robb1 Posted December 28, 2004 Share Posted December 28, 2004 after reading about all the head gasket issues and problems with the 2.5 interference type engine.....can anybody tell me why Subaru designs engines with rubber timing belts instead of metal ones? I,ve had many GM vehicles over 100,000 miles.......never replaced a timing belt on any. Starting to wonder about my own 98 2.2 Impreza...... and maybe the Forester i was going to buy for the wife needs some more thought..... any thoughts from you appreciated...! Link to comment Share on other sites More sharing options...
northguy Posted December 28, 2004 Share Posted December 28, 2004 The new 3.0, I've been told, is a chain drive. So, maybe that's a move in a different direction for the future. Link to comment Share on other sites More sharing options...
Commuter Posted December 28, 2004 Share Posted December 28, 2004 I saw quite a discussion on this on another board a few years ago when Subaru brought out the 3.0L H6 and people wondered why it had timing chains instead of a belt. (See answer below.) There are pros and cons to both belts and chains. This is just a very quick summary. Belts are less expensive, quieter and have lower losses. The downside is that they have to be changed more often. Even a chain wears and stretches over time. In the H6 engine, the chain reaches linear speeds of nearly 50 mph as I recall!! I saw a post of an article right form a Subaru engineer as to why they chose a chain for the H6 engine. One word... packaging! That is, they wanted to minimize the size of the engine, the length in particular. A belt would have added about an inch to the length of the engine. As it was, they managed to design the H6 just under an inch (22 mm) longer than the the 2.5L H4 engine. See where they were going? So sometimes the reason is not what you might expect. Commuter Link to comment Share on other sites More sharing options...
unverviking Posted December 28, 2004 Share Posted December 28, 2004 after reading about all the head gasket issues and problems with the 2.5interference type engine.....can anybody tell me why Subaru designs engines with rubber timing belts instead of metal ones? I,ve had many GM vehicles over 100,000 miles.......never replaced a timing belt on any. Starting to wonder about my own 98 2.2 Impreza...... and maybe the Forester i was going to buy for the wife needs some more thought..... any thoughts from you appreciated...! Nothing wrong with Rubber Timing Belts... I'd rather them over a chain. If the chain goes, it's (in my opinion) harder to replace than the belt. Most belts can run 100k miles without issue. I think that design of the motor has something to do with the difference between chain and belt... If I remember correctly, OHC (over head cam) has the belt driven timing and the OHV (over head valve) has the chain. The OHV has pushrods to actuate the valves. Much shorter distance on the chain (at least on the one's I've seen) than the belt's I've replaced. GM is not exempt from belts, I changed one on my wife's old Chevette. I wouldn't let these little thing stop you from buying Subaru. We were hardcore GM before our first (01 OBW) and the ride is far superior, not to mention the AWD. We've only had 2 issues in 72k and 4 years that needed dealer attention. 1 was a known problem that resulted in a reflash of the ECM, and the alternator bearing went after 60k. I complained about the alternator bearings and SOA covered 1/2 the cost. It was cheaper for me to have them do it than for me to do it alone. The reman alternator was close to $200. We paid $160 as our 1/2. We had to trade our 95 Corsica & 97 Cavalier because they were in the shop constantly, everything that could go wrong, did. We bought GM because my wife's entire family is all retired from there. Not any more. I won't even mention my Dodge experience... You think that Sube's have head gasket problems, you haven't owned a Chrysler product with their 2.2 4 banger in it... Link to comment Share on other sites More sharing options...
The Dude Posted December 29, 2004 Share Posted December 29, 2004 You're right to ask these questions. In general, interference engines are a bad deal for the owner. Interference engines provide a slight improvement in efficiency. But any problem with the timing belt can leave the owner paying for a replacement engine. The timing belt breaking isn't the only problem that will cause the engine to self-destruct. If the water pump freezes, if one of the idlers fail, if the tensioner gives out, or if the belt just "skips" a notch or two, kiss your engine goodbye. Some on this board will say, " Come on, if they're replaced on schedule, timing belts almost never fail". And they're right, BUT you're taking a pretty big risk for almost NO benefit. There are pros and cons to both timing chains and timing belts. But interefence engines are a real losers. Link to comment Share on other sites More sharing options...
cookie Posted December 29, 2004 Share Posted December 29, 2004 and have usually chosen my long term cars with a chain. Mentality is a bit different in Japan I think, and the theroretically best and most modern is often chosen. Most Japanese Subies will be junked before thier first timing belt change. Link to comment Share on other sites More sharing options...
Setright Posted December 29, 2004 Share Posted December 29, 2004 I just had the timing belt changed on my Impreza - the only thing I pay the dealer to do, because the stamp in the service book looks good when you sell the car! - and the belt had 60k and five years on it. Looked almost new. So, invisible internal stress notwithstanding the belt could probably have soldiered on for a while yet. Dealer says they have never seen one break. My EJ22 belt looked good as new when I replaced that, too. Link to comment Share on other sites More sharing options...
carfreak85 Posted December 29, 2004 Share Posted December 29, 2004 Looks like I've been beat to the explination and I just learned the answer in one of my engineering class! Link to comment Share on other sites More sharing options...
simbey1982 Posted December 29, 2004 Share Posted December 29, 2004 Um,,,The DUDE arent most subaru engines with exception to some of the newest ones, all non interference engines?? Far as i know the only thing that happens if the timing belt on my 97 impreza breaks it just means a tow and a timing belt.....im pretty sure most suby engines are non interference Cory Link to comment Share on other sites More sharing options...
ballitch Posted December 29, 2004 Share Posted December 29, 2004 yes someone please chime in with the correct info regarding subes being interference or non-interference motors. Link to comment Share on other sites More sharing options...
svxpert Posted December 30, 2004 Share Posted December 30, 2004 <<can anybody tell me why Subaru designs engines with rubber timing belts instead of metal ones?>> better gas mileage, and noise reduction. <<yes someone please chime in with the correct info regarding subes being interference or non-interference motors.>> this has been covered in previous posts but i'll post some answers EA series ER27 non inter- first gen EJ22 EG33 (only because it has cam gears that never fail) EJ18 inter- second generation EJ22 EJ25 EJ20 EJ255 Forester XT EJ237 STi Link to comment Share on other sites More sharing options...
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