2G Boost leak test wont build up

[lolumad]

Howdy dsmers. I've been stuck on this for a while now. I've posted for help on the newbie forum (facebook ) and have boost leak tested my turd (1995 GST). I recently engine swapped this 95' cam angle sensor replacement. Here are some important health tests I JUST ran..

I went in this sequence to get where I am at.
BLT(NOGOOD)-> COMPRESSION TEST(170's) -> LEAK DOWN(NO HISSING)

Leak down was done with PCV vacuum capped.. as well as valve cover.
Leak down test, @ 90psi through a compression tester hose (my harbor freight tester only testw15psi)
What I did was take a pvc pipe and listened inside the TB elbow, stuck my ear by the exhaust.. & felt w a wet finger on the dipstick tube. All cylinders were checked @ TDC.
-intake no hissing,
-exhaust no hissing
-dipstick not even a little bit (thank GOD)

The compression numbers were impressive to say the least
170 across the board (all performed dry..)
& this engine supposedly had 145k & also was supposedly a 98' style block (BS cause the cam gears etc)

Boost leak test:
was the weirdest test EVER.
I've done BLT on my cars before. Easy process.. I've never had to find TDC @ *30 PTDC. So what I did AT FIRST was.. Just attach the BLT to the turbo.. waited and listened.. Found several boost leaks mostly were the couplers. SO i cranked those down good. All was good until I started to cap at about 5psi (wow).. I tried changing my boost gauge hose since it was reading the same measurement as my JAFROMOBILE made BLT. It has a gauge, and a shrader valve stem. Works fine, tested it with soapy water.

My AFPR was leaking at the setting nut, added a rubber o ring.. sealed right up. Found a vac leak @ the intake to AFPR.. Fixed.. Last little leak was at the MDP sensor which I've already changed to a SD set up, so this gasket is good.. it was just the barb going to the 4 bar MAP sensor. All tested out great but only netted me 6psi. Ok, not the end of the world right?

WRONG.

I heard bubbling in my crank case so I bypassed the turbo and went straight to intake. Nothing, same crap. And anyone telling me its my TB shaft and biss screw, i recently rebuilt the TB with a 60mm 1g and also changed the gaskets. Ive been paranoid and spraying these parts the most with soapy water. My brake booster to intake hose was unplugged but I plugged it back in.. still only 6~psi. Ive luckily started a YT channel to help with DSMs and recorded HOW to do ALL of this. But now I'm stumped because its been a while now and I still havent figured it out. I have one more question.

I did a EGR delete with a block off. Im wondering if the RTV under the gasket is potentially leaking thru to the other port. The two holes to eachother. There are no bubbles on the outside so my block off gasket is good to the outside, but im wondering if that could be it. I hear no hissing and its driving me insane, Ive checked behind the intake like i've read most people who have this problem have figured but i sprayed and felt and NOTHING. Injector seals are good... Valve cover leaks a bit from the breather and the dipstick leaks a bit when BLT the intake and the turbo. But the leak down found me no leaks.. no audible leak at all on intake exhaust or dipstick. Also filled up on coolant and checked the radiator for bubbles.

EDIT: (DURING BLT)The only air I can feel being lost is coming from the breather hose from the valve cover(the hose routed to the Turbo intake, & the dipstick. BUT I HAVE BEEN TRYING TO FIND WHY IT WONT LEAK EVEN WHEN ITS @ TDC, 30* or even 40*!!!
WHAT IS GOING ON!! ..


Please dont get mad and say to search, I've done searching and found nothing but dead links and unresolved posts. Its pretty annoying actually. Someone should clean those posts so no one has to read the million posts to no resolution.

Regards, Yeshua.

1995 GST
95' 7 bolt
OEM internals & head

Bolt ons:
PTE 5031 on WG pressure (no boost controller atm)
FP manifold
1000 cc injectors
VRSF front mount
o2 w dump
60mm 1g TB rebuilt w TB shaft seals & biss screw
EGR delete
3" exhaust

ECU:
SD setup
MAF delete
DSMLINK v3 lite

no other mods I can think of that would affect the BLT.

 

[silvreclips]

Have you checked to see if it's leaking out the exhaust? Could be the valve overlap letting pressure out. I would start by just testing the intercooler piping. Cap the upper pipe at the TB and see if that holds pressure.

Are you using a decent compressor? A little tire compressor isn't going to cut it

 

[Archer Fabrications]

How big is your compressor? Sometimes they can’t keep up with the system volume if it’s tiny. As for bubbling it’s most likely air getting into the crank case and bubbling up your turbo drain. , when you do the BLT, is your throttlebody open or closed?

