I changed the cam-belt on my JTD over the weekend. Since the captive nuts for the wheel arch/engine shield were all rusted, I didn't complete re-assembling the beast for a test drive.. but it all started and ran okay.

But I have a few questiones which may be interesting/always cause me a head-scratch.

1) My crank pulley (i.e. not the aux-belt pulley) has a line on it. The engine case has a notch in it. You'd think that at TDC (according to the camshaft pulley) the line would point at the notch.. but no.

The notch is dead south ... the line is pointing somewhere close to 270 or 275 degrees. There's no other mark in the vicinity, other than a line I scraped myself in the past, to line up with it. All the pulleys in there seem to have locating pimples, so they can only go on one way.... so I dunno how the pulley could be fitted 90 degrees out... but could it? Or do I have a missing mark? Or is the line or the notch (or both) nothing to do with the engine timing?

2) When I fit my (admittedly cheap and made for an indeterminate Vauxhall (16v?) ) locking tool on the crank at TDC (or +90 degrees, as above, anyway), it doesn't line up with the pimple on the pulley, or the reference bolt hole. I have to squeeze the motor round a gnat's franger's width more to get the tool on. That makes the little white mark up on the camshaft pulley no longer point at the white painted pointed on the plastic cover behind it.

I *think* in the past I adjusted the cam backwards by 1 tooth, so that the crank tool and the pulley were locked and the cam-pulley mark pointed to the white arrow... but while it started okay, it ran like a box of spanners... so I think this is just an anomaly of my tool... (or I may have remembered it wrong) so curious if anyone knoes better.

3) The TDC sensor - I forgot what a Mo-Fo mine is. The countersunk Torx head screw that holds it on (after the bolt on the water pump is removed) was rounded off a long time ago and I've never been able to remove it. I change the water pump by bending the TDC sensor backing plate out of the way slightly, to get the ear of the pump in and out.

Now.. a previous mechanic and I have both nicked the water pump o-ring fitting a new pump around the moody sensor... and this time, I noticed that I'd had the usual slight water leak from the pump which had dripped onto the tensioner and seized it in the "perfectly adjusted" position. Belt tension was still good.. but the tensioner was seized/could have ended badly.

What's the best way to get a moody screw out? I suspect I'll have to remove the injection ECUs and/or the wing.. to be able to get a drill/tool on it... and I also suspect the TDC sensor itself will suffer collateral damage (you never know though). Has anyone done the same job?


4) Part number for those captive nuts? ePER is a bit slow and then gives an error. They're the two holding the L shaped plastic guard to the inner wing.


Ralf S.

Ralf S. said:

1) My crank pulley (i.e. not the aux-belt pulley) has a line on it. The engine case has a notch in it. You'd think that at TDC (according to the camshaft pulley) the line would point at the notch.. but no.

The notch is dead south ... the line is pointing somewhere close to 270 or 275 degrees. There's no other mark in the vicinity, other than a line I scraped myself in the past, to line up with it. All the pulleys in there seem to have locating pimples, so they can only go on one way.... so I dunno how the pulley could be fitted 90 degrees out... but could it? Or do I have a missing mark? Or is the line or the notch (or both) nothing to do with the engine timing?

Click to expand...

The notch at the bottom, front of the oil pump is nothing to do with engine timing. My guess is that the notch is there to allow water to drain out.
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That's the one!

The first time I changed it, it was a bit puzzling... but I locked it where the tool ftted it (plus a bit of +/- to get the locking tool to sit on the pimple and line up with the reference bolt... which then put the camshaft mark out by one tooth) and took it from there.

After that I scraped a mark at the 275 degree position but it's just always puzzled me what you'd line up the pulley with, if you didn't have the tool (or a slightly deformed one, like mine).


Ralf S.

Zoom in on pic and you can see the notch on pulley aligns with notch on bit of cover that forms belt shield.

Ralf S. said:

That's the one!

The first time I changed it, it was a bit puzzling... but I locked it where the tool ftted it (plus a bit of +/- to get the locking tool to sit on the pimple and line up with the reference bolt... which then put the camshaft mark out by one tooth) and took it from there.

After that I scraped a mark at the 275 degree position but it's just always puzzled me what you'd line up the pulley with, if you didn't have the tool (or a slightly deformed one, like mine).


Ralf S.

