Subaru Timing Belts

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Man, am I getting schooled on Subaru or what? With all the many model permutations and conflicting part numbers from various dealers and online catalogs, it is quite a challenge. Regarding timing belts specifically, for some reason, Subaru uses two different belts on their basic 2.5 SOHC non turbo engine. Does not appear to be any rhyme or reason. The two belts differ only in tooth profile. One is curvilinear and one is modified curvilinear. Gates told me using the wrong belt would cause erratic timing and probably throw a CE light. I got an Aisin kit which is not for my car because it has the wrong timing belt. No problem, I just got the right one. Still a tremendous deal. BUT, the kit also includes a cogged idler pulley. I assume I need to get a different cogged idler to match the belt profile, but I can not get a consistent answer from Subaru.

So, with all of that, does anyone know if you can use the same cogged idler pulley on both curvilinear and modified curvilinear belts? When I get the other belt, perhaps the difference in tooth profile will be easy to see.
 
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Originally Posted By: skyactiv
Nasioc.com would have that answer for you.


Right, but I need two more legitimate replies before I can ask a question.
 
Originally Posted By: Ethan1
Sounds like time to go OEM


I already bought the OEM idler which should be here in a couple days. Problem is I can not get a consistent story from various Subaru dealers regarding the correct part. They are looking at the same catalogs I am and they all say something different.

My problem is I do not have enough knowledge regarding curvilinear vs modified curvilinear tooth profiles. I found pictures of the tooth profile but no mention of the need for different cam sprockets or cogged idlers. For all I know, you can use either belt on the same cam sprocket.
 
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Never ever seen this on a 2.5 SOHC. Or any Subie t-belt I've done (many, many). Order the Aisin, Conti, whatever kit by year/make/model and install. I have yet to have a failure of any kind.
 
Originally Posted By: 14Accent
Never ever seen this on a 2.5 SOHC. Or any Subie t-belt I've done (many, many). Order the Aisin, Conti, whatever kit by year/make/model and install. I have yet to have a failure of any kind.


Aisin does not make a kit for the 07 OB 2.5i non turbo SOHC. However, in the kit they have, everything matches exactly except the belt and possibly the cogged idler pulley. The kit supplies a Mitsuboshi CD 304 and I need a CD 307. Common sense tells me a cogged idler designed for a 304 belt will not be right for a 307 belt. It would probably work ok but maybe noisy. I bet when I compare the OEM idler to the one in the kit and then see how the idlers mesh with the two belts, the differences will be apparent.
 
I just did a 2009 Forester with EJ25 2.5L non-turbo automatic. Used a GATES kit from NAPA and no problems. Did not know about the belt differences so rather interesting.
Job was fairly easy and we lucked out as the engine was running when about 20 teeth of the belt went away! Engine was at idle and just stopped. Thot the valves would be bent but did the belt change anyway.... it works! Runs great!

poikaa
 
Originally Posted By: poikaa
I just did a 2009 Forester with EJ25 2.5L non-turbo automatic. Used a GATES kit from NAPA and no problems. Did not know about the belt differences so rather interesting.
Job was fairly easy and we lucked out as the engine was running when about 20 teeth of the belt went away! Engine was at idle and just stopped. Thot the valves would be bent but did the belt change anyway.... it works! Runs great!

poikaa


Right, your kit included a modified curvilinear 304 belt. But, the sprocket idler is the same one they put in their kits with curvilinear 307 belts for The Outback/Legacy platform. ACDelco and Flennor do the same. I have also confirmed that Subaru uses the exact same sprocket idler groove profile for both curvilinear and modified curvilinear belts. Because the idler is under very low load and registration is not important, there is not any need to have application specific groove profiles.

Did you get the kit ending in “N” which is supposed to have all Japanese parts? Did you use Loctite (included in the kit, right?) on the tensioner bolt? Gates recommends this but the Subaru FSM does not. I wonder if Gates issued their technical bulletin on this as a response to the high rate of Gates tensioner failures? Why didn’t you buy the Aisin TKF006 kit?

How did you hold the crank pulley? Did you buy a new crank bolt or did you check existing bolt to make sure it had not been previously torqued beyond yield?
 
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Originally Posted By: Merkava_4
Is this for the 2007 Subaru Outback with the 2.5 Liter engine ?


My car is the 07 OB with 2.5 SOHC engine. It takes a curvilinear timing belt. I was responding the post re the Forester which takes a modified curvilinear belt. The Aisin TKF 006 kit is for the Forester among many others. But, everything in that kit will fit the OB except the belt. Buying the Aisin 006 kit is still the best deal, imo, even if you have to spend an extra $50 for a timing belt. Much better quality than a Gates kit and equal quality to OEM at much lower cost.
 
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Lots of Subarus in my family over the years and I've never heard of this two different T-belt thing for the EJ253. I'm not saying it's not a thing, just that I haven't seen this.
 
Originally Posted By: JTK
Lots of Subarus in my family over the years and I've never heard of this two different T-belt thing for the EJ253. I'm not saying it's not a thing, just that I haven't seen this.


Lookup timing belts for Forester/Impreza vs Legacy/Outback for a 2.5 SOHC non turbo for a 2007, for example. Conti belts actually include curvilinear and modified curvilinear designations in their product details under the info tab on Rockauto. You will see the former takes a 304 and the latter takes a 307. Both belts have 233 teeth with the exact same width and length. Only diff is tooth profile which is apparent to the naked eye. I have never personally tried a 304 belt on a 307 application (or vice versa). Maybe you would not know the difference, but Gates says you would. I believe Gates because they use the same cog idler on both engines and I am sure they would call for the same belt if they could. Also, I assume Bando and Mitsuboshi know a little bit about timing belts too.
 
Originally Posted By: artbuc
Originally Posted By: JTK
Lots of Subarus in my family over the years and I've never heard of this two different T-belt thing for the EJ253. I'm not saying it's not a thing, just that I haven't seen this.


Lookup timing belts for Forester/Impreza vs Legacy/Outback for a 2.5 SOHC non turbo for a 2007, for example. Conti belts actually include curvilinear and modified curvilinear designations in their product details under the info tab on Rockauto. You will see the former takes a 304 and the latter takes a 307. Both belts have 233 teeth with the exact same width and length. Only diff is tooth profile which is apparent to the naked eye. I have never personally tried a 304 belt on a 307 application (or vice versa). Maybe you would not know the difference, but Gates says you would. I believe Gates because they use the same cog idler on both engines and I am sure they would call for the same belt if they could. Also, I assume Bando and Mitsuboshi know a little bit about timing belts too.


Oops, 223 not 233 teeth. Gates also calls out modified curvilinear on their 304 belt:

https://www.autopartswarehouse.com/sku/Gates/Timing_Belt/GATT304.html
 
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Originally Posted By: zzyzzx
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So true! This is my wife’s friend’s car which I have been servicing since her husband died in 2012. I got involved just in time to convince Subaru corporate to pay for blown head gaskets. They did not want to because car was just out of warranty but eventually agreed to use goodwill since she has had dealer do all service since it was new. Shortly later a wheel bearing went out and I talked Subaru into paying for that too. They sent a very nice letter informing me that they would do no more. Couple years later had to replace both front axles since they located CV joints directly over exhaust and they blew wide open. Most recently, had to resolder SRS indicating light (which saved her a couple hundred bucks). All of these items are well known Subaru problems. Tried to talk her into trading Subie in before she spent $$ on timing belt/water pump service but she wants to keep it.
 
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