 

[lolumad]

Tb Boost leak tested with both open and closed throttle plate. The compressor is good, and has done Boost leak tests before. It’s a 21 gallon kobalt. I actually sprayed my Celica and rustoleum sunrise red painted it. Held up like a champ. The pressure I have it set at to the tool(a tire valve air hose) is @25 psi and I even set it up to 90psi. I should probably compile all the videos I’ve recorded. Ive documented everything on camera. It did Bubble up on the turbo(the bubbling sound from air getting into the crank case) so I by passed it by going to the intake manifold throttle body elbow with the original silicone intercooler sleeve and clamp attached to my jafromobile made BLTester. It’s crazy that I even changed my Boost gauges vacuum hose to make sure my gauge on the blt was working and it read the same both times.... They both read the same. I’m gonna go back outside tomorrow and fiddle around. Sad no ones come up with a solution to this. I guess that’s why I’m going thru it. I documented everything down to the boost leaks.

 

[Crackerman]

Intercooler leaking in the tube/fin area?

LOWER side of intake manifold to head?

Did you ever check the bov? Those leak all the time

 

[josh408]

I remember experiencing the bubbling before, it's been a while but the reason behind it was somewhere along the lines of what Archer Fab said.

 

[Tyeler18]

If you're still leaking out the crank case testing at the throttle body you're either A) bleeding through the PCV, or B) bleeding through the guides/seals/piston rings. The latter seems less likely due to your compression/leak down testing. Pinch the PCV line and retest.

 

[lolumad]

If you're still leaking out the crank case testing at the throttle body you're either A) bleeding through the PCV, or B) bleeding through the guides/seals/piston rings. The latter seems less likely due to your compression/leak down testing. Pinch the PCV line and retest.

The pcv valve has been capped off as well as the intake manifold barb pcv inlet.

The turbo has been bypassed to see if turbo seals was beyond the problem. I already set up the leak down to not hearing anything from my Tb during the leak down testing. I didn’t have a gauge since the harbor freight leak down tester has a 15psi limit so leak down testing with it is pointless on a cylinder that sees way more than 15psi looking for psi leak down. I put 90psi in the chamber and listened for leakdown. It was inaudible from the Tb with the shaft wot. No exhaust hissing nor dipstick blow by. But the Boost leak test is giving me blow by from the valve cover breather while Boost leak testing only not leak down testing where the cylinder is at top dead center.

 

[Tyeler18]

The PCV is capped during your boost leak test? I'm talking BLT not leak down. Like I said, if you're testing at the throttle body and you're leaking out the breather there's only 3 places for it to leak- PCV (if its capped during BLT this eliminates that), guides, or rings. Your compression test makes it hard to believe it's bleeding past the rings.

 

[chrysler kid]

just put a piece of metal behind the tb and use it as a block off plate and re test the system. Or hook up a coke can to where the throttle elbow bolts down to test the pre manifold boost

 

[lolumad]

The PCV is capped during your boost leak test? I'm talking BLT not leak down. Like I said, if you're testing at the throttle body and you're leaking out the breather there's only 3 places for it to leak- PCV (if its capped during BLT this eliminates that), guides, or rings. Your compression test makes it hard to believe it's bleeding past the rings.

The pcv is capped with a vacuum cap at the pcv valve and the intake manifold. The rings seem too good to be true. I didn’t have a percentage leak down tester. But I did charge 100psi thru the compression tester spark plug thread to air fitting and listened for air at TDC. How would one check valve guides? I checked the intake and exhaust, no leakage audibly, no dipstick blow by or breather blow by. Only blow by I can feel is during this BLT. Thank you for the reply I will look into the guides leaking and post back. I hate dead threads where someone never came back and resolved this. This will be resolved without spending any unnecessary money.

 

[lolumad]

Ok guys, I'm back on track now. I guess I'm terrible at searching cause' I didn't find anything- close to my problem when I typed "Boost leak at 7Psi" -_- .. Like come on I'm "new" .


