engine hesitation

I have recently developed a severe hesitation problem. Cyl 1 shows
compression of 120. Other 3 have 150. If I squirt oil into 1, it
also shows 150. There has been no change in compression or vacuum
(18), but the hesitation and missing started suddenly as I was
driving last week. Prior to this, I ran smoothly at all speeds up to
85 mph., although the engine had been a little weak, I consume very
little oil, except at sustained very high speeds,

Now the engine idles nicely, but hesitates under load under any
driving conditions. I removed the #1 spark plug wire and grounded it
to the block. Car runs much smoother now on 3 cylinders at all speeds
than it had been on 4 with one missing..


Questions:
Will running the car like this on a short term basis damage the
engine?
Could raw gas ignite in the exhaust system and damage it? (I can't
shut off gas supply because this is a carb engine, not EFI.)
Is there any way to tell if problem is rings rather than valves
without pulling the cylinder head?

Thanks,

Tom


rec.autos.tech

sounds like a broken compression ring to me .
you should reconnect the plug wire ,even though it is unlikely that fuel
could ignite in the exhaust system because of the lack of sufficient oxygen
however a sudden backfire with a excess amount of unburned fuel in the
exhaust sytem could really do some damage......KABOOM
You could use a cylinder leakdown gauge, but it would just confirm what the
wet test indicated.
pull the head and the oil pan, pull the slug out and take a look see.....
--
Mad-Dog
'79 Chevy K-10
Slightly modified
pictures can be found he
http://mad-dog16.tripod.com/

--
"tom" > wrote in message
...
>I have recently developed a severe hesitation problem. Cyl 1 shows
> compression of 120. Other 3 have 150. If I squirt oil into 1, it
> also shows 150. There has been no change in compression or vacuum
> (18), but the hesitation and missing started suddenly as I was
> driving last week. Prior to this, I ran smoothly at all speeds up to
> 85 mph., although the engine had been a little weak, I consume very
> little oil, except at sustained very high speeds,
>
> Now the engine idles nicely, but hesitates under load under any
> driving conditions. I removed the #1 spark plug wire and grounded it
> to the block. Car runs much smoother now on 3 cylinders at all speeds
> than it had been on 4 with one missing..
>
>
> Questions:
> Will running the car like this on a short term basis damage the
> engine?
> Could raw gas ignite in the exhaust system and damage it? (I can't
> shut off gas supply because this is a carb engine, not EFI.)
> Is there any way to tell if problem is rings rather than valves
> without pulling the cylinder head?
>
> Thanks,
>
> Tom
>
>
> rec.autos.tech

"tom" > wrote in message
...
> I have recently developed a severe hesitation problem. Cyl 1 shows
> compression of 120. Other 3 have 150. If I squirt oil into 1, it
> also shows 150.

piston rings are worn or broken i.e. it's time to pull that engine apart.


> Questions:
> Will running the car like this on a short term basis damage the
> engine?

yes

> Could raw gas ignite in the exhaust system and damage it?

???

> shut off gas supply because this is a carb engine, not EFI.)
> Is there any way to tell if problem is rings rather than valves
> without pulling the cylinder head?

Duh.... <grin>

--
There are no words that can be heard unless someone listens....
Remove *flaps* to reply

You have a valve problem in cylinder #1. You should bring #1 to TDC
(compression) and inject compressed air (perhaps 5-10 PSI) and listen
for hissing at the exhaust and intake systems. This will tell you which
valve is not sealing. In any event... it will probably involve
disassebling the engine to the point where the valve can be serviced.

Professor
www.telstar-electronics.com


tom wrote:
> I have recently developed a severe hesitation problem. Cyl 1 shows
> compression of 120. Other 3 have 150. If I squirt oil into 1, it
> also shows 150. There has been no change in compression or vacuum
> (18), but the hesitation and missing started suddenly as I was
> driving last week. Prior to this, I ran smoothly at all speeds up to
> 85 mph., although the engine had been a little weak, I consume very
> little oil, except at sustained very high speeds,
>
> Now the engine idles nicely, but hesitates under load under any
> driving conditions. I removed the #1 spark plug wire and grounded it
> to the block. Car runs much smoother now on 3 cylinders at all
speeds
> than it had been on 4 with one missing..
>
>
> Questions:
> Will running the car like this on a short term basis damage the
> engine?
> Could raw gas ignite in the exhaust system and damage it? (I can't
> shut off gas supply because this is a carb engine, not EFI.)
> Is there any way to tell if problem is rings rather than valves
> without pulling the cylinder head?
>
> Thanks,
>
> Tom
>
>
> rec.autos.tech

> You have a valve problem in cylinder #1. You should bring #1 to TDC



NO - if his compression went up after he injected oil into the #1 cylinder!!
Oil goes down into the rings intern the pressure will raise.

Read what the OP says!!!!!



> > I have recently developed a severe hesitation problem. Cyl 1 shows
> > compression of 120. Other 3 have 150. If I squirt oil into 1, it
> > also shows 150. There has been no change in compression or vacuum



If no rise in compression then it would be the valve guides or a head or
possibly a valve leak


> (compression) and inject compressed air (perhaps 5-10 PSI) and listen



WTF -- Professor my ass!!! No, you would hear all kinds of leaks u friggen
dweeb!!!


