Gti6 Cambelt Change

[tagy 1]

I am reading up about changing the cambelt on a gti6. (think the waterpump is leaking at the moment)

 

All the guides say to loosen both cam pulleys before take the belt off, now I'm sure there is a good reason for this, but can anyone explain why?

 

Because my understanding is.. you would pin the 3 pulleys in place, replace roller, water pump, tensioner, put new belt on and tension it. Turn over, and check timing.

 

Also what is the best way to loosen the cam pulley bolts if needed? Is a bolt through the timing pin OK?

[welshpug 1,657]

Its to ensure that whatever the belt tension is set to the camshaft timing is still correct.

 

The Mi16/S16 had two tensioners to ensure the same thing was done, i.e correct cam timing.

 

 

A bolt through the timing pin is not ok at all, as they are only 5mm pins, and an M12 bolt!

 

You need a tool to hold the pulley, looks like this; (though a friend made one from flat bar and 3 bolts)

 

[SurGie 54]

Can you give us a part no for that WP ?

 

Also have a look on the 306 gti6 forum FAQ for changing the cam belt, it has some good advice there.

Edited July 26, 2010 by SurGie

[welshpug 1,657]

afraid not though I wouldn't be surprised if there is a Peugeot special tool that does have a part number.

[davev 1]

hmm. it seems like sevice box dont say a tool is used. just the locking pins should hold.

 

Without removing the rods :

 

* Slacken the 6 bolts (11 )

* Check that the pulleys (12 ) and (13 ) turn freely on their hubs (10 )

 

(i couldnt get the pic to transfer but thats the part for the cam bolts.)

[Toddy 7]

The correct tool that pug uses locks both pulleys together( a bolt and some suitable wedge shaped alloy would suffice), they also measure the belt tension electronically.

[davev 1]

hehe the fantum seam gauge. id be surprised if any garage even knew what one looks like.

[blessed6383 0]

Its to ensure that whatever the belt tension is set to the camshaft timing is still correct.

 

The Mi16/S16 had two tensioners to ensure the same thing was done, i.e correct cam timing.

 

 

does this need to be done on the mi16 aswell as im confused as when changed my mi16 belt never did this?

sorry to jack the thread

[Masekwm 2]

So No 11 here is really wrong? http://www.306gti6.com/forum/showthread.ph...0662&page=1

 

Ah got it, the tool is needed to hold the cam pulleys whilst the bolt is undone.

 

Tom - I need to change the belt on my '6 engine which is sat on the garage floor atm, feel free to help me try and understand the guides!

Edited July 27, 2010 by Masekwm

[welshpug 1,657]

I'm not surprised some DIY belt swaps go wrong when people follow that guide

 

Note that the tool is only needed for the later single bolt adjustable pulley, not the earlier 3 bolt ones.

 

shouldn't do as instructed in No3, (same as using a timing pin to lock the engine) a large flat screwdriver in the ring gear is better

 

No5 is wrong on the same lines as above, relying on the pins/belt to hold the cams in place, use tool pictured above.

 

11 is correct, but the method shown in 14 is wrong, relying on the pins as mentioned should not be done.

 

 

 

MI16's don't need the cam pulleys loosening

[hcmini1989 16]

As far as i can remember i have done 2 of these on mates cars and have never botherd with tounching these bolts just fitted belt and tensioned them up like any other belt .If you need an alloy peice to lock the cams try your local factors i know mice stocks aload of diffrent ones for locking twin cam engines

 

I think people are making things alot harder than they need to be

Edited July 27, 2010 by hcmini1989

[blessed6383 0]

I'm not surprised some DIY belt swaps go wrong when people follow that guide

 

MI16's don't need the cam pulleys loosening

 

didn't think so as wouldnt make any difference as they can only go on in 1 position but thought id ask the wise

[SurGie 54]

I'm not surprised some DIY belt swaps go wrong when people follow that guide

 

Note that the tool is only needed for the later single bolt adjustable pulley, not the earlier 3 bolt ones.

 

shouldn't do as instructed in No3, (same as using a timing pin to lock the engine) a large flat screwdriver in the ring gear is better

 

No5 is wrong on the same lines as above, relying on the pins/belt to hold the cams in place, use tool pictured above.

 

11 is correct, but the method shown in 14 is wrong, relying on the pins as mentioned should not be done.

