Intake/Vacuum Leaks and YOU! PICS INSIDE

Hello there,

This quick writeup is hopefully going to help those who are unfamiliar with their engine bay help find and fix the more simple vacuum and pressure/boost leaks most common with these cars.

These pictures will be used as a loose reference for those searching to see a physical picture of what is described by most members that could be causes of leaks and struggles.

Intake/Vac leaks are one of the biggest headaches when tuning so the opportunity to go through the engine bay and check things out is always a plus.

The biggest thing to make sure when reading this is it assumes you have checked to make sure all worm gear clamps and such are tightened down at the airbox,turbo inlet, top mounted intercooler coupler to throttle body and to intercooler. These are simple things some people don't check first and causes a bunch of headaches for them.

This is a video showing what kind of leaks are possible and then pictures breaking down specific areas

https://www.facebook.com/video.php?v=377734489070626

1. This first picture is showing the turbo's wastegate hose *silver bell*, The turbo inlet *bigger black hose connected to turbo*, The turbo nipple hose and the turbo to intercooler mounting flange. These areas are prone to leak if the intercooler is not mounted properly and flush, The hoses are not seated on the hose barbs and if the turbo inlet has been chewed away by the clamp being tightened too much/not enough or just adjusted too many times because of age. If its oily and looks like rubber is coming through the worm gears section of the clamp its probably leaking.

http://legacygt.com/forums/attachment.php?attachmentid=200133&d=1420422748

2. This next picture is part of the next picture as well when it comes to descriptions. These intercoolers can leak from the plastic end tanks once they have aged OR are pushed at higher boost levels. The aluminum "fingers" start to fold up and the black plastic end tank starts to move away from the core which causes leaks. This is pointing at the underside of the core to explain it can leak from the bottom as well as the top.

http://legacygt.com/forums/attachment.php?attachmentid=200134&d=1420422748

3.This picture shows what was discussed in the last picture which is leaks at the intercooler to end take mounting area. These "fingers" can start to fold up over time because of age or being ran at higher boost levels and cause the end tank to separate from the core. If you look closely you can see where oil is escaping in the boost vapor and actually causing a spot where the intercooler is leaking. This is a common issue with this models intercooler.

http://legacygt.com/forums/attachment.php?attachmentid=200135&d=1420422748

4. This next picture is on the drivers side of the intake manifold between the two intake manifold runners. This is another vac line that can pop off so its good to check and ziptie. This also points at the area you might see an intake manifold gasket or anything leaking related to the tgv assemblies.

http://legacygt.com/forums/attachment.php?attachmentid=200136&d=1420422748

5. There is a lot going on in this area so it needs to be checked and ziptied/clamped as best as possible. This is at the turbo inlet area to the left side of the alternator. This is where the Stock electronic boost controller mounts and there are a lot of lines in this area.

http://legacygt.com/forums/attachment.php?attachmentid=200137&d=1420422748

6. This next pic can be a little confusing but most of the arrows are pointing toward the lines coming to and from the blow off valve. These need to be free of obstruction and connected tightly. Also make sure the gasket is in place on the bov if equipped. The arrow pointing under the intercooler is actually supposed to be pointed at the throttle body coupler and the fact that sometimes to get to the clamp closest to the throttle body you may have to go from under the cooler. There is a plastic sleeve on the stock throttle body hose that's prone to leak and can cause strange high pitched sounds when pinched open under boost. This has been said to be removed without issue but some say its very hard to get it sealed without it because of the design.

http://legacygt.com/forums/attachment.php?attachmentid=200138&d=1420422748

7. This next pic was used from a google search as I couldn't find a good lighting pic to demonstrate its location best. This is conneted right near the center of the rear of the intake manifold right under the top mounted intercooler. Its very hard to get to with the intercooler in place but is well known for popping off and causing people hassles. This can be ziptied or replaced with a barbed T fitting *one is supplied by a forum vendor turkeylord*.

http://legacygt.com/forums/attachment.php?attachmentid=200139&d=1420422748

This writeup is designed to help and the more comments and such people can provide will help others in their searches for leaks and hassles. Always keep in mind the age of the vehicles and that vacuum lines can crack or wear through with contact so the leak may not always be at one end of the hose either.

