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Valve adjustment for smarties!

Discussion in ''How To' & 'Handy Hints'' started by Schmoburger, Jan 20, 2007.

  1. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    ANother longwinded and mundane tutorial brought to you by KC's favourite pedant, Schmeaux!

    If you dont want the theory and just want to adjust your valve clearance, skip to the next post...

    THE THEORY
    If you have owned a VW for any ammount of time, you have no doubt been told of the importance of maintaining correct "valve/tappet
    clearance/adjustment"... if not then it is only a matter of time before it comes up over a beer or two at the pub, over snags on the barbie etc...

    If you are not entirely savvy with the inner workings of an internal combustion engine, you could be siting there thinking.. "hmmm... yeh i should adjust my valves!... hang on... how do I do that??... and why is it so bloody important anyway???"...

    Well... a little bit about valves and associated hardware first.

    In a typical automotive piston engine, the crankhaft is turned by an explosion of fuel/air mixture in the cylinder combudstion chambers forcing the pistons downwards inside the barrels, this movement being transmitted to the crankshaft by conrods... however this is unimportant for the purpose of this excercise.

    Valves are flat, circular things on long "stems" which are pushed into the combustion chamber to allow for the entry of combustion mixture (fuel and air) into the cylinder when it is needed, or to allow exhaust gases to exit into the exhaust system for expulsion into the atmoshere after combustion. for these two operations, there are two different valves in each cylinder, both similar in construction (exhaust valves are slightly smaller) and identical in operation.

    In a VW engine these valves are operated by a metal fulcrums on a shaft, known as rockers. These in turn are pivoted upon there axis by pushrods actuated by a camshaft via solid cam followers or hydraulic lifters. On the intake stroke, the eccentric cam lobe pushes the rod for the inlet valve "up" (actually outwards), which in turn pushes on and pivots the rocker arm, which presses on the end of the valve stem thereby opening the valve and allowing fuel mixture to be drawn into the cylinder. it is then pulled closed by a spring as the cam lobe turns away. The same operation happens on the exhaust stroke, however in this case, the exhaust valve is opening to allow exhaust gases to be pushed out of the combustion chamber.

    For the engine to operate properly, the valves must shut closely against there seat, providing a tight seal. If a valve does not seat fully, the result will be significant loss of compression in that cylinder, and hence a loss of power. ALso, whilst a valve is not seated, it is sitting out in the combustion chamber, so becomes succeptible to the abbrasive effect of the hot combustion gases. Inlet valves are not quite so succeptible to "burning" as they are cooled to some degree by the inlet charge. exhaust valves however are subject to gases exiting at extreme temperatures from both the outlet side and the combustion chamber, so if they do not seat correctly heat that would normally be transferred to the seat remains in the valve, they begin to be erroded by the gases, and will generally burn to the point of dropping a valve
    head into the cylinder within 3-5000km if uncorrected.

    This is where tappet clearance comes into play... to allow for the expansion of components as the engine heats up to operating temperatures, there must be 6 thousandths of an inch clearance maintained between the valve stem tip and the tip of the adjusting screw on the rocker arm when the engine is cold. If enough clearance is not maintained, as the engine heats up, the clearance will narrow to the point of the screw making permanent contact with the valve. As the engine keeps heating up and the pushrods, cam followers, and valve stems lengthen further, the valves begin to no longer seat properly, leading to decreased performance and damaging the valves.

    To ensure valve clearance is maintained correctly, it must be checked with the engine cold after every 6000km... this is also the interval at which the oil should be changed, so it is a good idea to keep your oil changes up to date and check and if necessary adjust valves with every oil change. :)

    If your engine was made after 1977 it will have hydraulic lifters, and hence will not require periodic tappet adjustment.

    Now for the important bit... note that this specifically deals with Type 4 Kombi engines... same principals and clearance values apply for 1600's, however the methods used to locate TDC positions and such vary slightly.

    read on...
     
    Last edited: Jan 20, 2007
  2. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    ADJUSTING YOUR VALVES IN EASY STEPS.

    WHAT YOU WILL NEED:

    1m of thin nylon rope
    14mm socket and ratchet or bar.
    14mm combination spanner
    medium to large flat screwdriver
    large adjustable spanner (shifter)
    prybar (optional but highly recommended)
    10mm open end spanner(only needed if 2nd timing mark is not present)
    30cm length of string (as above)
    liquid paper (as above)
    tape measure (as above)


    PROCEDURE:

    1. Leave engine to cool completely before adjusting, and place transmission in neutral with handbrake pulled on firmly.

    2. feed end of rope through left hand side rocker cover retaining clip, then tie a thumbnot around the prybar, ratchet handle or breaker bar using both the ends of the rope.

