Subaru Engine Block Piston Size Identifier:
The picture below of this paragraph shows the location of piston size and main journal size information on all Subaru engines. As the figure illustrates, it is possible to have more than one piston size in the same engine.
As we mentioned, it takes a special tool to work within the limited clearance area between the cylinder heads and the frame rails. The ST 498187 is a three part tool. One part wraps around the cam lobes, a second touches the outer edges of two shim buckets, and a third eccentric bolt exerts the necessary pressure to push a pair of shim buckets away from the cam lobe to make shim removal and replacement possible.
The tool installed in the three steps:
• Wrap the first half of the tool (part A) around the lobes.
• Attach the second half (part B) to part A by sliding its pins through the slotted holes in part A.
• Install the eccentric bolt (part C) into the hole in part A.
The eccentric bolt forces parts A and B away from one another. Because part A can’t move (it’s wedged against the cam lobes), the only thing that can move is part B. Part B moves by forcing the shim buckets downward, away from the camshaft.
The first versions of the 2.5 liter twin cam engines employed non-hydraulic valve actuation. Like the timing belt, the clearance between the engine valves and the shim and bucket valve actuators does not require inspection and/or adjustment until 105,000 miles have elapsed. However, various circumstances may require an adjustment before that milestone is reached.
Clearance is tight and there is little room to work between the cylinder heads and the left and right frame rails. A special tool (ST 49818700) is available for depressing the valves and removing the adjusting shims. Without this tool, the job is impossible to accomplish with the engine in the car. Once again, we had the benefit of working on an engine that had already been removed from the car. Before you can adjust the valves, the engine must be cold. Consult the service manual to determine the parts that will need to be moved or removed to make some room to work.
Unlike some overhead cam engines that require you to rotate the cam until each cam lobe is facing 180 degrees away from the adjustment shim, Subaru has very specific procedures for adjusting four valves at a time (a pair of intakes and a pair of exhausts). The pairs of intakes and exhausts are never for the same cylinder, which makes things rather interesting. This system requires you to turn the crankshaft a total of four times to complete the adjustment procedure.
This is a step by step guide on replacing the valve cover gasket on Subaru flat four engines. This guide will work for most Subaru turbo cars 02-07+ and most other naturally aspirated Subaru cars.
1.) Jack your car up and drain the oil. Remember to put the car on jack stands. You don’t want the car dropping on you.A lot of people do this job with the oil still in the pan, but its better to rather play it safe and drain the oil completely.
2.) Remove the front air scoop. It takes two 10mm bolts.
3.) Remove the nice Cold Air intake box.
4.) After removing all that, you should see this a total of 8 outer bolts and the 2 inner which holds the spark plug coils.
5.) Unscrew them and label them. You don’t want the bolts going into the wrong place. It was a very hard to get any decent clearance so take your time.
The primary purpose of a TGV delete is to remove the divider bar and butterfly valve inside the TGV assembly to improve airflow to your engine.
HP gain is 12 HP. This figure is highly debated as different manufacturers use different dynos with different cars with different levels of mods.
What is the purpose of TGV Deletes? The are meant to reduce cold idle emissions. Nothing more, nothing less. Once your vehicle is warm, the butterfly valves open fully and remain that way.
Which manufacturer is best? This topic is highly debated with no real winner in terms of performance. There are several companies that offer the TGV delete service as well as purpose built units or Japanese models which are, in essence, hollow units.
Japanese model, what is that? TGV internal assemblies are only used for cold start emissions on US cars. Hence, the Japanese TGVs do not have the divider plate or butterfly valves. Some models are one piece intake manifolds with longer runners that make up the TGV portion and other models are just like their US cousins with no internal plates or butterfly assemblies. Neither units have the associated TGV external motor controllers as well.
Which TGV Delete has the best gains? There is no irrefutable evidence that any TGV Delete option has better gains than another. The consensus, if there is one, is they are all within 5HP or less, gain wise, of each other.
Do TGV Deletes cause a CEL? Yes. By removing the TGV motors, it will throw quite a few CELs. The bad news with this, is the TGV CELs will throw your car into limp mode, meaning unlike some other CELs that you can still drive around with and have no fear, the TGV codes limit boost/RPM operation meaning they must be taken care of in order to drive your car for any reasonable distance.
How do I fix the TGV CEL? You have three methods:
1. Normally, you remove the TGV motors and the rod that holds the butterfly valves in place. You could leave the rod in place (sans butterfly valves) and reinstall the TGV motors. This would allow them to actuate normally making the system think everything is working correctly.
2. APS makes a block that you attach the TGV motors to, this allows them to actuate normally making the system think everything is working correctly. These are not sold separately though, but can occasionally be purchased in the Private For Sale Forum or on eBay.
