Valve seats

[Rick007]

Hi all ,

Bin working on my engine and discoverd i had a leaking valve , so a rebuild is eminent . But searching tru the forum and internet gave me different opinions if installing
hardened valve seats would be a plus or not . 
The general opinion is that our engines have no trouble with the modern unleaded fuel ......after seeing my valves i'm not so sure. 
In normal driving i always used an addetiff to guard the valves , and try to find the highest octane fuel avalable , as a sort of peace of mind ...but still .
My question is ; would installling hardened valve seats have any disadvantage at all ?

 

[stickandrudderman]

No disadvantage that I know off, plus you have added peace of mind.
The original seats however are capable of withtanding the forces to which they are subjected when using unleaded fuel.

[Shvegel]

Lead has been totally banned since 1991. In that time countless miles have been driven on our cars and there does not appear to be any epidemic of valve issues.  I am a fan of leaving well enough alone in this area.  I have seen too many well meaning machinists make things worse by trying to fix the unbroken. 

Unless the seats have been machined so much that they are too high in the head I would leave them be.

[Rick007]

Your absolutly right in leaving things alone that work and proven themself ......but then again my valves did'nt looked that good and a total rebuild is taking place anyway .
Is it not good practice then to have them installed ? I can't find any agrument not to do this . 
And does E10 gasoline , wich here in Europe at least is becomming a standard in the near future , effect the valves in any way ? 
BTW leaded fuel over here ( and in Germany ) was still available untill aprox 5 years ago.   

[ja17]

Your engine came from the factory with hardened valve seats and valve alloys.  If you own a Mercedes which was produced in 1955 or older you may have to change the valve seats for modern fuels.