can the cam belt be too tight???

Post 741737 by theflyingbrick on 2014-10-12 17:38:07

well ive been busy with work and other non interesting ventures so my car still sits dormant needing valve guides replacing :( however I had today off and thought it would be nice to fit a pair of na cams to my dads car seeing as the cam cover was leaking and had to come off anyways ;) anyway my question is, after fitting it all back together,the cam belt feels a little tight,the up and down tension between the cam pulleys I mean,is there a rule of thumb or any actual reference to the tightness of the belt??

Post 741738 by oblark on 2014-10-12 17:42:27

The cam belt is tensioned by the damper so it`s pre set on the tension :)

Post 741739 by Harvey on 2014-10-12 17:47:38

I know on mine the setting is down to the air temp it's fitted, think what's Oblark saying. [ATTACH=CONFIG]27132[/ATTACH]

Post 741740 by merc85 on 2014-10-12 17:48:40

do you mean tight to turn over? or tight in tension of the belt?

Post 741747 by theflyingbrick on 2014-10-12 17:59:55

I mean the actual tension of the belt....if you grab the belt with your finger and thumb between the cam pulleys theres hardly any up n down movement!! in my head theres something about movement of +- 10mm but that might be for the old go kart chains lol

Post 741749 by theflyingbrick on 2014-10-12 18:01:18

[QUOTE=Harvey;741739]I know on mine the setting is down to the air temp it's fitted, think what's Oblark saying. [ATTACH=CONFIG]27132[/ATTACH][/QUOTE] its an 850 mate so not much by the way of advanced tension mechanisms.................just a piston that goes up to tension the belt lol

Post 741751 by merc85 on 2014-10-12 18:04:58

If its timed up and all bolted down correct and level i wouldnt worry. Turn it over by hand 1st a few times to make sure tho ;) see how it feels then

Post 741752 by merc85 on 2014-10-12 18:06:41

Are the cam wheels/pulleys the same size and amount of teeth na / t5?

Post 741753 by theflyingbrick on 2014-10-12 18:16:14

yeah they all the same size pulleys,it turns over nice by hand no hard spots or anything like that but I had my bonnet open and for some reason I fiddled with my belt and it feels looser than my dads does now!!! maybe mines too loose lol

Post 741778 by JamesT5 on 2014-10-12 19:15:01

Cambelts and Tensioners. I'll be leaving mine to a Volvo Specialist - I'm brave but not that much.

Post 741794 by theflyingbrick on 2014-10-12 19:55:05

lol i dont trust volvo specialists they rely too much on computers and not enough of them have any real brains!!!

Post 741828 by stribo on 2014-10-12 21:00:53

You don't want a lot of slack, as it'll jump teeth, as I see it, the 2 cams rotate at the same speed, so the tension will remain static, also once the belt's been through a heat cycle a few times, I'm sure it'll soften slightly.

Post 741829 by JamesT5 on 2014-10-12 21:05:18

[QUOTE=theflyingbrick;741794]lol i dont trust volvo specialists they rely too much on computers and not enough of them have any real brains!!![/QUOTE] The one I use are all time-served Volvo Technicians.

Post 741851 by theflyingbrick on 2014-10-12 21:54:07

[QUOTE=JamesT5;741829]The one I use are all time-served Volvo Technicians.[/QUOTE] so your cars running good then?

Post 741856 by JamesT5 on 2014-10-12 22:07:22

[QUOTE=theflyingbrick;741851]so your cars running good then?[/QUOTE] I used them for fitting my clutch after the first one broke (they didn't fit the first one, someone else did). They also repaired my 16T, I've not had any issues with their work.

Post 741857 by hemihusky on 2014-10-12 22:07:30

Id say you dont want it extremely tight as i would imagine that would put a bit of stress on the pulleys and such but dunno if this same rule applies for cam belts. on our diesel engines at work the belts we generaly set so that at its longest point between items (say, the cam and the 1st pulley or a alternator n crankshaft pulley ect ect) you can just about turn the belt 90 degrees in the middle with your hand. not easily but just so there is still a slight bit of give

Post 741864 by Kingsford G on 2014-10-12 22:33:42

Yr car uses a hydraulic tentioner so shouldn`t be too tight mate.I`ve done a few with no issues.From what u saying it sounds good to me,it`ll set up right when u run it cos as I said its a hydraulic tentioner.

Post 741876 by RollingThunder on 2014-10-13 09:06:05

The way to fit the timing belt is to have the belt teeth engage on the crankshaft pulley first, then pull it taut up to the intake cam gear - there should be minimal slack on this run. Then pull the belt taut over the exhaust cam gear, again there should be no slack there at all. The run between the cam gears is so short that the belt should engage on the gear teeth exactly without any discernible slack. Then fit the rest of the belt and set the tensioner as per Harvey's diagram - you'll have this older mechanical tensioner, not a hydraulic one on an 850. As also suggested above, once the belt is fitted turn it over by hand at least two complete engine revolutions by putting a socket on the crank pulley bolt (30 or 32mm IIRC). Once you've done this, check the timing marks again before firing up the engine. You'll feel some resistance due to compression but apart from that it should turn over ok. If you're not sure about detecting the difference between compression resistance and valve/piston contact, then remove the spark plugs - any resistance will then be due to unwanted contact :) If you find you're a tooth out, then I'd recommend you refit the belt until its spot on. It will run with a tooth out, but not optimally (I found my V70R's belt was a tooth out when I renewed it a few weeks ago).

Post 741885 by merc85 on 2014-10-13 09:37:50

[QUOTE=RollingThunder;741876]you'll have this older mechanical tensioner, not a hydraulic one on an 850.[/QUOTE] [ATTACH=CONFIG]27133[/ATTACH] This is what KG is referring to, Hydraulic Damper that pushes the mechanical tensioner onto the belt.

Post 741891 by LeeT5 on 2014-10-13 10:14:18

[QUOTE=theflyingbrick;741737]well ive been busy with work and other non interesting ventures so my car still sits dormant needing valve guides replacing :( however I had today off and thought it would be nice to fit a pair of na cams to my dads car seeing as the cam cover was leaking and had to come off anyways ;) anyway my question is, after fitting it all back together,the cam belt feels a little tight,the up and down tension between the cam pulleys I mean,is there a rule of thumb or any actual reference to the tightness of the belt??[/QUOTE] To answer you original question....checked mine when I did the PCV (I had the timing covers off to clean them) and mine was as tight as a Nuns chaff!! and I don't have any running issues. :)

Post 741901 by Doingitsideways on 2014-10-13 10:57:43

[QUOTE=LeeT5;741891]as tight as a Nuns chaff!![/QUOTE] Love it :D

Post 742027 by theflyingbrick on 2014-10-13 20:49:42

[QUOTE=LeeT5;741891]To answer you original question....checked mine when I did the PCV (I had the timing covers off to clean them) and mine was as tight as a Nuns chaff!! and I don't have any running issues. :)[/QUOTE] thanks mate just what i wanted to hear ;)

Post 742140 by LeeT5 on 2014-10-14 09:20:39

[QUOTE=theflyingbrick;742027]thanks mate just what i wanted to hear ;)[/QUOTE] What, that mine is as tight as a Nuns chaff? or that it's tight? :wink: we like it tight boys, well I do anyway!