Does my 2004 impreza 2.5SOHC auto have interference or non interference valves? Also if its not interference if my timing belt or tensioner break will my piston still smash into my vavles and ruin everything?

Everything since 1998 has been interference. And a timing belt break or tooth slippage is not a guaranteed destruction. You can find threads here and elsewhere that these things have happened and the engine was ok.

 

That being said, if it hasn't broke and it's due, overdue, or you have concerns get it replaced or checked out.

 

Just because it doesn't destroy something everytime doesn't mean yours won't do major damage if it fails.

 

If it has failed the only way your going to know is to put a belt on it and find out or tear the engine down.

With interference engines, don't wait for the interval. Be proactive and change the belts, pulleys, tensioner, etc. in one go a little before their due date. Just not worth the "worse" case scenario when it's so easily avoidable.

Edited July 6, 201510 yr by Bushwick

definitely interference and not worth taking the risk with. Yes, some have been lucky & had no damage - others, not so lucky...

 

It is far cheaper to take care of timing belts and related components ahead of schedule than to wait and "hope" it doesnt destroy the heads and/or pistons when it does break.

I don't understand people who ignore the timing belt just because it isn't interference. It doesn't matter if I'm on a road trip or my way to work, if the belt breaks it interferes with my day; therefor all engines are interference to me.

Replacing the timing belt, idlers, and water pump is a lazy afternoon job and only costs around $200 for the Gates kit, no excuse not to get it done.

Edited July 6, 201510 yr by 987687

I don't understand people who ignore the timing belt just because it isn't interference. It doesn't matter if I'm on a road trip or my way to work, if the belt breaks it interferes with my day; therefor all engines are interference to me.

Replacing the timing belt, idlers, and water pump is a lazy afternoon job and only costs around $200 for the Gates kit, no excuse not to get it done.

Who is saying people ignore them? It's a piece of mind thing to be honest. I still don't understand why interference are even offered w/o chains as most cars are still under warranty and MANY people don't even know their engine has a timing belt, let alone that are supposed to replace it. Has to really take a chunk out of profits. If the NA 2.2L makes 130hp with non interference, the hp bump is hardly worth it to go with interference, especially with turbo'd cars where they detune the NA engine then make up for it with the turbo.

 

My mom gave me her old Geo Storm Si many years ago and it had a 1.6L DOHC non interference. I had it for about a month when the belt went out at 52k miles. Was completely clueless back then. Thankfully a $45 tow and $25 belt later and it was back on the road. Definitely nice NOT having interference if car has a rubber belt. But doubt people are "lazy" about it.

Uhm the recommended interval change for most timing belts is AFTER the warranty has expired. Most manufacturers now have a 100k+ interval change.

 

On top of that no warranty is going to cover a snapped timing belt, bad tensioner, or failrd idler if it was not replaced or inspected at the recommended time.

 

And a timing belt requires less power to move than a timing chain which increase engine power.

you would be EXTREMELY lucky to suffer a timing belt failure without valve destruction in that 2.5.

 

I changed my WRX's timing stuff at 8.5 years, mileage was way under the 105K. Glad I did too, the toothed idler was crunchy and a little wobbly. Another was very loose and slightly noisy. belt was fine. That idler would have puked it's bearings before 105K I feel certain.

 

And, I will probably accelerate the next change to 6 years or so. (unless I start putting more miles on) because I didn't change the waterpump or cam/crank seals.

Edited July 6, 201510 yr by 1 Lucky Texan

Who is saying people ignore them? It's a piece of mind thing to be honest. I still don't understand why interference are even offered w/o chains as most cars are still under warranty and MANY people don't even know their engine has a timing belt, let alone that are supposed to replace it. Has to really take a chunk out of profits. If the NA 2.2L makes 130hp with non interference, the hp bump is hardly worth it to go with interference, especially with turbo'd cars where they detune the NA engine then make up for it with the turbo.

