Desperate Help needed! Boost leak testing

[2_blue]

I've read quite a lot of boost leak testing threads and I've read the tech article on the topic and have consulted vfaqs as well ... but I still need help.

I'm trying to test my intake for leaks and I've made the tester. I've removed the air can and have hooked up the tester to the turbo inlet but it doesn't build pressure at all. I'm using a bicycle pump to presurize the intake.

I'm stuck at a friends place and I need to get this done tonight ... please help!

 

[oldman]

1. Disconnect your MBC, there's a bleeder hole on most MBCs.

2. Bring #1 cylnder to TDC so all intake valves are closed, make sure you don't turn the crank ccw.

3. If you're not sure how old you pcv valve is, diconnect the hose from the intake manifold and cap off the nipple.

4. Get yourself an air compressor.

 

[2_blue]

THanks for the suggestions old man. I just limped to a gas stating and used the compresser. I have a HUGE leak ... the boost guage didn't even move. The air is leaking from the Turbo air outlet. The gaskit is blown. I'll fix that and move on from there.

Thanks again.

 

[oldman]

You're welcome. I would also suggest getting a $60 compressor from Walmart, you will meed it. Good luck.

 

[2_blue]

ok ... I fixed the J-pipe gasket and tested the system again. It still didn't hold any pressure. It seems to be leaking from under the exhaust-manifold right next to the turbo outlet. Is there any other line under there other then the J-pipe/turbo compressor outlet? could it be the compressor housing? I'm stumped so any help would be greatly appreciated!

 

[oldman]

What problems were you having which led you to the leak test. I had a similar leak months ago but it blew due to other reasons before I can figure it out. I'm suspecting the turbo seal and maybe air is leaking to the exhuast side however I've never taken apart a turbo so some one else would have to chip in as to whether that's possible.

 

[cfisher]

Boost leak test should not reach your exhaust manifold. I'm assuming that it's the turbine housing on the intake side is probably leaking air. Looks like you need to either rebuild that turbo or get a new one.

 

[2_blue]

Well, I knew I had a leak somewhere but I was driving it anyways ... waiting for the weather to get a little better. At times it drove ok, but at other times it would hardly move. Then one day I accelerated and under high boost (14 psi) it started bucking and missfireing ... like a machinegun sound as someone said in another post. As soon as I let go it was fine. A couple of days later it became almost undrivable. stuttering, bucking, poping ... everything. Thats when I knew something was blown and decided to the the leak test ... even with a 5 F windchill outside

 

[2_blue]

Boost leak test should not reach your exhaust manifold. I'm assuming that it's the turbine housing on the intake side is probably leaking air. Looks like you need to either rebuild that turbo or get a new one.

The air is leaking from under the leftmost exh-mani runner. Its more like right below the turbo compressor outlet ... somwhere in that area.

The turbo seems to be working ... when I press the accelerator and it starts building boost, the car starts the stuttering thing but when I let go I do hear the pressure release sound.

 

[oldman]

That doesn't really tell you much, I have a blown 16g with little shaft paly and spools perfectly fine. Pull the intake pipe and check for shaft paly and oil.

 

[2_blue]

I just checked for shaft play and there is non. Nor is there any oil in there.

Here are some pics that might give you idea where the leak is at. Not very good but it might help.

Note: The oil on the turbo exhaust housing is because I losened the oil like to fit the J-pipe.

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[oldman]

The pipe is the water feed and the bolt is just for mounting it. As for the leak, I don't know it's definitely not the same as mine. Remove the heat shield and spray soap water to see if you can isolate it. I told you you will need a compressor, there are probably others waiting to be discovered as you are able to pump it up towards 20psi.

 

[ddavisaf]

This might sound stupid, but this was my problem. Check the mounting bolt under the fuse box. Make sure it's holding the hose in place. If it's not, when your motor shifts, it lifts the hose off the intercooler and causes a leak, but when the motor settles it pops right back on. Car was in the shop for 3 days trying to figure this out. We found it by chance. Hopefully your problem is something as minor as this.

 

[1fast97gsx]

you did brind cylinders 1 and 4 to tdc and make sure all the valves are closed right? If you hear it hissing into the exhaust manifold that would mean your valves are open at some point.

 

[2_blue]

How do I do that? closing all the valves?

