Now remove the HT lead (spark plug cap) for safety 
reasons, then lift the front wheels until the handles reach the ground at the 
rear.  Free any grass caught between the blade and the deck.  Stand the 
mower back on the ground on all four wheels, replace the cap on the 
sparkplug and start in the normal way. 
 

C: 

Hydraulic Lock occurs if the mower has been tilted forwards and oil settles  
between the piston and cylinder head, sticking the piston to the cylinder roof. 

 

Remove and clean the spark plug completely.  ONLY USE A GENUINE 
SPARKPLUG SPANNER.  

Do not replace the plug yet.

 

 

If the cord will not pull free, tilt the mower BACKWARDS, reach underneath 
and turn the blade (in either direction) to free it.  Clear any grass blockage.

 

 

With the sparkplug removed, prime the engine 6 times with the primer 
button, hold in the OPC lever and pull the engine over with the pull cord 6 
times to eject any oil from the spark plug hole.

 

 

Replace the plug and start the engine in the normal way.  The engine might 
smoke quite badly at first, but allow the engine to continue running for at 
least ten minutes.  The smoke will begin to dissipate.  Let the mower run 
until the smoke has gone.

 

NB  During subsequent uses (for maybe a further 8-10 hours) the mower may 
smoke a little.  Droplets of oil may come from the exhaust onto the deck as 
the oil is cleared from the cylinder.  Simply wipe these away with a cloth. 
 

For best practice, only to tip your mower BACKWARDS. 

 

Summary of Contents for classic 450 series

Page 1: ...s and Smokes Heavily 15 6 Engine Cutting Out or Running Unevenly 17 7 Pull Cord Not Pulling or Snatching Back 20 8 Cutting and Collecting Grass Vibration 22 9 Loss of Drive on Self Propelled Mowers 10 Transportation and Handling 26 30 11 Maintenance and Storage 31 12 Guarantee Spare Parts Repairs 32 If after reading this guide you feel you are either unsure of what is required or that you do not h...

Page 2: ...Only use the lawnmower for the purpose for which it was designed i e for cutting and collecting grass Any other use can be hazardous causing damage to the machine Examples of improper use may include but are not limited to Transport of people children or animals on the machine Being transported by the machine Using the machine to tow or push loads Using the machine for leaf or debris collection Us...

Page 3: ...the screws and cutting assembly are not worn or damaged Replace worn or damaged blades and screws in sets to preserve balance 6 Before mowing attach the discharge opening guards grass catcher or stone guard OPERATION 1 Do not operate the engine in a confined space where dangerous carbon monoxide fumes can collect 2 Mow only in daylight or good artificial light 3 If possible avoid operating the equ...

Page 4: ...GE 1 Keep all nuts bolts and screws tight to be sure the equipment is in safe working condition Regular maintenance is essential for safety and performance 2 Never store the equipment with fuel in the tank inside a building where vapour may reach a flame or a spark or a source of extreme heat 3 Allow the engine to cool before storing in an enclosed space 4 To reduce the fire hazard keep the engine...

Page 5: ... Grasp the machine at the points that offer a safe grip taking account of the weight and its distribution Use an appropriate number of people for the weight of the machine and the characteristics of the vehicle or the place where it has to be placed or collected 2 During transport fasten the machine securely with ropes or chains ...

Page 6: ...ne holds 0 5 litre of oil the other engines hold 0 6 litre of oil NB Wipe the dipstick then fully replace it by screwing it in now withdraw it to gain an accurate reading The use of multi viscosity oils in hot temperatures will result in a higher than normal oil consumption It is important therefore to check the oil level more frequently Do not mix oils of different brands and features Do not over...

Page 7: ... spark jump across the end of the plug H T Lead spark plug cap and Spark Plug Spark Plug The spark plug gap for all these Briggs Stratton engines should be 0 76mm or 0 03 30 1000 Champion LM19 or QJ19LM DRAINING FUEL We advise that the engine should be drained of fuel before storage for more than 30 days One should only buy fuel in quantities that can be used up within a few weeks When emptying th...

Page 8: ...arry out any sediment with it Engine Oil Mountfield MX855 SAE30 lawnmower oil 10W 30 oil Oil capacity is 0 5 litre for 450 Series engines other engines 0 6 litre Mountfield MX855 four stroke oil is readily available through either the B Q chain or through our own dealer network Option 1 this is the more convenient method for these engines To drain oil from the oil fill tube run the engine to warm ...

