ZX cambelt fitting

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the_weaver
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ZX cambelt fitting

Post by the_weaver »

I'm trying to fit the cambelt on my ZX 1.9D using the method in the Haynes manual and it's not working. The problem is that the cambelt seems to be too tight to get on even though I've fully released the tension from the tensioner pulley.

The belt is a Dayco ISORAN type. I'm wondering if this belt is a bit shorter in length that a Citroen belt. I've got the camshaft pulley, diesel pump pulley and flywheel all locked up with bolts and rods as per the Haynes manual. However I've noticed that the distance between the teeth on the the camshaft pulley and diesel pump pulley (when locked up) doesn't quite match the distance on the teeth on the cambelt. The teeth on the cambelt don't go down fully into the teeth of the pulley and the radius of the curve that the cambelt follows as it goes around the pulley is greater which means that the belt is tighter and therefore more difficult to put on over the last pulley (water pump).

Has anybody else had this problem? What is the solution? Is there an alternative method that works? I've thinking of removing the locking bolts on one or more of the pulleys. Also I was thinking of using a spanner on one of the pulleys to pull the belt around and get more tension than I could get by hand. Would it be safe to turn the camshaft pulley slightly anti-clockwise with a spanner to get the cambelt to mesh properly in the teeth of the pulley? Or should I only turn the diesel pump pulley clockwise with a spanner instead?

Paul
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Post by citronut »

first thing i would do is count the teeth on the old and new belt,

just to make sure they are the same belt,

sometimes even with the crank locked/prged you can turn it very slightly both direction's,
this might give you just enough slack to slip it over the rest of the way,

did the engine run well/smothly with the old belt fitted, may be your pump is not timmed exactly which might cause the slack between the top two sprockets

regards malcolm
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Post by evilally »

The belt should go on fairly easily, I'll bet you've been supplied with the wrong belt. Can you compare old to new?
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Post by Peter.N. »

They can be a tight fit, if you slide it fully onto two of the pullys it won't go onto the third one, just get it onto the edge of each pully trying to keep the belt straight. Make sure the tensioner is fully retracted, lever against it with a tyre lever or similar then lock it but protect the surface with a piece of rag.

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Post by citronut »

this car should have the spring loaded tensioner with the big plundger sitting in the end engine mount, in which case it has a 3/4 drive square hole in the back plate for taking it off tension, no nead for any levers

regards malcolm
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Post by JohnD »

I agree with Peter, they can be tight to fit. As he says, put the belt only halfway on the pump and C.P and I usually also fit it on the W.P and push it on the tensioner pulley last.
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Post by the_weaver »

Thanks for the replies. I've managed to get the belt on now. I think the problem may have been the tensioner. Even though it looked fully off I had another go at pulling it back and the belt has gone on ok now.

I followed the instructions in the Haynes manual for putting the belt on and it says that you're supposed to rotate the crankshaft by hand twice. I couldn't get the 8mm rod in the flywheel on the second pass and I think I ended up rotating it three times. When I checked the camshaft pulley I was shocked to see it half a turn out. The alignment hole is at 9 o'clock instead of 3 o'clock. I stopped all work in case I've done something wrong. Is this normal? I'm hoping that one more turn of the crankshaft will bring the camshaft to the 3'oclock position. Does the crankshaft have to go around twice each time to get the camshaft to alignment again or has the belt slipped?

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Post by Chris570 »

the crank turns twice to the cam's once.
continue turning it by hand, mark 2 rotations of the cam and if all is well try and lock all the pulleys again, with the cam locked the rest should lock as well. if you can do that jobs a goodun
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Post by Peter.N. »

If its out it will stop dead, shouldn't do any damage at hand rotation speed.
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Post by the_weaver »

Thanks for the replies. I didn't have any difficulty turning the crankshaft and it certainly didn't lock up, so it looks like I'm ok then.

I'll turn the crankshaft one more turn which should bring it to four full turns in total, lock up the flywheel and then I'll try to get the alignment bolts back in the camshaft and diesel pump.

I'm relying on the auto-tensioner on the ZX to tension the cambelt. However I would like some method of double-checking the tension. Is there a rule of thumb that can be used on the ZX? I notice that the longest run of cambelt on the ZX is between the camshaft sprocket and the diesel pump sprocket and it's not very long. Does the "turning the belt through 90 degrees" method work on the ZX or does it need to be tighter than that because it's a short run?

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Post by citronut »

i find the rule of thumb still applies even between the cam and pump sprockets,

and i usualy let the spring bring the tension on then give it a gently presure with a 3/8th drive ratchet in the square hole provided,

regards malcolm
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Post by the_weaver »

I turned the crankshaft one more turn and placed the 8mm rod into the flywheel. The camshaft sprocket lined up ok. I can screw the M8 bolt in at the 3 o'clock position. The diesel pump sprocket very nearly lines up. One bolt screws in ok. The other bolt doesn't quite screw in. It'll go in one thread but then it jams on the side of the hole. Looking through an inspection mirror I can see that the hole is very slightly misaligned. Probably less than 1mm out. I think that's the closest I can get it. I can't move the sprocket one tooth as then it would be miles out. I'll have to live with the bolt not quite going in.

