good news bad news engine compression test

[chembrad]

Well I finally did my engine compression test on my G10 engine in my '94 Metro 5spd.

#1: 155
#2: 175
#3: 40

woof

So looks like a blown head gasket and possible valve stem guides.

This car has 169k miles on it. Anyone reworked one of these engines before that knows the basic parts that should be checked/replaced while I am doing the head gasket?

I heard parts dinosaur sells a lot of stuff for doing these engines.

Thanks!

[geozukigti]

With that much of a range, I would highly suggest you do the piston rings too while the engine is apart. An extra hour and a half job, and probably $60. Partsdinosaur is a great guy to deal with. I would have your head rebuilt too. Or for $350, send it to Mike Cove(Suprf1y on Teamswift) and he'll rebuild, unmask the valves, port, and polish it .

[Crvett69]

i would suspect burned valve on number 3 cyl. will cost you about $125 to have head rebuilt and if your gonna do that you should put rings in it too or it will probably start smoking. another option is getting one of the JDM engines and dropping in. costs about the same either way

[chembrad]

When you say "burned valve" what does that mean?

I saw a engine gasket/headbolts/valve kit at parts dinosaur for $104

That sounds like a good deal to me.

[SeanMurphy]

These engines are notorious for burning that one exhaust valve, unless an aftermarket exhaust is installed. The backpressure and heat from the exhaust gasses tends to cause the metal valve to deform or deteriorate, making it no longer seal properly, and you end up with low compression and poor power. Basically a dead cylinder.

[Crvett69]

when you take the head off one of the exhaust valves will look like someone took a bite out of it. once its starts leaking a little the hot exhaust gas acts like a torch and burns part of the valve away until compression is low enough that it no longer fires on that cylinder.

[chembrad]

Originally Posted by SeanMurphy

These engines are notorious for burning that one exhaust valve, unless an aftermarket exhaust is installed...

Who sells the good aftermarket exhausts? And why would an different exhaust make a difference?

I've also heard that one of the probs with #3 cylinder is that the EGR gets clogged with carbon deposits which somehow causes #3 to overheat and burn, etc.

Thanks for the info on what a burned valve is. Much appreciated.

[chembrad]

here is a site that mentions the Geo Metro burned valve syndrome:
http://www.forparts.com/geo2.htm

here is a site that tells how to perform an exhaust backpressure test:
http://www.gatewaycleanair.com/mecha...1/casestdy.htm