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Burnt valve?; No compression #3 cylinder
Topic Started: Sep 14 2012, 07:53 PM (808 Views)
red92
Advanced Member
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I just pulled the head off of my 90 LSI vert. I expected to see a broken valve since i had 0 compression.
I tried a compression test after putting oil in the cylinder but no change in compression test.

The small valve in the head looks irregular but not broken. It doesn't look round like #1 and 2 cylinder valves.

could it be warped?

The other two cylinders have 160 & 155 compression.

No carbon build up in the passageway in the head. I use seafoam regularly.

Comments?
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Scoobs
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:D

Take it to a machine shop and get a valve job. Your valve is burnt.
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starscream5000
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Got 70 MPG?

You just described what a burnt valve looks like :thumb
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red92
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Any idea what causes it to burn?

I had a 92 that the same valve had a piece broken out of it and the passageway was full of carbon.

#3 cylinder seems to have common issues.
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starscream5000
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Got 70 MPG?

Some people think it burns more often because it's right beside the EGR passage and runs hotter than the other two cylinders.
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red92
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Makes sense. Think ethanol effects our cars. It does cause problems with boat motors in this area.

Our local boat shops and mechanics have told me that.
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busteriver
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red92
Sep 14 2012, 08:21 PM
Makes sense. Think ethanol effects our cars. It does cause problems with boat motors in this area.

Our local boat shops and mechanics have told me that.
This must be the reason I can only get non ethanol fuel next to boat docks.
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JellyBeanDriver


red92
Sep 14 2012, 08:21 PM
Makes sense. Think ethanol effects our cars. It does cause problems with boat motors in this area.

Our local boat shops and mechanics have told me that.
And there's my oddity of a metro. 3/5, 422,000 miles, original engine and valves.
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red92
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Curious! Do you put any additives in gas or oil?
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Car Nut
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JellyBeanDriver
Sep 14 2012, 11:16 PM
And there's my oddity of a metro. 3/5, 422,000 miles, original engine and valves.
Gonna blow up next week now that you said that. :lol
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JellyBeanDriver


red92
Sep 15 2012, 10:26 AM
Curious! Do you put any additives in gas or oil?
Not with enough regularity that I would say it helped.
I think clean hydraulic lifters due to regular oil changes and all freeway driving is the reason.

Quote:
 
Gonna blow up next week now that you said that. :lol
I did think about this before I posted . . . .
Edited by JellyBeanDriver, Sep 15 2012, 08:54 PM.
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clarkdw


JellyBeanDriver
Sep 15 2012, 08:53 PM
red92
Sep 15 2012, 10:26 AM
Curious! Do you put any additives in gas or oil?
Not with enough regularity that I would say it helped.
I think clean hydraulic lifters due to regular oil changes and all freeway driving is the reason.

I think you hit a big nail right on the head. I am finding more and more evidence that the lifters could be a reason for a lot of the valve problems as I learn more about the G10. I think regular oil changes are very critical for us. Maybe Mwebb's OCD approach to oil has some merit :hmm although I think fastidious compliance to a carefully reasoned schedule of changes is far more important than simply what alphabet oil you use.

I have rebuilt a lot of sticky lifters and seen numerous cases of poor cold running from pumped up lifters even in a reasonably small sample of cars.
Edited by clarkdw, Sep 15 2012, 09:09 PM.
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