Page 9: ...s Selfhelp Guide 2011 Issue 1 0 ENGINE MANUFACTURER S RECOMMENDATIONS As a guide the information below has been copied from the engine manufacturer s user manual Classic and Sprint engines NB Please refer to the engine manufacturer s manual for specific information on all engines 450 Series Engines ...

Page 10: ...the rear 2 Check the H T lead 1 in the diagram is correctly fitted to the spark plug 3 On 400 Series engines only set the throttle lever to the FAST position 4 Push the primer bulb 1 at least three times When starting from cold or for new engines it may be necessary to prime the engine eight to ten times continuously to bleed the fuel system of any air pockets 5 Check the Operator Presence Control...

Page 11: ...air filter unit and remove the foam from within If very oily squeeze the sponge into some kitchen roll to remove any excess oil Then clean the sponge in hot soapy water Dry it thoroughly then work one tablespoon of oil into the sponge so that it is sticky to the touch Re install the air filter 3 The air filter should be checked and maintained once a month during the cutting season especially if th...

Page 12: ...ot hear petrol squirting into the engine or feel no resistance to your finger as you press the primer button check there is at least a third of a tank of fresh petrol Again prime the engine If there is still no evidence of petrol being fed to the engine there may be an air lock Remove the air filter assembly from above the primer bulb It is held by a long screw flat bladed screwdriver required Onc...

Page 13: ...n or stain a patio iii Remove the grassbox remove the fuel cap and tip the mower BACKWARDS to drain as much of the fuel as possible iv For the fuel which remains in the tank carefully dip a clean rag into the fuel tank do not force it in as you could damage the fuel pick up pipe Allow the fuel to soak into the rag remove it Repeat this until the old fuel is removed Arrange safe disposal of fuel so...

Page 14: ... covering directly below the fuel filler 3 Release the plastic cable cover by compressing the 2 lugs inwards on the end of the plastic cable cover that are splayed out and hold it in place Feed the black plastic cable cover BACKWARDS through the bracket to release the cable 4 Disconnect the Z end of the OPC cable from the lever which moved when you held the OPC bar back to the handle in Step 2 abo...

Page 15: ...ray is in place to catch the oil Tilt the machine backwards onto the rear left wheel closest to the oil fill three wheels will be clear of the ground As the angle increases the oil will pour from the fill and into the tray Drain excess oil and make sure the level of oil in the tank does not show above the MAX mark on the dipstick Engine Oil Mountfield MX855 SAE30 lawnmower oil 10W 30 oil Oil capac...

Page 16: ...Dry it thoroughly then work one tablespoon of oil into the sponge so that it is sticky to the touch Re install the air filter Never cut grass with the air filter assembly removed Remove and clean the spark plug completely ONLY USE A GENUINE SPARKPLUG SPANNER With the sparkplug removed prime the engine with the primer bulb 10 times hold in the OPC and pull the engine over with the pull cord 6 times...

Page 17: ...aphragm sits Otherwise refer to a service dealer Primer bulb has a hole in it Mice sometimes chew a hole in the rubber primer bulb over the winter period Replace the primer bulb see B or refer to a service dealer A Changing the Diaphragm These engines do not have a petrol pump They have a DIAPHRAGM When the diaphragm is ready to be replaced typically after some 18 months use it leaks air and feeds...

Page 18: ...E THE CARBURETTOR AND FUEL TANK 1 Remove the 5 screws securing the carburettor to the tank 2 Remove the carburettor from the tank 3 Remove the diaphragm and gasket from the tank REPLACE THE DIAPHRAGM AND GASKET 1 Place the new diaphragm on the tank top then place the new gasket on top of the diaphragm NOTE It is worthwhile cleaning around the top of the tank with a clean cloth with some petrol on ...

Page 19: ...repair If you are of a mechanical or practical nature you can buy the part from a local parts service dealer Using the instructions and diagrams in A above and remembering to work cleanly and not introduce dirt when carrying out this procedure 1 Remove the carburettor and fuel tank and separate the carburettor and fuel tank as described above 2 Slide the jet screen off the carburettor body Please ...

Page 20: ...ur wheels replace the cap on the sparkplug and start in the normal way C Hydraulic Lock occurs if the mower has been tilted forwards and oil settles between the piston and cylinder head sticking the piston to the cylinder roof Remove and clean the spark plug completely ONLY USE A GENUINE SPARKPLUG SPANNER Do not replace the plug yet If the cord will not pull free tilt the mower BACKWARDS reach und...