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Probably nothing a lot of engine's now have no timing mark's and require tools in order to chnage Beltsville ect

Sometimes you will get a vehicle that someone has sheared the alignment key between the cam sprocket and cam then just tightened the retaining bolt insanely tight. That clearly makes the mark on the camshaft pulley "out of time" in fact it makes it a hazard.
I had one that the mark was about 90 degrees out,
Luckily it came to me as a runner. Still took me a while to work out what was wrong by removing valve cover and looking where mark was when both valves on number 4 cylinder equally open. Replaced cam pulley and it all made sense again.

The other one came to me as a non runner when a garage started belt change then couldn't get engine to turn by hand without locking up.

Mark on that cam pulley was about 200 degrees out, didn't help it was a renault who number their cylinders backwards.
Timed that cam by eye looking at valves and it's still going strong. That was diesel kangoo owner did not want to replace cam pulley.

Ralf S. said:

What's the best way to get a moody screw out? I suspect I'll have to remove the injection ECUs and/or the wing.. to be able to get a drill/tool on it... and I also suspect the TDC sensor itself will suffer collateral damage (you never know though). Has anyone done the same job?

Ralf S.

Click to expand...

It really depends on what access you have. Sometimes you might be able to get a small pair of Stilsons on the head, Sometimes if you can get a cut across the head an impact driver might work. Sometimes if there's enough meat left on the stub/bit remaining you can weld an arm. Sometimes you might have to drill and use an extractor, or re-tap, or helicoil. Sometimes you have to take the engine out and put it on a spark eroding machine , okay that's worse case .

In terms of timing an engine, I've always used my own marks typically centre punch and hacksaw cuts, then highlighting with paint pen

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Maxcaddy said:

It really depends on what access you have. Sometimes you might be able to get a small pair of Stilsons on the head, Sometimes if you can get a cut across the head an impact driver might work. Sometimes if there's enough meat left on the stub/bit remaining you can weld an arm. Sometimes you might have to drill and use an extractor, or re-tap, or helicoil. Sometimes you have to take the engine out and put it on a spark eroding machine , okay that's worse case .

In terms of timing an engine, I've always used my own marks typically centre punch and hacksaw cuts, then highlighting with paint pen

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Click to expand...

The OE bolt has a gcountersunk head, with a Torx star cut into the top.. presumably so it's not in the way of any moving parts (although a hex head bolt would have worked equally well and at least given me something to get the wrench onto.. )

As it is, it's practically flush with the TDC sensor plate, so there's nothing to grab a hold of, even if the TDC sensor wasn't going to get in the way of the wrench as I rotated it.

My best idea is to use a dremel to cut a slot into the head so that I can try a regular screwdriver on it.. but I suspect this will just weaken the bolt head so that when I try to unscrew it, it shears off, leaving just 2mm or so of bolt shank sticking out, and a floppy TDC sensor (now with no bolt to hold it down).

On the other hand, I'll use this moment to replace the water pump and get a straight approach into its apperture, so the o-ring doesn't get nicked..

So I've left it alone a few times... but it's had three water pumps in my time with it and two of them have been nipped in the o-ring (painful..! ). The odd bit of drip from the pump didn't strike me as too severe before... but the tensioner was seized up this time, so I think it's time for that seized screw to go.

Sooner or later, I guess that the TDC sensor plate will start to crack, the number of times its been bent slightly one way then the other..

Hmmmmm. I'm vexed.


Ralf S.

I got a picture of my 1.6 where the pulley is "on time".

Ralf S. said:

The OE bolt has a gcountersunk head, with a Torx star cut into the top.. presumably so it's not in the way of any moving parts (although a hex head bolt would have worked equally well and at least given me something to get the wrench onto.. )

As it is, it's practically flush with the TDC sensor plate, so there's nothing to grab a hold of, even if the TDC sensor wasn't going to get in the way of the wrench as I rotated it.

My best idea is to use a dremel to cut a slot into the head so that I can try a regular screwdriver on it.. but I suspect this will just weaken the bolt head so that when I try to unscrew it, it shears off, leaving just 2mm or so of bolt shank sticking out, and a floppy TDC sensor (now with no bolt to hold it down).

On the other hand, I'll use this moment to replace the water pump and get a straight approach into its apperture, so the o-ring doesn't get nicked..

So I've left it alone a few times... but it's had three water pumps in my time with it and two of them have been nipped in the o-ring (painful..! ). The odd bit of drip from the pump didn't strike me as too severe before... but the tensioner was seized up this time, so I think it's time for that seized screw to go.

Sooner or later, I guess that the TDC sensor plate will start to crack, the number of times its been bent slightly one way then the other..

Hmmmmm. I'm vexed.


