E-9 Turbo Air Leak

[B8136]

I have a problem that I am unable to remedy. My E-9 has a leak somewhere between the turbo and the combustion chamber. The problem only shows up when are on the high side of the transmission and in a good pull. You can watch the boost pressure guage go from arond 23 psi to no more that 10, sometimes 0 boost. The entire time that that you have this reduction in boost you can hear the whistling sound of an air leak. You can change the tone of the air leak with the throttle. Now if you were to stop or coast in nuetral for a few seconds the leak will seal itself off. You can keep it from blowing off by keeping the boost under 20 psi on the high side of the transmission. It has become aggravating.

I have aired up the the entire system to 33 psi and no leaks. Actually held the pressure. This is from the intake on the turbo.

There is no wastegate on the turbo.

I have replaced all the 0-rings in the system and changed the gaskets on the air plenum.

I have disconnected the hoses and checked them out

I have replace the band clamps on the hoses.

I have not changed the hoses because the held alot more pressure than the engine will make.

Now it seems it would be easy to find. Somedays it's pretty good other days it makes you want to park the truck. I've just about run out of ideas. Any help would be appreciated.

[Rob]

I have a problem that I am unable to remedy. My E-9 has a leak somewhere between the turbo and the combustion chamber. The problem only shows up when are on the high side of the transmission and in a good pull. You can watch the boost pressure guage go from arond 23 psi to no more that 10, sometimes 0 boost. The entire time that that you have this reduction in boost you can hear the whistling sound of an air leak. You can change the tone of the air leak with the throttle. Now if you were to stop or coast in nuetral for a few seconds the leak will seal itself off. You can keep it from blowing off by keeping the boost under 20 psi on the high side of the transmission. It has become aggravating.

I have aired up the the entire system to 33 psi and no leaks. Actually held the pressure. This is from the intake on the turbo.

There is no wastegate on the turbo.

I have replaced all the 0-rings in the system and changed the gaskets on the air plenum.

I have disconnected the hoses and checked them out

I have replace the band clamps on the hoses.

I have not changed the hoses because the held alot more pressure than the engine will make.

Now it seems it would be easy to find. Somedays it's pretty good other days it makes you want to park the truck. I've just about run out of ideas. Any help would be appreciated.

Do you have any external signs of leakage such as oil or coolant trails? did you look around the base of the rocker covers, and jake spacers, along with the cylinder heads to block mating surface? Evaluate that you are not pressurizing the coolant system by having the radiator cap off when you charge the intake tract with shop air to about 35 psi. You very possibly could have the seal between the intake and exhaust side of the turbocharger blown with the expansion of the turbin housing due to heat allowing the leak. This in theory, could allow the intake pressure at cool temperatures, but allow rapid falloff of boost pressure when worked harder due to heat. The turbo whine tells me the turbocharger is trying to it's job well.

Keep me posted with your progress.

Rob

[Superdog]

Only time I ever lost pressure on the boost guage was when my air to air intercooler got a crack in it,did you check that?

[B8136]

There are no signs of external leakage. If I pressurize the system to 35psi and there was a coolant problem I would think the radiator cap is only rated at 8 to 12 psi. I do not believe it is pressure going into my coolant system or crankcase.

Now the thermal expansion of the turbo might be a the best theory. When the boost "blows off" the sound seems to be coming from the area near the firewall, best I can tell which doesn't mean much, travelling 60 to 70 MPH with the hood down. Now the question is how do you test this. I will call around to a few turbo shops and see what I can dig up. I'll keep you posted.

[theakerstwo]

I have a problem that I am unable to remedy. My E-9 has a leak somewhere between the turbo and the combustion chamber. The problem only shows up when are on the high side of the transmission and in a good pull. You can watch the boost pressure guage go from arond 23 psi to no more that 10, sometimes 0 boost. The entire time that that you have this reduction in boost you can hear the whistling sound of an air leak. You can change the tone of the air leak with the throttle. Now if you were to stop or coast in nuetral for a few seconds the leak will seal itself off. You can keep it from blowing off by keeping the boost under 20 psi on the high side of the transmission. It has become aggravating.

I have aired up the the entire system to 33 psi and no leaks. Actually held the pressure. This is from the intake on the turbo.

There is no wastegate on the turbo.

I have replaced all the 0-rings in the system and changed the gaskets on the air plenum.

I have disconnected the hoses and checked them out

I have replace the band clamps on the hoses.

I have not changed the hoses because the held alot more pressure than the engine will make.

Now it seems it would be easy to find. Somedays it's pretty good other days it makes you want to park the truck. I've just about run out of ideas. Any help would be appreciated.

You need to pressure the air to air up against the heads to check the complete syatem now some will tell you thatcant be done but i do it all time .if air leaks passed the vavles just turn engine a littel till the vavle seal and should hold air .Now i am talking about all 6 cyl. engines but should work on v8 engine as well.. I use 25psi and you will get a ideal what is going on.I do not remember where the air compressor gets it intahe air so look there and some air diers will let air leak thru them on the purge vavle when it is discharged. Glenn Akers