3. Various engine management systems can remove the associated CELs.
Do I need to perform the CEL fix? Yes. The TGV CEL codes will throw your car into limp mode. This will limit boost/RPM seen by your vehicle. It will still drive, but it should only be driven a short distance with the TGV CEL. Meaning you can drive it across town or a few short trips, but by no means should you drive it as a daily driven car for weeks on end until you get the proper fix.
Tools used:
3/8 Ratchet
1/2 Ratchet
10, 12, 14, 22mm sockets
short extension
Impact wrench or strap wrench (I used both on separate occasions.)
Torque Wrench
Small metal ruler to measure belt deflection.
Drain pan and funnel for the coolant.
Brake Kleen
Lots of paper towels/shop rags.
3/8 socket driver (very handy.)
Feeler gauges
2mm allen wrench
allen socket for the right camshaft (6mm maybe?)
C-Clamp
Gates TCK328RB Timing Belt Component Kit
Gates 42030 Water Pump
Gates 34012 Thermostat
NYPPD Billet Timing Belt Guide Subaru Impreza WRX EJ20 STi EJ25 2002-2013 Turbo
Genuine Subaru SOA868V9270 Super Coolant
Subaru SOA635071 OEM Coolant System Conditioner
Helpful tools:
Subaru Camlock Tool for Subaru 2.0L and 2.5L DOHC turbo engines C23-506
Subaru Crank Pulley Tool C23-503
Subaru STD Int/Exh Cam Sprocket Tool – similar to 499207400-A
Subaru Cam Sprocket Tool – AVCS Int C23-501
Go to the next page to get started.
Refer to your owners manual for recommendations. Alternately, you can visit an auto parts store or online retailer for recommendations on suitable spark plugs designed for your vehicle. Major manufacturers are:
a. NGK
b. Bosch
c. Denso
d. Autolite
e. Champion
Who are the specialty spark plug manufacturers? These manufacturers make specialty plugs that have unique compositions or designs that claim increases over traditional plugs. They are listed for advanced users or those with interest.
a. Torquemaster
b. Beru (specifically the Silverstones found here)
c. SplitFire
d. PREP spark plugs
e. E3 spark plugs
f. Pulstar plugs
What types are there? There are really three main types:
a. conventional nickel alloy (commonly referred to as “copper”)
b. platinum
c. iridium
Which type should I use? That depends on how often you are interested in changing the spark plugs. Conventional spark plugs generally last one year. Platinum or iridium can last, depending on manufacturer specifications, up to seven years.
What’s some good background spark plug information?
Materials: The three main types of spark plug materials are nickel alloy, iridium, and platinum. Copper can be used in the core all plugs.
All ground electrodes are made of nickel. The use of Platinum and Iridium, which are stronger, allow for much finer CENTER electrodes (the ground electrode is still Nickel). These finer electrodes do not quench the flame core as much as a conventional style plug. This increases ignitability, therefore increasing HP. It’s not a huge gain, but cylinder pressures are measurably higher.
Platinum or iridium can be used as a thin pad which is laser welded on the ground electrode (the “J” strap), this serves to increase the life of the plug.
The primary purpose of an aftermarket pulley is to reduce the size and/or mass of the stock unit. They serve two purposes: to reduce horsepower loss and increase throttle response. Notice the use of “reduce horsepower loss”. Pulleys DO NOT add horsepower, rather they free up horsepower due to the reduction of rotational mass.
Grimmspeed Lightweight Crank Pulley Black – Subaru All EJ Engines
HP gain is 5-10HP. These HP figures are a range as there have been very few before/after dyno runs with lightened or under driven pulleys.
What is a lightened pulley? Generally, it is an exact copy of the OEM pulley only CNC machined out of aircraft grade aluminum and powder coated for corrosion protection and aesthetic appeal.
What is an under driven pulley? This is a pulley that mimics the function of the OEM unit, but is smaller in diameter. This will reduce the duty cycle of the pulley and proportionally the parasitic drag on the engine.
Are under driven pulleys bad? It depends on the amount they are under driven. Some under driven pulleys can lead to reduced A/C output, lighting problems, stereo problems, and other voltage issues. Some are lightly under driven and some more so.
Isn’t replacing the stock harmonic damper (pulley) bad? Subarus do not come with a harmonic damper or balancer like some other vehicles do. For other manufacturers’ vehicles, this is a legitimate concern. Proof:
“Thank you for your patience as I checked with our Technical Services Department regarding your message below. They advised that the crank pulley is a pulley and nothing else. It is not used as a harmonic damper/balancer.
Thanks for the opportunity to be of assistance. If you need any future assistance, please feel free to contact us again.”
Best wishes,
John J. Mergen
Customer Service Department
Subaru of America, Inc.