Long story short, I didn't have the brake booster's check valve installed into the brake booster vacuum tube I had fit onto the brake booster from the intake manifold. The 3/8 nipple on the back by emmissions... When I was deleting emmissions I must have overlooked the fact- that the vacuum to the booster would be boosted from that 3/8 nipple.. After reading people having trouble boost leak testing.. I haven't done the 35* timing degree "rule" or anything. I just hook up the tester now and from the TB it's boosting up to 15psi with a bicycle pump! I got somewhere after putting a "check valve" from ADVANCED auto parts. Their check valve was the largest(to fit to the booster vacuum hose) as opposed to the oreillys check valve. Never checked autozone but they DID apparently have the part when I searched for one. Advance auto had about 50 cents cheaper on their stock and since I'm a cheap man, I cheaped out.

I then turn on the car realizing turbo seals werent going to seal. A little bit of pressure was leaking from the dipstick tube and valve cover breather but I'm hoping once I start her up and warm up the seals it will not leak any into the crank case.

Plan on Installing a d1 crappy 2 vent catch can with a 3rd 3/8ths nipple I installed, and am pulling vacuum to the turbo intake. I am probably going to delete the pcv valve since it's leaking and I don't want to deal w the nonsense of a leaking new one- that I keep hearing is happening to people. I'm going to order a USplastics check valve and install one after a new nipple is placed , which i believe can actually be taken from the back of an intake manifold(which i do have another ruined intake anyway that leaks like crazy from the vacuum port on the top right of the intake manifold.) I can scavenge that nipple and place it on the pcv port.. Which is what i've read a few years ago when this turd was going down the first time.

SORRY to rant so much, I just feel like there needs to be closure and hopefully someone can read this down the road.

As you might tell I've had a lot of help from willing people and am very thankful.. I did all the things everyone said to no avail. I was randomly looking up blow by into the breather and dipstick and Oldman had referenced that the brake booster has a one way check valve.

I'll link that at the bottom. Thank you so much for your help guys. I will ask to close this once I turn her on tomorrow, I was trying to crank it- and a o ring was shooting out fuel, fixed that.. Battery was not happy even w a jump. My alternator started smoking on my celica 95 st daily . I guess I gotta go to the junkyard for another battery. I might be able to just return it to walmart since its a everstart. Glad I was filling everyone in since it is a good reminder to not spend the 33 @ the junkyard. Which BTW..

*NEWS*

If you want a cheap battery
WITH A WARRANTY,

Go to your junkyard-
find a battery that is a recent purchase.
EX: sticker on it that says 6/19

That would declare the battery is from June 2019,
usually batteries have a labeled warranty on the side like
"3 year warranty"
"2 year warranty".

These batterys are from wrecked cars..

If you have a core replacment(your bad battery)
the core will remove some 10ish dollars.
Batterys here are 44@ the yard,
33 after a 11$ core.

If the battery dies within 90 days, trade..

BUT if the battery dies and it has a warranty..


New battery for 33$..

That's what I'm doing tomorrow. God bless all you hard working dsmers!



https://www.dsmtuners.com/threads/brake-booster-check-valve.374328/
Link to the discussion of reading about the check valve.

 

[lolumad]

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Here is my resolution to the brake booster check valve. I didn't use an OEM check valve inside of the brake booster since I believe they are discontinued. Didn't stop me from trying another check valve. The valve I ended up buying is from ADVANCED AUTO PARTS. I went to autozone etc and they didn't have the part I used.

The part number for the check valve I used is
80189
it is a "UNIVERSAL"
"POWER BRAKE CHECK VALVE w/ GROMMETS"

It contains a 3/8ths to 1/4" check valve.

Don't quote me on that 1/4" measurement I just made that one up I THINK THATS what it is
it's just smaller than 3/8" and Im bad at math so i guessed .

But that part number was found @ advanced. SHOUT TO ADVANCED for usually getting me parts I need
they don't always get it right, no one ever does.. Not oreilly, not autzone.. They all are equally terrible at finding parts but
ADVANCED was just the lucky one for me.

Anyway if you guys need any help I DO NOT POST a lot on DSMTUNERS,
I usually check my YT channel tho so definitely check out my YT channel that I posted above with the resolution to this problem for me.


Again my symptoms were..

During a boost leak test:
air was coming from the dipstick tube
valve cover vent breather
couldn't build up past 5-7psi
even with all the boost leaks figured out and fixed..

UNTIL "80189" one way check valve was installed into my 3/8" brake booster hose that was NOT FACTORY.

It was some ebay special the previous owner had installed on the car. I did end up reinstalling another one of the same quality
not realizing they never had a check valve on it either.

I wonder if thats why they gave up on the car.

I was 5 minutes away from giving up on this car till I read the dsm post above about the check valve needing to be there.

GOD BLESS <3