What will foul spark plugs

The seals on the turbine shaft are robust, but they can be victims of heat and poor oil quality. The oil that lubricates the shaft can enter into the pressurized intake and eventually the combustion chamber. Most of these problems relate to cylinder deactivation and variable valve timing. The main culprit in these problems is vacuum generated in the cylinders that sucks engine oil past the rings and into the combustion chamber. On vehicles with cylinder deactivation, the deactivated cylinder has negative pressure and draws oil droplets in the crankcase past the ring and eventually into the converter.

This has happened on some GM and Honda engines. On some vehicles with variable valve timing typically on the exhaust and intake cams , the valve timing could produce higher-than-normal vacuum pressures that could suck oil past the rings. This was the case for some recent Toyota, Honda and GM models. The customer would report increased oil consumption that exceeded one quart every 1, miles. Advertisement Beyond the oil getting past the rings, the oil trapped in the rings can become carbonized and cause damage to the cylinder walls.

This can lead to even more damage and more oil consumption. In some cases, the oil consumption results in a low-oil condition that would cause damage to the bearing surfaces. Internal coolant leaks can foul a spark plug and cause a misfire. The problem could be a leaking intake manifold or a head gasket, and the fouled plug might be localized to one or two adjacent cylinders.

The burned coolant leaves ashy, white deposits on the electrodes and insulator, creating hot spots that could cause pre-ignition and a misfire code to be set. Advertisement When the plug is pulled, it might have a chalky appearance on the ground strap and center electrode. Modern coolants do not cause this type of buildup quickly, due to the reduction of phosphate, zinc and other additives that can contaminate the catalytic converters. Unfortunately, it also means that drivers will run a vehicle with a coolant leak for several thousand miles, while the plug becomes slowly fouled.

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Select Language. Symptoms of Bad Spark Plugs. Message Regarding Your Privacy. I accept Submit Submit. Effects of Failing Spark Plugs. This often happens in cold weather conditions, when spark plugs that are previously worn or fouled require a higher voltage to ignite the engine. In this case, the best thing a driver can do is either wait for the plugs to dry, or remove the plugs and clean them off.

Wet fouling is less common on modern fuel-injected engines, but can happen due to a number of mechanical failures, states AA1Car.

One example is a leaking cold start injector. This will increase the cost to run the vehicle and can cause permanent damage. A professional mechanic on AutoGuru can diagnose these faults by inspecting your spark plugs and THEN determine the best course of action to rectify the problem. Zak has been working in the auto industry for 40 years.

For the past decade, he has been in the education business, training apprentices and preparing them for a career in the light vehicle and auto electrical trades. Why do my spark plugs keep getting dirty? Updated 10 Oct Zak Zuiderduin.