Need to change my cambelt on my TZD

Frequently asked technical questions and common modifications/improvements
ellevie
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Post by ellevie » Mon Mar 31, 2008 9:56 pm

I would advise you not to embark on this project until you get a good understanding of the important role that the timing belt (cam belt) plays. If you do it incorrectly you could seriously damage the engine. A basic explanation of the engine workings can be found here,
http://auto.howstuffworks.com/engine.htm


There are 2 kinds of timing,
1) piston--valve--fuel injection pump timing
2) Ignition timing

Your picture with red arrows refers to type 2 timing which determines when the sparks occur.

Type 1 timing aims to synchronise 3 independent subsystems,
1) pistons + crankshaft + flywheel
2) valves + camshaft
3) diesel injection pump

If the timing relationship between 1 and 2 is wrong the piston can smash into the valves causing serious and expensive damage. The diesel pump must ensure that diesel is delivered at the correct time to each cylinder.

Each of the subsystems has a sprocket which engages with the toothed cambelt. The camshaft sprocket has a small hole which must be aligned with a matching hole on the engine block by inserting an 8mm pin. An 8mm bolt or an 8mm drill can be used for this. You can also buy a meter length of M8 studding (threaded bar) and cut off suitable lengths. The diesel injection pump sprocket similarly has 2 holes and matching holes on the block into which must be inserted 2 further 8mm pins. The crankshaft sprocket is not accessible so instead there is a hole in the flywheel and a matching hole in the block into which the 4th pin must be inserted (the junior hacksaw can be used instead of the pin).

For correct timing, the small holes in the sprockets and flywheel must be aligned with the corresponding holes in the engine block. This is what the 8mm pins are for.

Painting marks everywhere does not work because the camshaft turns at half the crankshaft speed.

if your French is better than your English then this link might help,
http://bxworld.free.fr/modules.php?name ... tit&lid=21
David

BX19TRS 118K E Reg 1992-2008
BX19TRS auto abs 96k F Reg
BX19TXD 150k K Reg

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mat_fenwick
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Post by mat_fenwick » Mon Mar 31, 2008 10:18 pm

TB2 wrote:
it often helps to remove fuel pump locking pin and slightly rotate pump clockwise before putting the belt on its pulley to get all slack out of the front run
What do you mean by "fuel pump locking pin"? And what about the diesel pump?
This IS the diesel pump...you will see 2 holes in the diesel pump pully into which you can either screw in a special locking pin, OR 2 M8 bolts. The other M8 bolt acts as a locking pin for the camshaft and screws into the head.
TB2 wrote:
Yep, all you need are 3 x M8 bolts, one for the cam pulley, and 2 for the pump, then a suitable drill or similar to go through the block and the hole in the flywheel. For the sake of 5 mins, unbolt the starter motor, and you will see the hole in the block, it will be much easier
Why do I "need" 3xM8 bolts? I guess they already are in place, I just remove them and reattach them later, right? What is meant by "a suitable drill"? Do I get this right: That there's a deep hole in the middle of the flywheel and I have to remove it with a long socket to get the flywheel off and remove the belt?
The flywheel is at the gearbox end of the engine. The clutch is mounted on it. Underneath the starter motor, there is a small hole in the block into which you can fit a short 8mm drill and into the flywheel. There is a photo above in this thread that shows a hacksaw frame being used instead of a suitable drill. The drill (or hacksaw frame) can be called a locking pin
So now your flywheel (and therefore crankshaft), camshaft, and diesel pump cannot turn. The belt can then be taken off without having to mark everything with paint, but obviously all the locking pins (i.e. M8 bolts and 8mm drill) have to be taken out before you start the engine.
TB2 wrote:
Finally, when the belt is fitted and retensioned, remove all the pins (I usually cable tie the pins with bright coloured cable ties to ensure this!!!!)
What pins? Why remove them, where did they come from all of a sudden? Do I need to place some pins there to lock the flywheel?

