cambelt

[renaultman]

iv been Reading all the threads about cam belt changes and I'm asking is there any need to slacken th cams? the only reason for doing this is if you were changing the vvt pulley .. it tells you to carry out procedure 2 if you do not replace the vvt and tell you to tension normally . I'm in the motor trade and have askes 4 Renault technician to check and they all said there is no reason to carry out procedure 1 on a normal cam belt change is this right?

http://www.fastchip.nl/media/doc/clio2/F4R_730.pdf

 

[Sean6545]

Iv never slackend either pulleys for just a timing belt change.

 

[renaultman]

Iv never slackend either pulleys for just a timing belt change.

i worked for renault for 3 year and never even heard of it till i came on hear

 

[BenR]

I slacken it all.

 

[sideways danny]

i worked for renault for 3 year and never even heard of it till i came on hear

that'll be why there are som many with wrong timing then.

Slacken everything

 

[DanD182]

that'll be why there are som many with wrong timing then.

Slacken everything

Prime example of why you don't take your clio sport to renault to have it serviced, when people who have worked for renault for 3 years and didn't know that.

 

[renaultman]

Prime example of why you don't take your clio sport to renault to have it serviced, when people who have worked for renault for 3 years and didn't know that.

but for a standard belt change the Renault guide dose not tell you to slacken all the pulleys

 

[Sean6545]

that'll be why there are som many with wrong timing then.

Slacken everything

Iv done hundreds of these belts and all of them have been spot on.

 

[renaultman]

same. i don't see how the timing could be out, if you use the tools then spin the engine over by hand and then refit the tools if they fit then the timing is spot on.

 

[Icarus]

same. i don't see how the timing could be out, if you use the tools then spin the engine over by hand and then refit the tools if they fit then the timing is spot on.

You're assuming the fully floating crank pulley doesn't move/relax when the tension of the bottom pulley/securing bolt is removed. If it does and you've marked it on the pulley then the timing is no longer correct, even if the cam locking tool and crank locking pin still fit. A single degree can cost several bhp. If you tension the belt up with the crank pulley unlocked then this just doubles the risk of the pulley being pulled round on the crank by the tension of the belt.

FWIW on all the race engines we do belts every 24hr or 3000KM's, whichever is sooner and always slacken and ensure free rotation of all three pulleys with the crank and cams immobilised in order to ensure correct cam timing.

Cheers
M

 

[BenR]

If you dont slacken the pulleys your also assuming the centre to centre distance between each cam stays a constant, which is unlikely with a new belt and tension value.

So not only is the LCA changing, but so is the LSA.

 

[renaultman]

You're assuming the fully floating crank pulley doesn't move/relax when the tension of the bottom pulley/securing bolt is removed. If it does and you've marked it on the pulley then the timing is no longer correct, even if the cam locking tool and crank locking pin still fit. A single degree can cost several bhp. If you tension the belt up with the crank pulley unlocked then this just doubles the risk of the pulley being pulled round on the crank by the tension of the belt.

FWIW on all the race engines we do belts every 24hr or 3000KM's, whichever is sooner and always slacken and ensure free rotation of all three pulleys with the crank and cams immobilised in order to ensure correct cam timing.

Cheers
M[/qu


I know the crank pulley moves it needs to spin free but the crank is lock so how can it move? and then you would tension it up then bolt the crank up then spin the engin over by hand and then refit the tools check they free without force and make sure the tension is ok , I also asked RTEs and they said there is no need the guide only says to do this if changing any pulleys (vvt)

 

[Fred@BTM]

with the crank pin in the crank can still move a tiny bit, don't forget you have to lock the flywheel too

i know the man who did look after all the renaultsport F4R engines for the UK and guess how he did them???

 

[wilco_clio]

you always slacken the pulleys it is supposed to help with putting the belt on,also from past experience it makes it possible to lock the engine up and still rotate the belt freely,i think by the book you are meant to turn it 6 times on the cam pulley,theres a special tool to rotate the cams

 

[Cup ov Ste 53]

I'm plannin on doin mine soon, pleased i read this. Didn't even considered doing this.
Let my get this right, with the cam tails locked (with the jig) and the btm end pinned. You slacken the cam pulley fixing bolts to allow the pulleys to move independantly of the locked camshafts ?
How are the pulleys located onto the camshafts ? Arn't they keyed ? Surely they shouldn't be able move ? (rotate)

 

[Fred@BTM]

no keys mate, fricton

you also need the pulley locking tool

all this lot

 

[renaultman]

OK if you do slacken all the pulleys lock the crank, back of the cams , then remove the belt put the tool on the front of the cams slacken them with the tool still in the back of the cams (replace the bolt and nut) replace the belt and tension it spin the belt over via the exhaust cam re-check the tension. then tighten and cams and crank remove the tool from the back of the cams and crank , then spin the engine over and repace the tools to make sure its ok and check the belt tension. if the tension out a bit (the marks not lined up on the tensioner) do you just ajust it, or slacken everything again ?

