Why did my valve hit my piston?

ford141 · May 19, 2014

So I have my motor apart for head gaskets. I sent the heads out to get checked and the machine shop had to replace 5 valves (1 intake and 4 exhaust). I was curious as to why the valves were bad so I took a closer look at the bottom end. I noticed this:

The circle shows where the exhaust valve hit the piston and the arrow shows a crack that starts at the edge of the valve damage.

I'm really wondering what happened here. I do have a mini maxx on the truck but I've never turned it up all the way and I don't beat on the truck. I've also never manually shifted the truck so it has never revved beyond what the computer will let it. Are the stock valve springs that weak? Motor has 107k on it.

As of right now I'm planning to replace just the one piston with a factory stocker and button it back up. All other pistons look fine and the cylinders look beautiful. I don't have the money to upgrade pistons so it is what it is.

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njjeep · May 19, 2014

Did you blow your head gaskets?

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ford141 · May 19, 2014

They were leaking. It would puke the coolant bottle if I drove for an extended length of time.

powerstroked08 · May 19, 2014

Excessive back pressure or maybe an over rev.

Dzchey21 · May 19, 2014

you might want to check piston protrusion before you botton it up

78f100 · May 19, 2014

powerstroked08 said:
Excessive back pressure or maybe an over rev.

Dzchey21 said:
you might want to check piston protrusion before you botton it up

What they said, also has the motor ever been into before? I have seen several sets of heads below min spec, even remans. We don't have much forgiveness on these engines so measure protrusion and heads make sure it's in spec.

ford141 · May 19, 2014

I honestly don't know if it has been opened up before, but it doesn't appear to have been. I bought it used with 77k on it and I have no idea what the history was in it. I do know that it was bone stock when I got it and didn't appear to ever have been modded. I have never overevved it in the 30k miles that I have put on it.

What would cause excessive piston protrusion?

I will measure the heads since I know the machine shop milled cut them for flatness.

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ford141 · May 19, 2014

Excess back pressure may be a clue since I have gotten a code for high back pressure while towing with the mini maxx set on mild.

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B585Ford · May 19, 2014

ford141 said:
Excess back pressure may be a clue since I have gotten a code for high back pressure while towing with the mini maxx set on mild.

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That's odd. I ran the canned tunes for over a year and never had excessive EBP except on the hottest tunes....of course, I do have a few mods. Any chance the VGT is acting up?

Stroked777 · May 20, 2014

I'm gunna say high ebp, there are several reason as to what caused it, a sensor starting to go bad can give funky numbers and make your back pressure spike dangerously high, also vanes could have been sticking too

ford141 · May 20, 2014

Each time it has done it I was towing up some steep grades with about 10,000lbs behind me. Mini maxx set on mild. Motor wasn't working real hard, mid rpm. When it throws the code it goes into limp and I have to pull over and reset it. It has happen 4-5 times in the 2years I've had it.

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ford141 · May 20, 2014

Vgt works very freely and it has never given me a code. Beyond that I'm not sure if it has had problems, but as far as I can tell it works like it should.

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ford141 · May 20, 2014

Soooo, given my valve contact problem, blown head gaskets, and ebp issues, I'm thinking I should be investing in a waste gate, right?

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Jethro · May 20, 2014

Do you have an egr delete?

B585Ford · May 20, 2014

ford141 said:
Soooo, given my valve contact problem, blown head gaskets, and ebp issues, I'm thinking I should be investing in a waste gate, right?

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A gate never hurts for insurance, but I would look into what caused it. I had 20k miles last year hooked to a trailer that weighed almost 7500 empty and up to 24k loaded (grossing over 30k). On Mild I was never close to having too high of EBPs.

Stroked777 · May 20, 2014

A good idea would be looking into valve springs

sootie · May 20, 2014

replace the ebp sensor

ford141 · May 20, 2014

It has a new EBP sensor now (little late). I do have a full EGR/DPF delete, 4" turbo back, S&B, and No Limit CAC.

I'm going to pull the VGT apart to make sure everything is OK, although it feels very free.

If I do valve springs do I also need to upgrade the pushrods? What springs should I be running with essentially a stock motor with an H&S?

sootie · May 20, 2014

give morgan @ Midwest diesel a call. he will fix you up with everything you require. stage 1 chromoly pushrods will be fine.

B585Ford · May 20, 2014

ford141 said:
It has a new EBP sensor now (little late). I do have a full EGR/DPF delete, 4" turbo back, S&B, and No Limit CAC.

I'm going to pull the VGT apart to make sure everything is OK, although it feels very free.

If I do valve springs do I also need to upgrade the pushrods? What springs should I be running with essentially a stock motor with an H&S?

IMO if you do springs, you should do pushrods. Go with the lowest stage or rating (depends on what brand you go with as to what they call it). Going with a much higher spring rating simply puts strain on the rest of the valvetrain and is not necessary with stock fuel and turbos. If float a valve with your setup on any combination of springs and pushrods above stock, you have an underlying issue that needs to be addressed. Personally, if I was going to upgrade the valvetrain, I would replace the lifters and rockers with OEMs for cheap insurance.