 

My mom gave me her old Geo Storm Si many years ago and it had a 1.6L DOHC non interference. I had it for about a month when the belt went out at 52k miles. Was completely clueless back then. Thankfully a $45 tow and $25 belt later and it was back on the road. Definitely nice NOT having interference if car has a rubber belt. But doubt people are "lazy" about it.

 

People totally are lazy about it, I read posts on here all the time asking if the engine is interference or not. Then stating "well I can ignore this for another year blah blah blah"

 

They changed the pistons in 97, so 97 up is interference, yes even the 2.2. It has to do with making the flow in the combustion chamber more efficient or something like that, the byproduct of which causes valves to hit pistons when the belt breaks.

i buy cheap water pumps and change the belts when the pump goes out and change the idlers and tensiones every other belt it works out to around 60k each time the belts always look good when there changed but hay why risk it i would much rather change a timing belt than replace valves

 

Most manufacturers now have a 100k+ interval change.

in the mid 90s,

california ''required'' a 100k belt.

so starting in 96 all of the US ej25d engines have a 105k interval.

there was also a 105k belt for the ej22 to meet the cali requirement.

(at my advance auto, it is cheaper and a special order.)

the rest of the country was still 60k on the ej22 90 - 98.

 

but get this,

in the rest of the world,

the interval for the ej25 (96 - 04) and ej22 (90 - 00) is 100k Km, or 60k miles.

go figure.

i doubt the idlers or the belts are any different, USDM vs. JDM,

any one know.?

 

i assume the interval for newer ej25 is the same,

but i do not know.

Edited July 7, 201510 yr by johnceggleston

People totally are lazy about it, I read posts on here all the time asking if the engine is interference or not. Then stating "well I can ignore this for another year blah blah blah"

 

They changed the pistons in 97, so 97 up is interference, yes even the 2.2. It has to do with making the flow in the combustion chamber more efficient or something like that, the byproduct of which causes valves to hit pistons when the belt breaks.

That's an opinion, but it's true it's not as much of a life/death scenario.

 

Yes, my point is the increase from interference designs is so minute it's hardly worth the hassle. Turbo engines even less so as the engine's NA power level can be 90 hp then shoot up to 275-300hp with a small turbo. Keep the cat less restrictive with larger downpipe diameter and you'll never see the see the hp difference with minimal lag.

 

As far as rubber belts stealing less hp and be quieter is true, but again not worth it. Talking about a 5hp difference which can be negated with a tuned intake and exhaust. Noise is hardly noticeable. Ford ran chains in the DOHC 4.6L which I've owned and that engine was quieter than the EJ22 I own now. My 4.6L made around 300hp+ at the crank, so it was making around 150hp per 4 cylinder bank = 2.3L or 65hp per liter vs 2.2L  making 59 hp per liter. So the entire "belts are worth it over chains" is rubbish when talking a daily driver. Was still running the factory chain in the 4.6L at 125k miles when I sold it. They can last 200k miles though will be overly stretched by that point.

Edited July 7, 201510 yr by Bushwick

You all do know that the new FB engines (all of them except turbo) since last year are running chains, not belts?  Kind of a scaled down version of the EZ30.

Yeah, but chains need replaced as well and timing belts usually tend to be cheaper.

Yeah, but chains need replaced as well and timing belts usually tend to be cheaper.

Chains can go 150-200k miles on average. Meaning a belt would need changed 3-4 times in the same span vs. 1 chain replacement. Cost depends on the actual engine.

 

Good to hear chains are being used in newer engines. While belts definitely have their advantages, having a freak failure that tosses one or causes it to skip a cog on an interference engine really stinks. 

Yeah, but chains need replaced as well and timing belts usually tend to be cheaper.

The turbo DIT FB engines are indeed chain drive (15 wrx, forester xt) but the STI still uses an EJ belt driven

The STi is not an FB engine.