With the exception of the current STi you won’t find a timing belt equipped vehicle in Subaru’s line up. But if you are like myself you fancy the older EJ equipped Subarus and with that comes the timing belt maintenance. While replacing a timing belt seems like a pain, I’d much rather deal with it versus Subaru’s timing chain setup.

Subaru, Gates, Aisin, are a few of the big names when you look into timing belt kits, belts, pulleys and water pumps. So which are the most regarded? What parts should you avoid and how do you buy the best parts without wrecking your bank account? With that said let’s delve in the EJ257 and EJ255 parts.

Aisin timing belt kit is very nice and complete. Some have stated an NTN tensioner comes while others have found an Aisin tensioner within the kit.

Timing belts

Let’s start with our OEM’s offerings, as it sets the bar for the others. We will start with the belt part number 13028AA240 which is made by Unitta for Subaru. If you are wondering who Unitta is, they are the Asian division of Gates known as Gates Unitta. If the standard belt doesn’t do it for you, you can step up to the racing version that is Kevlar laced STI timing belt with part number ST130284S000 also made by Unitta, it also comes stylized with a spot of cherry blossom pink.

With all this talk of Gates we will head to their line of belts, their standard O.e. spec belt is part number T325. It touts O.e. or better quality, which is humorous given they are standard belt manufacturer for this engine. Gates also offers a racing version in blue for those who want to push the limits of their engine. If this is your ideal belt your part number is Gates T328RB Belt. I have yet to test out the Blue racing version but have had many years of service on both my STi and Forester with the standard Gates belt.

Last up we will take a look at a lesser known players in this category. If you are purchasing a Aisin timing belt kit you will be getting a Mitsuboshi belt part number CD328. Another large belt manufacturer Dayco 95328 also has their offering. I haven’t had any first hand experience with either of these timing belts.

Tensioners and Pulleys

Starting off with tensioners let’s look at the Subaru oem part first, once again you will find identification on the front of the tensioner, showing the name NTN along with the part number atu106j-1. This can be ordered from Subaru under the part number 13033AA042. This is probably your best choice, you won’t find a more reliable unit out there. The Gates kit and Aisin kit will come with a non-marked tensioner that looks extremely similar to the NTN unit but without the text on it

NTN tensioner, it’s well worth it’s weight in gold.

There are four different pulleys on the front of the engine that route the belt to the proper places. The pulleys on the passenger side which are identical, the cog pulley located near the water pump and the small idler pulley on the driver’s side. The brands that make up the Oem pulleys will be Koyo PU306030RR9H, NTN NEP31003B4, and NSK 59TB0515.

Here is the assortment of pulleys. Koyo idlers on the left side in black. The NTN pulley and tensioner in the upper right corner. Then lastly the NSK cogged pulley alongside the Aisin water pump.

These can be purchased directly from the above listed brands or if you don’t want to search them out, Subaru has their own part numbers and boxes for you for a bit higher price. Passenger side Idlers 13073AA142 Cogged Idler 13085AA080 Driver’s side small pulley 13073AA230

If you purchase an Aisin timing belt kit you will get the oem equivalent pulleys from the above brands, with the possibility of either an NTN tensioner or Aisin tensioner. If you purchase the Gates kit it will be determined by the kit number you purchase will determine the quality TCK328N and TCK328A, the N designates OEM quality while the A is OEM improved.

My preference lies within the brands that make up both the Oem version and Aisin kit. These have been fitted to countless Subarus with minimal early failures.

Water pumps

If you are searching for the producer of the factory water pump then look no further than the Aisin water pump. You can buy this directly from them which includes the pump, gasket and rubber timing belt cover seal. This is also available from Subaru but without the the extras for a bit more coin.

Aisin water pump is the Subaru oem version. But you can buy it cheaper by not buying it through Subaru.

With the Gates kit you will get a Gates made pump. I had the chance to it side by side with the Aisin pump and you can see why the Gates pump costs less. The quality is just not there, you will find many jagged edges where the Aisin pump is nice smooth and well designed for the best operation.

I would highly recommend to use the Aisin unit here, I have personally witnessed issues within the Gates water pumps to say the Aisin pump is well worth the price difference,

Conclusions

Now with all this info what is the best setup to have? That is one that might come down to personal preferences to the above brands. My experience working on Subaru at work and at home have shown me the high quality that was put into the oem pieces. I feel like most Subarus will just need the belt replaced when 105k miles/105 months elapses. I have witnesses plenty of tensioners, water pumps and pulleys.

But just like every car on the road things may be different for your vehicle. Is there anything wrong with replacing all the pulleys for peace of mind, absolutely not.

My recommendation as I am using on my current engine overhaul is buy a Gates belt, Aisin water pump, NTN tensioner and any of the other pulleys directly from their manufacturers. If you feel the urge to replace everything without sourcing each part out individually I would highly recommend Aisin timing belt kit.