Cam belt tension advice from Gates

[earthman]

https://pmmonline.co.uk/technical/g...tm_medium=email&utm_campaign=28-december-2020


Some may find the above link useful.

Now is having slots in spockets on the end of camshafts a common thing now? I had to check the camchain timing on my modern motorcycle some months back and found the same thing, after manually rotating the crank and getting all the marks to line up, I had to undo and adjust the spockets slightly.
I've never seen this design myself.

 

[doubleboost]

Many of the VAG group are like this
Many also have no key on the bottom pulley

 

[Ruffian]

Always have. As it also tells you to check the tolerance settings via diagnosis also as can tell the timing deviation between cam and crank timing.

 

[mike os]

Vag have used this for years, except they use a jig to lock the crank pulley

 

[m_c]

Must be a slow PR day for Gate.
Who would ever have guessed that not following manufacturer's instructions may result in premature timing belt failure


Although seeing that's a Renault engine, it's reminded me off the Renault Trucks training course I went on, where they were asked to also show us how to do timing belts on the 1.9 engine in Trafics/Vivaros.
It started off with the instructor wheeling out an engine, which I promptly highlighted was actually 2.2, as I'd already done belts on both engines, but he was convinced it was a 1.9. That resulted in everybody walking outside so he could prove it was identical to the 1.9 traffic they had in the car park. It wasn't.
Then he just about had a heart attack when I said I'd just used a bottle of tipex as we couldn't get the cam alignment tools, along with a mirror to see the tensioner (you were supposed to use a fancy jig/gauge that re-created the pointers above the engine).
He also had the same response when I said I set the valve clearances on the lorries with the engine running.
Stupid engine setup meant you couldn't turn the crank by hand, and you were meant to remove the starter motor to install a dummy pinion to turn the engine with a ratchet.
There was also the argument over the big ZF AS-Tronic gearbox on a stand in the workshop, which he told us was a pure Renault product. His answer to why ZF was cast in to the side of it, and not Renault, was they licensed it to ZF

 

[earthman]

Always have. As it also tells you to check the tolerance settings via diagnosis also as can tell the timing deviation between cam and crank timing.

Er, how far back does 'always' cover exactly? Not being funny but the cars that I've done cam belts on haven't had this design of cam sprockets. I've yet to do the belt on my wife's 2013 Panda, is that likely to have it for example??

 

[roofman]

Adjustable cam sprockets were only readily available in the after market and tuning world and were expensive too...As for a bikes camchain i have always and still do count the pins and have not come across cams being out on marks or teeth in Jap Bikes

 

[armalites]

It's such common thing to do yet there are so many differences. Some engines just by taking the covers off it's clear where everything lines up. On others you'd never spot the marks unless you knew.

Slackening cam pulley is not a new thing, VW diesels have been like this since the 80s.

 

[Fazerruss]

If you don't lock all the pulleys just the crank then then tension will be alright. I've done this way for years as I didn't have the locking tools. The timing might be out by a fannys hair due to different belt tolerances but I'm not racing F1 cars and they always ran sweet.

 

[doubleboost]

Tipex is very Widley used just to "make Sure"

 

[Ruffian]

Er, how far back does 'always' cover exactly? Not being funny but the cars that I've done cam belts on haven't had this design of cam sprockets. I've yet to do the belt on my wife's 2013 Panda, is that likely to have it for example??

I'm only 33 so been in the trade 15 years. Early PD engines came out 1998/9

 

[Moose McAlpine]

Some may find the above link useful.

Now is having slots in spockets on the end of camshafts a common thing now?

Yes, has been for some time. Some use floating pullies that are only locked to the cam/crank by their bolt's clamping force. Some engines have floating pullies locked by tapers onto the cams and a locking tool indexes onto the cam and the pulley has no marks.

Many also have no key on the bottom pulley

I forget which it is, but i'm sure there's one where all pullies are floating? Maybe a Ford 16v?

