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Check the compression pressure in the cylinders

Checking the compression pressure in the cylinders can provide valuable information about the general state of the upper part of the mechanical engine (pistons, piston rings, valves, cylinder head gaskets). Of particular importance is the ability to determine whether the cause of the fall of the compression pressure leakage caused by wear and tear of piston rings or valve defects and their saddles, or the reason lies in the violation of the integrity of the lining of the head or body.

To perform this test the engine must be warmed up to normal operating temperature and the battery is fully charged.

PERFORMANCE ORDER

Start with cleaning candle niches (using compressed air, a little or a simple bicycle pump). This will prevent the engine debris when removing spark plugs. Remove all spark plugs (Chapter Settings and maintenance). Fix the throttle in the fully open position. Remove the coil wire from the center terminal of the distributor cap and ground it on the motor housing. To ensure a quality use of grounding wire, equipped with both ends of the clamp-type "crocodile". Also, you should temporarily disable the circuit of the fuel pump (Chapter power supply system and exhaust). Set compression gauge in the spark plug hole of the first cylinder. Preferably use compressometer not pinch type, equipped with a threaded nozzle is screwed into the spark plug hole. Crank the engine, the pistons having spent at least seven of the compression stroke, reading readings. The pressure in the cylinder serviceable engine should rise quickly. If the low pressure in the first cycle is accompanied by a gradual rise in the future it is evidence of poor condition of the piston rings. Low pressure in all cycles of said valve leaks or defect cylinder head gasket (the reason could also be the presence of cracks in the molding of the head). Often the cause of low compression pressure is excessive carbon formation on the plates of valves. Record the maximum reading compressometer. Repeat measurements for all remaining cylinders and compare the results with the requirements of the Specifications. Fill in each of the cylinders through the spark plug hole it a little (about three teaspoons) of motor oil and recheck. If the addition of oil has led to the normalization (increase) of the compression pressure, the cause of his low readings during the initial inspection is the wear of piston rings. If a significant pressure increase is not observed, there are leaking valves or head gasket. Valve leakage can be caused progaraniem their seats and / or deformation of the working surfaces of the chamfers, as well as bending valve stem or cracking in the plates. If the pressure in the two adjacent cylinders are equally low, it is a very strong argument in favor of the existence of a breach of integrity jumper head gasket therebetween. Confirmed this assumption of coolant in the combustion chamber or crankcase. If the pressure in one cylinder is different from the remaining approximately 20%, and this is accompanied by a minor violation of stability idle speed should be inspected for signs of wear on the exhaust valve cam of a camshaft. Unusually high compression pressure indicates a strong possibility of carbon formation in combustion chambers. In this case, must be removed and the head (s) and to carry out its (their) decarbonization. The pressure drop or a noticeable difference in its various cylinders talks about the need for a check engine for leaks in the workshop car service. This test will help locate the source of the leak and assess the severity of the defect.