What are the symptoms of a damaged intake manifold check valve in the Buick Excelle?
4 Answers
The symptoms of a faulty check valve in the Buick Excelle include increased air flow velocity at the carburetor throat, higher fuel discharge from the injector, and consequently elevated fuel consumption. 1. For carburetor or throttle body fuel injection engines: The intake manifold refers to the air passage from the carburetor/throttle body to the cylinder head intake ports. Its function is to distribute the air-fuel mixture from the carburetor/throttle body to each cylinder's intake port. 2. For port fuel injection engines or diesel engines: The intake manifold solely distributes clean air to each cylinder's intake ports. The intake manifold must distribute the air-fuel mixture or clean air as evenly as possible to all cylinders, requiring equal-length flow paths inside the manifold. To reduce airflow resistance and improve intake efficiency, the inner walls of the intake manifold should be smooth.
Last time my friend's Excelle had a similar issue with a faulty one-way valve. The most obvious symptom was the engine shaking like it was dancing at idle, with the RPM needle jumping up and down erratically. Pressing the accelerator hard felt particularly strenuous, as if the car was being held back and couldn't move. The fuel consumption inexplicably increased a lot, and although the dashboard didn't show any warning lights, there was a faint smell of gasoline mixed with engine oil. Later, we noticed blue smoke coming from the exhaust pipe, and everything returned to normal after replacing the valve. I suggest you get a cylinder pressure test done as soon as possible. Small component issues like this can get worse if left unattended.
I've encountered this issue before! When the one-way valve is damaged, the engine will experience vacuum leaks. You can clearly hear a hissing sound from the engine compartment at idle. The most annoying part is that cold starts become particularly difficult, requiring three or four attempts to ignite. When the air conditioning is turned on, the power drops significantly, and even flooring the throttle on uphill sections won't increase speed. Once, the check engine light suddenly came on, indicating a lean fuel mixture. After checking for a long time, I finally discovered that the one-way valve diaphragm was torn. This small component is hidden behind the intake manifold, and replacing it yourself requires removing a lot of parts.
I've handled similar cases before. The most typical symptom of a faulty one-way valve is abnormal crankcase pressure. You'll notice white smoke puffing out from the dipstick tube and oil filler cap, along with intermittent power loss during highway driving - making overtaking particularly dangerous. The cabin also gets filled with pungent exhaust fumes, like a mix of burnt plastic and engine oil smells. Some people mistakenly think it's a carbon buildup issue and end up unnecessarily cleaning the throttle body. I recommend focusing on checking the PCV valve pressure readings - a properly functioning engine should maintain vacuum in the air filter box during operation.
