What is the reason for the occasional stiffness of the Great Wall H6 vacuum booster?
3 Answers
The occasional stiffness of the Great Wall H6 vacuum booster is due to air leakage in the booster pump pipe. The following are specific symptoms of vacuum pump failure: 1. Hard brake feel: When stepping on the brake, if the brake feels noticeably hard, with each pedal stroke being very small, or even pushing the foot back, it is likely due to air leakage in the brake vacuum pump, causing the vacuum pump's boosting effect to fail. 2. Abnormal noise from the vacuum pump: Poor-quality vacuum pumps may produce noticeable abnormal noises, but this does not affect the car's braking performance. 3. Brake pedal not returning or returning slowly: If after stepping on the brake pedal, the pedal neither rises nor offers resistance, this is a sign of the brake not returning. It is necessary to check whether the brake vacuum pump, master cylinder, or wheel cylinder components are damaged.
Last time I drove my friend's Haval H6, I also encountered a situation where the vacuum booster became stiff. The experienced mechanic at the repair shop removed the front wheel and found that the vacuum hose connector had aged and cracked. Rubber hoses become brittle over time, especially those near the turbocharger, which are exposed to prolonged high temperatures—once cracked, they leak vacuum. The mechanic also checked the one-way valve; if it's clogged or doesn't seal properly, it can cause insufficient vacuum. Additionally, I’d advise you to check the condition of the vacuum pump in the engine bay. Insufficient oil lubrication or degraded piston seals can affect its performance. I remember one case where a owner modified the intake but forgot to reconnect the vacuum hose, making the brake pedal as hard as a brick. Don’t ignore such issues—check the seals immediately.
My H6 developed intermittent brake booster issues after five years of use. Inspection revealed pinhole leaks in the vacuum reservoir tank. Rust on the metal tank interior created micro-leak points, causing insufficient vacuum during cold starts - the first brake pedal press would always be terrifyingly stiff. Eventually, I replaced all vacuum lines between the engine and booster (using more durable high-temperature silicone hoses) and installed a new vacuum pressure sensor. Experienced owners advised me to also check turbocharger seals, as exhaust turbo leaks can compromise vacuum pressure. Now during every maintenance, I have mechanics verify brake assist vacuum with a gauge - it must maintain -80kPa to be considered normal.
