As the Astra has a timing belt (as did the L300 V6 and the Honda-powered V6 VUE) and all other Saturs have a timing chain, I wanted to stsrt a thread on the pros and cons of both. Both have thier vulnerabilities and good points. Saturn belts are good for 100K mi, which is more than many out there.
Googling for this info revealed lots of useful info. Gave me a a good heads up on both to ponder.
My 2001 LW300 V6 had almost 100K on it when I replaced the timing belt. The belt had practically no observable wear at that point and was otherwise in good shape. I bought the car with 40K on it and will assume that nothing happened in the previous life that required a new belt.
would have replaced the belt myself except for the large amount of special tools to hold the cams locked into position and align everything. there are two tensioners and the relation between the two sets a fine timing position. Way too tricky and catastrophic to the engine if a mistake was to be made. I've done chains and belts on other less complicated engines. On Chain drives, you have to remove more of the front of the engine to get the front cover off.
Oppie
Ever since most of the ISPs killed alt groups, I've been using teranews for most of my ng access. Lately, I haven't been able to post and article retention is getting pretty bad. Just realized that I could still access this group through the verizon ng server. I'm going to have to find another independent usenet provider and tell teranews to take a hike.
I have no preference either way. I've had vehicles with chains ('87 Nissan, '94 Jimmy, '98 Maxima, '06 Avalanche) and with belts ('93 Altima, '02 Sedona, '05 Vue). Both work.
The only thing you have to remember is to change the belt when it is time.
No big deal.
It's basically a $$$ thing which adds to the cost of ownership ... with a properly maintained engine, a timing chain should realistically last the life of the vehicle. With timing belts, you'll spend $ changing the timing belt (and likely the water pump too as preventive measure) every change interval.
As one point of reference here, one vehicle I own has a 60K mile timing belt replacement interval, so this means it will be changed 3 times for me over my average of 12 years of ownership. The price for that service on that vehicle is currently $1K, so this is not insignificant. Also, check to see if the engine is interference or non-interference. This will tell you if the engine will be destroyed if the timing belt breaks ... this allows you to decide whether to take the risk and go longer that the recommended interval. Non-interference engines are preferred, but may sacrifice power.
Bob
Not that timing chains are perfect either. Back in my ford years, I rebuilt two engines that were damaged by a failed timing chain. The chain itself was still in reasonable shape as was the crankshaft sprocket but the camshaft sprocket which had Nylon (iirc) molded teeth was worn and allowed the chain to skip.
That being said, it is important to add that most 'modern' engines with timing chains now include some sort of chain tensioner to not only tension it but to damp it from flopping about at high speeds. All the tensioners I've seen lately are a combination of spring and hydraulic assist (operated from engine oil pressure). Oppie
A/C Compressor is usually driven by its own belt. Water pump can be driven by either a serpentine belt or in some designs, by the timing belt. I've never seen these both driven by the timing chain in any vehicles I've worked on.
Bob
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