replacing HG, burnt exhaust valve???

[futeki_supra]

I am a complete n00b when it comes to anything w/ out a rotary in it so please bare with me guys....


I bought my mk3, drove it like 3 times, and then blew the headgasket.
took it to a local mechanic who only works on exotic sports cars,

bmw,saabs,rx7,lotus, yada yada yada...

he is a verry good mechanic and has been a family friend for years.

well I took my supra to him after this happened and he called me today to tell me it was going to be more expensive than he quoted me.

at first he quoted me around 1k.

he called me this morning to tell me that the car has a burnt exhaust valve.
( I dont know what that is )
and that the valves are going to get grinded,
and the price now will be around 1300-1400$ from what I have been reading that still isn't a horrible price for the whole job.

he also said a coolant hose was disconnected on the verry back of the head that goes to the intake mani,

but I think that prolly poped off when I was driving it to his shop while it was overheating.

I dunno anything about this stuff.

so if you guys could kinda just make sure all that sounds right or w/e
I would appriciate it.

 

[johnathan1]

That sounds like a VERY good priced for a headgasket and valve job...unless that's just labor...

 

[futeki_supra]

thats with all parts and labor
full gasket set ( not just hg )
machining the head, and now a valve job I guess.

I am assuming that when they are re-assembling everything, they will replace cracked vacuum lines and what not correct?

 

[johnathan1]

Good deal if it's done right. I was quoted $3000 by one shop, just to replace my head gasket.

 

[futeki_supra]

so what is a burnt exhaust valve?

 

[futeki_supra]

when I first talked to him he said it would be around
200$ for the gasket set,
and 800$ for labor.

 

[johnathan1]

$800 for labor is good.

I'm not exactly sure what a "burnt valve" is, but I would guess that i has something to do with detonation...like the valve got partially melted, and now it isn't sealing correctly, so compression is being lost?

 

[MassSupra89]

He's cutting you a daamn good deal it seems. I wish I lived closer haha.

 

[mattjk]

my 7mgte had a burnt exhaust valve. usually it is from improper valve lash, particles in the combustion camber, and rarely detonation. Mine was caused by a bad batch of gas and running lean. I had the gas anylized. I probably had a damaged seat too... it's hard to say.

What happens is a chunk off the sealing end of the valve literally melts off. Most common cause is an improper seal. Instead of keeping the combustion gases in during the combustion stroke, the hot gases leak past a small section of the valve and melt it away.

 

[johnathan1]

Matt, what brand was the bad gas?

 

[mattjk]

chevron, do a google search, you'll see alot of threads pop up.

 

[futeki_supra]

the previous owner changed the timing belt himself, and I am pretty sure the timing was off,
would that cause a burnt valve?

 

[mattjk]

no. probably no. It could though... cam timing and ignition timing could be very retarded and cause alot of heat.