 

[Fred@BTM]

basically when you set the tension it will only tighten up on the tensioner side of the belt (ie crank to exhaust pulley) you spin it round a few times to equalise the tension on the entire belt then lock the pullies and tighten them all up

http://www.angel-works.co.uk/articles/f4rbuild.php

 

[Cup ov Ste 53]

What about the btm pulley Is that the same, no key ?

 

[Fred@BTM]

no key on any of them

 

[Cup ov Ste 53]

I understand now. Another special tool to buy !

 

[renaultman]

ok quick question thou after you tension it and have tigtened ever think up and spin the engine over via the crank if the tension is out slighty do you slacken all the pulleys again or just adjust

 

[Cup ov Ste 53]

Again i'm pleased i read this. I would have been a bit surprised to say the least if i'd have got down there n found no key !
I can see how doing it as you've said is the way to evenly distribute the tension throughout the belt....nice one

 

[sideways danny]

ok quick question thou after you tension it and have tigtened ever think up and spin the engine over via the crank if the tension is out slighty do you slacken all the pulleys again or just adjust

you need to slacken it all again if it's wrong. happens fairly infrequently but still happens sometimes

 

[renaultman]

and do you replace the seals behind the cam pulleys like on the guide?

 

[ben_p]

yep! ^

 

[renaultman]

i take it you just tap then in with the hammer no tool needed like the oil seals on the back of the cams

 

[Fred@BTM]

no tool need for them either, hammer!

 

[Steviant]

Think Tom needs to read this thread.

He didn't listen to me.

 

[Summeh]

Why would Renault provide 2 methods if one (procedure 2) was going to lose power/result in the timing being out?

Once the engine has been turned over a few times then tension (between exh and crank) will be evenly distributed. It then tells you to check and make sure the timing is still all lined up, if it is (should be) then all is fine. no?

Procedure 2 is no different (in theory) to the old F7R/F7P engine and cambelt procedure, and never any issues with those?

??????????????

 

[Fred@BTM]

welcome to the wonderful world of renaults! lol

 

[Summeh]

very helpful fred

Seriously though... I want to do the cambelt on my 182 this weekend, procedure 2 looks fine?

 

[Fred@BTM]

BPM - slacken everything
AWT - slacken everything
BTM - slacken everything
GDI - slacken everything
Yozzasport - slacken everything
R-sport engine lookafterer - slacken everything
Rentech - ? i assume slacken everything
Birchdown - ? i assume slacken everything
K-tec - ? i assume slacken everything

 

[Summeh]

Ok so because all those do procedure 1 then procedure 1 must be the best method?

 

[Fred@BTM]

well a gaggle of specialists and motorsport engineers/engine builders (one of which is renault sport france authorised) do it that way, you decide fella!

hence why i always bang on about the mickey mouse tools being s**t, a) they bend and b) they don't have the pulley tool

 

[Summeh]

Aye that is what i'm trying to do... get the facts behind my decision first though.

I don't see the "slacken" route as being much extra work... just think its odd renault would provide 2 methods if 1 of them was defective?

I wouldn't assume some of those above use the slacken method btw.

 

[Fred@BTM]

i always check the timing first as a matter of course as i'm pulling the thing apart, its surprising how many are out really!!

i think personally the "easy route" is intended for the non VVT F4R engines

 

[BenR]

Just check you've got the right tools as a conventional angle gauge on the ex pulley nut is virtually impossible.

And completely degrease all the pulleys before they go back on.

 

[Summeh]

Good point. I will check the timing on mine as im taking it apart. It's never been done so will be interesting to see if its out due to 'stretch'.

 

[Fred@BTM]

sexy vibrating snap on torque wrench has its uses!

benji the exhaust pulley is 30nm + 86deg (approx) IIRC? how does all 7stone on china man manage to do that? you must be hanging off the thing! always wondered that