Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
Furlough trivia
Rear belt removed from my D4, question is; how many revolutions has it done to nearest 1000?
It can when others can't,
It will when others won't,
It goes where others don't.
28th Jan 2021 10:09 am
Scott #55
Member Since: 15 Apr 2015
Location: Glasgow
Posts: 1664
Surely we need to know the mielage of your D4 when the belt came off?2014 - D4 2010 HSE Nara Bronze
2012 - FL2 2009 GS Stornoway Grey
2001 - VW Passat Estate Inky Blue
1999 - Ford Mondeo Light Blue
1998 - Rover 25 Red
28th Jan 2021 12:33 pm
Scott #55
Member Since: 15 Apr 2015
Location: Glasgow
Posts: 1664
And what's the diameter of the belt?2014 - D4 2010 HSE Nara Bronze
2012 - FL2 2009 GS Stornoway Grey
2001 - VW Passat Estate Inky Blue
1999 - Ford Mondeo Light Blue
1998 - Rover 25 Red
28th Jan 2021 12:33 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Surely dia of the pulleys more useful info?
Anyway pretty sure it is going to be a trick question.
28th Jan 2021 12:47 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
Ok as no one is prepared to make a guess here is mine and how I arrive at the figure, belts need changing at 112k miles or 7years, I chose to change early at 97k miles courtesy of the lockdown.
So to round figures up;
100,000 miles at an average of 50 mph = 2000hours engine running time
2000hours at 2000rpm (Revolutions per minute) = (2000*2000)*60=240,000,000
Less differential of cam timing belt length to pump belt length = 2 to 1 = 120,000,000 revolutions
Although all the belts “look” to be in good condition if figures are correct* they have earned early retirement and I am sure I made the right decision.
Thanks to everyone that contributed particularly Disco Mikey who started the ball rolling, I would not have attempted without your help and advise.
*I stand to be corrected!It can when others can't,
It will when others won't,
It goes where others don't.
30th Jan 2021 7:29 pm
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20727
I like your thinking, but we really need to know how many teeth are on the cam pulley to determine how many revolutions the belt has done
And the HPFP belt isn't half the length of the front belt either...My D3 Build Thread
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20727
Seeing as their isn't much else to do on a lockdown Saturday night
Assuming initial calculations are correct, the crank has done 240,000,000 revolutions ( ) then the passenger side exhaust cam has done 120,000,000 revolutions
HPFP pump pulley has 24 teeth, with cam drive pulley having 48 teeth, and the belt having 80 teeth, so 48/80=0.6
For each camshaft revolution, the belt does 0.6 of a turn, which is 2 crank revolutions, so for every crank revolution, the HPFP belt does 0.3 revolutions
So, 240,000,000*0.3=72,000,000 belt revolutions, give or take a few gins worth My D3 Build Thread
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
Well I’m not far out only 48,000,000 It can when others can't,
It will when others won't,
It goes where others don't.
30th Jan 2021 9:35 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
Thinking more about it I question if you have got it quite right if the belt has 80 teeth and the cam pulley 48 the timing marks on the pump belt would never(or nearly never) line up, The belt is either 96 teeth or the cam pulley is 40 teeth
Anyway forget it tonight, you’ve probably seen enough LRs for one dayIt can when others can't,
It will when others won't,
It goes where others don't.
30th Jan 2021 10:40 pm
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20727
I can show my workings, sir
In any case, rightly or wrongly, there was copious amount of gin involved, so... My D3 Build Thread
Member Since: 01 Aug 2005
Location: Cornwall
Posts: 2572
I once tried frying my head with working out how many times a piston had accelerated from zero to max and back to zero, with a bonus question of what is max speed of the piston.
Care to tackle that one?
These kind of thoughts make you wonder how engines survive at all!
back on topic... and given the distances travelled etc, the belt doesn't look too bad Long succession of Disco's since 2001...
SIII Lightweight - neglected & rusting. Bulkhead, A panels, vent panel & outriggers now disintegrated - Next years project!
31st Jan 2021 9:19 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8072
DaveT, “ These kind of thoughts make you wonder how engines survive at all!”
That’s exactly the point I’m trying to make!
The pump belt has 80 teeth and the cam belt has 195(I’ve counted them 3 times ), the pump pulley has 24 teeth and the cam shaft pulley(pump belt end) has 48 teeth.It can when others can't,
It will when others won't,
It goes where others don't.
31st Jan 2021 7:27 pm
BBDisco3
Member Since: 23 Nov 2008
Location: Cheshire
Posts: 3640
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