Cost of repair Audi BMW Saab...(crossposting)

snipped-for-privacy@4ax.com

Regards

Wolfgang

Say folks, do you read the thread?

I already said you were right.

Regards

Wolfgang

Interesting enough. That seems to remind me of Michelle Moutton's innovative technique quite a few years ago; and how did with Quattro!

I don't, so there...

But maybe I hate formatted e-mails...

;-) DAS

In what town are you in? Randstad...?...

DAS

Top 10 sellers in UK in first quarter 04:-

43,115 Ford Focus 33,355 Vauxhall Corsa 29,479 Peugeot 206 27,217 Ford Fiesta 23,496 Vauxhall Astra 22,283 Renault Megane 21,688 ditto Clio 19,067 Ford Mondeo 18,366 VW Golf 17,830 Peugeot 307

See UK data here:

You can download a spreadsheet and a Word document with commentary.

DAS

Do they? 330i: 225HP, 20/28 with automatic. Honda Accord: 240HP,

21/30 with automatic.

Neither do most Saabs (GM's V6 excepted).

in article snipped-for-privacy@4ax.com, dizzy at snipped-for-privacy@nospam.invalid wrote on 5/12/04 6:22 PM:

Obviously no way to prove or disprove which engine is more efficient from the above. Too many other variables, not the least of which is published vs actual mileage which often varies a lot. My take is that the BMW engines are very good in this respect, and perform very close to claims. Certainly there are others that do equally well. My 330i was surprisingly fuel efficient given the acceleration capability. Even my M3 does pretty good as long as you don't "nail it"

I'm in the Randstad, yes. Admittedly, not the best place to live in.

Well, the roads are certainly busy...

Am just curious, in which town are you, actually?

DAS

That's interesting. Since all of the brands of cars which I have owned have had them, I just assumed ...

Anyway, how 'bout educating me on two things. Just exactly what do timing belts do? (Yes, I am pretty dumb in this area.) And what do the BMWs w/o timing belts have which perform that function?

Thanks, Bob

Timing belts or chains connect the crankshaft to the camshaft(s). As the crankshaft turns, the cams are rotated to open and close the valves.

In the old days they always used chains. Chains tend to be a little noisier - not much, just a little. In an attempt to eliminate the sound, very slight additional vibration, and to cut production costs, many manufacturers started using timing belts. Because it's a high stress application, timing belts typically go 60K miles although some now go 100K miles. Chains last well over 100K miles in most engines.

The failure of a timing belt can range from "you stop and call a tow truck" to "you just destroyed your valves, pistons, and are looking at $3-6K in repair costs". That depends on engine design and is related to a whole bunch of other issues. That is, it's not that engineers can't design engines that fail gracefully when the belt goes, it's that it forces other compromises to use that type of design. Replacement of a timing belt ranges from $250 to $600 with most engines.

Better name is cam belt - as it drives the camshaft. It may well drive other things as well like the waterpump on some designs.

They went back to chains with the twin cam engines. The rubber band to drive the camshaft didn't arrive - globally - until about '70 - before that most used chains, although there were other ways.

Bob,

Timing belts operate the "overhead cams", which are the things that open and close the valves that let fuel and air into each cylinder of the engine (the "intake valves") and let the exhaust out of the cylinders ("exhaust valves"). The valves need to open and close in sync with the operation of the pistons and the rest of what is going on in the engine. In some cars this is done using a belt. Belts are quieter and (usually) less expensive, but less durable than the alternative of using a chain. Some engines with a timing chain can be almost as quiet as those with a belt, but it has to be carefully engineered. Chains can wear too, and when that happens they tend to get very noisy. Belts usually give no notice that they are about to break like a wearing chain does. The problem is when the belt or chain breaks, the engine stops. In some engines, the pistons keep moving for a few seconds - just long enough to crash into the now stopped valves which potentially destroys the engine (this is known as an "interference" engine). Other engines are designed so that there is still enough room so that the valves and pistons don't crash together when this happens (this is a "non-interference" engine).

Some engines based on older designs don't use belts or chains, but they usually only have two valves per cylinder (one intake and one exhaust) instead of the typical four valves per cylinder that modern (and usually more efficient), overhead cam design engines allow. (Some of the preceding is personal opinion.)

Walt Kienzle

I do not think HP is a very good indicator of engine efficiency, do you? And mpg will only work if the two cars the engines are in are the same (of the same weight and coefficient of drag).

-Fred

Timing belts go from the crankshaft to the camshaft(s), turning the cams to open and close the valves at the appropriate times. Some cars use timing belts, and are subject to frequent replacements, expensive probelms if the belts break, and so on. They are quieter, though.

Other cars, such as most (all non-V6) Saab engines and apparently some BMW engines, use a timing chain rather than a belt. It will wear and stretch over a few hundred thousand miles, but catastrophic failures of timing chains are very rare...they usually get very rattly for a very long time before anything goes wrong, giving the driver plenty of time (months) to do something about it.

Earlier, Saab used timing gears in the V4 engines, which were again noisier than a rubber band (oops, "belt") but give more positive and reliable timing.

I don't know which Audi uses, but I personally will avoid any engine with timing belts. Internal engine components, which you can't visually inspect, aren't something I'm willing to put up with.

Dave Hinz

A timing belt drives the camshaft and valves, by taking power from the crankshaft. The other alternative is a chain and sprockets, which all newer US model BMWs have. A few cars like Ferraris have gear driven valvetrains.

The only US model BMW engines with timing belts are the "small six" engines, which are in the 80s 3 Series, and some 5 series cars -- the 325e, 325i, 528e, and early 525i. The rare 524td is also a small six w/ a belt.

Matt O.

It might be, coming from someone who hasn't *been here* as many years as I have. You'll notice not many of our regulars have taken me up on that remark.

Hey, compared to most other cars, I *liked* my Audis! It's just that I didn't happen to *own* most other cars. I *do* happen to have owned and/or driven lots of *very* entertaining cars over the years, so my perspective is quite different from most Audi devotees.

-- C.R. Krieger (Still cranky)