dropped valve seat....

[catoiler]

Well we were on our way to the lake and going down the fwy at about 68 mph when the motor starts making a chirping noise. The kid looks over at me and and we go oh oh this ain't good!pull over and the truck goes clunk and backfires and started missing. First thought lost an injector,then I talked to Jake(drag diesel)and he said maybe valve seat. After a long night thinking about it I am pretty sure that is what it is. He said their were a few others that had dropped a seat as well. My question is why are they dropping out?Are the tolerance to loose?Of all the motors I have built this is the first to drop a seat,and on a stock head to boot!I am sure it is #5 or 6. I will get it back home and pull the head and find out what went wrong!I was wondering just how many have lost a seat?Oh well time to get some sleep!

 

[RustyJC]

Are the tolerance too loose?

Insufficent interference fit can cause a dropped valve seat. Unfortunately, excessive interference fit can also cause a dropped valve seat since the valve seat will collapse and fail due to excessive hoop stresses at high temperature when it tries to grow. Experience with several brands of large industrial engines we manufacture has demonstrated that there's a very narrow range of acceptable interference fit that will hold a valve seat insert in place.



Rusty

 

[n7gxz]

Could #5 & #6 be dropping seats because of a lack of cooling? Is the head getting too warm and with just a little too loose of an interference fit they are dropping out.



Kevin

 

[Gary - K7GLD]

It may well be a dropped seat - but don't rule out something less serious, such as broken valve spring, or a damaged or loosened rocker arm...

 

[Bob4x4]

How much you want to bet that head has seen at least 1600 degrees?I've seen you run that red truc Mike



Bob

 

[catoiler]

How much you want to bet that head has seen at least 1600 degrees?I've seen you run that red truc Mike



Bob

not this one!this is a new one :-laf well got it home,now to continue the vacation!when i get back i'll rip into it and see what went south!gotta say even missing a cyl it still ran great!!