What are the symptoms of a leaky valve?

With the development of the economy, cars have become a very common means of transportation. While cars bring convenience to everyone, they also have a great impact on people. In life, no matter what it is, after using it for a period of time, there will be some faults, and the same is true for cars. The most common car failure is valve leakage. What are the general symptoms of valve leakage?

(1) Causes of valve leakage

1) The working inclined surfaces of the valve and valve seat are worn, burned, have spots or depressions, and have carbon deposits.

2) The gap between the valve stem and the valve guide is too large, the valve stem shakes or bends, and the valve head is tilted, resulting in the valve not closing tightly.

3) The valve spring may weaken, lose its elasticity or break, which may also cause the valve and valve seat to not fit tightly together.

4) The valve clearance is small. When the valve stem expands due to heat, the push rod and rocker arm push the valve open, so that the valve cannot be completely closed and leaks air.

(2) Troubleshooting method: If you hear a "hinging" sound at the exhaust muffler, it means that there is a leak in the engine exhaust valve; if you hear a "hissing" sound at the intake and exhaust side, it means that there is a leak in the engine intake valve.

1) The probability of component failure is ranked from highest to lowest: valve, valve guide, cylinder head.

2) Best way to deal with it: Disassemble and inspect the engine cylinder head, check the fault location according to the actual situation, and repair or replace the related worn and damaged parts.

Diesel engine valve leakage can cause power loss, starting difficulties and other faults. To determine if the valve is leaking, you can use the following methods to check.

1. Remove the cylinder head cover, air filter and exhaust muffler, but ensure that the connection parts of the intake and exhaust pipes are reliably sealed.

2. Check the sealing of the intake valve. Slowly crank the crankshaft, pay attention to the movement of the exhaust valve, and stop cranking when the exhaust valve is about to open. Cover the intake pipe opening with your palm and continue to crank the crankshaft until the exhaust valve is closed. If you feel exhaust coming out of the intake pipe opening, it means the intake valve is not sealed tightly; otherwise, it is well sealed.

3. Check the exhaust valve. Continue to slowly crank the crankshaft, and when the intake valve is about to open, cover the exhaust pipe opening with your palm. Crank the shaft until the intake valve closes. If you feel air in the palm of your hand, it means that the exhaust valve is not sealed tightly; otherwise, it is well sealed.

The above method requires the cooperation of two people, one to crank the crankshaft and the other to check. The above method is simple and easy to implement, the judgment is accurate, and blind disassembly can be avoided.