Cylinder 6 Meldown

[hlfbkd420]

Blew the ring land ?
Cracked and broke away or melted ? Same area as OP, intake side of piston ?

I cannot confirm one way or another, that is just what the dealer assumed. When I took it in, you could tell the car was hurt. Down on power and smoke above 4k RPM. Dealership took a look and came back and said the compression test revealed cylinder 6 was low on compression and I had a leaking valve cover and there was oil all over the headers. The wanted to take the valve cover off to diagnose and see if there was any valve train damage, but by the way, it's not under warranty because of the headers. They listed some other things too but wanted about $1000 for just that bit of work. Geico sold me mechanical breakdown coverage when I bought the car, so I called them. I told them the blower was included on my insurance and that I had modded it with headers, tune, suspension, and everything else I had done. They told me they normally deny any claims that the dealership or manufacturer does but they would call me back.

When they called me back, they said they would fix it, but only because they sold me the coverage when they shouldn't have. When I called to get insurance and mentioned the blower, the person on the phone should have NOT offered the coverage. They said they were just going to replace the whole thing without diagnosing it. Made me put the exhaust manifolds back on (had less than 1000 miles on them) and I had to have the Roush tune put back on as well. Geico paid $13,500 and then dropped me before renewal.

Had the car back for less than a week and took it out for a ride on a hot summer day. I beat on it quite a bit and after awhile it was pulling power. I saw the temperature gauge was close to the red zone so I drove it nicely home and parked it. It threw a check engine light for cats two days later. Melted them. Dealer didn't want to but they replaced them under the Ford warranty. Once they were done and I knew the car was running okay... I tuned it again because the Roush tune sucks for drivability. Car still has high CHT's but I'm done with the dealer.

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[furdfan2018]

Broken ring lands and a melted piston crown are 2 very different things.

I couldn't agree more that the factory ring gap is too tight on these cars, but melting a piston is a different problem entirely.

 

[HKusp]

Broken ring lands and a melted piston crown are 2 very different things.

I couldn't agree more that the factory ring gap is too tight on these cars, but melting a piston is a different problem entirely.

Agreed, but that picture looks wonky that's why I asked him to show a pic of the piston when he gets it out, if he can.

 

[GregO]

Agreed, but that picture looks wonky that's why I asked him to show a pic of the piston when he gets it out, if he can.

Right but it looks smooth with a fine sand blasted texture and the deposits on the cylinder wall coincide with molten aluminum.
I’m curious as it’s on the cooler side of piston area.

Now your pix are clearly 100% detonation related.
Two Stroke related piston failures and a guy learns real fast.
As the Pro level Dyno operators say;
Die and Learn ….

 

[HKusp]

Right but it looks smooth with a fine sand blasted texture and the deposits on the cylinder wall coincide with molten aluminum.
I’m curious as it’s on the cooler side of piston area.

Looking at it again, it certainly does. The melting point of aluminum is about 1200-1300 degrees F and certain aluminum alloy's are anywhere from 800-1250ish, so there was a shit ton of heat for an extended period in order to do that to that piston.

 

[GregO]

Looking at it again, it certainly does. The melting point of aluminum is about 1200-1300 degrees F and certain aluminum alloy's are anywhere from 800-1250ish, so there was a shit ton of heat for an extended period in order to do that to that piston.

I’m jumping the gun here and going straight to my standard default of localized hotspot due to a cooling system anomaly. Undersized cooling system, improperly purged system or low coolant causing such.
A piston melted away on the cooler intake side and for aluminum to adhere to the steel sleeve raises my eyebrow especially when the hot exhaust side looks to be in fair to good condition.

 

[hlfbkd420]

Understood. I was just agreeing that cylinder 6 is a bitch. When they replaced the cats, they also said there was aluminum in the cooling system that was pooled at the thermostat. Causing the high CHT's... I don't know if it was a piston, ring land, etc... Just cylinder 6... That is all.

 

[GregO]

Understood. I was just agreeing that cylinder 6 is a bitch. When they replaced the cats, they also said there was aluminum in the cooling system that was pooled at the thermostat. Causing the high CHT's... I don't know if it was a piston, ring land, etc... Just cylinder 6... That is all.

Could be a habitual hot spot someplace around that cylinder.

 

[mustangdriver]

The original poster said he has a "bad ass tune", does that mean the knock sensors are turned off?

 

[Whitedevil95]

Empty IC coolant res means IAT2 thorugh the roof. High IATs mean deotonation which means break ringland.

 

[MarcasswellbMD]

Thank God for this Forum and all you guy's.. I always get a wealth of information on things I never knew about..

 

[Grimreaper]

Love to know why that side of the piston melted.

I do wonder if weather was a factor for possible kr. Cool dry air requires less timing to stay out of kr on pump.

The air load difference and subsequent timing tolerated can be quite large for the same pulley/ setup (almost two pulley sizes difference from 90* and humid to sub 45*and dry). If the timing tables were built in hot humid air they will be over advanced by several degrees for cooler temps. The dew point average has bit me before as the seasons change. Have to leave some on the table or log regularly and adjust timing.

E85 over compensates so non issue.

 

[Brian-17S550]

Hey everyone, sorry I’ve been busy so I haven’t gotten back to this.

I still haven’t had a chance to break the old block down, but someone was commenting about how it looks like the part of the piston was sandblasted, and then a portion of the piston is on the sleeves. When looking it over last week, me and a friend definitely noticed that it looks like the sleeves were not gouged, but they looked like they had the piston melted on them. My oil pan was full of grains of metal and chunks of metal.

My empty intercooler reservoir was because I had a hole in one of my intercooler bricks. Both of these things happened what I think is at the same time. Hole in the inner cooler, and burned up cylinder six.

Right now I’m just focused on building the new block to get my car back on the road. Just waiting on a new oil pick up tube so I can mount the oil pan and timing cover.

 

[Brian-17S550]

I had the car back together for a few weeks now. It’s running great. 860 HP on the dyno. If anyone needs any help feel free to reach out.

 

[Brian-17S550]

Thanks

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