www.tdiclub.com

Economy - Longevity - Performance
The #1 Source of TDI Information on the Web!
Forums Articles Links Meets
Orders TDI Club Cards TDIFest 2016 Gone, but not forgotten VAG-Com List Unit Conversions TDIClub Chat Thank You

Order your TDIClub merchandise and help support TDIClub


Go Back   TDIClub Forums > VW TDI Discussion Areas > TDI 101

TDI 101 Got a simple/basic TDI question? Are you a newbie (new to the forums). Feel free to post your question here.

Reply
 
Thread Tools
Old April 11th, 2009, 07:00   #1
mjhandy
Veteran Member
 
mjhandy's Avatar
 
Join Date: Jun 2007
Location: Kitchener, Ontario
Default why a timing belt over a chain?

I've always wondered why not a chain driven system rather than a belt? Wouldn't a chain last longer?
__________________
Mark J. Handy
HEX + CAN usb
2009 Touareg TDI
2000 Jetta TDI, 568K km, Bye bye

mjhandy is offline   Reply With Quote
Old April 11th, 2009, 07:20   #2
tditom
Veteran Member
 
Join Date: Sep 2001
Location: san antonio & austin
Fuel Economy: Golf: 54/48/43.5 B4 Passat: 52/48.5/45 B5.5 Passat: 30 mpg mixed
Default

the chain would last longer than a belt, but both wear and stretch. the belt tension is easily adjusted as the belt stretches. Chain (and other components) would still need to be changed eventually (maybe by 500K km?). the chain would need to be lubed. chain is noisier.

look at it this way: the complete path of wear parts is being renewed every 160K km using a belt for a cost of approx 265 km/$.
__________________
-tom
autos: 19 Subaru Forester, 14 BMW 535d xDrive
Find your VW part numbers here.
Why I recommend fuel additive.
tditom is offline   Reply With Quote
Old April 11th, 2009, 07:21   #3
HopefulFred
Veteran Member
 
HopefulFred's Avatar
 
Join Date: Sep 2002
Location: Atlanta, GA
Fuel Economy: ~39 USMPG
Default

Many chains last longer, but don't (as I understand it) perform to the same standards or, generally, deal with as high loads as vw requires.

The question is, why not a serviceble system which maintains very precise control of timing? The answer is the timing belt.

Consider the BMW is saw in the shop this week - less than 200K and a broken timing chain tensioner - 32 hours labor to remove the engine and replace the chain and tensioner. Or the Ford I saw two weeks ago - over-revved and broken - no start.

The belts, on the other hand, don't stretch, don't rattle (like old Altimas and plenty of other old engines), and require regular service.

I'm happy with this compromise.
__________________
Novice VCDS user.
Proud owner and successful two-time user of AST timing belt tool kit.
HopefulFred is offline   Reply With Quote
Old April 11th, 2009, 07:25   #4
grizzlydiesel
Veteran Member
 
grizzlydiesel's Avatar
 
Join Date: Feb 2009
Location: Virginia, USA
Default

also might have something to do with diesel operation, diesels have much higher... not sure of the right term here, "shock loading" perhaps? than a gasoline engine. The resulting noise and vibrations from a chain driven system are fine for a semi truck with a detroit diesel, but in a passenger car, comfort and such things are priority. Im sure the belt was a better choice based on those standards.

keep in mind, that for 2009, all gasoline engines from VW are timing chains, but the 2.0L TDI is still a timing belt. im sure there is a reason.
__________________
"A toast to us, may we all stay crazy and live the B****IN life."
-Robin Williams

2000 Jetta GL TDi 5 speed
(completely bone stock... for now.)

1986 M1009 6.2L diesel/TH400/NP208/10bolts/33in MT-R's



grizzlydiesel is offline   Reply With Quote
Old April 11th, 2009, 08:46   #5
i_dont_golf
Veteran Member
 
Join Date: Jul 2008
Location: san diego, ca
Default

what about the indestructible old mercedes diesels? they all have timing chains. and just noise is no excuse.... you drive a diesel car. would you really hear the timing chain much?
__________________
2000 golf GLS. 5 speed swap, pp764, tune, bilstein
i_dont_golf is offline   Reply With Quote
Old April 11th, 2009, 09:11   #6
TDICADDGUY
Veteran Member
 
TDICADDGUY's Avatar
 
Join Date: Jul 2007
Location: Blaine, MN
Fuel Economy: 42/46/51 with 5 speed - was 36/40/42 with 01M
Default

Ahh crap not this again.

