GNX & GN Turbo Boost Line

[JohnP]

I am relatively new to the Buick world and was curious about something read in Kirban's Guide to buying a Buick Turbo Regal. On page 23(bottom paragraph) and page 161(2nd paragraph), Dennis discusses inspecting the boost line. I have looked in the Turbocharger section 6J in the chassis service manual and am not sure what exactly this "boost line" refers to. Is there a part #. Has anyone had any issues or replaced this line. My GNX has approx 9100 mi and looks all stock so I am thinking the boost line is original.

Any info on this would be appreciated

 

[626gn]

I am relatively new to the Buick world and was curious about something read in Kirban's Guide to buying a Buick Turbo Regal. On page 23(bottom paragraph) and page 161(2nd paragraph), Dennis discusses inspecting the boost line. I have looked in the Turbocharger section 6J in the chassis service manual and am not sure what exactly this "boost line" refers to. Is there a part #. Has anyone had any issues or replaced this line. My GNX has approx 9100 mi and looks all stock so I am thinking the boost line is original.

Any info on this would be appreciated

What you're looking for is the hose that goes from the wastegate solenoid on the passenger side valve cover and branches off to your wastegate actuator and turbo compressor (see attached illustration). Commonly called a "Y" hose because of its shape. If yours is original to the car it should be replaced. Rub your fingers on the hose. If your fingers get black you needed one yesterday. If this hose should develop a split or crack it will cause an overboosting issue. Problem is I believe its a discontinued part. Kirban used to have it but I think they only sell the y fitting now. You could try posting in the parts wanted section or just replace the hose sections and reuse your y fitting. Although, on a 9k mile GNX you will probably want to find a factory replacement...

 

[texasmr2]

I am relatively new to the Buick world and was curious about something read in Kirban's Guide to buying a Buick Turbo Regal. On page 23(bottom paragraph) and page 161(2nd paragraph), Dennis discusses inspecting the boost line. I have looked in the Turbocharger section 6J in the chassis service manual and am not sure what exactly this "boost line" refers to. Is there a part #. Has anyone had any issues or replaced this line. My GNX has approx 9100 mi and looks all stock so I am thinking the boost line is original.

Any info on this would be appreciated

John,
If you look at the diagram on page 160 and read the paragraph below it will help explain it a little more but....if your stock lines are still connected the KISS method can be used as it helped me on my first turbo vehicle. I believe all the hoses from the WG and turbo are all the same size (like mine were) and you can remove one hose at a time and measure it and then replace it, so on so forth on with the other line and get them cut to length at any auto parts store. Also in the diagram there seems to be a T connector that is plastic and they can and will can get brittle and cracked and cause leaks.

I hope this helps you.

PS, You may want to consider some heavy duty silicone hoses that stand up to the heat a lot better. You can also get you some of those hose heat protector shields. Just a thought.

 

[JohnP]

Thank you for the responses. I have inspected the three hoses for feel. They are clean and still feel soft, although this does not convince me that replacement might occur down the way. After doing some reading, I have a much better understanding of how the wastegate works. It appears that the wastegate actuator is controlled by the pressure from the cold air side via a restrictor in one side of the "Y" fitting. This air leaves through the other side of the Y to push on a spring loaded diaphram of some sorts. One unknown thought is what is actually occurring at the wastegate solenoid. I understand that it is plugged in and sending some type of electrical signal to the engine controller, but what is actually occurring in terms of the air pressure. At close look at the solenoid, it almost looks as if there is some type of vent or connection. Is the solenoid at some point opening(venting) and closing or is it only sending an electronic signal and the air pressure dead ending.

Also, thank you for the info on the black silicone replacement hoses.

 

[gnX405]

One unknown thought is what is actually occurring at the wastegate solenoid. I understand that it is plugged in and sending some type of electrical signal to the engine controller, but what is actually occurring in terms of the air pressure. At close look at the solenoid, it almost looks as if there is some type of vent or connection. Is the solenoid at some point opening(venting) and closing or is it only sending an electronic signal and the air pressure dead ending.

The solenoid receives a Pulse Width Modulated (PWM) signal from the ECU which controls how much boost pressure gets sent to the wastegate actuator. You are correct in that the solenoid vents to atmosphere.

Another way of explaining it is the solenoid receives full boost pressure from the compressor outlet and, depending on the commands from the engine controller, EITHER full boost pressure is sent on to the actuator, OR the solenoid reduces the pressure sent to the actuator by partially venting some of the pressure to atmosphere.

HTH

 

[JohnP]

Thanks GNX 405 for the good info.