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Compression loss - what happenned?

I left the trusty old cavalier at my father's house whilst I went on holiday for 2 weeks. I told him there was no need to drive or run it to charge the battery. However, when I returned he informed me that he had "run it for a few minutes to charge the battery", ugh.

When I attempted to start it, it ran for 1 or 2 seconds then stopped. When cranking it again I could hear there was little or no compression on any cylinders.

After several more cranking/rest cycles, I could hear compression returning to one or more cylinders, and eventually there was enough compression for the engine to start. It ran rough for a minute or so but eventually returned to normal and has been fine since.

I suspected that condensation from the short period of idling that my father gave it could have corroded some of the exposed valve stems, causing them to stick temporarily. is this likely to be the case?

cheers Paul.

Reply to
Paul Andrews
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Not really, no. More likely all the oils drained out of the hydraulic lifters.

Reply to
Duncan Wood

Could it be "bore wash"? The engine gets flooded, and the fuel washes the oil off the rings, so they don't seal properly. The suggested solution is to remove the plugs, put a small amount of engine oil directly into each cylinder, clean the plugs up of course, put them back and try again.

Reply to
Ben C

You can hear compression? Why Granddad what big ears you have!!

Reply to
Phaeton

I wondered what that was too! :)

Reply to
Lin Chung

"Duncan Wood" wrote in news:op.tnu5cyrqyuobwl@lucy:

That was my thought too.

Reply to
Tunku

Paul Andrews has brought this to us :

You cannot hear the compression. You can hear it cranking faster than normal, or if you turned the engine over by hand you might hear the compression leaking away on the compression strokes, but not the compression or lack of while it is cranking at normal speeds.

Reply to
Harry Bloomfield

what I meant was that I could hear the starter motor turning faster than usual, without the normal speed (and hence sound) variations caused by the extra load on the starter motor due to compression strokes. Does that make any sense of my original post, or are people just being pedantic?

Paul.

Reply to
Paul Andrews

Just trying to be clear on what you actually meant.

Have you checked the cam belt and confirmed it is going round?

Reply to
Harry Bloomfield

Well unless it's a self healing belt, I presume it's OK. The OP stated the car has been fine since.

Reply to
Sandy Nuts

I bet you could hear it if you put your ear to the exhaust.

(do not put your ear to the exhaust)

Reply to
Ian Stirling

No?

So, you _can_ hear (an effect of) loss of compression.

Is this a strange philisophical discussion about what "compression" sounds like?

It's really quite simple: an engine which for some reason has lost compression will sound different to one which hasn't. You CAN hear it.

Reply to
David Taylor

After serious thinking David Taylor wrote (and still got it wrong):

Not quite. You can hear the effects or symptoms of the compression, rather than the actual compression - simple really. Take the plugs out or the exhaust manifold off and you will then hear the actual whoosh noise of the compression.

The idea of the original questioning of the 'hearing of the compression' was to simply help work out a little more of the problem.

Reply to
Harry Bloomfield

Is that the actual whoosh noise of the compression? With no plugs, there is no compression, only a whooshing sound as the air that would have been compressed is blown out of the plug holes.

In other words, what you are hearing is no more than a mere indirect epiphenomenon of compression, not the actual compression itself.

Reply to
Ben C

Ben C explained on 19/02/2007 :

If there were no compression, then there could not be any movement of the air. The reason why it moves is that there is a difference in pressure, the whoosh resolves that difference.

Reply to
Harry Bloomfield

If you can't hear air being compressed then you're deaf :-) & if it's not compressed it won't blow out the plug hole.

Reply to
Duncan Wood

But then, everything you can hear is a soundwave, or air being compressed....

Reply to
David Taylor

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