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Cam belt replacement


Guest glyn.harper

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Guest glyn.harper

Hey chaps..

What's the score with changing the cambelt in situe?

Last time I changed it was probably 6 years ago (gulp!) and the engine was out.

Is this easy enough to do, or can anyone recommend a good place to take it to get it done in the northwest?

I've heard you can make the job easier by cutting a panel in the firewall. I'm all up for this if it'll help.

Cheers,

Glyn Harper.

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It is possible to do a cambelt change in situ, I have done so a couple of times now and just needs a little patience and attention to detail.

Don't start cutting holes in the firewall as this will reduce some rigidity to the bodywork no matter how tight you try to bolt it back together and although it may not effect performance you could start seeing some twisiting in the shell causing cracks near the b or c pillars.

I will find the post on piston heads that I followed for the cambelt change, the only other advice I got and have is to use some cable ties and some kitchen tissue to stop it cutting into belt, on the top camsprockets when you push it down to do the crank end. That way it won't slip.

Other way I used that may sound daft, is to put some tipex marks on the sprockets and belt before taking it off, then lined up very carefully and transfered the marks to the new belt. If all has been put together right the marks on the belt, and the three sprockets should all line up.

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Cambelt replacement guide as posted by Lotusguy (Jim) on the Piston heads forum

Friday 15th August 2003

--------------------------------------------------------------------------------

Hi All,

Ok...to change the timing belt...

1. Set engine to TDC.

You can do this by disconnecting the battery, removing or loosening the sparkplugs and leads, putting the car in 5th gear. Push it forward until the timing dots or dimples on the rim of both the intake and exhaust pulleys line up. If you run out of forward room, put the car in neutral, push it back, re-engage 5th gear and push forward again until the dots line up (right next to one another, not on opposite sides). Once you have the dots aligned, check the timing pointer with the marking on the flywheel to ensure you are in fact at TDC (there is some slight variation, so if the pointer isn't exactly lined up, but a degree or two off, it's ok. The variation is due to design tolerances and whether the head has previously been milled etc.). Set the parking break, and keep in gear so it doesn't move.

2. Drain some coolant.

This is because you will need to disconnect both the upper coolant hose/pipe as well as the other large coolant hose from the waterpump as they 'live' inside the circle created by the timing belt. You'll need to drain approx. 1/2 gal. to drop the coolant level below this hose, save for later refill. Remove the lower coolant hose from underneath after removing the engine undertray.

3. Remove the Alternator.

First remove both electrical connections to the Alternator. Next, unbolt (13mm) the three bolts/nuts securing the alternator and remove both the alternator and it's triangle bracket. Also the 'V' belt. Do this from above.

4. Loosen the AC compressor.

from it's bracket sufficiently that you can remove it's 'V' belt. No trick to either of these, just loosen the bolts securing them. Do this from below .

5. Loosen the vacuum pump.

This uses two Allen set screws. An 8mm Hex socket works well. An Allen wrench may work, but is likely to be too long to get into the tight space. Another trick is to cut off a piece from an 8mm Allen wrench approx 1" long and insert it into the set screw, then use an 8mm closed end wrench to turn it. Remove the Vacuum pump/Waterpump 'V' belt.

6. Remove the Crank 'V' belt pulley.

With the engine in gear, parking brake on, use a 21mm socket to loosen the securing bolt and conical washer. Pulley should come right off, if not, tap gently around the rim w/ a Dead Blow Hammer, or lacking that, a regular hammer with a piece of wood as a drift. I have only seen one stuck, all the others merely came free.

7. Re-check TDC position.

Check to see that the engine has remained at TDC and that nothing has moved when you removed 'V' belt pulley. Again, nothing should have moved, but it's good to check.

8. Check alignment of Auxillary shaft pulley.

It's good to make a witness mark w/ a white paint pen or White Out on both the Aux. Shaft pulley and the block to insure it is repositioned properly when installing the new belt. If not, your ignition timing will be off.

