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Discussion Starter #1
Ive got a 2002 Outback 2.5 and wanted to do a top engine cleaning so I ordered the Subaru Engine MX Kit which as a throttle plate spray, a fuel additive, and the bottle of Subaru Top Engine Cleaner. I ordered the top engine tool, SOA868V9430, from Subaru that fits on top of the Bottle to siphon out the top engine cleaner. It has a plastic tube that screws down onto the bottle with a cap fitting on top and a plastic tube to goes out of the top of the bottle to feed the chemical into the engine. I have not received it yet but the dealer said it did not come with instructions.

The question I have is where does the hose end go to do a complete cleaning?. I asked a mech at the dealer today and he said it goes on the brake booster vacuum line but they dont use the tool in the shop. If I feed it into the brake booster line will it get the whole intake and pistons or will it just get one side. Is there another line that I can feed it into to get the whole intake and pistons evenly? Or will feeding off the brake booster line be good enough? Would I be better off going with the seafoam spray since it goes into the throttle plate opening as an aerosol? These Subaru products only come in a liquid, not an aerosol can.

The Subaru mech said to feed the cleaners in slow to prevent damage to the catalytic converter, which might be why subaru makes the special tool. I also ordered the Carbon Clean which is a separate product from the Top Engine Cleaner. Does anyone know if there is a difference in the two as they both seem to get the carbon off? This bottle also uses the Subaru Top Engine Tool to apply it.


Thanks for any advice as I have not done this service before and want to do it right.
 

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Lawn ornament XT
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14,366 Posts
As far as I can tell, the throttle body itself is the only entry point that will give snake oil balanced distribution to all cylinders. The brake booster (and other vacuum ports) are heavily biased to one side or even just single cylinders.

The new seafoam spray looks like it makes this easier.

Personally, I have no faith in any of these products... but if you like them, hit the throttle body itself to guarantee even distro.
 

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2005 Legacy 2.5i Wagon 4EAT; 2005 Forester XS 4EAT
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I used the Seafoam Spray in mine, and ran 2 tanks of Chevron Techron.

Between that, new air & fuel filters, and cleaning the PCV valve, I noticed an improvement.
 

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01 Outback LL Bean
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There is no doubt that these products make a difference. Gasoline and oil are not particularly clean unless the manufacture adds more detergents. But that costs money. If a particular company can sell you a gallon of 87 and it meets government purity laws they will sell you the minimum. Of course there are going to be companies that sell higher quality products with better detergents. Chevron puts Techron in some of its gas lines. It also sells it in a can.

Some of the biggest differences in oil these days is the add packs which include the detergents that keep gunk and varnish from building up. The higher quality oils basically have larger amount and better versions of the add packs. While I think everyone should use Mobil1, its expensive though and people like to "save" money so not everyone will.

Overtime though if you use lower quality gasoline and oils, build up occurs. Adding products like these is like adding them after the fact. Not as effective, IMHO, but effective.

These products are trying to do two things. Clean up deposits on valves which effects air (and fuel) flow into the engine. And clean up build up and deposits in injectors which effects fuel metering and distribution into the cylinder.

Here is a site that talks about detergent standards and is trying to push for higher standards.

Top Tier Gasoline
 

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Discussion Starter #6
Thanks for the info. Looking into this more it seems like the best way to go in using the engine vacuum is through the pcv valve hose because it looks like it goes in right behind the throttle plate. The mech at the dealer said the brake booster but that would never hit all the cylinders from its location. Does anyone know if the pcv valve hose disconected from the valve with this top engine tool connected to the bottle of cleaner will hit all the areas? Its on the left side of the throttle body inside of the plate but looks like it should disperse to every side for the most part.

I also heard some recommend disconnecting the Airflow sensor connection even though the car will go into fail safe mode for the cleaning is important to prevent messing up the sensor, any thoughts on this?

Thanks for any advice.

2002 Outback 2.5 manual
 

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Discussion Starter #8
Ive got that top engine tool, works good. The best place to go on a 2002 outback is to pull off the pcv valve line which goes into the throttle body after the air cleaner but before the throttle plate. The tool has a ball valve on it to meter the flow, you barely have to crack it or you will flood the engine out, you can see the fluid flow through the line as a reference. The tool comes with a hanger to hang the bottle above the engine so I suspended it and worked the valve while moving the throttle linkage with my other hand. You need to idle the engine higher than normal or the engine will bog down when the fluid goes in. Using the pcv line input will hit every cylinder because its before the throttle plate, the brake booster line is on the left manifold so it would not get all the cylinders. In order to use the tool you need a bottle of the subaru top engine cleaner or the subaru carbon clean as the tool fits those bottles. After you use the bottle save it and you can fill it with seafoam or whatever cleaner you want.
 
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