cambelt jumped a tooth.

lou · Feb 17th, 2010, 21:36

hi all, think me cambelt has jumped a tooth, have now checked it 3 times and it still comes back to the same postion, your thoughts please.

and im 100% the crank is lined up. is in the same postion as this one.

charlotte001 · Feb 17th, 2010, 21:38

I would check to see if the tensioner is operating correctly and or is the belt stretched oh did you use a new belt? Hopefully you haven't bent any valves as it's half a tooth out and depending on how many times you've tried to start the car you may or may not have done damage to the valves.

Replace the belt and see if that resolves any issues with the car

make sure the engine rotates without resistance if there is a lot then the head will have to be removed to check the valves for bending otherwise try replacing the belt

dan · Feb 17th, 2010, 22:00

my timing jumped on my s70 t5 it cut out and wouldn't restart then when i dismantled it 13 valves were bent . i cant remember the exact details of timing marks as it was over a year ago but i fitted a new tensioner when i put car back together and it hasn't happened since it was about 70 quid for part . strange thing was old tensioner was still working but must have lost its strength for a sec to let belt slip . hope this helps .

lou · Feb 17th, 2010, 23:57

Quote:

Originally Posted by charlotte001

I would check to see if the tensioner is operating correctly and or is the belt stretched oh did you use a new belt? Hopefully you haven't bent any valves as it's half a tooth out and depending on how many times you've tried to start the car you may or may not have done damage to the valves.

Replace the belt and see if that resolves any issues with the car

make sure the engine rotates without resistance if there is a lot then the head will have to be removed to check the valves for bending otherwise try replacing the belt

not yet changed the belt, and it starts first time etc, just it runs on when you turn it off, has been doing it for a few wks etc. gunna try and up load the short vid of it .

lou · Feb 18th, 2010, 00:25

how do you put the link on for a vid from youtube, and do you have to be signed into youtube for others to view.

no1toker · Feb 18th, 2010, 00:42

ooooppppps

thealchemyst · Feb 18th, 2010, 03:08

what makes you think its out? and why would it have changed if youve not had the belt off? looking at the picture you seem to have marked the tooth gap and on the other sprocket the tooth itself! that will make it difficult to line up properly even if its not jumped out!.
every car ive ever known that the belt has jumped has usually been more than 1 tooth and engine damage has resulted the only times ive known the belt to be/ or appear to be 1 or 1/2 a tooth out has been when the belt has been changed and mis-timed.
check the belt is under proper tension as if its not it will effect the position of the cam wheels in relation to each other and the crank.

laurence · Feb 20th, 2010, 17:45

Quote:

Originally Posted by lou

hi all, think me cambelt has jumped a tooth, have now checked it 3 times and it still comes back to the same postion, your thoughts please.

and im 100% the crank is lined up. is in the same postion as this one.

you cant line up the timing belt on the outer pulley marks this is for static timing with a timing gun you must remove the crank pulley that the fan belt goes on to and the marks are on the timing belt pulley under that its the only way to check if its lined up
Also a timing belt rarely ever jumps and if it does it will remove other teeth off the belt in the process and 99 times out of 100 it will cause valve to piston contact
hope this helps

laurence

KBB · Feb 20th, 2010, 18:03

Caution here mate, just because the cam pulley marks are out dose not mean the timing is incorrect. When we replace timing belts we use the rear cam locking tool to time the cams correctly and lock the crank with a dedicated pin.

The cam pully is attached to the cams by 3 bolts, the puley holes are elongated which alows the cam puleys to move. This is so during setting the tensioner the load is distributed on the full run of the belt.

To confirm cam and crank correct sequensing an oscilloscope is used to vew cam and crank corilation. Also your compressions do not indicate incorrect valve timing. A vaccume guage should show around 22 hg at idle confirming correct valve timing.

lou · Feb 20th, 2010, 21:28

ok thanks very much for your info.

Feb 17th, 2010, 21:36	#1
lou Senior Member Last Online: Jun 3rd, 2010 19:27 Join Date: Oct 2009 Location: stoke on trent	cambelt jumped a tooth. hi all, think me cambelt has jumped a tooth, have now checked it 3 times and it still comes back to the same postion, your thoughts please. and im 100% the crank is lined up. is in the same postion as this one. __________________ volvo 850 2.5 and she smokes. Last edited by lou; Feb 17th, 2010 at 21:41.