And another question:
Regarding the timing, is it possible to just paint marks everywhere on the pulleys and the engine block to just refit everything the way it was before taking of the belt or isn't that working. Also, to set the timings manually, is there something like this on the BX?

I took this picture from a Toyota Tacoma How-To, where the pulleys are aligned to those numbers to set the timing right. Is that the way it's done on a BX?
No, there are no marks, just the holes into which locking pins are placed to hold everything stationary.
TB2 wrote: And what the heck is that "plunger" thing?
And I always thought I'd need a torque wrench somewhere in this process, isn't that true?
The plunger is part of the cambelt tensioner/engine mount. A large spring presses against a lever, on the other end of the lever is a roller on which the cambelt rolls.
Image
This is a photo of the cambelt end of the engine. The gold shiny item is the cambelt tensioner, which the plunger pushing on the lower right end of it. There is a square hole on the other end, just below the camshaft pulley which you use to move the tensioner to the slack position to remove the belt. You can also see the M8 bolts locking the diesel pump and camshaft.
Once the new belt is on (make sure all the slack is on the length bewteen the crankshaft and the camshaft), allow the tensioner to press against the belt, tightnen its securing bolts and rotate the engine at least 2 times, then check that when the 8mm drill goes through the block into the flywheel, you can also get the M8 bolts into the holes behind the camshaft pulley and diesel pump pulley. Then slacken the tensioner securing bolts, to take up any slack that may have been redistributed around the belt, and then tighten them.

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TB2
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Post by TB2 » Mon Mar 31, 2008 11:35 pm

Thanks a lot for clearing that up! I knew that the timings are crucial and that a wrong timing can break the valves. But now I finially understand what all the pins are about. That's quite a practical way of making sure that the timings are right.

So basically - regarding the timing - it's like this:

1. Lock all the pulleys and wheels in place with pins or other pin-like things
2. Remove the old belt, refit a new one - having all the slack between crankshaft and camshaft - and let the tenisioner press against the belt
3. Remove all the pins and carefully turn the engine twice
4. If it seems fine, put all the pins back in place to ensure that the timing is still right and then finally remove them.

Right?

Man I'm glad I now understand what all this is about, thanks a lot! :)

Btw, that French manual is absolutely amazing!! I know some French, so it will be useful to me. Thanks.


...more or less off topic:
I had a quick look at the engine today to check where the belt runs, how much space there is and what I need to remove before reaching the belt. Doing this I was amazed how good looking this engine still is. After that incident with the hydraulic pipe blowing off from one of the spiders, towing the car away and having to clean up those huge oil stains on the street I lost all faith in this car but today I realised that it still has only 55k miles and that it is in good condition nevertheless. Let's hope there won't be any other problems like that soon... Once the cambelt is changed I'll finally be able to enjoy this car without having to fear that anything can break any minute :) Btw, this is a '89 model, but the HP pipes coming from the front spheres are looking like new and they're coated with some green stuff. It seems to me like they have been replaced a while ago...
Carl

1989 TRD "Entreprise" Turbo Diesel
1989 16 Valve
---
Parts needed:
- One black leather headrest.
- FDV overhaul kit (95.669.034)
Please contact me through PN if you have any of this.

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mat_fenwick
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Post by mat_fenwick » Tue Apr 01, 2008 12:25 am

Yes, that is the basic summary...

You will almost certain struggle to undo the 22mm headed bolt holding the crankshaft pulley in place, although I have heard you can wriggle the belt out without removing it. One tip I heard is to wedge a long breaker bar (long wrench) against the subframe whilst on the bolt head and turn the starter briefly. Make sure the car won't start by disconnecting the fuel stop solenoid on top of the diesel pump.
I have used a long 6 foot (1.8m) bar to undo it whilst holding the engine stationary with a high tensile (strong) M8 bolt in the flywheel hole. The strength of a bolt is stamped on the head - look for one with 12.9 stamped on it if you use this method.
TB2 wrote:that incident with the hydraulic pipe blowing off from one of the spiders, towing the car away and having to clean up those huge oil stains on the street
At least all the spilt oil will help prevent the car from rust :) Good luck!