Always have. As it also tells you to check the tolerance settings via diagnosis also as can tell the timing deviation between cam and crank timing.

Old VW 5-cylinder TDIs are like that. The sync angle for the injector pump is set by the belt. One tensioner and one eccentric guide pulley. Adjusting both with the engine running to get tension and sync angle bang on.. while down in the footwell going through an access panel..

Must be a slow PR day for Gate.
Who would ever have guessed that not following manufacturer's instructions may result in premature timing belt failure


He also had the same response when I said I set the valve clearances on the lorries with the engine running.

There was also the argument over the big ZF AS-Tronic gearbox on a stand in the workshop, which he told us was a pure Renault product.

Truly. Pretty sure if you're doing a belt and didn't know that you probably shouldn't be changing timing belts..

Running adjustment is not much fun, only done it a couple times and would happily never do it again.

Even the Renault trucks manual boxes are ZF. Don't think many of the truck manufacturers make their own boxes? (I think Volvo and Merc do?)

 

[Woody.v8]

Been like this for years, even 300tdi discovery had the same set up and that was years ago, and floating pulleys on the crankshaft have been out for a good while.

 

[doubleboost]

Yes, has been for some time. Some use floating pullies that are only locked to the cam/crank by their bolt's clamping force. Some engines have floating pullies locked by tapers onto the cams and a locking tool indexes onto the cam and the pulley has no marks.



I forget which it is, but i'm sure there's one where all pullies are floating? Maybe a Ford 16v?



Old VW 5-cylinder TDIs are like that. The sync angle for the injector pump is set by the belt. One tensioner and one eccentric guide pulley. Adjusting both with the engine running to get tension and sync angle bang on.. while down in the footwell going through an access panel..

View attachment 266632 View attachment 266633




Truly. Pretty sure if you're doing a belt and didn't know that you probably shouldn't be changing timing belts..

Running adjustment is not much fun, only done it a couple times and would happily never do it again.

Even the Renault trucks manual boxes are ZF. Don't think many of the truck manufacturers make their own boxes? (I think Volvo and Merc do?)

The small petrol fords have no marks or keys at all , with all the pulleys loose you can rotate the belt without the engine turning. There is no room at all for error

 

[Moose McAlpine]

The small petrol fords have no marks or keys at all , with all the pulleys loose you can rotate the belt without the engine turning. There is no room at all for error

That's what it is then. (Zetec i guess?)

I remember a mate leaving a ratchet on the crank pulley bolt while preparing to change the belt. Engine got cranked over, bolt loosened but miraculously no damage occured. Not sure how he got away with that. Was an anxious belt change to see if it started after.. was an old Mk1 Focus.

 

[Woody.v8]

As long as you use locking pins you can't go wrong.

 

[Ruffian]

That's what it is then. (Zetec i guess?)

I remember a mate leaving a ratchet on the crank pulley bolt while preparing to change the belt. Engine got cranked over, bolt loosened but miraculously no damage occured. Not sure how he got away with that. Was an anxious belt change to see if it started after.. was an old Mk1 Focus.

Zetec do have fully floating pulleys on all 3.
Same as the i4 petrol mk6 transit but they had a diamond crush washer to pin the pulley to the crank. Was a pain as needed replacing as single use item.

Yes the lt35 diesel pumps were adjustable pulleys.

The one I did nearly go wrong on was a td4 freelander (Peugeot engine one) as the crank pulley is on a double with key way with a single width woodraft key. Could have easily set the crank timing out on that so had to drop the starter off to pin the crank in location. (Whilst the belt was off)

 

[m_c]

As long as you use locking pins you can't go wrong.

How much are you willing to bet on that?

 

[doubleboost]

I must have changed hundreds of belts ,
Every time I fire one up for the first time I get that feeling in the pit of my stomach

 

[keithski122]

As long as you use locking pins you can't go wrong.

You can if you accidentally leave the locking pin in...........seen it done on a peugeot engine with the locking pin in the flywheel.