rounded teeth vs trapezoid teethed timing belts? | Ford Escort Owners Association (FEOA)
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rounded teeth vs trapezoid teethed timing belts?

Discussion in 'Tech & Repair' started by headmn, Jun 12, 2020.

  1. headmn

    headmn FEOA Member

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    hello all.
    i am FINALLY posting a guestion about possible differences in
    timing belts? amongst other things like reman heads, new rings
    and waterpump installs, i am having problems with timing belts
    replacement ...the new one has lined top on the teeth instead

    of rounded tops like the old busted one! i am also having prob-
    lem with the tentioner difficulties.i keep coming up with slippage
    or too slack. i have heard of rounded teeth vs trapezoid teeth-
    ed belts, is there anything to my fears. by the way i have a

    95 scort 1.9L LX and have been lurking this wonderful site for
    months. my dialup isp is SLOW and CLUMSY ,so i read alot. thx
    for all the wonderful tips from the knowledged posters.
    headmn
  2. pextor

    pextor Moderator Staff Member

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    What brand is the new belt? The ones I've always seen had the rounded teeth.
  3. Joey_Twowagons

    Joey_Twowagons FEOA Member

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    I think the switch to rounded teeth occurred quite early, around the 1990-91 time frame.
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  4. marclar

    marclar Administrator Staff Member

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    95 should have rounded teeth. i believe the square tooth was more of a 1st gen thing. can you post pictures of what you are in qustion about?
  5. headmn

    headmn FEOA Member

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    thanks for the replys. the brand name for the belt is a DAYCO
    94221/95194 . along the top of EACH tooth there is a shallow
    depressed line. this belt was bought at Autozone. the belt that
    i took off did not have this line but teeth tops were smooth and
    round. Do i have the wrong belt?
    I have no dig camera to work with @ present but I do have a pic
    of my blue scort with alot less dings to upload(?)
    my net speeds @ this time of day is S-L-0-W. headmn
  6. denisond3

    denisond3 Moderator Staff Member

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    I think there are olny two types of timing belts. The ones for the 1st gen and up to the beginning of the 1991 production year had squared teeth - to match with the squared teeth on the sprockets. After that, for the entire 2nd gen LX engines, the belt had rounded teeth. There might have been a sort of semigroove in the top of the teeth, but its basically a rounded tooth, nothing else. They were the same from 91 through 96 and maybe later as well. This is for the SOHC (LX) engines; I dont know what the DOHC (GT) engines had for a timing belt.

    The cam sprocket, the crankshaft sprocket, and the water pump sprocket all needed to have the same shaped teeth; either all the rounded shape, or all the squared shape.
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  7. headmn

    headmn FEOA Member

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    Oh no, more intrigue...i got the belt and water pump as a KIT re-
    placement for a seized pump with a broken belt. since everything
    has to match, i am thinking that the pump cog is made for this

    belt and so is matched with it. that however could mean that the
    cam and crank cogs dont like this arangement? i ll have to look
    and try to resolve this match up. stay tuned , headmn
  8. denisond3

    denisond3 Moderator Staff Member

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    The cam and crank sprocket teeth need to look the same as the teeth on the water pump (and the inverse of the teeth on the belt). They are distinct; it wont be a mystery if you see the teeth that are 'flat' on their outer part of the cam/crank sprockets, instead of being rounded.
  9. Pizzaman5000

    Pizzaman5000 FEOA Donator

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    On the subject of slack.... The little "spring" in the tensioner is a joke. I use a pry bar to tighten with one hand, and tighten down the idler with my other hand.

    How tight you go is up to you, but I go for the "longest" run of the timing belt being able to twist 90° with my fingers.

    And as others have said, square teeth ended mid 1991 models.
    The peaks and valleys of a square tooth are both square, a "round" tooth has round valleys.
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  10. denisond3

    denisond3 Moderator Staff Member

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    On the 2nd gen LX models, my limited experience is to let the spring in the tensioner do its job, and not help it to become tighter. When I did my first rebuild, I used a wooden prybar to add additional tension, above what the spring was providing. I could just barely turn the belt 90 degrees with my fingers, on the long run from the front of the cam sprocket down to the crankshaft sprocket. For whatever reason that belt snapped after 30,000 miles, when it was being driven in town by my then son-in-law, (right after he got his suspended drvers license reinstated. So I dont know what he might have been doing).
    Anyway, after that I let the spring do all of the tensioning. I use a wooden prybar to push the tensioiner back, compressing the spring so I could get the timing belt installed; Then let the tensioner move out, pushed by the spring; and torque down the tensioner bolt.
    Even so, I commonly replace a timing belt after about 60,000 miles, usually just before we would be taking it on a long drive, such as across the USA to the west coast; as our grandsons live in West Seattle.

    I also loosen and retighten that tensioner after turning the crankshaft 4 or 5 times.

    The husband of a niece of ours is an auto mechanic, who mentioned that their guidance (from an online industry source) had said that the replacement interval for Escorts, Hondas and other vehicles having rubber timing belt, had been reduced from 100,000 miles to 60,000 miles. Hr didnt know why, but he said that was they were now doing. Me too.
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  11. zzyzzx

    zzyzzx FEOA Member

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    They probably just assume all engines are interference engines.
    Having written that, I had a timing belt tensioner go at around 60K, and an actual belt at 97K.
  12. denisond3

    denisond3 Moderator Staff Member

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    My neighbor in TX had a tensioner go bad after 10k miles; and it was whatever brand O'Reillys sells.
  13. headmn

    headmn FEOA Member

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    yes, after carefully looking @ the old belt vs new,the old pump and new
    (installed!) one, i can conclude that i have the wrong pump and its belt.
    i am now interested in buying another KIT, but the right one! that one

    should have rounded tops on the belt teeth along with its water pump
    companion. it should be for a 2nd gen scort '95 1.9L. A doofus mistake,if
    i hadnt have been in such a HURRY and TOOK NOTICE that there was a

    DIFFERENCE, this wouldnt have become a snafu.DOUBLE check your
    parts replacements for correctness before buying and then installing! now
    i ve got purchase, removal and reinstall of the correct (round) belt/water pump.
    thx all for inputs. headmn
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  14. headmn

    headmn FEOA Member

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  15. headmn

    headmn FEOA Member

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    Update on the Dayco timing belt with the small
    flat tips on the tops of the pointed teeth.The
    flat tips are a wear resistance featured accord-
    ing to store employee. thats a Dayco94221/95194
    @Autozne.

    it is the CORRECT belt for the Ford scort 1.9L
    and is WORKING at present in my car. I stand
    corrected for a premature, earlier conclusion.

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