Ralf S.

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I you need to remove cam sprocket for better access be careful not to shear off key between sprocket and camshaft when reinstalling retaining bolt, ha ha (-:

Ralf S. said:

The OE bolt has a countersunk head, with a Torx star cut into the top..

My best idea is to use a dremel to cut a slot into the head so that I can try a regular screwdriver on it..

Ralf S.

Click to expand...

Okay not wishing to teach granny, but a bolt has 3 parts, the thread, the shank, and the head, that being the case if you were to drill/cut off the Torx head, could you pull the plate over the remaining shank to then get a better grip on (more of) the shank to undo it ?

If you can cut a slot with something, then an impact screwdriver would perhaps help.

In both cases, some applied heat will help as long as you don't set anything else on fire

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The countersunk screw is pre-treated with thread lock compound, so is likely to be more difficult to remove than expected if the screw head is damaged.

Last time I bought new screws, the countersunk one had been changed from Torx to Allen head.

The screw screws into the aluminium cylinder head, so any heat applied to to assist removal is likely to be absorbed by the cylinder head.
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Dot punch on bolt face then tap round?
May have to remove cam pulley for access

Davren said:

The countersunk screw is pre-treated with thread lock compound, so is likely to be more difficult to remove than expected if the screw head is damaged.

Last time I bought new screws, the countersunk one had been changed from Torx to Allen head.

The screw screws into the aluminium cylinder head, so any heat applied to to assist removal is likely to be absorbed by the cylinder head.
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Click to expand...

As usual excellant detail from Davren :worship:

As a first step I would try to cut a slot across the head and if I could get in there an impact screwdriver, but I would still get some localised heat if I could, if only to help break the seal. It looks to be a 6mm thread so shouldn't be that tight in there.

If that didn't work I would drill the head off as it looks like the plate will slide over it. With the plate off the tension of holding it on would go, and the stub should come out fairly easily.

If you get that far and its still in there, come back for more words of good advice

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Davren said:

The countersunk screw is pre-treated with thread lock compound, so is likely to be more difficult to remove than expected if the screw head is damaged.

Last time I bought new screws, the countersunk one had been changed from Torx to Allen head.

The screw screws into the aluminium cylinder head, so any heat applied to to assist removal is likely to be absorbed by the cylinder head.
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Click to expand...

I'm worried that you have a photo of every nook of your car.. but that's exactly what mine looks like (although the screw head is more mashed than yours).

My thought about cutting the head off the bolt is that the shank might not project out enough to get a decent grip on it. At least the head gives me more of something to lever/tap against, depending on how I tackle it.

It'd be a head-off job to be able to get a drill onto it.. the photo makes it look like there's loads of room but in reality there's probably enough for an impact driver but not enough to be able to hit it with a mallet.

If I can cut a notch into the screw I might be able to tap it loose. Or, if it just deforms, I wonder if a new TDC sensor might do... then unbolt the old one from the water pump, weld the screw to the TDC back plate (which might kill the sensor), and then rotate the whole thing, having eased the pimple out of its locating hole...? Hmmm...



Ralf S.

Ralf S. said:

If I can cut a notch into the screw I might be able to tap it loose. Or, if it just deforms, I wonder if a new TDC sensor might do... then unbolt the old one from the water pump, weld the screw to the TDC back plate (which might kill the sensor), and then rotate the whole thing, having eased the pimple out of its locating hole...? Hmmm...

Ralf S.

Click to expand...

Yep, that sounds like it might work as long there's nothing else stopping the plate from turning :slayer:

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Ralf S. said:

If I can cut a notch into the screw I might be able to tap it loose.

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I got the screw in my picture out by hammering something into it. I think it was a piece Imperial size Allen key.
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Which is the problem with Torx heads, a lot of folk think they are socket heads so try an Allen key to find it 'rounds off' the head, and by then it's too late to get a proper Torx driver to fit and work .

Maxcaddy said:

Which is the problem with Torx heads, a lot of folk think they are socket heads so try an Allen key to find it 'rounds off' the head, and by then it's too late to get a proper Torx driver to fit and work .

Click to expand...

How some people look at torx head and thing it looks like a hex ill never know


Now torx spline and Ribe I could understand

I have undone Torx's with an Allen key, just because I didn't have a Torx.. but as I came across more and more of them, I decided to invest in a Torx socket set.

To be fair.. this is the only Torx I've encountered where the inside was stripped.. but it was already a bit mangled.. I just succeeded incompletely rounding it..


Ralf S.