Q: Need information about a Blow Off Valve

asked by on

Hi I own a Subaru Impreza Sti 2013 I bought it new in 2013 it has 100000km on it now I have a question: Can a blow off valve 50-50 blow a engine!.... ??? I've already spoke with my local Subaru and they have told my NO its impossible then I contact the close tunning shop and they told me the exact same thing now I am looking to find out more from an expert! Thanks Marc
My car has a manual transmission.

Hi Marc, First, it is important to understand what a blow off valve does and what it’s function is on a turbo charged motor. The only job a blow-off valve is supposed to perform is to relieve excess turbo pressure that results from shutting the throttle rapidly under boost conditions. It is necessary to release this pressure because it will try to find a way out of the system, and the only way is back out through the turbo. The pressure side of the valve is attached to the pipe between the turbo and the throttle, and a vacuum hose on the top of the valve is hooked up to the inlet manifold after the throttle body. A spring holds the valve shut. When you are on the throttle, the pressure in the turbo piping and the inlet manifold is equal. This creates pressure on each side of the valve that is equal, thereby canceling itself out, leaving the spring holding the valve shut. When you lift off the throttle, you have high pressure in the turbo piping, and a vacuum in the inlet manifold. The pressure on the bottom of the valve and the vacuum on the top combine to lift the valve open and release the pressure in the turbo piping, since it can no longer go into the engine. For this reason, it cannot damage your motor as the excess pressure simply gets released via the exhaust.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Need information about a Blow Off Valve

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car cranks strong but will not start - 2000 Subaru Outback

Hi there. It sounds like you've certainly done some good checks. However, what was the fuel pressure? Each manufacturer has a specified fuel pressure required for the engine to run. There can definitely be plenty of fuel coming out of...

Q: Hi Josh. I just bought a 2015 Base STI. I'm moving to Phoenix in a month. Should I upgrade intercooler, Radiator

While the temperatures in Arizona are much hotter, the factory radiator and inter-cooler are designed to withstand temperatures that are consistent with Arizona. Car manufacturers design vehicles with the idea in mind that the vehicle may operate in any number...

Q: How much will it be to replace my timing belt and have them installed?

Hi there. Without knowing the specific OBD-II error code that you're receiving, it's hard to tell you for sure that the timing belt needs to be replaced. Quite often, error codes similar to this are caused by sensors that are...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...