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Volkswagen Golf, Volkswagen, Car Buying, Diesel, Gasoline, Future Vehicle, Hatchback
Apr 06, 2010 (6:49 am)
Cruising on level ground the TDI should be fine between 1,500 and 2,000 rpm. No need to cruise at 2300.
#186 of 224 cruising at low RPM - [dudleyr]
Apr 06, 2010 (8:22 am)
Dudley, that is true... but the key workds are "cruise" and "level ground". If you are putting a load on the engine, then you put an unnecessary stress on the turbo when you drive at low RPM in one of the higher gears. If you are climbing hills, just because your TDI can make it all the way to the top at 2000 RPM in 6th, while every else is slowing down or downshifting, does not mean you should drive that way.
The engine computer will put your TDI engine into "limp mode" if you try to do something that will damage the turbo. This is more likely to happen if you stomp on the accelerator at 1500-1800 RPM in a high gear, or try to accelerate briskly if your engine is already under a heavy load at low RPM.
In case of "limp mode", you have to do an engine restart. I have done this a couple times over the years by just pushing in the clutch and doing a quick restart; but of course it is much safer to pull off the road first.
The advice I give here applies for the life of the car. During the break-in period, the driver should not be babying the engine or at least not babying it all the time.
#187 of 224 TDI Golf/Jetta
May 24, 2010 (7:15 am)
As the previous owner of a number of VWs I was contemplating the purchase of the new clean TDI until I found out that VW is clinging to the rubber cam belt set up for the TDI. I had presumed that all of their engines now used chain driven cams as does the 2.5 but the TDI continues with the rubber belts, a cost saving measure. You pay more up front for the TDI and then will have a thousand dollar maintence bill to replace the belts somewhere between 40 and 80K miles. I will wait for the gasoline Polo to appear to evaluate.
#188 of 224 Re: TDI Golf/Jetta [us1]
May 24, 2010 (9:41 am)
Interesting and in 80K miles you'd save about 1000 gallons of gasoline with the TDI over the 2.5. Between the price difference and the extra maintenance cost, it is probably pretty close to a wash between the two assuming that the other extra standard features on the TDI are worth, say, $2000.
#189 of 224 Re: TDI Golf/Jetta [us1]
May 24, 2010 (6:37 pm)
I do not beleive using belt for cam is a "cost saving measure".
An engine-designer needs to consider a large number of variables when developing a new design. Sure, one of them may be cost... but that is often near the bottom of the list.
A belt-driven cam has a lot of advantages over chain.
*)no lubrication required
*) Power-pulses of diesel engine can tear a chain up pretty quick while belt is more forgiving.
*)Belt replacement is 100,000 miles on my TDI...not a big deal.
A chain DOES wear out and WILL need to be replaced at some point. With the beating from a diesel-engine, it may be LESS than 100,000 miles. (even gear-driven may not stand up to the beating.)
Why do you think that Harley Davenson motorcycles use BELT DRIVE to rear wheel instaead of chain?... because the belt lasts longer than chain with a big , pulsing, engine. (the belt soaks up the pulses...a chain would break prematurley)
If the presense of a belt-driven cam is the ONLY reason you are staying away... then I feel your reasoning is flawed.
Let me ask you these things....
Are you aware that the pully on the TDI alternator is specially designed specifically because the diesel engine can decellerate faster than the alternator rotor?
Are you aware that the teeth on the clean-diesel timing-belt pullies have variable-spacing specifically to compensate for the power-pulses from the crankshaft?
Bottom line... you are making a mistake when you second-guess the German engineers who designed the engine. (they know what they are doing)
#190 of 224 Re: TDI Golf/Jetta [us1]
May 24, 2010 (9:23 pm)
Since the 2002 model year, all TDIs have had either an 80k-mile or 100k-mile timing belt replacement interval. As for the cost of replacement, there are TDI experts in most states who will do the work for well under $1000, and this includes replacing not just the TB and tensioner but also the roller/idlers, the water pump, the serpentine belt, and any of the various torque-to-yield bolts which should not be replaced. Typically, if you have this job done at a VW dealership, it will cost MORE than $1000 and the only new parts you get are the TB and tensioner, and MAYBE the water pump.
So visit www.tdiclub.com and check out the "recommended TDI mechanics" sticky thread for a TDI expert near your location. Then ask for a review of the nearby mechanics from club members who have used their services. VW dealerships should be avoided after the warranty period -- this is not just my opinion, despite the efforts of Stefan Jacoby (the president of VWoA) the dealership service departments still suck.
#191 of 224 Re: TDI Golf/Jetta [jbaustian]
May 25, 2010 (4:04 pm)
Very helpful post.
#192 of 224 Re: TDI Golf/Jetta [cdnpinhead]
May 25, 2010 (9:25 pm)
I meant to say that the torque-to-yield bolts which should ALWAYS be replaced. But VW dealerships never do, most do not even stock those special bolts. If they are reused, if they are torqued incorrectly, the bolts can break and the engine can come loose from the engine mount on the passenger-side end. It has happened lots of times. Sometimes the bolt rips out of the engine block and the block itself cannot be repaired but must be replaced. Lots of expensive damage that can be prevented by replacing these $2 bolts every 100k miles.
#193 of 224 Re: TDI Golf/Jetta [bpeebles]
May 26, 2010 (7:41 am)
It may be that the timing belt on the TDI is a perfectly reasonable design, but I do not buy the arguments that it is superior to a properly designed chain drive system. I would guess that there are diesel engines that do have a chain and that the chain typically never requires replacement.
#194 of 224 Re: TDI Golf/Jetta [jeffyscott]
May 26, 2010 (8:05 am)
Timing belts are superior when precise timing is required, because they do not stretch as they age. As the links in a chain wear, the chain becomes more "sloppy". Usually an expert mechanic can warn the owner when a chain needs to be replaced, but if a chain fails there is even more damage than when a belt fails. I had a timing chain fail in a Saab 2-liter gas engine once and it threw a chunk of metal through the valve cover. I should have just replaced the engine, it would have cost about as much as the repairs.
Chains and gear-driven valve-timing systems tend to be found in the more-expensive engines -- not only because they are more expensive to design and manufacture, but because they are more expensive to maintain. The typical middle-class driver cannot afford to buy or maintain the high-priced cars with chain-driven timing systems. That does not mean timing belts are an inferior solution to the problem, however,
Porsche timing belt