This has been discussed before, many times. Do you know very much about timing chains and their issues on OHC engines? I see that the low-revving and overbuilt MB diesel has already been brought up. You can't compare it to a small high-revving Volkswagen diesel....apples and oranges.

Chains do wear out and it is much harder to make a chain perform reliably in an OHC application. Look at the difference in length between an OHC and an OHV engine. Chains and all the tensioner getup would be much more expensive to replace as well.

The VW belt system (with 100k components) gives reliable, noise-free and maintenance-free service for 100,000 miles. $300 in parts if you replace it yourself. ~$800 to have a TDI guru do it. That is pretty cheap for a 100k mile interval.
__________________
2012 BMW X5 35D 2000 NB with 3 pedal mod, RC3, PP520's, Eurojet SMIC, SBC 3, 2.5" side exit straight pipe, 2" lift.
TDICADDGUY is offline   Reply With Quote
Old April 11th, 2009, 09:13   #7
Lug_Nut
TDIClub Enthusiast
Pre-Forum Veteran Member
 
Lug_Nut's Avatar
 
Join Date: Jun 1998
Location: Sterling, Massachusetts. USA
Fuel Economy: 116 mpg(e), 36 mpg gas, 100 mpg combined
Default

Chains last 2 to 3 times longer and then cost 4 times as much to replace.
__________________
If the quantity of carbonic acid increases in geometric progression,
the augmentation of the temperature will increase nearly in arithmetic progression.

Svante Arrhenius 1896

Cogito ergo soy (I think, therefore: Biodiesel)
Lug_Nut is offline   Reply With Quote
Old April 11th, 2009, 11:03   #8
mjhandy
Veteran Member
 
mjhandy's Avatar
 
Join Date: Jun 2007
Location: Kitchener, Ontario
Default

thanks guys. didn't mean to rehash something, but it was something i'd always wondered about.

Cheers
__________________
Mark J. Handy
HEX + CAN usb
2009 Touareg TDI
2000 Jetta TDI, 568K km, Bye bye

mjhandy is offline   Reply With Quote
Old April 11th, 2009, 11:27   #9
Matthew_S
Veteran Member
 
Matthew_S's Avatar
 
Join Date: Mar 2006
Location: Renton/Redmond, WA
Fuel Economy: 41-46
Default

In most cases a chain wil last the life of the car. In many cases the chain will be the thing that ends the life of the car.
Matthew_S is offline   Reply With Quote
Old April 11th, 2009, 13:18   #10
Velocity1896
Newbie
 
Join Date: Aug 2008
Location: Portland, Oregon
Default

I wouldn't take either, I prefer gear drive. Even though its would never happen in TDIs. I have done tons of work on Detroit Diesel Series 60 engines and the old 6V92s. They both use a "Bull Gear" in place of a timing belt or chain. Granted this is a whole realm, but I have seen gear drive on some older muscle cars, it is a bit noisy but you never have to replace it. Granted you will get some metal in the oil due to gear backlash, but it has never been an issue. As long as it doesn't get too much play its good to go. OK i'll shut up now
Velocity1896 is offline   Reply With Quote
Old April 11th, 2009, 16:38   #11
Lug_Nut
TDIClub Enthusiast
Pre-Forum Veteran Member
 
Lug_Nut's Avatar
 
Join Date: Jun 1998
Location: Sterling, Massachusetts. USA
Fuel Economy: 116 mpg(e), 36 mpg gas, 100 mpg combined
Default

Gears are heavy and their rotational inertia adds to the same apparent power loss as a heavy flywheel or larger brakes or larger tire and wheel sets.
Yeah, I have a geared cam drive on my 1.5 liter V4 Saab. A big slow revving class 8 OTR truck won't mind the extra spinning mass, but a 2 liter definitely does.
__________________
If the quantity of carbonic acid increases in geometric progression,
the augmentation of the temperature will increase nearly in arithmetic progression.