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TB2
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Post by TB2 » Tue Apr 01, 2008 10:07 am

All right, I'll get going on Sunday.

One last question: Is it necessary to jack up the car and do some work from under the engine or is it possible to do everything from above? If not, I'll have to buy ramps or axle stands (which I wanted to buy anyway) before I start working.
Carl

1989 TRD "Entreprise" Turbo Diesel
1989 16 Valve
---
Parts needed:
- One black leather headrest.
- FDV overhaul kit (95.669.034)
Please contact me through PN if you have any of this.

ellevie
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Post by ellevie » Tue Apr 01, 2008 11:11 am

On safety grounds alone it is essential to use axle stands or ramps as appropriate when working on these cars. A decent set of stands and trolley jack is a good investment. I got a really robust jack which goes up to about 500mm for about £40.

You will need stands to access the lower run of the belt with the wheel removed. Also, as described by Stewart (Oily!) in this thread, you can raise and lower the engine slightly using a jack to facilitate the job and this can be useful because adjusting the tensioner is really awkward in such a confined space. I found it helpful to unbolt the alternator and move it to one side. I didn't need to remove the crankshaft pulley; the plastic guard behind the pulley is flexible enough to bend so that it can be removed.
David

BX19TRS 118K E Reg 1992-2008
BX19TRS auto abs 96k F Reg
BX19TXD 150k K Reg

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mat_fenwick
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Post by mat_fenwick » Tue Apr 01, 2008 12:13 pm

Ramps would be no use in this case, as you have to take the wheel off on the cambelt end to gain access... But they are useful to have anyway.

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TB2
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Post by TB2 » Fri Apr 04, 2008 10:25 pm

A friend just asked me if I'll be going to change the thermostat, too (as it is commonly done on an Audi 90 when changing the cambelt). Well, is that necessary? I've never read about thermostat issues in here...
Carl

1989 TRD "Entreprise" Turbo Diesel
1989 16 Valve
---
Parts needed:
- One black leather headrest.
- FDV overhaul kit (95.669.034)
Please contact me through PN if you have any of this.

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ken newbold
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Post by ken newbold » Fri Apr 04, 2008 11:33 pm

First thing first. If the crankshaft bolt is too tight to undo, leave it alone, as has been said, you can get the belt on and off with the pulley in place. Just undo the two 11mm bolts that hold the lower plastic guard in place.

As for the thermostat. Unless it's knacked, leave it alone. Depending which variation you have, it will have 3 or 4 bolts holding it's housing in place. You can almost guarantee at least one of them will shear off :evil:
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TB2
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Post by TB2 » Mon May 12, 2008 1:36 pm

Ok, so today I jacked up the engine and removed the upper engine mount. No problem so far. Then, I wanted to turn the engine to align the gears and put in the bolts. Engaged 5th gear, and tried to rotate the front left wheel. But the wheel just wouldn't move. I thought maybe the break pads were rusted against the discs, so I removed that wheel but it seemd right. I took a look at the manual and found out that the hand brake also locks the front wheels. Never had that on previous cars :wink:

Anyways, I disengaged the handbrake and turned the wheel. And then it really turned the engine. I took a look on the other side at how far I would need to turn it to be able to place the pins, went back to the front left wheel, turned it again, and suddenly the engine stopped moving with the wheel. I didn't do anything, I just turned the wheel and saw the cambelt move with it, and then suddenly it stopped moving, and moving the wheel wouldn't turn the engine anymore. I tried all different gears, but it's not working anymore. I also noticed that if there's no gear engaged, the wheel just turns rather freely, and if it's in any gear, there's a bit of a *clonk* sound when turning the wheel. So if it's in gear, there's a sector of about 5° in which the wheel moves easily, and then it goes *clonk* and becomes a bit heavier to turn. So it seems like it's grabbing something, but the engine just wont turn anymore :?

What's wrong now? Did I screw up?
Carl

1989 TRD "Entreprise" Turbo Diesel
1989 16 Valve
---
Parts needed:
- One black leather headrest.
- FDV overhaul kit (95.669.034)
Please contact me through PN if you have any of this.