 

 

 

MI16's don't need the cam pulleys loosening

 

So basically WP that long tool is to keep the cams and timing hole in line precisely ? Also i was not keen on using drill bits like what he uses because when i tested them with belt still on they did move a little, so i will be using/getting those tools for when i get round to changing the belt before i fit the engine in sometime this year all being well. Mine has the 136 metal tension-er belt system.

 

Will Pug/Citroen sell them and if so how much are they ?

[DrSarty 90 1 Cars]

I know this is old, but I have my first '6 engine and am fitting a new cambelt kit prior to dropping the engine in the 205.

 

Firstly, there are SO MANY versions/guides out there for fitting a cambelt to the '6 engine, no wonder people (including me) get confused. This includes the Haynes manual, and is doubly confusing due to there being different 'phases' of the engine.

 

There are different tensioners and cambelt teeth counts (136 vs 137), but most importantly there are 2 different types of vernier/adjustable cam pulley/sprocket, i.e. a typical 3 small locking bolt sprocket versus a sprocket which is clamped to the camshaft using just the large central bolt.

 

However in both cases they do the same, they allow the cam sprocket to rotate (within limits) independently to the camshaft itself. This is important to remember!

 

Now I'm no expert, but I've carefully and I believe logically deduced the following:

> With standard cams, the timing is basically fixed

> It's fixed, i.e. not really adjustable (or rather tuneable) despite having adjustable cam sprockets, because the camshafts and the crankshaft get locked by 3 pins

> First confusion arises as the crank pulley has a rubber insert which means the outer part of the crank pulley can, after time and use, rotate slightly or slip independently of the crank itself, meaning the crank locking pin hole won't be at the correct orientation in the outer part of the crank pulley (about 11 o'clock) despite the centre part of the pulley being correctly aligned with the slot in the block (actually in the alloy oil pump cover) so any crank locking pin cannot be inserted even though all pistons are at mid-way and the crank in basically the correct position

> Solutions to the latter are as follows, but ALWAYS involve locking the cams first! 2 x M6 bolts or drill bits (or pucka locking pins) at about 5 o'clock INLET and 7 o'clock EXHAUST will lock the camshafts. NOTE: With these pins in position, providing the belt was fitted correctly in the first place and the engine timed right, the crank WILL be in the correct position, regardless as to where the crank pulley outer pulley locking hole is orientated; it's the inner crank pulley hole that matters

 

The below pics should indicate for 3-bolt and single-bolt sprockets the "o'clock" orientation I've mentioned above:

 

 

 

> With the camshafts locked, IF the crank pulley locking pin cannot be inserted at 11 o'clock, then simply replace the crank pulley with either a new/good OE item that has its locking holes aligned, or a solid after market crank pulley, or a solid XU 8v crank pulley PURELY for timing purposes only

> Here's the important bit - the M6 pins in the cam sprockets are actually locking the camshafts; they are not really locking the sprockets, as when the 3 bolts or single central bolt is loosened on each camshaft, the sprocket can rotate independently, BUT this isn't really for timing purposes, it's for cambelt tensioning purposes

> The purpose and importance of a tool, off the shelf or homemade, which is used to lock the cam sprockets is SOLELY for the purpose of holding things still and safely locked at the correct timing whilst the cam sprocket adjustment locking bolts or bolt are undone. As Welshpug said, this tool isn't really required for the cam sprockets with 3 small bolts in, as the M6 pin is sufficient to lock the camshaft whilst these 3 bolts are loosened. However the tool is VITAL for holding the cams still whilst loosening the single cam sprocket bolt in each camshaft. FAILURE to use such a tool, and rely on just the M6 pins is likely to at least snap the pins, and/or the casting in the head made for the pins, AND WORSE to allow the camshaft(s) to rotate upsetting the timing and WORST of all allow the valves to clip, which may bend them and create a 'tapper' of an engine which will no doubt drop a valve in due course after being noisy and down on power

 

Finally, and hopefully the conclusion you've reached like me, is that the camshafts locked with pins, then the pistons at half-way relative to the cams (i.e. there are 2 possibilities of 'half-way', hence the crank sometimes needs to be rotated twice to align the cam locking holes) and ideally the crank pulley locked in that position by pin or other means, IS THE ENGINE TIMED, there's nothing more to it than that.

 

Then once the timing's locked, it's only a matter of fitting the cambelt correctly (rotation arrow if applicable, correct number of teeth to suit tensioner, clean and routed correctly) and to the correct tension.