Svante Arrhenius 1896

Cogito ergo soy (I think, therefore: Biodiesel)
Lug_Nut is offline   Reply With Quote
Old April 11th, 2009, 17:24   #12
oldiesel
Veteran Member
 
Join Date: Apr 2005
Location: Ortona Florida
Fuel Economy: 14 tanks 47.4 mpg avg
Default

Actually the chain in my 300d 2.5 Mercedes was much easier to replace and also less expensive than the belt and related hardware on my Jetta and the Jetta is the easiest of the TDIs as it is an AHU.The Mercedes had over 240,000 miles when i did it just as a precaution as it was showing more than 5deg of wear.Sort of comparing apples and watermelon as there is such a great difference in the price these cars were built to, i guess MB could afford to build a longer lasting system. Don
__________________
This is only temporary unless it works. "Red Green"
87 Mercedes TDT
oldiesel is offline   Reply With Quote
Old April 11th, 2009, 17:48   #13
weedeater
Veteran Member
 
Join Date: Mar 2001
Location: Reston, VA
Fuel Economy: 54/43/38
Default

I always ask myself this question whenever I see a Harley go by with a belt rather than a chain.
__________________
It may seem like I am doing nothing, but on a cellular level I'm really quite busy.

The game of Bridge is like Sex: You need either a good partner or a good hand.

You're either part of the solution or you're part of the precipitate.
weedeater is offline   Reply With Quote
Old April 11th, 2009, 17:49   #14
mrGutWrench
Veteran Member
 
mrGutWrench's Avatar
 
Join Date: Aug 2002
Location: Wallace, NC
Fuel Economy: 63 MPG/56/47 (2nd tank) '02 Sedab
Default

Quote:
Originally Posted by oldiesel
Actually the chain in my 300d 2.5 Mercedes was much easier to replace and also less expensive than the belt and related hardware on my Jetta and the Jetta is the easiest of the TDIs as it is an AHU.The Mercedes had over 240,000 miles when i did it just as a precaution as it was showing more than 5deg of wear.Sort of comparing apples and watermelon as there is such a great difference in the price these cars were built to, i guess MB could afford to build a longer lasting system. Don
__. Talk about comparing apples to oranges! The old MB's are big, slow-turning engines with compact timng system layouts. Chains are imprecise and don't like revs. A chain on a TDI would be whipped to a frazzle. A chain would be a bad choice for a TDI, as much as for the imprecision of the timing as anything else. A few degrees on a TDI and valves are intimately associated with pistons and that means a head rebuild 99% of the time. Chains "stretch" and have imprecise tensioning systems. Chains would not be good on a TDI. The belt is about as good a system as you'll get.
__________________
MrG, Wallace NC (2002 Jetta, Totalled by drunk, 11/'06; 130K mi in 4 1/2 years/~57 MPG lifetime); New car, '03 Jetta Wagon, CAT filter, .681 top gear, 350K mi. in 11 1/2 yr, ~52.
mrGutWrench is offline   Reply With Quote
Old April 11th, 2009, 17:54   #15
mrGutWrench
Veteran Member
 
mrGutWrench's Avatar
 
Join Date: Aug 2002
Location: Wallace, NC
Fuel Economy: 63 MPG/56/47 (2nd tank) '02 Sedab
Default

Quote:
Originally Posted by TDICADDGUY
Ahh crap not this again.

This has been discussed before, many times. (snip)
__. But don't you unnerstann? Mah gran-daddy had a flathead Ford peekup truck - changed the awl ever 1000 mahls with 99 cent a quart awl fum the Wawmott and thet truck ran over 200,000 mahls. An it hed a tahmin chain. Whutt's gudd enuff fer that truck oughtta be gudd enuff fer them flimsy little furrin thangs!
__________________
MrG, Wallace NC (2002 Jetta, Totalled by drunk, 11/'06; 130K mi in 4 1/2 years/~57 MPG lifetime); New car, '03 Jetta Wagon, CAT filter, .681 top gear, 350K mi. in 11 1/2 yr, ~52.
mrGutWrench is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 09:08.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright - TDIClub Online LTD - 2017
Contact Us | Privacy Statement | Forum Rules | Disclaimer
TDIClub Online Ltd (TDIClub.com) is not affiliated with the VWoA or VWAG and is supported by contributions from viewers like you.
© 1996 - 2020, All Rights Reserved
Page generated in 0.20012 seconds with 12 queries
[Output: 126.61 Kb. compressed to 105.13 Kb. by saving 21.48 Kb. (16.96%)]