Feb 17th, 2010, 21:38	#2
charlotte001 Premier Member Last Online: Jul 26th, 2012 11:13 Join Date: Jul 2009 Location: norwich	cam belt I would check to see if the tensioner is operating correctly and or is the belt stretched oh did you use a new belt? Hopefully you haven't bent any valves as it's half a tooth out and depending on how many times you've tried to start the car you may or may not have done damage to the valves. Replace the belt and see if that resolves any issues with the car make sure the engine rotates without resistance if there is a lot then the head will have to be removed to check the valves for bending otherwise try replacing the belt __________________ Previous Volvos:850 GLT 2.5 20V Auto Saloon Silver. 1997 850 T-5 Auto Estate Nautic Blue Chipped ECU, V70 TCV, Carbon Cased Filter, 17inch alloys, Rattling Engine masking the suspension rattles. Engine doesn't rattle anymore Last edited by charlotte001; Feb 17th, 2010 at 21:48.

Feb 17th, 2010, 22:00	#3
dan New Member Last Online: Jan 4th, 2022 17:46 Join Date: Jan 2009 Location: north of scotland	jumped tooth my timing jumped on my s70 t5 it cut out and wouldn't restart then when i dismantled it 13 valves were bent . i cant remember the exact details of timing marks as it was over a year ago but i fitted a new tensioner when i put car back together and it hasn't happened since it was about 70 quid for part . strange thing was old tensioner was still working but must have lost its strength for a sec to let belt slip . hope this helps .

Feb 18th, 2010, 00:25	#5
lou Senior Member Last Online: Jun 3rd, 2010 19:27 Join Date: Oct 2009 Location: stoke on trent	how do you put the link on for a vid from youtube, and do you have to be signed into youtube for others to view. __________________ volvo 850 2.5 and she smokes. Last edited by lou; Feb 18th, 2010 at 00:31.

Feb 18th, 2010, 00:42	#6
no1toker Junior Member Last Online: Jul 27th, 2020 07:43 Join Date: Aug 2009 Location: bristol / walsall	ooooppppps __________________ if in doubt go flat out

Feb 18th, 2010, 03:08	#7
thealchemyst Master Member Last Online: Aug 22nd, 2018 20:57 Join Date: Apr 2009 Location: Coalville/Leicestershire	what makes you think its out? and why would it have changed if youve not had the belt off? looking at the picture you seem to have marked the tooth gap and on the other sprocket the tooth itself! that will make it difficult to line up properly even if its not jumped out!. every car ive ever known that the belt has jumped has usually been more than 1 tooth and engine damage has resulted the only times ive known the belt to be/ or appear to be 1 or 1/2 a tooth out has been when the belt has been changed and mis-timed. check the belt is under proper tension as if its not it will effect the position of the cam wheels in relation to each other and the crank. __________________ 1995 850 t5 glt estate purple,FK-40mm,stainless exhaust polybushed,wilwood4pot+s60r discs,mbc,019 battery,18" c30 alloys,michelin pilots,silicone hoses,braided brake lines,HID's,ipd track swaybars 25+mpg :0) @Prescott Hillclimb

Feb 20th, 2010, 18:03	#9
KBB Master Tech Last Online: May 18th, 2020 10:57 Join Date: Dec 2006 Location: On Contract Dubai Automotve Technical Academy	Caution here mate, just because the cam pulley marks are out dose not mean the timing is incorrect. When we replace timing belts we use the rear cam locking tool to time the cams correctly and lock the crank with a dedicated pin. The cam pully is attached to the cams by 3 bolts, the puley holes are elongated which alows the cam puleys to move. This is so during setting the tensioner the load is distributed on the full run of the belt. To confirm cam and crank correct sequensing an oscilloscope is used to vew cam and crank corilation. Also your compressions do not indicate incorrect valve timing. A vaccume guage should show around 22 hg at idle confirming correct valve timing.

Feb 20th, 2010, 21:28	#10
lou Senior Member Last Online: Jun 3rd, 2010 19:27 Join Date: Oct 2009 Location: stoke on trent	ok thanks very much for your info. __________________ volvo 850 2.5 and she smokes.

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