I am not going to disagree with this, but have not really experienced this
problem as a result soley of low compression. I have three cars with very worn,
somewhat low-on-compression engines. I did have lots of trouble getting them
started, but that went away when I replaced the spark plugs. The biggest
problem that I have had with worn out cars is fouled spark plugs. The more worn
the engine, the faster they foul out. They do seem to start easier and run
okay, though, when the plugs are fresh. I have also gone further without
fouling if I install the "next hotter" plug. I don't know exactly what that
means, but I learned about it while driving worn out cars when I was in high
school.
I think low compression is a more serious problem with diesel powered cars. If
a diesel car is low on compression it won't start.
If any of my Imperials sit around a lot and run in neutral in place in the
garage (with the doors open, of course)without being driven very much, they
foul plugs even if the engines aren't worn out. I don't start any of my cars
any more unless I am going to drive them someplace. If they sit long enough
that I think I need to move the engine, I turn it over with the starter with
the coil disconnected. Sometimes I do that if I am going to start them, to
circulate the engine oil a bit before an actual start.
Good topic!
Paul
In a message dated 8/18/2004 7:41:43 PM Eastern Daylight Time, "Dick Benjamin"
<dickb@xxxxxxxxx> writes:
>The short answer is yes, low compression will show up first in difficulty
>starting. Compression is an easy thing to measure, and tells a very large
>percentage of the whole story about your engine's condition. As an example,
>I offer my 300,000 Mi + "Mahogany" 81 Imperial - even at the end of life,
>it drove perfectly, burned no oil, and was fairly smooth and quiet, but it
>did have a somewhat rough idle. It also would emit some oil smoke when
>started if it had not been driven for a week or so. It showed no
>deterioration in MPG or performance that I could detect. It was a tired
>looking car when I bought it, in 1988 or so with about 130,000 on it, but it
>was supremely comfortable (cloth seats in the 1981 only style loose pillow
>design) and I drove it everywhere for about 12 years.
>
>It became harder and harder to start - finally to the point that I began
>carrying a few ounces of gas with me when I was going anywhere. The
>compression was in the 90-110 range on 6 of the cylinders, and 40 on one, 70
>on the last one - signs of a very tired engine (which I already knew, of
>course). I sold that car in 2002 (as a parts car) to another collector -
>he is in Finland and I have not had a report as to what he did with it - but
>he had a much nicer one so I suspect it hasn't been driven since. I did tell
>him how to start it, though.
>
>If you put a pressure gauge on the fuel inlet to your HSA (the smaller of
>the two metal lines), you can measure the fuel available for starting. You
>should see about 12-14 PSI there when the purge cycle is occurring. You
>should also see a squirt from the fuel nozzles above the butterfly throttle
>valves. If you have the fuel there, the car should start right up. If it
>doesn't it's time to start looking for another cause.
>
>I assume your plugs, wires, cap, rotor etc. are all in great shape. As you
>probably know, there has been a reported high failure rate of the reluctor
>coil in the distributor which has caused many high temperature running
>problems, but I'd not expect this to cause only a starting problem - if the
>pickup is failing, that would also cause your engine to stop anytime, not
>just when starting.
>
>Dick
>
>
>>From: "Dick Benjamin" wrote: snip
>>If you have not done so, I think it's time to check the compression on this
>
>>engine.
>
>Why do you think I should run a compression test? The car runs fine and
>doesn't burn oil. It just takes some time to start. If you have been
>driving it and shut it off for a second or two it will usually start
>immediately. Only two big problems I had were on HOT days after a stop of
>between a half hour and an hour. For these reasons and the aftermarket fuel
>
>pump sucking fuel UP through the inactive in-tank pump, I suspect a fuel
>line problem. Would compression affect the starting, but let it run this
>well?
>
>Thanks again,
>Rob
>
>
>
>
>
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