Mix
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 posted on 9/1/05 at 10:10 AM |
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Zetec cambelt tension
I'm in the process of replacing my cambelt. The new kit came with a post and spring which, when fitted, apply a force to the tensioning pulley.
Can anyone advise me if this is supposed to set the correct belt tension? Haynes implies that it does but the belt seems too slack to me.
Thanks Mick
I remember Givemethebighammer, (I think) posting a question along these lines in the past but when I do a search entries stop November 2003. 
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jollygreengiant
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| posted on 9/1/05 at 11:01 AM |
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It was a modification by Ford and it does work fine. If the belt is replaced properly then there is NO other tension applied to the belt other than by
this spring arrangement because both the top pulleys are turning freely with no tensions applied by either cam shaft. (because you have used the
locking bar at the back of the cams and you have undone both the pulley bolts.)
Enjoy. 13 days to go.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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Mix
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| posted on 9/1/05 at 11:58 AM |
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(because you have used the locking bar at the back of the cams and you have undone both the pulley bolts.)
Err not quite.
As I was only replacing the belt because it was a convenient time, (I was replacing the Mondeo water pump with an Escort one), I didn't slacken
the camshaft pulley bolts. I set TDC on no 1 cylinder and checked that the tool could be fitted into the slots at the other end of the camshafts both
before and after replacing the belt. I'm happy that the timing is correct but I can see how the valve spring pressure on the camshafts can
influence how the belt tensions.
Do you now how Ford recommended setting the tension before the spring modification?
Thanks Mick
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rusty nuts
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| posted on 9/1/05 at 12:08 PM |
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You have to slacken the cam pulley securing bolts so that pulleys are free to rotate on cams. Make up a forked tool to fit into holes in pulleys when
undoing and tightening bolts DO NOT USE CAM TIMING TOOL FOR THIS. .Once bolts are slack release tensioner bolt,the spring should take up slack in
belt. Then retighten pulley bolts, recheck timing. Use a piece of scrap metal to make tool . Rusty
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jollygreengiant
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| posted on 9/1/05 at 02:26 PM |
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quote:
Originally posted by Mix
I'm happy that the timing is correct but I can see how the valve spring pressure on the camshafts can influence how the belt
tensions.
Consider the cam lobe as a lever. The valve spring is pushing up against that lever, this causes a rotational moment on the camshaft which can cause
inapropriate tension in the cambelt.
quote:
originally posted by Mix
Do you now how Ford recommended setting the tension before the spring modification?
Thanks Mick
By use of a cam belt tension guage. (about £150)
Enjoy.13 Days to go.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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Mix
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| posted on 9/1/05 at 03:58 PM |
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Originally posted by Mix
I'm happy that the timing is correct but I can see how the valve spring pressure on the camshafts can influence how the belt tensions.
This is all good info, but as I said, I understand how the valve springs can influence the cambelt tension locally. surely though there must be a way
of setting the tension without releasing the pulleys. After all the pitch of the teeth on the belts must be the same so the timing should not be
affected by changing it. I would prefer to not tinker with something which is working fine unless I have to.
Sorry if I'm being a pain Mick
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givemethebighammer
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| posted on 9/1/05 at 07:29 PM |
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Mix, changing the cam belt on my zetec caused me several headaches (mainly because I did not understand what I was doing or how it should look)
1. Firstly make a tool like the one in the attached picture (as per haynes mondeo book spec).
2. Turn the engine to TDC with a socket on the crank bolt.
3. insert a 5mm bar across the back of the two cams to lock them
4. Lock the flywheel with a pair of "hooked" tools as per haynes spec
5. Slacked the belt tensioner and remove the old belt and if renewing (as I did) all the pulleys and the tensioner.
6. Fit the new belt pulleys and tensioner inc spring).
Then using the tool in the picture loosen the bolts securing two cam verier pulleys (one at a time)and retighten again using the tool to take up any
slack in the belt between the vernier pulleys.
When everything is fitted and tight, remove the locking devices from the back of the cams and the flywheel. Then turn the engine over a few whole
cycles with a socket on the crank bolt.
Recheck the belt tension
All taken from the haynes mondeo book (I just extracted it a bit more logically).
I'm no expert but after a fair degree of uncertainty I feel I got it right and the engine starts and runs OK.
Sure Conrod may have an easier way of doing this, but I bet he's changed loads of these before.
original post here:
http://www.locostbuilders.co.uk/viewthread.php?tid=6411
[Edited on 9/1/05 by givemethebighammer]
 
Rescued attachment cam tool.jpg
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theconrodkid
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| posted on 9/1/05 at 07:39 PM |
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just do as jgg says,if you dont loosen cam sprockets you can get slack there and that will cause probs,ps like the sprocket too you made
who cares who wins
pass the pork pies
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givemethebighammer
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| posted on 9/1/05 at 07:44 PM |
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I didn't make that one Conrod, but mine looks the same just found the photo on the zetec website.
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Mix
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| posted on 10/1/05 at 09:16 AM |
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Thanks for the advice, back to the garage in a minute
GMTBH That was the post I was looking for.
Cheers Mick
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