9. Release tension on the tensioner.

On >'85 cars, you can merely unscrew the tensioner bolt using a 19mm? socket. On earlier cars equipped w/ semi-automatic tensioner, you need to apply pressure to the timing belt to compress the tensioner's piston. Then, insert a 4mm drift, or 4mm drill bit into the tensioner body to lock the tensioner. But, this is only for the pre-'86 cars.

10. Remove the timing belt.

Simply work it off the 3 pulleys and the crank pulley. Extract from either the top or bottom.

11. Install new belt.

Thread the new belt around the Exh., Int. and Aux. pulleys, over the tensioner roller and onto the crank pulley (it will be tight and you may need a screwdriver to use as a lever to start the belt over the crank pulley), making sure that the Aux. pulley lines up w/ the witness mark you made previously. Make new witness marks on both the belt and both the Exh. and Int. pulleys to insure the belt does not move when tensioning it.

12. Tension the new belt.

Using the same 19mm? socket as before, tighten the tensioner until you get a reading of 90-95 Lbs. (engine cold) on a Burroughs Gauge, 55 lbs. on a Kriket Gauge, or until you can just twist the belt 90

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Cambelt replacement guide as posted by Lotusguy (Jim) on the Piston heads forum

Friday 15th August 2003 

--------------------------------------------------------------------------------

1. Set engine to TDC.

You can do this by disconnecting the battery, removing or loosening the sparkplugs and leads, putting the car in 5th gear. Push it forward until the timing dots or dimples on the rim of both the intake and exhaust pulleys line up. If you run out of forward room, put the car in neutral, push it back, re-engage 5th gear and push forward again until the dots line up

<chop>

5. Loosen the vacuum pump.

This uses two Allen set screws. An 8mm Hex socket works well. An Allen wrench may work, but is likely to be too long to get into the tight space. Another trick is to cut off a piece from an 8mm Allen wrench approx 1" long and insert it into the set screw, then use an 8mm closed end wrench to turn it. Remove the Vacuum pump/Waterpump 'V' belt.

<chop>

8. Check alignment of Auxillary shaft pulley.

It's good to make a witness mark w/ a white paint pen or White Out on both the Aux. Shaft pulley and the block to insure it is repositioned properly when installing the new belt. If not, your ignition timing will be off.

<chop>

13. Rotate engine and recheck witness marks and timing dimples and belt tension.

<{POST_SNAPBACK}>

A few additions for chargecooler equipped cars; when pushing the car backwards, you must take it out of gear to stop the engine rotating backwards, also when rotating the crank you must not rotate it backwards. The reason for this is the crappy chargecooler pump will shed its vanes if it's rotated in the wrong direction, or a nearby gnat decides to fart. If you're rotating the engine while the belt is off then the aux shaft won't turn so the chargecooler pump won't care. Don't turn the aux shaft backwards basically.

Also the vacuum pump allen-head bolts can be easily removed if you have one of those impact drivers that you hit with a hammer, or anything that has similar hexagonal profile bits, my impact driver bits are a snug fit in the allen heads and can then be turned with a normal spanner.

Finally, if you have a fuel-injected car with electronic timing, the positioning of the auxilliary shaft isn't important as the shaft only turns the oil pump and the chargecooler pump, on earlier cars it turned the alternator which is why the remark about timing being off is in the original text.

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Good note on the chagecooler pump, unless your a lucky owner who chanegd for an electric model.

Although if you think about it , it's obvious to take it out of gear to push it back after pushing it forwrd, otherwise there would have been no point in pushing it forward in the first place :P

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Although if you think about it , it's obvious to take it out of gear to push it back after pushing it forwrd, otherwise there would have been no point in pushing it forward in the first place  :P

<{POST_SNAPBACK}>

Aha smarty pants, I was thinking about if someone had overshot the mark and wanted to turn the engine back rather than go around again, which is what the original article correctly recommended. See, I'm not as daft as I think! I mean you think. I think.

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Finally, if you have a fuel-injected car with electronic timing, the positioning of the auxilliary shaft isn't important as the shaft only turns the oil pump and the chargecooler pump, on earlier cars it turned the alternator which is why the remark about timing being off is in the original text.

