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[JamesV6CDX]

The lurching and slight resistance is normal - in fact is good - its valve spring pressure.

Ok so …

With the crank sprocket mark still at 4pm:

Thoroughly check Cambelt kit (belt for missing teeth or damage, and ensure the tensioners and idlers turn ok and don’t feel rough)

If all good -

Align and lock cams in their positions (numbers 1,2,3,4 on the cogs aligning with the backplates)

Installl and set up the Cambelt kit

Ensure engine turns over through several revolutions okay by hand

If it does, I’d be tempted to fire it up.

NB to achieve correct tension this must be done with the spark plugs fitted

[JamesV6CDX]

I’m still at an absolute loss as to what those pins are though.

All I can suggest is ensuring that all of ancillaries above the crank pulley are ok.

If you’re not confident setting up the belt I’m sure I can make time in the very near future to pop up for a half day or whatever is needed

In reality though you’re making great progress and if you have time on your side there’s zero barrier to you even achieving a head-off job with us all to support and advise as you go

[JamesV6CDX]

If your cams turn through 360 deg with the engine at 4pm then you may have dodged a bullet. Mine got completely stuck with metallic resistance (although it didn’t sleep 3 teeth, it shed its belt)

I wouldn’t like to guess how well your valves will seat after slipping 3 teeth - but your post does suggest they are all going up and down.

Which makes me think it’s definitely worth timing up and compression testing it.

As I said before I worked on one which slipped exactly 3 teeth in that same direction - and it came back from the dead once set up correctly

[Dave G]

Huge thanks again James. 
I’ll follow your instructions - to the letter this time! I got a bit ahead of myself yesterday I think.

Those pins - I was showing them to my son yesterday and he just said ‘where are those magnets from?’  Yes they are all stuck to each other. It didn’t strike me before but they are little magnets.

Is there a Hall effect or induction type sensor in the vicinity?

[JamesV6CDX]

Interesting - I’ll have a think on the pins

Only Hall effect sensors are cam and crank and they don’t resemble anything like those

[Migv6 le Frog Fan]

Alternator ? 

[JamesV6CDX]

Here you go.



No threading, slightly bevelled ends - very shiny.
Centre sections quite dull as if they were load bearing?

Whatever they've come out of there must be more - nothing with a roller bearing has just four rollers...??

Does anyone know if either the belt tensioner or idler uses this kind of thing?
Or maybe someone has a scrap one to take apart to check??

I have been staring at this for ages trying to work it out.

To get into the bottom sprocket area they would HAVE to have been from something behind the plastic Cambelt cover - and from above

Literally the only thing there is the water pump.

If anything fell off the PAS / alternator etc then it would have no way of getting into the Cambelt cover without penetrating it.

I’m going to see if I’ve got an old water pump laying around and take it apart, watch this space

[Nick W]

How are rollers that big going to fit inside the water pump? 


When you get a pump apart, you'll find the impeller runs in bushes, not bearings.

[Enceladus]

My earlier suggestion of the locking/shipping pin for the aux belt tensioner is clearly wrong as there are now four pins.

I now suspect that the pins are camshaft sprocket locking pins. GM# 90501111. Four per V6 engine. The later sprocket design is a one size fits all. One mark for inlet timing  and one mark for exhaust timing. And two positions for the locking pin.

If so, at some point at least the sprockets and maybe the cam shafts have been removed and replaced/reinstated. Perhaps the pins were dropped or otherwise not reinstated or left somewhere by magnetism and fell down.

Anyway I'd want to be certain that the sprockets, as fitted now, each have the pin in-situ. I suspect they must be in place since the cams haven't been disturbed for years. Or have they been disturbed recently?

[Dave G]

Hi. Well I’ve had the car from new - Oct 2002 - and camshafts have never been removed or disturbed.
I did mention earlier that 4 of the 1-2 bank cam cover bolts were only finger tight, but that may be irrelevant.
I don’t suppose access to the pin's location is a) easy or b) possible?
Once the sprocket is fitted, do the pins still have a purpose on this engine? Or are they just for installation alignment?

[Dave G]

Maybe me being a bit thick, but if two components are locked by a pin going into each component, then wouldn’t those components have to come a long way apart before the pin could drop out?
Unless it’s been pushed in through an open hole I suppose…

[Dave G]

… and all 4 at once?

[Doctor Gollum]

Or taken apart.

[Raeturbo]

Russian sabotage?🕵🏿‍♂️

[Enceladus]

Hi. Well I’ve had the car from new - Oct 2002 - and camshafts have never been removed or disturbed.
I did mention earlier that 4 of the 1-2 bank cam cover bolts were only finger tight, but that may be irrelevant.
I don’t suppose access to the pin's location is a) easy or b) possible?
Once the sprocket is fitted, do the pins still have a purpose on this engine? Or are they just for installation alignment?

The pins are a permanent feature. They lock the sprocket orientation on the camshaft. At least until the bolt is fully tightened.

I agree, I can't see how they can fall out unless the sprocket bolts are removed and the sprockets are loose enough. That would probably wreck the valves if the engine was running. So they must have been removed and lost/mislaid when the sprockets were removed in the past for maintenance, which you are certain hasn't happened. If the pins were mislaid it doesn't mean they are not now present. Perhaps new pins were installed when the originals were mislaid. I doubt if it happened at the factory.

It is not usually necessary to remove the sprockets unless you want to work on the camshafts or valves. EG routine changing of the timing belt doesn't require sprocket removal.

As to the cam cover bolts, the torque is 8Nm. That's finger tight and a bit.

The pins you found look like the cam sprocket pins but they may well be from something else.