My Citroen XM 3.0 PR-Vestige
- White Exec
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Re: My Citroen XM 3.0 PR-Vestige
Will, this is daft.
What you've said means that the belt can start life with limited side-contact, and therefore limited grip, and accelerated wear.
Then "I'm sure that once the belt wears and drops below the outer circumference of the pulley, the angle of v is irrelevant, as the belt has already worn to whatever angle the pulley is."
This means that the belt is slackening as it wears down, which we know just aggravates the situation.
For minimum wear - and maximum grip - the belt must match the vee for width, height and angle. Anything else just compromises power transfer and service life.
Come on guys!
What you've said means that the belt can start life with limited side-contact, and therefore limited grip, and accelerated wear.
Then "I'm sure that once the belt wears and drops below the outer circumference of the pulley, the angle of v is irrelevant, as the belt has already worn to whatever angle the pulley is."
This means that the belt is slackening as it wears down, which we know just aggravates the situation.
For minimum wear - and maximum grip - the belt must match the vee for width, height and angle. Anything else just compromises power transfer and service life.
Come on guys!
Chris
1996 XM 2.5TD Exclusive RP7165 Polar White
1992 BX19D Millesime RP5800 Sable
1989 BX19RD Delage Red Deceased; 1998 ZX 1.9D Avantage auto Triton Green Company car 1998..2001; 2001 Xantia 1.8i auto Wicked Red Company car 2001..2003
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1992 BX19D Millesime RP5800 Sable
1989 BX19RD Delage Red Deceased; 1998 ZX 1.9D Avantage auto Triton Green Company car 1998..2001; 2001 Xantia 1.8i auto Wicked Red Company car 2001..2003
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Re: My Citroen XM 3.0 PR-Vestige
You have a knack of mis-contsruing what is said.
A belt supplier will supply a correctly profiled belt, but once it has worn down into the v, it has to have adopted the angle of the metal pulley. As we know they continue to wear rapidly at that point, even though they have the profile of the v. The one thing that has changed is that the belt is down below the circumferance of the pulley.
A belt supplier will supply a correctly profiled belt, but once it has worn down into the v, it has to have adopted the angle of the metal pulley. As we know they continue to wear rapidly at that point, even though they have the profile of the v. The one thing that has changed is that the belt is down below the circumferance of the pulley.
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- Dean
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Re: My Citroen XM 3.0 PR-Vestige
Contact area cannot be that critical to power transmission as a solid belt would transmit higher power compared to a toothed belt if that were the case and it doesn't.
Pressure on the contact area is probably the largest factor but then i would guess so is heat, as the belt heats beyond its operating temperature the belts ability to transmit power decreases.
I would guess if the belt and pulley were matched exactly the heat generated by excess friction as the belt enters and exits the pulley would lead to overheating and rapid destruction.
I think the fact is the gearing of the pump drive due to low drive speed of the camshaft are running the v belt setup at the limits of what it can cope with, if things are not perfect rapid destruction of the belt ensues. Citroen knew this which is why they were forced to increase driven pulley size as a bodge, modified cars with the later 100mm pump pulley probably are not running a large margin between fluid volume required and generated at idle which is why they didn't go any larger with the pulley.
D
Pressure on the contact area is probably the largest factor but then i would guess so is heat, as the belt heats beyond its operating temperature the belts ability to transmit power decreases.
I would guess if the belt and pulley were matched exactly the heat generated by excess friction as the belt enters and exits the pulley would lead to overheating and rapid destruction.
I think the fact is the gearing of the pump drive due to low drive speed of the camshaft are running the v belt setup at the limits of what it can cope with, if things are not perfect rapid destruction of the belt ensues. Citroen knew this which is why they were forced to increase driven pulley size as a bodge, modified cars with the later 100mm pump pulley probably are not running a large margin between fluid volume required and generated at idle which is why they didn't go any larger with the pulley.
D
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- MTXM
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Re: My Citroen XM 3.0 PR-Vestige
I still think that if your car is eating belts (any sort) there has to be an issue Dean surely and is playing with other types and designs not just circumventing the problem? Regards, Matthew T.
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- Dean
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Re: My Citroen XM 3.0 PR-Vestige
Yes you are right Matthew, however, i have rebuilt a spare FDV and fitted that, and stripped, cleaned and re-calibrated my Pressure reg, checked all pipes for restrictions and reassembled so there is nothing else i can do/
D
D
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- White Exec
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Re: My Citroen XM 3.0 PR-Vestige
Good bit of info here:
http://info.gates.com/rs/gatescorp/imag ... e-0314.pdf
http://vulcan-grip.com/pages/belt-slippage-basics
http://info.gates.com/rs/gatescorp/imag ... e-0314.pdf
http://vulcan-grip.com/pages/belt-slippage-basics
Chris
1996 XM 2.5TD Exclusive RP7165 Polar White
1992 BX19D Millesime RP5800 Sable
1989 BX19RD Delage Red Deceased; 1998 ZX 1.9D Avantage auto Triton Green Company car 1998..2001; 2001 Xantia 1.8i auto Wicked Red Company car 2001..2003
1996 XM 2.5TD Exclusive RP7165 Polar White
1992 BX19D Millesime RP5800 Sable
1989 BX19RD Delage Red Deceased; 1998 ZX 1.9D Avantage auto Triton Green Company car 1998..2001; 2001 Xantia 1.8i auto Wicked Red Company car 2001..2003
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Re: My Citroen XM 3.0 PR-Vestige
I don't really believe that this is primarily caused by bad design. There were many (100,000?) PRV engined XMs made, and there seem to have been very few that need the belt replacing every week.
I think that it is likely that one or more of your pulleys is worn (due to previous prolonged running with a loose belt) so that the effective contact area with a new belt is at the wrong angle. My dad was an auto-electrician, and this was an uncommon but known problem with the fan-belts on some models of vehicle. Usually the owner would come in complaining that no matter how tight the belt was adjusted, it still squealed.
I think that it is likely that one or more of your pulleys is worn (due to previous prolonged running with a loose belt) so that the effective contact area with a new belt is at the wrong angle. My dad was an auto-electrician, and this was an uncommon but known problem with the fan-belts on some models of vehicle. Usually the owner would come in complaining that no matter how tight the belt was adjusted, it still squealed.
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- Jan-hendrik
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Re: My Citroen XM 3.0 PR-Vestige
The final answer - probably. As Chris mentioned, this is basic stuff.I think that it is likely that one or more of your pulleys is worn (due to previous prolonged running with a loose belt) so that the effective contact area with a new belt is at the wrong angle.
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- Dean
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Re: My Citroen XM 3.0 PR-Vestige
Only 30 miles today but so far so good, the belt is holding up fine with no chirping or slip evident.
D
D
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- russ92xmsed
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Re: My Citroen XM 3.0 PR-Vestige
That's sounding positive. Hope that hasn't just jinxed it....
Russ
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1992 K reg XM 2.1 Auto SED RP 5712
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Also
2003 C5 2.2 HDI Exclusive
I sell Engine bay, 1990 COTY, Total & Club XM Sticker Decals
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