Ring engine problem - CRACKED / BROKEN

First and second compression rings commonly break causing low compression and misfiring. The main cause of compression rings being cracked and broken is that the engine was being driven under detonation/ conditions.

This dangerous condition is present and made evident by engine pinging. Even slight pinging over a long period will eventually result in ring damage. This condition is usually present when the ignition timing is too advanced (base intermediate or total) or the fuel is of too low an octane rating to suit the compression ratio. Severe detonation can exist if engine is run overloaded or at high temperatures.

Detonation will also damage and crack the piston ring groves and piston crown. Most engine components will sustain damage if an engine is run while pinging is evident.

Another cause of broken rings is excessive side wear. This side wear is usually the result of abrasive contamination. Incorrect assembly of rings into bores is another common cause. (Compression problem exists at initial start up.)

Another common cause is insufficient ring end gap when assembled. (Assembly fault) Engine overheating or incorrect rings fitted (wrong radial depth or material choice) can also be the primary cause.
 

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: Every care has been taken in writing this information and procedures, but no responsibility can be excepted for errors, omissions or misuse of this information and procedures. The information available on this site is for your instruction only and cannot be copied for sale, © copyright 2001 UMR Engines www.engineproblem.com.au

Ring engine problem - FLOGGED / WORN OUT

Once the cylinder head is removed, a tell tale sign of ring wear is washing of the outer edge of the piston. At high mileage this is a perfectly natural occurrence even when strict service guidelines are adhered too. The average medium sedan generally travels around 150,000 kilometres before being affected by worn out rings. We could be considering worn out rings a premature condition anything under this mileage, depending upon driving conditions and service records.

Premature ring wear is generally caused by poor service of the air and oil filter system. Performance of rings is effected by both the quality of the air and of the oil. Driving conditions will determine if service intervals should be shortened to guarantee the protection of the engine. Wrong choice of ring material to the application can be a cause. Eg: cast iron instead of chrome top rings.

Abrasive wear is the most common cause of ring failure soon after an engine rebuild. This condition is a result of poor workmanship and can never be blamed on the parts. Close inspection of the worn rings will confirm the cause. Multitudes of vertical scratches will be visible on the rings and the piston skirt. Normally the oil ring will be extremely worn and the piston will now measure under acceptable wear specifications. The edges of all rings will be excessively sharp. The engine oil will be extremely black within the first 1000 kms. Due to the cause of this failure almost every other engine component can be effected with abnormal premature wear. The engine will be destroyed before the first 800 km engine service. Due to the nature of the abrasive material involved it will also become imbedded in the bearings resulting in abnormal crankshaft wear.

The term used to describe an engine that has accelerated ring and bore wear due to air born abrasive contamination is a "DUSTED" engine. An engine subject to air borne contamination can be destroyed in a very short period. Poor air filter service procedures, inadequate filter system, vacuum leaks, intake hose leaks, intake manifold leak and leaking PVC system etc. can all lead to excessive premature ring wear and bore wear. The cause of this wear is very evident at strip down. An initial examination of the intake manifold can reveal the contaminant as it gets trapped in blind crevices and the rough casting areas. The air cleaner tube or the engine side of the air filter may also show evidence of the contaminant. Often at first glance the inside of the intake manifold looks abnormally clean with all marks and stains polished off. Upon dismantling the engine wear is very evident on the upper bores. The compression rings will have fine vertical scratches and the bores will have a worn polished look with no hone pattern evident. The ridge left by the top compression ring will be rather excessive and often all around the cylinder, rather different to normal ridge wear. All the rings will be excessively worn as the rings are subject not only to the airborne contaminant but also to the fine iron particles as the bores and rings wear out. If an engine operates in a dusty enviroment it is important to shorten the service intervals and ensure all filtration systems are adequate and well maintained.

Disclaimer Agreement

: Every care has been taken in writing this information and procedures, but no responsibility can be excepted for errors, omissions or misuse of this information and procedures. The information available on this site is for your instruction only and cannot be copied for sale, © copyright 2001 UMR Engines www.engineproblem.com.au

Ring engine problem - SEIZED

Piston crown damage from a foreign body entering the combustion chamber can cause distortion of the ring groove and seizure of the compression rings in the ring groove. (Always remove the piston and check for this condition when carrying out this repair.

Don't assume that minor crown damage will not cause a more serious problem) Incorrect rings fitted (excessive wall pressure or insufficient back clearance) will cause excessive contact pressure and welding of ring material to the cylinder wall, complete breakdown of lubrication with rings totally seized or compacted in piston ring grooves. Excessive overheating and insufficient lubrication will contribute to this condition.

Compression rings can seize in piston ring groove when excessive oil useage produces excessive carbon which builds up above top ring and in the ring grooves. This problem is a secondry result and is not the primary failure. Possible worn valve guide or seal failure could be the reason for oil burning. If a engine is driven considerable miles with glazed up cylinders, the carbon build up will eventually seize the rings in the pistons grooves.

Disclaimer Agreement

: Every care has been taken in writing this information and procedures, but no responsibility can be excepted for errors, omissions or misuse of this information and procedures. The information available on this site is for your instruction only and cannot be copied for sale, © copyright 2001 UMR Engines www.engineproblem.com.au