<{POST_SNAPBACK}>

You mean distributor, not alternator, shirley. :P

Paul.

PS. Are you the guy in the 'addiction' DVD ?

Edited by PVK 596Y
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You mean distributor, not alternator, shirley. :)

Paul.

PS. Are you the guy in the 'addiction' DVD ?

<{POST_SNAPBACK}>

Whoops! Yes I do, the output of the alternator might not be a D.C. signal but it's certainly not good enough to be used for firing the plugs directly...

And yes I am the chap in the Addiction DVD, filmed doing the higly complicated job of putting the flywheel back on, and once the camera was off, taking it off again as it needs sorting out! It took me about 6 attempts to put the flywheel on once the camera was going, it's amazing how many variations on orientation I was able to find, including the cluch mating surface towards the engine.

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Whoops!  Yes I do, the output of the alternator might not be a D.C. signal but it's certainly not good enough to be used for firing the plugs directly...

And yes I am the chap in the Addiction DVD, filmed doing the higly complicated job of putting the flywheel back on, and once the camera was off, taking it off again as it needs sorting out!  It took me about 6 attempts to put the flywheel on once the camera was going, it's amazing how many variations on orientation I was able to find, including the cluch mating surface towards the engine.

<{POST_SNAPBACK}>

Don't feel too bad, I could probably do that without a camera around to make me nervous if I was having a bad day. :)

Is your car on the road now, or are you still enjoying working on it ?

Paul.

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Still in bits, I'm rebuilding the engine and lots more too, previous to this I'd hardly ever even changed a wheel on a car so it's been a slow but very educational experience. The cams are back on now, next jobs for this weekend are to re-do the oil pump fixings, strip and re-paint the cam covers and clean up or replace the coil pack's rusty nipples. I tend not to work very fast because it's nice sitting in the garage pottering about with it, going too fast makes it far too much like work, which is something to be avoided!

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Guest teigan
Still in bits ... I tend not to work very fast because it's nice sitting in the garage pottering about with it, going too fast makes it far too much like work, which is something to be avoided!

<{POST_SNAPBACK}>

i have to agree with you there. but not just about the car in the garage. this is a good approach to life. aren't i dead yet?

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How much time should this process take to complete?

How difficult on a scale of 1 to 10, 10 being the hardest?

<{POST_SNAPBACK}>

Assuming you're talking about the cambelt, then given that you don't know the answer already it's safe to assume that you've never done it before or haven't done enough work in the engine bay to hazard a guess. In that case I'd reckon that if you had no problems you might get it done in 1-2 days, but if you find that you can't go forward without a certain part or certain tool, which is my experience is the most common cause of delays even with a decent toolbox, then the time goes up depending on the availability of tools and parts in your area.

An experienced lotus mechanic could get the whole lot done in perhaps 2-3 hours I reckon but they don't need to sit there thinking about whether they're doing the right thing and nervously chewing on their fingers like we do ;-)

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Is twisting the belt through 90 degrees really a suitable and sensible way of checking the tension?

I ask only because not having an appropriate guage is enough to put me off tackling the job! Clearly it isn't taking much to dent my resolve!

Ian

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Is twisting the belt through 90 degrees really a suitable and sensible way of checking the tension?

I ask only because not having an appropriate guage is enough to put me off tackling the job!  Clearly it isn't taking much to dent my resolve!

<{POST_SNAPBACK}>

As a side issue,when i bought my car...

The belt on my SE was fine for tension! ...Wahey! :(

It was changed 5,000 miles ago! ...Spiffing! :)

Five years ago. ...Oh. :(

Say i have a bungee cord. I heat it to engine temp and beyond for five

summers. The let it chill for five winters. Then i look at it and it looks fine.

Who's up for jumping eh?

:)

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Is twisting the belt through 90 degrees really a suitable and sensible way of checking the tension?

I ask only because not having an appropriate guage is enough to put me off tackling the job!

Edited by The_Del
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