Cambelt tension

  1. Central South Joined: Jun 2006 East Sussex Posts: 3105 VTS :)
    #1
    This about right, paranoid it's too loose.

  2. Infrequent Poster Joined: Jan 2011 BURTON ON TRENT Posts: 111 Renault Clio (past) Vauxhall Corsa (past) Fiat Bra
    #2
    if u think its too loose pal, take it to a garage and ask them if it feels ok, but if you reali are thinking bad then just get it changed m8, peace of mind.
  3. Saxperience Hardcore! Joined: May 2007 Posts: 16839 Saxo VTS, Westfield
    #3
    Id say thats a little on the slack side tbh.
  4. Saxperience Post Whore Joined: Jul 2009 Costa Del Posts: 8010
    #4
    Way to slack IMO.

    If it skips some teeth then ouch.
  5. Saxperience Forum Bum Joined: Jan 2003 Scotland Posts: 3380
    #5
    try the same test when engine is hot
  6. Central South Joined: Jun 2006 East Sussex Posts: 3105 VTS :)
    #6
    This is after doing the belt, pulleys etc.
    Trying to get it to right tension.

    Was going off the 1/4 turn method, I've hand cranked it a few times and no contact but don't want to start just yet.
  7. Established Member Joined: Mar 2010 Basildon, Essex Posts: 1042 Citroen AX VTS
    #7
    LOL worried the cambelt is loose so advice is to run the engine?!

    Tip top!

    that does look loose mate, the second twisting motion you did on the vid, you should only be able to do that 90 degrees on the longest run of the belt - that looks like it go further so you'll want to tighten it up a bit
  8. Frequent Poster Joined: Jun 2007 warrington Posts: 722 saxo vts turbo
    #8
    way to loose . line it all up again and push the tenchen thing down more then tighten
  9. Saxperience Forum Bum Joined: Jan 2003 Scotland Posts: 3380
    #9
    Quote:
    Originally Posted by Alex View Post
    This is after doing the belt, pulleys etc.
    Trying to get it to right tension.

    Was going off the 1/4 turn method, I've hand cranked it a few times and no contact but don't want to start just yet.
    the method you are suggesting is totally wrong -but I understand why people suggest this .
    first thing to recognise is the fact that the adjustable pulleys are not there to make it easy to swing the cams but for getting the correct belt tension.

    correct method:

    lock crank with 6mm pin in flywheel
    lock pulleys with 8mm pins with all 6 of the 6mm bolts loose
    the whole point of having the cam wheel bolts loose is to stop the cams exerting tension on the belt due to the fact that they will be trying to turn because they are lifting valves so will want to pull against this lifting action + therefore give a false impression of belt tension.
    so with all pins in place and cam bolts loose fit the "seems" belt tension tool to the belt and adjust the tensioner until correct value is obtained
    Then and only then tighten up the cam pulley bolts .

    Now I understand that not many people will have the "seems" electronic strain gauge , so you need another way to do it .

    you can use exactly the same method ,but you will have to decide how tight to tension it while the lock pins are in .
    the next very important part of doing the belt tension is to run the engine untill it is hot .
    you will then see a big difference in the belt tension as the alloy head expands upwards and puts more tension on the belt .

    THIS IS WHY YOU SHOULD USE THE PROPER TOOL.

    because setting the belt tension with engine cold, using the tool, allows for the extra tension you will get when engine is hot ,so you don,t have to go through all the messing about of fitting lock pins in a hot engine .
    the number of times I have read of people having water pumps fail shortly after doing rebuilds --its because they have over tensioned the belt when cold ,so it either stresses the pump bearings or in extreme cases causes the tensioner stud to snap or bend .

    YOU MUST CHECK BELT TENSION WHEN ENGINE IS HOT IF YOU DO NOT USE THE STRAIN GAUGE TO SET TENSION WHEN COLD
    DO NOT REFIT BELT COVER UNTIL YOU HAD ENGINE HOT
    apart from anything else extra belt tension snaps power

    JP4 engines have no adjustable pulleys but do have a spring type tensioner that will compensate for engine expansion .
    I would not suggest that you use the JP4 type tensioner for high revving engines with lumpy cams + light flywheels + tight piston/valve clearance
    change to j4 type of set-up

    yes the video is showing too much slack in belt
  10. Saxperience Forum Bum Joined: Jan 2003 Scotland Posts: 3380
    #10
    Quote:
    Originally Posted by Gareth_R View Post
    LOL worried the cambelt is loose so advice is to run the engine?!

    Tip top!

    that does look loose mate, the second twisting motion you did on the vid, you should only be able to do that 90 degrees on the longest run of the belt - that looks like it go further so you'll want to tighten it up a bit
    I am presuming he has enough common sene to know that what he is showing is too loose ,if not he shouldn,t be doing it in the first place

    your 90degrees is another urban myth and may work
    but as there are NO "longruns" on this belt ,
    its not an old pinto engine !!,
    it is not a good way to do it
    what happens when he down changes and lets up the clutch a bit quick --all the belt play will go other side and if piston/valve clearance is tight --BINGO bent valves
  11. Established Member Joined: Mar 2010 Basildon, Essex Posts: 1042 Citroen AX VTS
    #11
    No it's not the absolute rule but it's not a bad guide to know its too loose

    And the question he asked was about whether it was too loose, so clearly he needed a bit more guidance than 'test it hot' - granted your second reply was much better. Bravo