Page 21: ...on of the cutter causing a snatch back If the engine is cold select a firm surface for starting the mower If the engine is warm always pull the mower back onto a pre mown area where the grass is already short to prevent unnecessary jamming E To check the blade pull the cap off the sparkplug for safety and remove the grass catcher from the rear of the mower Tilt the mower BACKWARDS so that the hand...

Page 22: ...specially in the Spring when the grass may be long and lush do not attempt to cut too much grass at any one time If the lawn is several inches in length then raise the height of cut and gradually reduce the lawn in stages to prevent blocking It may also help to remove the grass catcher cut the grass first on the highest setting and work down to lower settings and collecting the grass If the grass ...

Page 23: ...h of clippings into tiny particles and concealing them in the remaining standing grass Leaving grass to reach 5 6 high would make it impossible for any mower to hide 3 4 of chopped clippings in just 2 of lawn 3 Cut often Remove only one third of the grass length at each mowing Try to mow weekly especially in spring cutting too much at once stresses the grass Every two weeks will probably be often ...

Page 24: ...e securing bolt If these have sheered then the blade can move If the blade mount has failed a replacement can be purchased through your local Mountfield dealer The Blade mount is only likely to fail because the blade has come into contact with an obstruction of some form The blade mount is designed to fail in order to offer some degree of protection to the engine crankshaft Check the condition of ...

Page 25: ...lows air to pass through it If heavily soiled wash it in warm soapy water to clear old deposits of grass juices and debris A good airflow is essential for efficient grass collection 3 If grass is very long remove the grass catcher and work with the deflector plate stone guard in position Clippings can be collected after a few hours drying by simply going over the lawn again with the grass catcher ...

Page 26: ...doubt please contact the Helpline service on 0845 600 2912 Monday to Saturday 9am 5pm and Sunday 10am 4pm A ADJUSTING THE TENSION ON THE CLUTCH CABLE FOR MOWERS WITH THE CLUTCH ON THE RIGHT HAND SIDE OF THE HANDLE a Check the clutch cable runs up the right hand side of the main handle right hand side viewed from behind the mower and through the tension bracket shown as 1 in the diagram above If th...

Page 27: ...ake up un required slack in the cable NOTE The cable should have about of play on it c If the above steps do not return the tension to the cable and restore the drive the cause of the problem may be the belt has come off the drive pulleys see Section B or the clutch cable has broken or become detached see a service dealer B REPLACING THE BELT To replace the belt on these machines it will involve t...

Page 28: ...on the back wheels close to the edge of the workbench 4 Raise the stone guard flap tip the mower BACKWARDS with the handle hanging over the edge of the bench it will stand upright like this 5 Mark the blade so that after removing it you can replace it the correct way 6 Unscrew the blade normal thread so turn the spanner anti clockwise to unfasten 7 Remove the belt guard plate this is the protectiv...

Page 29: ...and re attach the blade the correct way up 11 Carefully lift the mower down onto the ground without tipping it forwards or sideways and replace the spark plug cap and air filter NOTE If the belt repeatedly comes adrift this is normally a sign that either grass is finding its way into the belt compartment or the belt is worn or damaged and should be replaced Whenever ordering spare parts ALWAYS quo...

Page 30: ...helpful to place a weight on the handle to maintain the mower in this position when working beneath the deck Whenever the machine is to be handled raised onto a workbench or transported first remove the HT Cap sparkplug cap 1 Wearing strong gloves and taking account of the weight and its distribution grasp the machine at the points that offer a safe grip 2 Use an appropriate number of people for t...

Page 31: ...leaves or excessive grease Do not leave containers of grass cuttings in rooms 5 Check the stone guard and grass collector frequently for wear and deterioration 6 If the fuel tank has to be drained this should be done outside and when the engine is cool 7 Wear strong work gloves while removing or assembling the blade 8 Keep the blade balanced during sharpening All operations on the blade dismantlin...

Page 32: ...link org uk or telephone the Helpline on 0845 600 2912 This guarantee is not transferable Proof of purchase will be required in the event of a claim Warranty is subject to the mower receiving annual service where there is a warranty for 2 or more years Normal wear and tear and the routine replacement of parts which are subject to normal wear and tear are not covered by this guarantee Likewise any ...

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