 

Here's where the process gets a bit vague again, but it's now quite easy to see that loosening the cam sprocket bolts (x3 per cam or x1), HAS GOT NOTHING TO DO WITH TIMING (because the camshafts themselves are already pinned/locked/timed); it's only to allow the cam sprockets to rotate a little freely to permit correct distribution of cambelt tension.

 

The cam sprocket locking tool is needed to loosen and then tighten the cam sprocket bolts (mainly just for the cam sprockets with ONLY a single central bolt). Guides indicate this central bolt should be loosened then pinched finger tight, belt fitted and initially tensioned, then tension released (fully or partly I'm unsure on currently), then sprocket bolts loosened to allow the sprockets to share the tension, then those bolts re-tightened (again using our special tool) and then a final tensioning procedure.

 

The tool itself should either be a double wedge or almost Xmas tree-shaped thing which 'wedges' between the 2 cam sprockets, geometrically locking them still. Alternatively, it can be a bar-type affair which is held or perhaps bolted to the head or block which grips a single or possibly both cam sprockets for the same 'hold everything still whilst I loosen this bolt' type effect.

 

So the first bit and any surrounding confusion highlighted by Surgie's post should be gone now, and all we need is an accurate tensioning procedure. 1 version is attached below.

 

***

These additional pics show the single bolt cam sprockets pinned and where the tension should be measured but end-on instead of at a funny angle, and this first attached document shows a proposed tensioning procedure based on the 1-bolt sprocket: (I have a procedure for the 3-bolt sprocket based on XU10J4R and XU7JP4)

peugeot_306_gti-6_service_guide (Cambelt ONLY).pdf

Edited December 11, 2013 by DrSarty

[welshpug 1,657]

tensioning procedure;

 

 

Whilst fitting belt, rotate the free moving cam sprockets clockwise so the correct tooth sits on the sprocket, then allow them to sit wherever they sit when tension is applied to the belt (they will rotate anti clockwise as more tension is added)

 

tension the belt as appropriate, two variants;

 

1 - manual eccentric tensioner,

 

use square drive to turn the pulley until the front run of the belt can be turned to roughly 45 degrees WITHOUT excessive force.

 

lock tensioner in place with the 13mm bolt.

 

lock camshaft sprocket to the camshaft sprocket hub, 3 bolt type, torque the three 10mm bolts to an applicable torque, DO NOT OVER TIGHTEN.

 

single bolt type, use camshaft sprocket holding tool and tighten the single bolt to specific torque (do not rely on 6mm pin to hold the camshaft in place)

 

 

2 - sprung eccentric tensioner.

 

use hex key in hub of pulley until pointer aligns with notch on pulley base plate, lock pulley in place.

 

secure pulleys as above.

[welshpug 1,657]

p.s, this is applicable to the XU7JP4 and XU10J4R as much as the RS.

 

much the same procedure is applied to the TU5J4 engine, which also has the same style pulleys as the early XU7/10J4R/RS engines.

 

AND also the ES9J4 and J4S, but have a 4 bolt pulley, and 4 off, and a VERY loooong belt...

[DrSarty 90 1 Cars]

Thanks, that's what I thought.

 

There is a bit more info regarding preparing the single sprocket bolts prior to belt fitment and tensioning steps in the attachment with my last post.

 

I'm also trying to reduce the XU7JP4 document (to under 500kb!) for similar extra detail concerning the 3-bolt sprocket type.

 

Overall, do you agree that it may have been useful to clarify that cam/engine timing is basically fixed (by way of the pins), and that the adjustable cam sprockets is just to aid tensioning?

 

I don't deny that some cam swing IS possible with these sprockets, but it's really not advised with OE cams and pistons and should be saved for bigger valve cut-outs and aftermarket cams on modified engines. Also, neither of these OE sprockets have the useful and accurate timing degree marks for advancing and retarding cams accurately.

XU10J4RS Cambelt (Reduced).pdf

Edited December 11, 2013 by DrSarty

[welshpug 1,657]

yes you are correct in that the cams themselves are not adjustable, its purely to ensure correct cam timing whatever the belt tension is set to.

 

 

Some good torque gains can be had by playing with the timing without sacrificing peak power, but as you said there isn't great margin for error.

[Mad Scientist 106]

They are not vernier pulleys in the true sense. That's not what they were designed to do. All they were designed to do is equalise the tension across both sides of the belt, when fitting a new cam belt.