valve to pistion contact

[Cutting-Edge Diesel]

Have a truck came in and had a lifter come apart. (cylinder 1) but on cylinder 8 noticed there was major valve contact on one of the exhaust valves and very slight on the other. Every time i have seen contact it has been even. Any ideas as to what could have caused this? The truck does have head studs so I imagine the heads have been decked but if that was and issue I would think it would be all the valves not just one.

 

[Gary]

Hmmm. not sure on that one, but any valve that hits a piston needs to be replaced, or they eventually break.

 

[Gearhead]

How did the valve spring test at the installed height?

 

[Dzchey21]

def need to check the spring, thats an intake valve so really it shouldnt ever hit, unless something got stuck between the valve and the seat but even then the valve should have probably dropped by now. That kinda looks like its been hitting for awhile

 

[Cutting-Edge Diesel]

its an exhaust valve

 

[Cutting-Edge Diesel]

How did the valve spring test at the installed height?

not following matt lol please explain.

 

[Dzchey21]

how much spring pressure at installed height i think is what he is asking

my bad i was looking at that wrong

 

[Cutting-Edge Diesel]

not sure i have the tools here to test that.

any one else have any ideas? Should i take the head to my head shop to get checked out?

 

[e.nickkk]

I have heard under high boost and weak valve spring that is could happen

 

[jimdawg185]

You can get installed height on a few of the other exhaust valves and compare. It might need a shim to bring it up to the others. Getting installed height can be done a few different ways. Easiest is with an installed height micrometer. But you can get fancy with inside mic's and such depending how the casting is in the way. If its out of wack that can get you goin down the correct road.

 

[dirk0]

High drive pressure and going deep into the rpm red zone

 

[Cutting-Edge Diesel]

I have heard under high boost and weak valve spring that is could happen

yup had this happen on my race truck.

but this truck is stock.

 

[e.nickkk]

Was this a stock truck that it happened to

 

[Crack85]

Was this a stock truck that it happened to

Yep. See post above

 

[dirk0]

Here is an example. Truck still runs. I'll send more pics of other cylinders if you want. Just send a pm.

 

[Cutting-Edge Diesel]

im confused as to what your trying to show. i know high drive pressure and high rpm can cause valve contact.

what im trying to figure out is why is it just this one. not just this one cylinder but this one valve.

 

[suprdzlduty]

like previously said, it looks as though its been hitting for a while...if the heads were decked and a lot was taken off, and they trimmed the top of the valve to compensate for the decking, maybe missed that one valve? I would check that particular valve height. also if a lifter went, I would check that lifter on that intake and see if its ok. could be coming apart too some how...just a thought.

 

[02POWERSTROKE7.3]

Hey Matt check that valve spring good and make sure its not cracked. Also need to check the heads are cut properly for the valves.

Sent from my SCH-I605 using Tapatalk 2

 

[Cutting-Edge Diesel]

I mesured the valve spring and it's the same hight as the others.

 

[dirk0]

I mesured the valve spring and it's the same hight as the others.

Are you able to measure what the spring rate is compared to the others?