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Burnt Valve Question



 
 
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  #1  
Old May 9th 05, 02:21 PM
mbjj
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Posts: n/a
Default Burnt Valve Question

Before I go taking off the head of this 1.0L Metro engine I'd like to know
how a burnt valve acts in relation to the performance of the engine. What it
is doing is acting like a bad miss. Like it even has water in the gas. It
sputters and misses when it's under load [like climbing a hill or
mountain]. On straight roads when the load is reduced it straightens out
and runs well. I'm going to do a compression check here in a little bit and
also change the plugs, wires and distributor cap before I get into the
head. We just bought this thing knowing it has a problem and the seller
seems to think he burned a valve. It also produces a puff of oil related
smoke out of the exhaust just after you start it [cold] and put it into
gear. It quickly goes away when shifting out of 1st and doesn't come back
again until it cools off and restarts.
Ads
  #2  
Old May 9th 05, 06:50 PM
external usenet poster
 
Posts: n/a
Default


"mbjj" > wrote in message
link.net...
> Before I go taking off the head of this 1.0L Metro engine I'd like to know
> how a burnt valve acts in relation to the performance of the engine. What

it
> is doing is acting like a bad miss. Like it even has water in the gas. It
> sputters and misses when it's under load [like climbing a hill or
> mountain]. On straight roads when the load is reduced it straightens out
> and runs well. I'm going to do a compression check here in a little bit

and
> also change the plugs, wires and distributor cap before I get into the
> head. We just bought this thing knowing it has a problem and the seller
> seems to think he burned a valve. It also produces a puff of oil related
> smoke out of the exhaust just after you start it [cold] and put it into
> gear. It quickly goes away when shifting out of 1st and doesn't come back
> again until it cools off and restarts.


The puff of blue smoke after a cold start often indicates worn valve guides
and/or
degraded valve guide seals. These seals are often easy to replace without
pulling the
head.

If you have a burned valve, it often shows up as a dead or nearly dead
cylinder.
At higher RPM the effect of a dead cylinder is less noticeable, but the loss
of power is
obvious. The engine may miss, or sometimes even backfire.

You can listen for a burned or poorly seating valve by disconnecting the
spark plugs so the engine
wont start, and turn the engine over with the starter. If every cylinder is
sealing about the same, you should have a consistent rhythm. If one, or
more, valves are burned, you will hear something different....like wa -wa -
WAH-wa-wa-WAH

A compression test is a better way.


  #3  
Old May 9th 05, 09:30 PM
mbjj
external usenet poster
 
Posts: n/a
Default

wrote:

>
> "mbjj" > wrote in message
> link.net...
>> Before I go taking off the head of this 1.0L Metro engine I'd like to
>> know how a burnt valve acts in relation to the performance of the engine.
>> What

> it
>> is doing is acting like a bad miss. Like it even has water in the gas. It
>> sputters and misses when it's under load [like climbing a hill or
>> mountain]. On straight roads when the load is reduced it straightens out
>> and runs well. I'm going to do a compression check here in a little bit

> and
>> also change the plugs, wires and distributor cap before I get into the
>> head. We just bought this thing knowing it has a problem and the seller
>> seems to think he burned a valve. It also produces a puff of oil related
>> smoke out of the exhaust just after you start it [cold] and put it into
>> gear. It quickly goes away when shifting out of 1st and doesn't come back
>> again until it cools off and restarts.

>
> The puff of blue smoke after a cold start often indicates worn valve
> guides and/or
> degraded valve guide seals. These seals are often easy to replace without
> pulling the
> head.
>
> If you have a burned valve, it often shows up as a dead or nearly dead
> cylinder.
> At higher RPM the effect of a dead cylinder is less noticeable, but the
> loss of power is
> obvious. The engine may miss, or sometimes even backfire.
>
> You can listen for a burned or poorly seating valve by disconnecting the
> spark plugs so the engine
> wont start, and turn the engine over with the starter. If every cylinder
> is sealing about the same, you should have a consistent rhythm. If one, or
> more, valves are burned, you will hear something different....like wa -wa
> - WAH-wa-wa-WAH
>
> A compression test is a better way.



