: burned exhaust valve's ?!?!



Snacky
08-10-03, 04:20 PM
Hey there ya'll

im quite new to this board and already have a big problem with my caddy :crying2:
ive been reading around allot but couldn't fine the answer to my question so here goes

I've a 1994 Cadillac Seville STS with 130k miles on it (European model)

because my car failed the CO emission test a couple months ago (not allowed to drive it now but hack its a caddy i gotta drive it)
so i went to a couple car dealers Cadillac and non Cadillac to see what they had to tell
they all seemed to know what the problem was ..

one told me its a electrical prob
another one told its the Cat and last one told me that there ar 2 exhaust valve's burned in cylinder 1 and 5 ...
all of them wanted loads of $$$ to fix it

the engine is running fine except the ideal seems a bit jumpy
I've no white smoke out of the tail pipe and no weird odors from the catalytic converter
its not using any oil or coolant
the dic does not show any trouble codes

so my Q is .. if theres something seriously wrong with the exhaust valve's would it set a code or not ?
and what ells could cause a high Co ?

stuff ive done in the past month (all OEM)
spark plugs
plug wires
fuel filter
air filter
CO2 sensors
fixed leaking vacuum line
PCV valve
cleaned injectors
cleaned Throttle body
oil change
drained / refilled coolant 50/50 mix
fuel pressure tested and checks out Ok

to do
EGR cleaning (but i don't think this is the problem though)


Sorry for the long post guys/garls

Appreciate all help
Richard

btw hope i didn't mess up to much with my spelling ...
im dutch so im not use to type in english

elwesso
08-10-03, 08:42 PM
Hey, and welcome aboard!!! Thanks for signing up :wave:

I dont think that a bad exhaust valve would cause a check engine light, although it could..... I dont know......

I would lean more towards the cat. converter.... Although, i dont really know..... Kind of a guess, if you get my drift.......

Someone else more knowledgeable will chime in.....

AKPsiMC03
08-10-03, 09:24 PM
CO.... ill look up what makes that over. If your EGR is dirty it may be enough to fail it but not trip a code.

Snacky
08-11-03, 03:16 PM
if the exhaust valve's are burned
does this means i have to do the timeserts ?
or is this just in case i strip the threads ?

and would it be smart to replace all of the intake and exhaust valve's ?
or just the bad one's

if it turns out to be the valves ill let a Non Cadillac shop fix it for me
They never ever seen a Cadillac before and sure not a Nortstar

so i know ill be taking a risk letting them do it but the nearest caddy dealer is a 3 hr drive away and they are asking 3500 $ for it
i really do trust the non caddy dealer ..i know them for many years now and they guaranty there work for 6 months :)


anyhow what parts do i miss... and does anyone know the part numbers ?

exhaust valve's
intake valve's (not sure if ill let them change those thou)
Valve Cover Gasket
Head Gasket
timeserts (?)

anything alls i should do or know of?

ill be going to a couple friends next month in Dallas TX so i figured that ill buy my parts wile i'm there ... just one exhaust valve here is already 30$

thanks for all the help guys
Richard

eehoepp
08-11-03, 06:15 PM
if the exhaust valve's are burned
does this means i have to do the timeserts ?
or is this just in case i strip the threads ?

anyhow what parts do i miss... and does anyone know the part numbers ?

Valve Cover Gasket
Head Gasket
timeserts (?)

anything alls i should do or know of?

ill be going to a couple friends next month in Dallas TX so i figured that ill buy my parts wile i'm there

You'll only need to put in the Time-serts if the head bolts come out with pieces of aluminum threads (from the block) on them. You will not know for sure until the engine comes apart, but I would be prepared to do them. The kit is available from Time Fastener in Reno, Nevada:
www.timesert.com

The kit comes with 10 inserts & will do one cylinder bank only. You will need to buy 10 more inserts to do the whole engine. If you find damage to one thread you should put the inserts in all the holes. If you buy the kit plus 10 extra inserts, the price will be over $300 US (plus shipping * taxes).

The cam cover (valve cover) gaskets are the silicone O-ring type and are reusable. The O-rings around the spark plug holes are also reusable. According to GM, they are reusable if they don't come out of the groove when you take things apart. When I took mine apart, all of the gaskets came partly out of the grooves. I did not replace them. I partly filled the grooves with Permatex Ultra Blue sealant & reused the gaskets / seals. I have driven 20,000 km since the repair and have no leaks so far.

The head gasket kit includes 10 new headbolts. One kit is needed for each head.

The heads cannot be removed with the engine in the car. If your engine block leaks oil at the case half seals, fix them when the engine / powertrain is out.

There are 4 gaskets between the coolant crossover at the back of the engine and the block / heads. These are also reusable, the they crumbled when I took my engine apart.

I would list the part numbers for these gaskets, but my receipts are lost in my garage.

Good luck with the repair.

Katshot
08-11-03, 07:58 PM
Richard,
IF you decide to tear down the engine, DEFINATELY do the Time-serts. As far as I know, GM does not advise doing head gaskets on any of their aluminum engines without using them or Heli-coils.
A burned exhaust valve is symptomatic of other issues in the engine, it doesn't just happen on it's own. Generally, anything that causes poor enough cylinder sealing and causes a mis-fire will drive up the HC. High CO means that you are getting SOME firing of the cylinder but it's incomplete. It is quite possible to have a burnt exhaust valve (although I've NEVER seen one on a Northstar), but I would make sure you do a cylinder leak-down test to confirm it before ripping into the engine.

ljklaiber
08-11-03, 08:38 PM
Find a non dealer mechanic and run a compression check on the engine. The gauge will tell you if you have a burnt valve. Bet the D head that told you , never ran the check.. It easy with a gauge and proper thread extension. A warm engeing should show little variance between cylinders and if a difference ..you will se it.