 

[oldman]

1. Disconnect your MBC, there's a bleeder hole on most MBCs.

2. Bring #1 cylnder to TDC so all intake valves are closed, make sure you don't turn the crank ccw.

3. If you're not sure how old you pcv valve is, diconnect the hose from the intake manifold and cap off the nipple.

4. Get yourself an air compressor.

You should really take people's suggestions more seriously, this is why #4 is important, kind of hard to do #1,2 and 3 at the gas station. The following link are instructions for a leakdown test, different from what you're doing but half way throught it shows how to bring #1 cylnder to TDC (top dead center).

http://www.dsmgrrrl.com/FAQs/leakdown.htm

 

[marcmsj]

hmmm.. here's something i don't understand. why must the valves be closed when doing an intake pressure test? if the throttle is closed, air shouldn't be getting into the intake manifold right?

 

[2_blue]

Thanks for the help guys. And oldman, I do take people's advice seriously. and I sincerely appreciate everyone who has taken time to help me out here. The problem is that I"m a starving student and I will be getting my paycheck this coming Friday and I will be buying a compressor and tank pretty soon.

I did the soap water testing and the compressor outlet gasket is still leaking. I removed it again and used a lot of rtv this time along with a new gasket. I'm hoping this should atleast make the car drivable.

I will keep you guys updated.

Thanks again.

 

[oldman]

Thanks for the help guys. And oldman, I do take people's advice seriously. and I sincerely appreciate everyone who has taken time to help me out here. The problem is that I"m a starving student and I will be getting my paycheck this coming Friday and I will be buying a compressor and tank pretty soon.

I did the soap water testing and the compressor outlet gasket is still leaking. I removed it again and used a lot of rtv this time along with a new gasket. I'm hoping this should atleast make the car drivable.

I will keep you guys updated.

Thanks again.

Didn't mean to come off harsh like that. Don't worry, most of us are starving or we wouldn't be modding a DSM, good luck. Oh make sure you give the RTV enough time to dry before you run the test again, or else it would just get blown out.

 

[2_blue]

Thats alright

The RTV has been on for about 26 hours now, the only catch is that the instructions say it takes 24 hours to completely cure it at 70F. the tepmeratures here have been below freeing. I'm going to give it another few hours to set and then I'll start the engine for a few minutes and let it idle so that things get nice and warm in there. Then tomorrow I'll do the leak test again.

 

[2_blue]

ok ... so the new gasket and RTV didn't seal the J-Pipe/Turbo Outlet joint. Turns out my J-pipe was slightly bent so it didn't seal. I ordered a J-pipe from Dejon Tool and installed it. The leak stopped.

So I did the leak test and it does hold pressure for about 5-7 seconds. I had three leaks: MBC - bleeder hole ... so I screwed it in all the way and it stopped leaking (whats the purpose of the bleeder hole anyways?) I'll readjust it once I fix all the other leaks.

The 2nd leak was the BISS screw, I'll get a new O-ring tomorrow.

The third leak is one of the vacume pipes unplugged from somwhere and I can't figure out where it goes. There are 4 pipes coming from behind the engine, under the intake manifold. One of them goes under the battery, the other two are hooked somewhere too. the 4th one is unplugged. Can anyone tell me where it goes? oldman?

Thanks for the help.

 

[oldman]

The bleeder hole on the mbc is for releasing pressure between the mbc and th actuator once the boost level falls below the mbc setting and the ball blocks the path to the actuator. Without this hole the wastegate will not close back up. As for the hose under the intake manifold, which one counting from the firewall, I'll look at mine this afternoon when I get home. Congrats, you're almost there.

 

[oldman]

This might help in the mean time. http://www.taboospeedshop.com/emissions.htm

 

[2_blue]

As for the hose under the intake manifold, which one counting from the firewall, I'll look at mine this afternoon when I get home. Congrats, you're almost there.

Thanks! The car is already working MUCH better than before

Standing on the passenger side, counting from the firewall, its the 4th vacume hose.

I looked at Taboo's website and its kind of confusing. I'll study the diagrams once I'm done with my classes for the day

 

[oldman]

Sorry I don't have any hoses on #3 and #4. Mine is just like the Taboo diagram. Reach down under the intake manifold from the driverside and try tracking down where the other end goes.