Engine Life: Golf V 2.5L VS Golf IV TDI 1.9L

kilimats

Veteran Member
Joined
Apr 16, 2007
Location
Vancouver, BC
TDI
2005 Wagon TDI
My buddy is saying his MK5 Engine would last pretty much the same as my MKIV TDI mainly because my 2002 TDI engine runs at higher RPM than older diesel engines.

Im not the engine techy guy, but from what ive been reading over and over the past few years, diesel usually last twice longer than Gas engine

Is that not the case anymore because of the higher RPM?

***
 

flatlanded

Veteran Member
Joined
Aug 1, 2009
Location
Saskatchewan
TDI
2002 Jetta
Yea, your friend is full of it. Gasses wear out much quicker regardless of RPMs. Diesels are built stronger, and their fuel is natural lubricant. Win win.
 
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GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
The 2.5 gas engine is not a high revving engine. Both engines when properly maintained will outlast what most owners will keep them for.

If you want to get him going, ask him what he plans to do if and when the timing chain tensioner and/or guides wear out. The TDI may need an occasional timing belt replacement ... but if anything ever happens with the timing chain on a 2.5, the transmission has to come out to fix it. It's the same timing chain design used on the VR6, and timing chain guides and tensioners weren't exactly fantastic strong points of that engine.

With the new 4-banger TSI engine, they've moved the timing chain to the front - where it belongs.
 

GoFaster

Moderator at Large
Joined
Jun 16, 1999
Location
Brampton, Ontario, Canada
TDI
2006 Jetta TDI
kilimats said:
... mainly because my 2002 TDI engine runs at higher RPM than older diesel engines.
By the way, that's wrong. The TDI is geared taller (lower revs at a given speed) than the old regular diesel and turbo-diesel (non-TDI) engines were. It's also geared taller than his 2.5 is.
 

kilimats

Veteran Member
Joined
Apr 16, 2007
Location
Vancouver, BC
TDI
2005 Wagon TDI
thanks guys, he is also saying Diesel engine runs hotter than gas, ***. why is the tdi so slow to heat up in winter then?
 

ruking

Top Post Dawg
Joined
Mar 27, 2003
Location
San Jose area, CA
TDI
2003 VW Jetta, 5 M, Reflex Silver: 09 Jetta, 6 Sp DSG, Candy White: 12 VW Touareg, 8 Sp A/T, Flint Gray
Another like for like, gasser/diesel (i.e., 2003 gasser/TDI 25 mpg vs 49 mpg), a diesel will burn less fuel, ergo LESS wear. Burning more fuel (40,000 gals/20,408 gals or 19,592 gals more: 49% less or 96% more (depending on ones perspective) to achieve the same work, i.e. 1,000,000 miles will wear... faster. Also VW diesel engines are built much STRONGER than VW gasser engines.

It is just that we are not accustomed to thinking like this. By the way, the VW TDI design life @ 80% loading is 25,000 hours. (very few tdi's are consistently run @ 80% loading) So if the average mph is 45/50 then * = 1,125,000/1,250,000 miles.
 
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coalminer16

Top Post Dawg
Joined
Dec 11, 2008
Location
Central Wisconsin
TDI
Golf 2004
I heard on a car show that gas rings on pistons on average last to around 200K miles. I can't attest to that as most cars blow there auto trannys before that but a diesel is hardly broke in at those miles.
 

Powder Hound

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Joined
Oct 25, 1999
Location
Under a Bridge, Crestview, FL, USA
TDI
'00 Golf 4dr White 5sp, '02 Jettachero 5sp, Wife's '03 NB Platinum Gray auto(!)
The real reason you get better wear on the diesel is that the gasser draws an air/fuel mixture into the cylinder. While it is being compressed, the cylinder walls are also becoming the home of liquid gasoline, which will dilute the oil film and reduce the amount of lubrication available for the piston rings. The cylinder wall and rings thus endure a higher wear level.

The direct injected gasser engine will be a little less likely to have greater wear, but it still has a lot of the same problems.

The diesel engine inhales and compresses only air. There is nothing to impinge on the cylinder wall's layer of lubricating oil, so the wall and rings experience the best lubrication the oil has to offer.

In addition, in an ideal setting, the injection event begins, and fuel droplets emitted from the injector nozzles will ignite and burn in the compressed air prior to having any chance at hitting the cylinder walls.

As far as burning hotter, this is not the case. As the above posters have mentioned, diesel does have more BTUs per gallon, so perhaps this is what is confusing your friend. The diesel engine also has a much longer stroke and thus converts more of the heat energy contained in the fuel to mechanical work. That thermodynamic efficiency is why they take a long time to heat up.

Diesel exhaust is typically about 400F cooler than an equivalent gasser engine. You might point out to him that in spite of water cooled turbochargers being available, it isn't necessary to have one on our diesel engines, but most gassers these days MUST have a water jacket to avoid coking the shaft, seals, and bearings in the turbocharger. Why would that be the case if a diesel runs hotter?
 
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