    3. after ensuring the knot is secure, grasp both ends of the bar with a hand at each end and yank sharply outwards and downwards until the clip disengages from its slots on the cover, then tap or pry it down onto the heater box.

    4. you should be able to now pull the rocker cover off fairly effortlessly by gripping the top half with a few fingers on each side and pulling so it pivots on the bottom endge, then slide it out. In some cases it will have been ill-advisedly stuck to the top of the rocker box with gasket goo or some other sealant, and will not come off. the only thing for this is GENTLE persuasion with a screwdriver. If you are over-zealous you can damage the rocker box edge and rocker cover which will promote messy and smelly oil leaks after the cover is put back on.

    5. undo the rope and pull it clear... then repeat steps 2 3 and 4 on the right hand rocker cover.

    6. pop the engine lid, then pull the HT lead out of the coil (the coil is a metal cylinder with wires at one end, the fat one in the middle being the HT), then move this lead out of the way.

    7. Undo the two clips holding on the distributor cap on, then noting the rough position of the #1 contact post, take of the cap and move it aside so that it is not in the way of the distributor rotor.

    8. grab the shifter, then adjust it so that it fits nicely around the nut on the alternator pully.

    9. using the shifter on the alternator pully nut, turn it clockwise until you see a little notch in the fan/crankshaft-pulley line up with the "0" mark on the plastic scale. If the metal piece on the distributor rotor button is pointing away from you, turn the pulley again until the notch is again lined up with "0", this time the metal contact on the rotor should now be pointing towards you (more or less). This means the engine is now at TDC (top dead center) on cylinder #1 (both valves closed, at the end of compression stroke... if the engine were running, it would be about to fire on #1).

    10. go round to the drivers side cylinder head and working bhind the rear wheel, locate the spring for #1 exhaust valve... this is the rearmost of the four springs. Take the feeler gauges and find the one reading .006 , then slide this between the tip of the threaded adjuster on the #1 exhaust rocker arm and the top of the round spring retainer. If clearance is correct you should be able to slide the gauge right through from the top of the spring and out the bottom with a slight drag. If a fair bit of resistance is felt, or there is a gap significantly greater than .006 (this is usually accompanied by a noisy clinking noise when running), they will need adjusting.

    11. If the clearance is tight, take the 14mm socket and ratchet and break torque on the #1 exhaust rocker locking nut and continue onto step 12. if clearance is too wide, move onto step 13.

    12. use the flat screwdriver to turn the theaded adjuster out (anticlockwise) until the gauge slides through.

    13. gently turn adjuster clockwise to tighten it down till it ever so slightly nips the gauges.

    14. holding the screw exactly in potition, put the open end of the 14mm combo spanner round the locking nut and tighten it, still holding the screw in position with the screwdriver. after this, switch spanner ends, put the screwdriver back in the slot, then give the locknut a final
    nip up and remove the gauge.

    15. repeat steps 10-14 with #1 inlet valve... this is the 2nd rocker and spring from the rear of the car on the right hand side.

    16. If your engine does not have a second timing mark already painted 180 degrees around from the factory notch on the fan read on with this step... if one is already painted on, move onto step 17. take the 10mm spanner and undo the plastic grill over the fan and remove it and the timing scale from the engine bay. take a piece of string and tape it exactly on the factory notch. then tape it down as close as you can to the exact opposite side of the fan. now take the tape measure and measure across the string at a 90 degree angle and adjust the position of the string at the non-marked side of the fan uuntil there is even distance between the string and either side of the fan. when this is measured, mark the position of the end of the string with liquid paper. a more permanent marking of this position on the fan can be made later. Remove the string and tape and reinstall the fan grille and timing scale, then turn engine back to #1 TDC position as described in step 9.

    17. turn the fan pully clockwise until the 180 mark lines up with the "0" timing mark and the rotor contact is pointing to the passenger side (sort of), then on the passenger side cylinder head, measure and adjust the #4 exhaust and inlet valves as described in steps 10-14. #4 exhaust is the rearmost spring, #4 is the one 2nd from the rear.

    18. turn pulley clockwise again until the factory timing notch is again lined up with "0", this time with the rotor contact poiting away from you. Go back to the passenger side cylinder head and check and adjust #3 inlet and exhaust valve clearances as before (steps 10-14). #3exhaust is the one closest to the front, #3 inlet is the one 2nd from the front.

    19. turn the pulley clockwise again, until the 180 degree mark is once again in line with "0", with the rotor contact still pointing away from you, then move back to the right hand side and check and adjust clearances for #2 exhaust and inlet valves as before. #2 exhaust is the frontmost valve on the right hand head, #2 inlet is the one 2nd from the front.

