Cracked Piston thread

Wemoy1 · Jan 7, 2013

I started a nono and figured before it got worse id better mover but what are alot of people seeing temp wise on there 6.4s EOT vs ECT before they know they have a cracked piston. My truck runs like 199 t 201 on EOT and 196 on coolant temp and am curious if what are the talltell sysmptems before the heads are pulled?

Dzchey21 · Jan 7, 2013

Usually there is no real sign.

They just kinda crack and leave a surging high pressure in the crankcase is usually the only symptom which is too late.

Mine were cracked slightly but no sign at all before hand

Beans71086 · Jan 7, 2013

Dzchey21 said:
Usually there is no real sign.

They just kinda crack and leave a surging high pressure in the crankcase is usually the only symptom which is too late.

Mine were cracked slightly but no sign at all before hand

:whs:

I had 3 with hairline cracks in them, truck still ran and drove fine.

Wemoy1 · Jan 7, 2013

ok no high oil temps or anything of that such. i have 63000 on my truck last 40000 have been with tune and wastegate just curious if that makes a differance. I am hoping to look at the engine with a borascope when I pull the injectors and see what the back pistons look like.

Mpoage · Jan 7, 2013

My buddy just cracked at least one in his truck saturday morning. He was pulling his camper and heard a loud pop and it started spewing oil from the passenger side of the motor. It has a lot of blow by as well. I drove it on the trailer but it had a hard time doing it. Pretty sure it blew a glow plug out of the hole, not sure why though.

Its not a small camper by any means.

Wemoy1 · Jan 7, 2013

ouch that sucks

Dzchey21 · Jan 7, 2013

Nope oil temps as normal.

The glow plug probably got damaged and or hydrolocked and pushed it out.

You gotta check carefully tho because more than likely it broke a piston and the crank case pressure forced the glow plug connector out of the valve cover. The glow plug is prob fine.

I do not feel bad about getting rid of my black truck now... Lol

WoodBoy · Jan 7, 2013

As far as starting cracking, like Dustin and Kelly said, there is no way to tell unless visually inspected, if you have signs of a cracked piston, you probably need to be looking for some .20 overs

Powerstrokeracing · Jan 7, 2013

ImageUploadedByTapatalk1357617721.717349.jpg

Found this Monday on a 6.fo. Suckers are hard on pistons lol

Powerstrokeracing · Jan 7, 2013

Dzchey21 said:
Nope oil temps as normal.

The glow plug probably got damaged and or hydrolocked and pushed it out.

You gotta check carefully tho because more than likely it broke a piston and the crank case pressure forced the glow plug connector out of the valve cover. The glow plug is prob fine.

I do not feel bad about getting rid of my black truck now... Lol

This happened to one we saw. Blow by pressures were through the roof and started pushing the glow plug harness out. Haven't seen many glow plugs damaged unless its real nasty.

Mpoage · Jan 7, 2013

Dzchey21 said:
I do not feel bad about getting rid of my black truck now... Lol

That right there. ^ That's one reason why I returned my 6.4 to stock and sold all the goodies. I was scared of cracking a piston. It ran really good but I just dont have the money to fix it if something were to happen.

Dzchey21 · Jan 7, 2013

Mpoage said:
That right there. ^ That's one reason why I returned my 6.4 to stock and sold all the goodies. I was scared of cracking a piston. It ran really good but I just dont have the money to fix it if something were to happen.

It wasn't even so much as that for me. The truck had a low mile long block in it and even then I was worried. I knew it could be fixed but the thought of sitting on the road side with my wife and kids with a broke engine and a Camper in no cell service areas... Freaked me out and I decided it was time to part ways.

As far as my reg cab goes... No big deal if one breaks...

HD F250 · Jan 7, 2013

I hope the HD coated pistons can hold up to the heat and pressure.

mike@haller's · Jan 8, 2013

Wemoy1 said:
ok no high oil temps or anything of that such. i have 63000 on my truck last 40000 have been with tune and wastegate just curious if that makes a differance. I am hoping to look at the engine with a borascope when I pull the injectors and see what the back pistons look like.

I havent found a boroscope that handy in finding the crack, unless its really big. The crack is almost always at the 3 o'clock or 6 o'clock position on the edge of the bowl from what ive seen atleast. When you look with the camera, your looking through the injector hole in the center and cant really see the edges very well. Plus there is usually soot and some diesel fuel that gets in that hides the crack. So just cause you dont see it through the injector hole doesnt mean its not there.

Morgan@Midwest Diesel & Auto · Jan 8, 2013

mike@haller's said:
I havent found a boroscope that handy in finding the crack, unless its really big. The crack is almost always at the 3 o'clock or 6 o'clock position on the edge of the bowl from what ive seen atleast. When you look with the camera, your looking through the injector hole in the center and cant really see the edges very well. Plus there is usually soot and some diesel fuel that gets in that hides the crack. So just cause you dont see it through the injector hole doesnt mean its not there.

Generally they crack along the plane that is parallel to the pin bore of the piston in any engine. That being because it is the thinnest place. That doesn't rule them out from cracking other places as well. The 6.4 piston on general is a poor design for many reasons one being the hollow cooling cavity cast into the bottom of the bowl area. The skirt and pin bore areas are also weak by design. Also whenever you can minimalize the bowl lip it will remove a thin spot where heat can't dissipate very fast and cracks start to form.

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these are of a Dmax I'm building right now. Guy had big compounds, dual pumps and nozzles. Cast pistons will not take that abuse very long......oh yea and that brings me to the last weak point of 6.4 pistons, cast aluminum!