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Help, my V6 won't start after new belts
Posted: Fri Mar 16, 2012 1:10 pm
by A1tony
My mechanic is pulling his hair out !
Just had the cam/crank seals replaced with new belts, pulleys and hydraulic tensioner. My mechanic did the belt last year but the crank seal failure meant doing it again so it's not like he doesn't know how to do it ( also he has been my mechanic and friend for 17 years and is utterly trustworthy)
Bottom line is it turns over fine (turned by hand also on rebuild for safety), there is spark, compression of +90 psi, fuel ( the plugs are wet) but it just won't fire. It's not the alarm because it wouldn't turn if it was live. Either way I need it back and it's beeched !!!
Any peculiarities need checking or other ideas welcome., and fast !!
Re: Help, my V6 won't start after new belts
Posted: Fri Mar 16, 2012 4:22 pm
by mikeWalsall
Has he got the valve timing right as 90psi seems low .. at a minimum I would have thought around 130-135psi (14.7 x 9) ..
Re: Help, my V6 won't start after new belts
Posted: Fri Mar 16, 2012 5:38 pm
by A1tony
Not sure on the Maths for right psi but I will pass it back to him. Problem is most of the components are held with Woodruff keys making it quite hard to get wrong. Still, it's a possibility !!
Thanks
Tony
Re: Help, my V6 won't start after new belts
Posted: Fri Mar 16, 2012 7:04 pm
by mikeWalsall
As rule of thumb .. 14.7psi (Atmospheric pressure) multiplied by the compression ratio of 9-1
If the valve timing is out the 24 valves will not seat properly ..
Re: Help, my V6 won't start after new belts
Posted: Sat Mar 17, 2012 4:17 pm
by teenmal
mikeWalsall wrote:As rule of thumb .. 14.7psi (Atmospheric pressure) multiplied by the compression ratio of 9-1 If the valve timing is out the 24 valves will not seat properly ..
Hi Mike,
Good bit of information,what would be the psi on a 2.5td be?
Cheers.
Re: Help, my V6 won't start after new belts
Posted: Sat Mar 17, 2012 5:39 pm
by mikeWalsall
14.7 psi x 19.8 C/R = 290+ psi ..
Re: Help, my V6 won't start after new belts
Posted: Sat Mar 17, 2012 6:01 pm
by teenmal
mikeWalsall wrote:14.7 psi x 19.8 C/R = 290+ psi ..
Hi Mike,
Thanks for the info but I thought a 2.5 Diesel would be more likely to be in the 400/450 psi mark.
I dont have my workshop WLT engine manual at the moment.
Cheers.
Re: Help, my V6 won't start after new belts
Posted: Sat Mar 17, 2012 7:34 pm
by mikeWalsall
Diesel 30 kg square cm @ 200rpm cranking speed ..
30 x 14.21 = 425+psi ..
Re: Help, my V6 won't start after new belts
Posted: Sat Mar 17, 2012 8:00 pm
by Simon Jones
Anyway, back to the original topic.....
It does seem like a timing issue. Has he re-checked it again? It sounds like you've got fuel, air and a spark but just not quite in the right order. Try calling Allan at
http://www.allansvehicleservices.co.uk/ as he has lots of experience changing cambelts on the V6.
Re: Help, my V6 won't start after new belts
Posted: Sat Mar 17, 2012 8:48 pm
by Doone
The compression does sound too low.