    20. When you are satisfied that the valves are correctly adjusted, get both rocker covers and wipe any grit or foreign material out of them, and replace the cork gaskets if you wish. do NOT put any gasketing compound on the side of the cork that is going to contact the rocker box.

    21. place the covers back over the rocker boxes, then slide the retainer clips up enuff to hold the covers just in place. one cover at a time, thread the rope through again as you did when you took them off, and holding the covers on, yank the rope until the clips hold firmly, then pry the clips up until they snap back into the notches on the cover.

    22. put the distributor cap back on top of the distibutor body and turn it till it locates in the keyed slots (it wont turn when it is located correctly). hold it in place and squeeze the metal clips one at a time towards the body until they snap over the edges of the cap.

    23. reconnect the HT lead to the coil securely and check the plug leads at either end to make sure they have not pulled loose. sheck that center HT lead is securely on at distributor cap end also.

    24. remove all tools, rope etc from the engine bay, close all things that are open, and drive another 6000km. :D


    I am anal retentive so check my valve clearance every 1000km, but this isnt necessary on a healthy engine with strong heads.

    Cheers!
     
    Last edited: Jan 20, 2007
  3. brookie

    brookie Guest

    Do you mean original meaning or the modern slang meaning

    Great post though !:cool:
     
  4. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    Modern slang meaning! :D

    CHeers!
     
  5. kombikid76

    kombikid76 New Member

    Messages:
    652
    Location:
    sunny sydney
    well done schmo, alot easier reading than a manual... now time for the pictorial? :p

    Trick i found to check clearance is to slide you feeler gauge under then grab the tappet and push/pull and see if you can feel it tapping, if so then you have too much clearance.

    Very important to get clearance spot on, if its anything less than 0.006" the valve may not totally seal and wont be able to disipate head to the valve seat leading to burnt, stretched, snapped or cracked valves aswell as poor performance
     
  6. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    Good advice there too Edward. :cool:... and another thing worth mentioning on this tangent now that I think about it, after you have adjusted all valves, do the push pull thing without the feeler gauge and see if there is a noticable difference in how far the rocker seems to move between any one valve... a tuned ear or eye will be able to see if this is the case.

    If one or more seem to have a lot more clearance than the others, you may have knackered adjusting screws, which means you may have way too much clearance. this will reduce valve lift and in severe cases affect performance, and will cause the offending tappet to make an annoying noisy clinking sound.

    These screws wear out over time, with the tip of the valve stem hammering into the center of the screw causing it to become hollow, thereby giving false clearance readings. If left for a long time the screws can eventually end up damaging the valve tips.

    Replacements can be bought from ROy and almost any other VW parts supplier. :)
     
  7. kombikid76

    kombikid76 New Member

    Messages:
    652
    Location:
    sunny sydney
    definantly worthy of a sticky schmo, and right on the money with the worn adjusters... think mine might be up for replacement!
     
  8. ttmck

    ttmck Super Moderator Staff Member

    Messages:
    2,733
    Location:
    Hallett Cove STH AUS
    schmoo take a look next time you do the valves you might just see a vw symbol stamped on the rocker cover , if you have the symbol facing the correct way so you can read it you know the rocker cover goes on that way
    just a hint good posting .alot of time / effort went into that one i have sometimes kicked the covers with my clumsy feet and then ummmm how does that go on ... the old vw symbol is the trick
    i use a very slight smear of grease on my gaskets . i have also seen acl cork gaskets fitted to engines and they are a very poor fit stay away from them .

    also from time to time i see the tappet screws pocket where they make contact with the valve might be a good idea to check to see it the screws have gone soft , replace them asap along with the lock nuts

    warren can you sticky this my moderation skills have been lost being on hol's hahah
     
    Last edited: Jan 23, 2007
  9. syncro

    syncro Well-Known Member

    Messages:
    8,953
    Location:
    Southern Highlands
    exhaust valves are 8 thou on a type 4 motor. 6 on a type 1.
     
  10. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    Hmmm... Ive always been told that the 6 thou specification for clearance had superceded the 8 tho exhaust spec.

    But either way it is not going to harm the engine... I still have plenty of clearance between rocker and valve even when the engine is hot and mine have always been set to 6 thou. :) :cool:

    But yeh... horses for courses! :D
     
  11. syncro

    syncro Well-Known Member

    Messages:
    8,953
    Location:
    Southern Highlands
    I think that someone has got confused here.
    On type 1 motors, 6 thou superceeded the 4 thou spec.
    I hope it wasn't a mechanic that told you that!
     