Hope this helps and bump it up to the top for others if you like the info

Dave

Hello there,

Normally IF the fuel trims are being influenced by a leak they will in fact go back down to "in spec" levels once the leaks are fixed.

Keep in mind there are a lot of things that can effect fuel trims as well if there is NOT a leak in the system.

A dying maf sensor,02 sensor, fuel pump etc are just a couple. Always remember the data you get from the ecu is only as good as the sensors measuring it.

Leaks are the most common reason for strayed fuel trims if scaling is proper, then you start digging deeper.

Glad a few people have already found this helpful.

Dave

Great writeup!

3.This picture shows what was discussed in the last picture which is leaks at the intercooler to end take mounting area. These "fingers" can start to fold up over time because of age or being ran at higher boost levels and cause the end tank to separate from the core. If you look closely you can see where oil is escaping in the boost vapor and actually causing a spot where the intercooler is leaking. This is a common issue with this models intercooler.

 

http://legacygt.com/forums/attachment.php?attachmentid=200135&d=1420422748

7. This next pic was used from a google search as I couldn't find a good lighting pic to demonstrate its location best. This is conneted right near the center of the rear of the intake manifold right under the top mounted intercooler. Its very hard to get to with the intercooler in place but is well known for popping off and causing people hassles. This can be ziptied or replaced with a barbed T fitting *one is supplied by a forum vendor turkeylord*.

 

http://legacygt.com/forums/attachment.php?attachmentid=200139&d=1420422748

Barbed Tees can be puchased from Company23 now.

http://www.company23.com/image/cache/data/subaru/526/526-comp-400x400.jpg

STICKY!

Thanks for this, as I've had to look through the forums for the various locations of possible vac leaks, and now here is it is in one location!

I'll be emailing you shortly as well.

Typical dumb question. I know about the blue T, but does the 07+ have this blue T? I have looked for it in the past and have not located this. I see the TB and the zip tie on the back of the manifold, in that pic, so I know where the location should be.

I believe it's just '05-'06 for LGTs.

That's what I've thought, since all the threads are for 05-06, and I've searched quite a bit for the 07. Thanks!

Correct the blue t is only on the 05/06 Lgt models.

BTW can a moderator change the title of this thread to

Intake/Vacuum/Boost Leaks and YOU! PICS INSIDE

Thanks

Dave

Mods? Could you change the ttile like mentioned in the thread above?

Thanks in advance

Dave

Dave thank you for this post. It is very helpful.

Jason

Wow good timing! As you know I'm trying to trace my leak down right now before you can finish my tune. Thanks for the assistance!

Sent from my iPhone using Tapatalk

So, Im a bit of a noob, I've worked on cars a bit but still need to learn alot. I don't mean to jack this thread, if this isn't the place to post this i am sorry.

I believe I have a boost leak. the engine is completely stock, and i have a boost gauge reading off the bpv reference hose (I think its called that). Lately I am reading 10 to 11 peak psi when it should be at 13.5psi. I have re sealed the fittings leading to the gauge because those used to be sealed poorly, and still 10 to 11 psi. I checked all the hose connections i could without taking anything apart and haven't found anything unconnected or any hoses that seem to have a hole or big crack. For a day the weather decided to get into the 30s (michigan) and all of a sudden i started to read 13.5 psi. Then it got cold out again (under 20) and my peak boost is once again around 11 psi. Therefore, I'm thinking some of the rubber has gotten old enough that at low temperatures it is no longer pliable enough to create a seal. Does that sound like it could be the case? Regardless if it is the case or not, what is a good way to check for leaks?

The ecu will increase and decrease boost based on temp due to efficency. What you are seeing is pretty normal stock.

Dave

Had someone asking where this was today so I figured I would bump it.

Dave

bump for ease of finding and new members inquiry's

Dave