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Way2go
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Post by Way2go » Mon May 12, 2008 4:29 pm

TB2 wrote:
What's wrong now? Did I screw up?
I read that this happens before you have changed the belt? So there should not be an interference problem. Now I'm no expert on diesel engines, but I do know they have very high compression so I take it that you have removed the glow plugs to allow ease of rotating the engine manually ? :?
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TB2
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Post by TB2 » Mon May 12, 2008 5:30 pm

Yes, I haven't removed the belt yet, just the engine mounting. And no, I have not removed the glow plugs and I hope I wont need to. Apparently, that's a pretty risky job (as parts of the head might come of if too much force is applied). And the glow plugs are perfectly fine, the engine starts immediatly if I preheat long enough (not only until the glow lamp goes off but until I hear the relay clicking).

Anyways I don't think that's necessary anyway, and appart from that, the engine should still be moving, right? Because I _was_ rotating the wheel. The wheel should block, too, if there's a problem with the engine locking up or something, but the wheel turns fine, except the engine doesn't turn with it. I can turn the wheel as much as I want, and as described, it feels like something in the gearbox or engine is moving, too, as I can feel something when rotating the wheel back and forth a bit several times. It goes *clonk* *clonk* *clonk* when doing that, while between the clonks it rotates easier than after the clonk, as if it's moving something in there. That *clonk* noise goes away if I don't engage a gear. It's there, if any gear is engaged.

Might there be something disconnected inside the gearbox?
Carl

1989 TRD "Entreprise" Turbo Diesel
1989 16 Valve
---
Parts needed:
- One black leather headrest.
- FDV overhaul kit (95.669.034)
Please contact me through PN if you have any of this.

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mat_fenwick
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Post by mat_fenwick » Mon May 12, 2008 9:52 pm

I've never had to take the glowplugs out when rotating a diesel, I usually use the 22m bolt on the crankshaft pully to rotate the engine and can usually do it with a standard ratchet handle.

If the wheel turns with it in gear, and the engine doesn't, it can't really be in gear. But why??? If the gear lever is mooving properly perhaps there is a problem with the gear linkage... If you start the engine and put it in first with 1 wheel off the ground does the wheel turn? That would establish whether it is really in gear. Be gentle, I wouldn't rev the engine as you have removed one of the mounts.

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Post by TB2 » Mon May 12, 2008 10:51 pm

I don't get it, I just rotated the wheel, the engine was turning with it, and then suddenly the engine stopped while I turned the wheel. I didn't use force, I didn't turn it fast or anything, it didn't even feel that much different when the engine stopped following the wheel.
And there even is a noticable difference when turning the wheel without a gear engaged compared to when I put in any gear. The *clonk* thing isn't happening with no gear in. I'm a bit scared of startin g the engine with the car stading on axle stands and with that mount removed.

I'll be working the next few days, but when I get the chance, I will rotate the engine using a ratched on the crankshaft and with a gear engaged. The wheels should then be turning. That would of course be a royal pain in the %&$ if something went wrong inside the gearbox. That would be just perfect. I never had any problems with the gears no behaving in the short time I was driving it. :?
Carl

1989 TRD "Entreprise" Turbo Diesel
1989 16 Valve
---
Parts needed:
- One black leather headrest.
- FDV overhaul kit (95.669.034)
Please contact me through PN if you have any of this.

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mat_fenwick
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Post by mat_fenwick » Mon May 12, 2008 11:14 pm

TB2 wrote:I'm a bit scared of startin g the engine with the car stading on axle stands and with that mount removed.
Probably sensible to be honest, there is a risk of the vibration knocking the car off the stands and although I have been OK, with hindsight I probably shouldn't have recommended it. I would do as you plan to do, and turn the engine over with the rachet (there is no need to have it in gear except to check the gearbox) You can then line up the pins directly and at least get the cambelt done! I think it is incredibly unlikely that there is a problem with the gearbox although I can't think what could be causing the symptons you decide. :?