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Boost leak testing

idreamidrive

Well-known member
Joined
Oct 10, 2012
Messages
430
Location
Murray, KY
Apparently I can't figure out how to do a proper boost leak test (BLT).

I did it at the turbo, and the pressure is going into the oil pan with a bubbling sound. Hot or cold engine, doesn't matter. Read if the bubbling was the case you should do it at the throttle body. So test there (with plugging up the other end of the pipe I pulled off), and now it's coming out of the turbine inlet, am I supposed to plug this off too? Is it just a turbo sealing issue? I didn't think a BLT would be this hard. This is all with a stock 14b turbo that was rebuilt about 30k miles ago by a turbo shop.

I know the bubbling issue wouldn't be the best thing, but I am running a remote oil cooler and that extra oil drains back into the pan when off for a while. If you check the oil just after shutting off the car, it's at the correct level on the dipstick, but will go up if you let it sit for a while.
 

mk2davis

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Joined
Mar 1, 2015
Messages
191
Location
Ventura, CA
I can't help with the BLT because my experience hasn't resulted in oil bubbles, although I have a 16g. Maybe it's the routing of the oil cooler?

You may want to adjust your oil level. Too much oil can cause foaming, but it's unclear how high your level gets when cold.
 

idreamidrive

Well-known member
Joined
Oct 10, 2012
Messages
430
Location
Murray, KY
The tuners link is why I tried to do it at the intercooler piping with no luck, as the pressure was now coming out of the turbo inlet. That is why I asked if I was supposed to plug that up too, or is there something wrong here?

How I thought I was supposed to do a BLT, put tester on turbo inlet and pressure system. This equals pressure going past turbo oil seal and into the oil pan, hence the bubble sound.
Took off upper intake piping and blocked one end, and put tester on other open end. This resulted in air coming out of the turbine inlet.

Someone did suggest making sure that the cams are in the correct position when doing the test to make sure all the valves are closed, or just the intake ones. I haven't had time to do this.
 

CutlassJim

Well-known member
Joined
Jul 17, 2006
Messages
1,698
Location
Manchester, NH
Quoting idreamidrive:
Apparently I can't figure out how to do a proper boost leak test (BLT).

I did it at the turbo, and the pressure is going into the oil pan with a bubbling sound. Hot or cold engine, doesn't matter. Read if the bubbling was the case you should do it at the throttle body. So test there (with plugging up the other end of the pipe I pulled off), and now it's coming out of the turbine inlet, am I supposed to plug this off too? Is it just a turbo sealing issue? I didn't think a BLT would be this hard. This is all with a stock 14b turbo that was rebuilt about 30k miles ago by a turbo shop.

I know the bubbling issue wouldn't be the best thing, but I am running a remote oil cooler and that extra oil drains back into the pan when off for a while. If you check the oil just after shutting off the car, it's at the correct level on the dipstick, but will go up if you let it sit for a while.




Isn't this the test doing it's job and letting you know you have a PCV valve not holding pressure? This is just an assumption but it's the only way for intake air to get into the crankcase that I can think of. I'm really not sure how it would bubble though and not just come out the intake tube vent or pop the dipstick out and come out there.

Doing it at the throttle body limits the point of the test. You want to do it at the turbo inlet so that all pressurized parts of the system are tested including the BOV and intercooler piping.

Is there a picture of your engine bay on here somewhere?

EDIT: I just read through the old tuners thread and it kind of mentions the same thing I did.

Also as an addition to the catch can thread and possibly for you this is what I run INSTEAD of an OEM PCV valve. If you have an extra kicking around the fitting on the intake manifold for the PCV also threads right into the valve cover.

click

 
Last edited:

gvr4ever

Well-known member
Joined
Aug 6, 2002
Messages
6,190
Location
central Indiana
I've always done it at the turbo outlet. First flexible pipe after the elbow.
 

idreamidrive

Well-known member
Joined
Oct 10, 2012
Messages
430
Location
Murray, KY
Quoting CutlassJim:
Quoting idreamidrive:
Apparently I can't figure out how to do a proper boost leak test (BLT).

I did it at the turbo, and the pressure is going into the oil pan with a bubbling sound. Hot or cold engine, doesn't matter. Read if the bubbling was the case you should do it at the throttle body. So test there (with plugging up the other end of the pipe I pulled off), and now it's coming out of the turbine inlet, am I supposed to plug this off too? Is it just a turbo sealing issue? I didn't think a BLT would be this hard. This is all with a stock 14b turbo that was rebuilt about 30k miles ago by a turbo shop.

I know the bubbling issue wouldn't be the best thing, but I am running a remote oil cooler and that extra oil drains back into the pan when off for a while. If you check the oil just after shutting off the car, it's at the correct level on the dipstick, but will go up if you let it sit for a while.




Isn't this the test doing it's job and letting you know you have a PCV valve not holding pressure? This is just an assumption but it's the only way for intake air to get into the crankcase that I can think of. I'm really not sure how it would bubble though and not just come out the intake tube vent or pop the dipstick out and come out there.

Doing it at the throttle body limits the point of the test. You want to do it at the turbo inlet so that all pressurized parts of the system are tested including the BOV and intercooler piping.

Is there a picture of your engine bay on here somewhere?

EDIT: I just read through the old tuners thread and it kind of mentions the same thing I did.

Also as an addition to the catch can thread and possibly for you this is what I run INSTEAD of an OEM PCV valve. If you have an extra kicking around the fitting on the intake manifold for the PCV also threads right into the valve cover.

click



I have that check valve installed right in line with the pcv.

I was under the impression that it didn't matter where you tested, as I thought it was like a giant tube that loops on itself, like a donut. It looks like I am wrong and I should test at the turbo j pipe connection. This makes more sense.
 
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