Car slow to build boost, won't go past 10 pounds

[3Bar_Mopar]

Made a leak tester and bought a bike pump.....connected the tester to the turbo inlet....the system, will not hold pressure...however I disconnected the pipe right before the TB and held my hand over the open end of the upper IC pipe and it build pressure as I pumped.....the guage on the pump didn't show anything, but it released a bunch of air when I removed my hand. Replaced some couplers with semi truck rad hose and took it for a spin.....5 psi. I'm stumped.

[tryingbe]

Well then, the problem is after the TB.

Get an air compressor and find that leak.

[thedon809]

You would need all the intake valves to be closed. Not sure if that's even possible with the cam still in it?

[tryingbe]

You would need all the intake valves to be closed. Not sure if that's even possible with the cam still in it?

As long as the intake OR the exhaust valves are closed for all cylinders, you'll be fine for the test.

[thedon809]

Yeah i guess the exhaust valves being closed would be fine. You would be pressurizing the cylinders as well.

[3Bar_Mopar]

If I'm leaking that much after the throttle body, wouldn't I have a large vacuum leak and high idle?

[acannell]

If I'm leaking that much after the throttle body, wouldn't I have a large vacuum leak and high idle?

yes

I think..

[3Bar_Mopar]

yes

I think..

Yeah...mine idles normally...runs great and drives fine...no power loss out of boost or anything...just got me stumped.

[Vigo]

If pressure doesn't show on the gauge of your bike pump, what makes you think you are replicating the conditions of the problem? Every pressure leak has a pressure it will start/stop leaking at. If you aren't pressurizing the system to your desired boost level, you aren't ruling out a leak at that boost level (that might not leak at the 0.7 psi you actually tested at).

I would retest the plumbing up to at least 15 psi, if not more. It'll take forever to pump it up with a bike pump, though. If you have a tire chuck on your test rig you could air it up with an electric tire compressor or from shop air.

[wheming]

Yeah...mine idles normally...runs great and drives fine...no power loss out of boost or anything...just got me stumped.

How about verifying the gauge you are reading this low observed boost is accurate.
Pump it up from where the line gets the boost signal. This way you test the tubing to the gauge.
If the car runs and drives fine, and you don't feel any power loss, then maybe you just have a bad gauge or the gauge line is leaking.

[3Bar_Mopar]

There's power loss in boost....I could spin tires at 45mph before at 20 pounds. Now it won't spin tires at all. Just out of boost it runs and drives normally.

How about verifying the gauge you are reading this low observed boost is accurate.
Pump it up from where the line gets the boost signal. This way you test the tubing to the gauge.
If the car runs and drives fine, and you don't feel any power loss, then maybe you just have a bad gauge or the gauge line is leaking.

- - - Updated - - -

I'm gonna try with shop air at some point this week

If pressure doesn't show on the gauge of your bike pump, what makes you think you are replicating the conditions of the problem? Every pressure leaks has a pressure it will start/stop leaking at. If you aren't pressurizing the system to your desired boost level, you aren't ruling out a leak at that boost level (that might not leak at the 0.7 psi you actually tested at).

I would retest the plumbing up to at least 15 psi, if not more. It'll take forever to pump it up with a bike pump, though. If you have a tire chuck on your test rig you could air it up with an electric tire compressor or from shop air.

[3Bar_Mopar]

So, I had a chance to test with shop air...it's leaking from between the intake halves....I must have blown the gasket out. Good news is that I found the leak....bad news is that the head is gonna have to come off.

[acannell]

So, I had a chance to test with shop air...it's leaking from between the intake halves....I must have blown the gasket out. Good news is that I found the leak....bad news is that the head is gonna have to come off.

I wonder why that didnt cause an idle/drivability issue?

And how does one blow out that gasket? Even at extreme boost pressures its not really dealing with much as far as blow out forces.

[3Bar_Mopar]

I wonder why that didnt cause an idle/drivability issue?

And how does one blow out that gasket? Even at extreme boost pressures its not really dealing with much as far as blow out forces.

Good questions....I wouldn't think so....Maybe the part that's leaking out is being sucked back against the leak under vacuum? It builds a good 5 pounds before it leaks... It's got a box upper half, so I'm wondering how the mating surfaces are and how the bolts are holding the halves....are they loose-ish? Did they back out a little? I may try to get a wrench on the bolts and maybe I can get them a turn or two to tighten.

[Vigo]

Well if it's anything like the t3 compressor cover you basically have a paper gasket there, and one likely thing is if you loosen the compressor cover to reclock but the gasket doesnt slide freely you could end up rolling/tearing it while rotating the housing. The o-rings used on other turbos seem MUCH more forgiving and reusable. :/

[3Bar_Mopar]

This is the gasket for the 2 piece intake manifold, not the turbo. It's leaking from about where 3 and 4 injector are located. I pressurized the intercooler pipes and I could feel hot air coming from under the intake top half. I tried to tighten the bolts holding the intake halves together and could only get to 3 of the bolts. I tightened them and it made a slight improvement.

Well if it's anything like the t3 compressor cover you basically have a paper gasket there, and one likely thing is if you loosen the compressor cover to reclock but the gasket doesnt slide freely you could end up rolling/tearing it while rotating the housing. The o-rings used on other turbos seem MUCH more forgiving and reusable. :/

[mopar-tech]

This is the gasket for the 2 piece intake manifold, not the turbo.

There is a gasket for the turbo, I use to sell them and may still have a stack.

[Vigo]

This is the gasket for the 2 piece intake manifold, not the turbo,

Oops, read that wrong then. I have never heard of the plenum gasket leaking on a 2pc. Unless the bolts worked loose over time?

[3Bar_Mopar]

Oops, read that wrong then. I have never heard of the plenum gasket leaking on a 2pc. Unless the bolts worked loose over time?

Yeah, I never have either.

[black86glhs]

If one of the 2 pieces are warped, they can. They are aluminum, they can warp.