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

Proud to say I did all those mentioned... Still leaking somewhere... hahaha -.-

Most recent was that farting tb hose that popped off.

Tb hose with the flaps taken off, it keeps sliding out from tb (not leaking anymore).

I was thinking about putting on some hair spray around the inside of the hose?

Thought I'd ask the experts first.

Thanks so much for this post! It saved us a trip to the Suby dealer after setting P0171 error a couple of times. Turns out the blue "t" below the intercooler had come loose and just needed reconnecting. Will have to look into a better permanent fix now that we know what was causing the problem.

Thank you! Thank you! Thank you!

Parker

Thanks so much for this post! It saved us a trip to the Suby dealer after setting P0171 error a couple of times. Turns out the blue "t" below the intercooler had come loose and just needed reconnecting. Will have to look into a better permanent fix now that we know what was causing the problem.

 

Thank you! Thank you! Thank you!

 

Parker

Parker, here is the perfect replacement. Not only purchasing a quality part, but supporting a fellow member.

http://legacygt.com/forums/showthread.php/subaru-blue-tee-replacement-218783.html

Parker, here is the perfect replacement. Not only purchasing a quality part, but supporting a fellow member.

 

 

http://legacygt.com/forums/showthread.php/subaru-blue-tee-replacement-218783.html

This is what I'm working from putting mine back together...

http://legacygt.com/forums/attachment.php?attachmentid=167975&d=1384657978

I'm vacuum checking each connection before I attach it to the manifold, BPV, TIH, etc., to make sure that "section" doesn't leak. Also using Oetiker clamps to seal each line to its fitting.

Two areas that I saw on tear-down, that I immediately thought "vacuum leak" were the IM-to-TGV gaskets - mine were brittle and ready for change-out - nearly flat on one side, and the actual TGV-to-Intake gaskets - again, mine were definitely ready for change. The hoses under the IM were pretty hard, but seemed to be holding okay, so that's another area that I'd check for leaks, especially on a high-mileage engine that hasn't had anything done to those areas.

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

 

 

Where does the other end of this line connect?

Where does the other end of this line connect?

FPR. Fuel pressure regulator. so that the fuel pressure's ~43 psi can account for changes in atmospheric or boost pressure. aka, fuel pressure isn't absolute 43 psi, it's relative to manifold pressure. or should be, if tube connected and FPR working.

Glad this is still helping people out. Bump for the newbies.

Dave

This is the most common cause for customers having delays during etuning. Smoke testing and pressure testing your system is always a good idea if you just installed new parts.

Thanks

Dave

Bump to the top for customers in need!

Thanks

Dave

Is there a preferential location for pressurising the intake? Got a whistle that i'm trying to narrow down after the decat.

On third gens people tend to just pop one of the vac hoses off the manifold but thats not so easy for us.

Made this which fits perfectly in place of the MAF pipe. Should the intake system be able to actually hold pressure or is it likely one of the valves is open and letting it flow through?

http://i1149.photobucket.com/albums/o594/andy_mac1/5392694C-AF19-4512-996A-3108EE62EE63_zpsqr8sgmbu.jpg

The maf pipe is normally my go to as well as vac lines on the manifold.

Dave

Found a very hard to track exhaust leak the other day by smoke testing. When the engine was warm it was not leaking but would leak on cold starts due to thermal expansion. Very good use for one of my favorite tools in the tool box for sure.

Dave

Having more and more customers report intake manifold gasket leaks on mild mileage cars. Not a bad idea to have tested if you suspect leaks and have looked everywhere else.

Dave

Maybe somebody can help me out here. I just found a vaccum leak coming from a sensor im not familiar with.

Sensor is black and bolted to the top rear passenger head, under the turbo kinda. What is this sensor and how does it seal? Bubbles like crazy with soap/pressure test.

Turns out its a camshaft sensor. I went ahead and pulled it out and it has an oring to seal.

I guess im buying a $100 oring now.