  12. kombimatt

    kombimatt Active Member

    Messages:
    1,768
    Location:
    Dodges Ferry, TAS
    Huh!

    I didn't know smarties had valvles!

    The things you learn on the KC forums. Bahahahaha!

    Matt
     
  13. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    Nope... about 3 different manuals! :D

    but anyway... easily maintains enough clearance with 6 thou even when hot, so all good.... 8 thou is better but a little noisier. :)

    Cheers!
     
  14. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    sticky sticky? :D
     
  15. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    a bump for posterity. :)
     
  16. GypsyWannabe

    GypsyWannabe Active Member

    Messages:
    3,032
    Location:
    Quakers Hill, Sydney
    Schmo,

    I was going to post here to say that my 1800 dual carb engine has a sticker on it to say the clearance on the exhaust valves should be .008.

    But, I just re-read your original post and now I'm worried I've set my clearances totally wrong because... I thought the valves were in the same order as the spark plugs???

    I returned the John Muir book to the library - this explains things much better than the Bentley. I thought that the valves went this way:

    (From front)
    Right - #1 inlet, #1 exhaust
    Right - #2 inlet, #2 exhaust
    Left - #3 inlet, #3 exhaust
    Left - #4 inlet, #4 exhaust

    But your post seems to say that the valves run this way:

    (From front)
    Right - #2 exhaust, # 2 inlet
    Right - #1 inlet, # 1 exhaust
    Left - #3 exhaust, #3 inlet
    Left - #4 inlet, #4 exhaust

    Your post also says you set the clearances in this order: 1, 4, 3, 2. I know this is the firing order, so....

    I think I may have set everything wrong, with some exhaust and inlet valves ass about plus #2 set as #1 etc., which could explain why I've had trouble getting the timing right. Good thing is, I'm not driving it, I guess!

    Can you please clarify for the mechanically inept? :eek:

    Thanks again,

    Baz

    PS. I know I set them right the 1st time round with the John Muir book from the library in front of me!
     
  17. Schmoburger

    Schmoburger Active Member

    Messages:
    4,381
    Location:
    Nowra/Jervis Bay area, NSW.
    Gday Baz...

    Doesnt really matter which order you adjust them in, so long as you adjust the exhaust and inlet valves on each cylinder at exactly TDC (piston at top of travel on compression stroke ) one after the other before moving onto the next cylinder.

    The valve configuration on both heads and cylinder numbering are as follows...

    [​IMG]

    But yeh...to be safe set the clearances to 8 thou on exhaust. :)

    CHeers!
     
  18. Marty

    Marty Active Member

    Messages:
    2,290
    Location:
    Sunny Melbourne
    That diagram helped a lot. I did it differently though, I had a mate turn the engine over with an adjustable wrench while I had my finger on the valve I wanted to adjust. You can then feel when it's in/out etc. the order you do them then doesn't matter.
     
  19. GypsyWannabe

    GypsyWannabe Active Member

    Messages:
    3,032
    Location:
    Quakers Hill, Sydney
    Yeah, the diagram is a great help, thanks. Now I know...

    INtake on the INside. EXhaust on the EXtremity. :)

    Just one thing Schmo... go back and read your 2nd post in this thread...
    Point 10 is what threw me:

    10. go round to the drivers side cylinder head and working bhind the rear wheel, locate the spring for #1 exhaust valve... this is the rearmost of the four springs. Take the feeler gauges and find the one reading .006 , then slide this between the tip of the threaded adjuster on the #1 exhaust rocker arm and the top of the round spring retainer. If clearance is correct you should be able to slide the gauge right through from the top of the spring and out the bottom with a slight drag. If a fair bit of resistance is felt, or there is a gap significantly greater than .006 (this is usually accompanied by a noisy clinking noise when running), they will need adjusting.

    That's where I think I got all mixed up.... apart from getting INs confused with my EXs! :)

    Cheers!

    Baz
     
  20. Kamper

    Kamper New Member

    Messages:
    75
    Location:
    Ferntree Gully, Melbourne
    The best way to know exactly when the end of compression stroke, is to use a power-light tester.

    1. Connect the lead of the tester to the earth of the coil and have the pointed part touching earth on engine. i usually wedge it between something so u can just leave it there.

    2. Turn ignition key to acc. on.

    3. Rotate engine so distributor rotor button turns anti-clockwise.

    3.a Tester light will go on when each cylinder is fired.
    This next step is most important to getting all valves adjusted equal.

    3.b Carefully keep turning, and then....
    4. When the light goes out, STOP turning. both valves have fully closed.

    Hope this has shed some light.
    I don't do this any other way on all my vw's and it works.

    --Al
     

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