> for hissing at the exhaust and intake systems. This will tell you which



Gawd what a ****in moron!! the only way to accurately test for a leak at the
head is to remove the ****ing HEAD!!!!


> valve is not sealing. In any event... it will probably involve
> disassebling the engine to the point where the valve can be serviced.



Perhaps electronics is your forte, NOT automotive diagnostics i.e. you display
little or no actual hands-on real life knowledge!




> Professor
> www.telstar-electronics.com
>
>
> tom wrote:
> > I have recently developed a severe hesitation problem. Cyl 1 shows
> > compression of 120. Other 3 have 150. If I squirt oil into 1, it
> > also shows 150. There has been no change in compression or vacuum
> > (18), but the hesitation and missing started suddenly as I was
> > driving last week. Prior to this, I ran smoothly at all speeds up to
> > 85 mph., although the engine had been a little weak, I consume very
> > little oil, except at sustained very high speeds,
> >
> > Now the engine idles nicely, but hesitates under load under any
> > driving conditions. I removed the #1 spark plug wire and grounded it
> > to the block. Car runs much smoother now on 3 cylinders at all
> speeds
> > than it had been on 4 with one missing..
> >
> >
> > Questions:
> > Will running the car like this on a short term basis damage the
> > engine?
> > Could raw gas ignite in the exhaust system and damage it? (I can't
> > shut off gas supply because this is a carb engine, not EFI.)
> > Is there any way to tell if problem is rings rather than valves
> > without pulling the cylinder head?
> >
> > Thanks,
> >
> > Tom
> >
> >
> > rec.autos.tech
>

You're right, I misread the part about the pressure increasing after
the oil squirting. No need to get nasty about it.

Professor
www.telstar-electronics.com


Backbone wrote:
> > You have a valve problem in cylinder #1. You should bring #1 to TDC
>
>
>
> NO - if his compression went up after he injected oil into the #1
cylinder!!
> Oil goes down into the rings intern the pressure will raise.
>
> Read what the OP says!!!!!
>
>
>
> > > I have recently developed a severe hesitation problem. Cyl 1
shows
> > > compression of 120. Other 3 have 150. If I squirt oil into 1,
it
> > > also shows 150. There has been no change in compression or
vacuum
>
>
>
> If no rise in compression then it would be the valve guides or a head
or
> possibly a valve leak
>
>
> > (compression) and inject compressed air (perhaps 5-10 PSI) and
listen
>
>
>
> WTF -- Professor my ass!!! No, you would hear all kinds of leaks u
friggen
> dweeb!!!
>
>
> > for hissing at the exhaust and intake systems. This will tell you
which
>
>
>
> Gawd what a ****in moron!! the only way to accurately test for a leak
at the
> head is to remove the ****ing HEAD!!!!
>
>
> > valve is not sealing. In any event... it will probably involve
> > disassebling the engine to the point where the valve can be
serviced.
>
>
>
> Perhaps electronics is your forte, NOT automotive diagnostics i.e.
you display
> little or no actual hands-on real life knowledge!
>
>
>
>
> > Professor
> > www.telstar-electronics.com
> >
> >
> > tom wrote:
> > > I have recently developed a severe hesitation problem. Cyl 1
shows
> > > compression of 120. Other 3 have 150. If I squirt oil into 1,
it
> > > also shows 150. There has been no change in compression or
vacuum
> > > (18), but the hesitation and missing started suddenly as I was
> > > driving last week. Prior to this, I ran smoothly at all speeds
up to
> > > 85 mph., although the engine had been a little weak, I consume
very
> > > little oil, except at sustained very high speeds,
> > >
> > > Now the engine idles nicely, but hesitates under load under any
> > > driving conditions. I removed the #1 spark plug wire and
grounded it
> > > to the block. Car runs much smoother now on 3 cylinders at all
> > speeds
> > > than it had been on 4 with one missing..
> > >
> > >
> > > Questions:
> > > Will running the car like this on a short term basis damage the
> > > engine?
> > > Could raw gas ignite in the exhaust system and damage it? (I
can't
> > > shut off gas supply because this is a carb engine, not EFI.)
> > > Is there any way to tell if problem is rings rather than valves
> > > without pulling the cylinder head?
> > >
> > > Thanks,
> > >
> > > Tom
> > >
> > >
> > > rec.autos.tech
> >

On Sat, 16 Apr 2005, Professor wrote:

> You're right, I misread the part about the pressure increasing after
> the oil squirting. No need to get nasty about it.

I think the reason why people get "nasty" with you is that you tend to
shoot your mouth off with guesses and fabrications pawned off as fact.

Sorry you feel that way. I'm entitled to my opinion... as you are to
yours. I know that people that are intelligent don't resort to such
tactics. I have shown that I'm not ashamed of admitting when I'm
wrong... I wonder when some out there will be able to do the same.

Professor
www.telstar-electronics.com