Thanks for the info. The compression test showed an even 175 PSI across all
3 cylinders. The plugs were in need of replacement. The bad miss was in all
liklihood due to a bad plug in #3. I replaced all 3 plugs and put on new
wires, cap and rotor button. The miss is gone so I guess I can breathe a
little easier on the valve. I still have to look for the puff of smoke to
see if I took care of that too. After I run it awhile I'll keep a close eye
on the smoke and react accordingly.
  #4  
Old May 10th 05, 01:43 AM
JazzMan
external usenet poster
 
Posts: n/a
Default

mbjj wrote:
>
> Before I go taking off the head of this 1.0L Metro engine I'd like to know
> how a burnt valve acts in relation to the performance of the engine. What it
> is doing is acting like a bad miss. Like it even has water in the gas. It
> sputters and misses when it's under load [like climbing a hill or
> mountain]. On straight roads when the load is reduced it straightens out
> and runs well. I'm going to do a compression check here in a little bit and
> also change the plugs, wires and distributor cap before I get into the
> head. We just bought this thing knowing it has a problem and the seller
> seems to think he burned a valve. It also produces a puff of oil related
> smoke out of the exhaust just after you start it [cold] and put it into
> gear. It quickly goes away when shifting out of 1st and doesn't come back
> again until it cools off and restarts.


The 1.0 3-cyl is notorious for burning exhaust valves. The
effect is to lose compression on one one cylinder, creating
a miss. Just get a rebuilt head and install it along with
a new timing belt and you'll be fine. The last one I did
the head was $325 at the local rebuilder.

JazzMan
--
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************************************************** ********
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live under the laws of justice and mercy." - Wendell Berry
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  #5  
Old May 10th 05, 06:52 PM
external usenet poster
 
Posts: n/a
Default


"JazzMan" > wrote in message
...
> mbjj wrote:
> >
> > Before I go taking off the head of this 1.0L Metro engine I'd like to

know
> > how a burnt valve acts in relation to the performance of the engine.

What it
> > is doing is acting like a bad miss. Like it even has water in the gas.

It
> > sputters and misses when it's under load [like climbing a hill or
> > mountain]. On straight roads when the load is reduced it straightens out
> > and runs well. I'm going to do a compression check here in a little bit

and
> > also change the plugs, wires and distributor cap before I get into the
> > head. We just bought this thing knowing it has a problem and the seller
> > seems to think he burned a valve. It also produces a puff of oil related
> > smoke out of the exhaust just after you start it [cold] and put it into
> > gear. It quickly goes away when shifting out of 1st and doesn't come

back
> > again until it cools off and restarts.

>
> The 1.0 3-cyl is notorious for burning exhaust valves. The
> effect is to lose compression on one one cylinder, creating
> a miss. Just get a rebuilt head and install it along with
> a new timing belt and you'll be fine. The last one I did
> the head was $325 at the local rebuilder.
>
> JazzMan



Usually a machine shop will grind the valves, install new seals, and even
true the mating surface
for a lot less than that. Essentially a head rebuild... is there something
special about this one
that would make you pay for a head exchange at this cost rather than
revamping the old one?


  #6  
Old May 11th 05, 03:03 AM
JazzMan
external usenet poster
 
Posts: n/a
Default

wrote:
>
> "JazzMan" > wrote in message
> ...
> > mbjj wrote:
> > >
> > > Before I go taking off the head of this 1.0L Metro engine I'd like to

> know
> > > how a burnt valve acts in relation to the performance of the engine.

> What it
> > > is doing is acting like a bad miss. Like it even has water in the gas.

> It
> > > sputters and misses when it's under load [like climbing a hill or
> > > mountain]. On straight roads when the load is reduced it straightens out
> > > and runs well. I'm going to do a compression check here in a little bit

> and
> > > also change the plugs, wires and distributor cap before I get into the
> > > head. We just bought this thing knowing it has a problem and the seller
> > > seems to think he burned a valve. It also produces a puff of oil related
> > > smoke out of the exhaust just after you start it [cold] and put it into
> > > gear. It quickly goes away when shifting out of 1st and doesn't come

> back
> > > again until it cools off and restarts.

> >
> > The 1.0 3-cyl is notorious for burning exhaust valves. The
> > effect is to lose compression on one one cylinder, creating
> > a miss. Just get a rebuilt head and install it along with
> > a new timing belt and you'll be fine. The last one I did
> > the head was $325 at the local rebuilder.
> >
> > JazzMan

>
> Usually a machine shop will grind the valves, install new seals, and even
> true the mating surface
> for a lot less than that. Essentially a head rebuild... is there something
> special about this one
> that would make you pay for a head exchange at this cost rather than
> revamping the old one?


The $325 included a fully rebuilt head with new valves
and a FelPro top end set including head gasket, it was
a complete plug and play installation. Time from pulling
the old head to installing the new head was less than two
hours.

JazzMan
--
************************************************** ********
Please reply to jsavage"at"airmail.net.
Curse those darned bulk e-mailers!
************************************************** ********
"Rats and roaches live by competition under the laws of
supply and demand. It is the privilege of human beings to
live under the laws of justice and mercy." - Wendell Berry
************************************************** ********
 




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