Now I'm working on getting the correct cambelt tension. I searched around on the internet to see if there were any cheap tension gauges for sale. The cheapest are over £30 and there's no guarantee that it will have the info needed for the ZX.

I noticed that there are some very expensive instruments for sale which check the tension by measuring the frequency of vibration of the belt. Has anybody used one of these? If so, can you tell me what the correct frequency should be for the ZX 1.9D or XUD. There must be a user guide or table of cambelt frequencies for various cars out there somewhere. I can't find any info for the ZX at all. No frequencies, or SEEM units, or any other similar information. It must be around somewhere. Is there an Autodata manual which contains this sort of info?

Paul
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Post by JohnD »

On a succession of BX; 205s and Xantia 2.1 I've always found the auto-tensioner very satisfactory. Now when all my engines are without the auto tensioners, I use an American Burroughs gauge:-

Image

It's scaled in Newtons but to convert to SEEM I use the Autodata conversion chart. You can find it in here:-

http://www.autodata-online.com/uk/tbinfo.pdf
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Post by the_weaver »

Thanks for the reply John. I think I'll rely on the ZX's self-tensioner as it seems to be doing a reasonable job. That pdf is quite a handy guide. It says "Do NOT lever or force the belt onto it's sprockets.... Under no circumstances should any form of lever be applied to the belt to force it into place...". Then it says "It may be necessary to stretch the belt slightly over the first sprocket". Well I never used any levers but my belt was very tight and difficult to get on. I wonder if I stretched it a bit and that might be why the diesel pump sprocket doesn't quite line up perfectly. I read somewhere that new cambelts appear to be about a quarter of an inch too short when you first try to fit them. If this is the case then they must have to stretch a bit on fitting. So you can stretch them a bit but not too much.

When I first tried to fit my cambelt, the teeth of the belt wouldn't drop down fully into the teeth of the diesel pump sprocket and camshaft sprocket at the same time when the sprockets were locked with the bolts. The next day the cambelt teeth did seem to drop down into sprocket teeth. The teeth not meshing fully is what caused me so much trouble. I'm wondering whether the problem is that I'm using M8 bolts to lock the camshaft and diesel pump sprockets. These bolts don't allow any movement in the sprockets. However I think I've seen some commercial locking pin kits which have two sets of locking pins. One looks like the M8 bolts, the other set looks like an M8 bolt which has a section that has been turned down to a smaller diameter on a lathe. This would allow a bit of movement in the sprockets and make the job of fitting a tight belt much easier. I don't know which car these locking pins were for. I never looked for a ZX or XUD locking kit. I wonder if anybody has ever used one of these for a XUD and can shed some light on this.

On a slightly different subject. Can anybody tell me how to check the tensioner pulley and idler pulley for wear/problems? I was thinking of replacing them as they are probably the originals and my car has done 217,000 miles in 17 years. However I get the feeling that I might cause more problems for myself if I try to replace them so maybe they are best left alone if not causing a problem. The tensioner seems quite difficult to replace from what I have read. How long do the pulleys last? How do I check them? Where should the cambelt run on the pulleys normally? My belt seems to run close to the edge on the camshaft and diesel pump sprockets. It runs close to the sprocket edge towards the offside wing. My sprockets are shiny where the belt has been running but there's a dull section on the side closest to the engine. Is this correct? How close to the edge is acceptable?

Paul
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Post by CitroJim »

@JohnD: That's a very useful document you posted from Autodata. many thanks for that!
the_weaver wrote:This would allow a bit of movement in the sprockets and make the job of fitting a tight belt much easier. I don't know which car these locking pins were for. I never looked for a ZX or XUD locking kit. I wonder if anybody has ever used one of these for a XUD and can shed some light on this.
Hi Paul,

I've always used M8 bolts on the cam and pump sprockets with no problems but I know what you mean about getting the teeth lined up between the sprockets. The DW8 engine and many 16V twin cam engines have vernier pulleys for just this reason. The XUD relies on the belt being of good quality (which a Dayco is) and very good engineering tolerances in the engine itself. The run from cam to pump will be tight as a result and as long as the teeth have nicely meshed after two rotations, no problems. The belt installation must always be "started" between cam and pump sprockets. I always use a piece of brake pipe to lock the crank and this does give a small tad of "give". It's normal too for the belt not to run the full width of the sprockets or sit exactly in the middle. New belts may ride in a slightly different spot.
the_weaver wrote:On a slightly different subject. Can anybody tell me how to check the tensioner pulley and idler pulley for wear/problems?
The XUD tensioners rarely wear in my experience and can be checked by spinning them by hand with the belt off and listening/feeling for graunchiness and noise. By hand again, check for side to side play by grasping the tensioner wheel. Any side to side play is a sure sign they're worn and need replacing.
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