ARISTOh

iTrader: (3)

My GSh has been having misfire issues, Lexus dealer took 2+ months to diagnose and said there is a small valve leak. They decided to send the head to a machine shop to have it shaved. What are the scientific/mechanical pros and cons to having the head machined and could they have just put a NEW head on? - 07 GSh

corradoMR2

Interesting. I'm off today "Family Day" and I'm late on chores my wife expects of me. I better get to it!

DaveGS4

iTrader: (2)

It looks like he's working on an attachment....wait for it (I hope )

ARISTOh

iTrader: (3)

It didn't work it was a .mov so I changed my mind and asked a question

Harbinger

A couple hundred for machine work vs $$$ for a new head. Machining + a new HG will make it good as new. Really there is no need for a new head unless yours is severly warped, in which case you would have had other, more significant issues. The amount of material removed is negligible, and they are essentially making a new mating surface to bring the clearances back into spec(and usually better than). If too much material is removed than it would raise your compression, however this can be counteracted with a thicker HG. If it is royally screwed up(too much material removed, wrong thickness gasket), then you could ultimately end up with bent valves - however this is worst case scenario. I would actually be more concerned if they were interested in replacing the head than performing basic machine work.

Have they already performed a thorough valve job, confirming that you do not have any burnt valves, and that the retainers and springs are a-ok?

ARISTOh

iTrader: (3)

One of the valves was "leaking" pressure" but I will ask the mechanic when I pick up the car if they did a valve inspection to confirm, I'm just wondering if the text book certified mechanics at Lexus can do something like this job and do it right....

Byprodrive

iTrader: (1)

This is a simple job for any COMPETANT machine shop. Just need to grind/reface the valve & valve seat, then resurface the head to insure a perfectly flat surface for the head gasket. They should only remove .001-.002" & use stock head gasket. If engine has 40K+ miles I would insist the resurface all valves.