These are all good points. In addition, if a blown head gasket becomes a likely culprit, it is also possible that an overheating problem could be diagnosed at the same time. Although it has not happened to me, I understand that a blown head gasket could (although not always) lead to overheating by forcing hot exhaust gases into the cooling system. I believe another symptom of this would be excessive foaming in the radiator tank. Paul In a message dated 5/7/2004 8:50:19 AM Eastern Daylight Time, jbachan@xxxxxxxxxxxxxxxxxx writes: > > > I'm sorry but I have to disagree with the quoted > statment below. A compression test can tell a great > deal more that just the condition of the top > compression ring of a weak cylinder. For example first > if you have two weak cylinder side by side this is a > good indicator of a blown head gasked 'tween the > cylinders, 2. if a weak cylinder compresion has the > same low dry compression as wet (a few squits of oil > down the spark plug hole to seal any weak rings) > you're probally looking at burnt valves. and third if > the compression increased after putting the oil down > the spark plug hole (wet compression reading) your > probally looking at rings. Further more rings tend to > wear evenly unless on breaks if the oil ring failed > the second compression ring would remove the oil. Yes > in time it would build up carbon and break but this > two would cause weak compression and you would see > signs as oil consumpsion or fowled plugs. I'm soory I > have to disaggree with the old service guy on this > one. > Joe > 76NYB > ... > > Compression test? As the old line Chrysler service > > mangager pointed out to me years ago, all the > > compression test will check is the top (compression) > > ring. It can still hold good compression and the > > oil rings can still have enough wear and age > > (including loss of tension) to not effectively > > scrape the oil from the cylinder wall. The other > > thing on a compression test is to use it as a point > > of reference, one cylinder to another cylinder, not > > looking for hard and fast numbers per se, but how > > they all relate to each other. > > > > > >