2012F-150

Hi. I am a Ford dealer trained mechanic but I have NEVER posted on ANY forum of ANY kind before so I really don't know what I am doing here, but here it goes. As I said, I am a dealer trained tech but I have been out of it for about 10 yrs. I own 5 Fords & my wife's 2012 F-150 has a strange problem. It recently started running real rough at all speeds & the check engine light came on. I read the code & it was a misfire code (P0305) it has approx. 66K miles on it which I thought was a bit low for the plugs to be worn out but I changed them anyway. It ran OK for about 50 miles (on the Interstate) & then I heard what sounded like valve pinging/rattling & it started to run real rough again. The check engine light also came back on with the same code. When I pulled the plugs back out, I noticed that #5 was black with oil soot (the orig #5 was like this too) so I know that it's burning oil in this cyl. I checked the compression & it is almost nothing--approx 12-13 lbs. The only thing that I can think of is a stuck valve, broken valve spring, cracked/hole in the piston. I have a '13 model with the same engine & it is fine with about 35K miles on it. When I was going down the Interstate after I put the new plugs in it, riiiiiiiight before it started running rough & the check engine light came on, I heard the valves rattle again. Has this engine had any problems with this sort of thing? I have looked all over the internet & not found ANYTHING like this. I thought if it was TiVCT related the whole bank would be messed up but the other cyls plugs all look fine & the engine runs OK otherwise. It will run better if you gouge down on it however, I'm stumped.....
Next day...I just got the valve cover off & looking at all of the associated hardware for that cyl, I can't immediately see anything wrong with anything. Still stumped....

93Cobra#2771

iTrader: (2)

I'm going to give you the answer you don't want to get. If compression is that low there a hole in the piston, the block, or a valve is compromised. I suppose something in valve train could be fudged too. That air is going somewhere.

Not a very usual problem on 5.0s, in fact it's first one I've heard.

2012F-150

Don't worry you are not telling me anything that I haven't already thought of. You are also probably right in that this a rare problem on the 5.0L. It would be my luck that I am the first one that has anything like this on a 5.0L. When this first happened I got on the internet to see what I could find & low & behold there was NOTHING. Figures. Guess I will try & find an engine for it 'cause I owe too much on it to junk it & it's a nice truck. I figure it has either a hole in the piston or a cracked piston. This is the only way I can explain both the lack of compression & the high oil consumption. As I stated, I took the valve cover off & didn't observe anything broken, out of place, etc. I also had a helper crank the engine over (with the fuel pump relay removed) & watched the valve train & it looked OK. What next??

Northernexposure

Next, use a bore scope and have a look see at the top of the piston... might find a crack or hole, or worse, the head of a valve stuck in the piston. No sense in going any further if you see something major.

93Cobra#2771

iTrader: (2)

You might also turn it over by hand and listening to see if you can hear air escaping back into the intake or down into the crankcase. In fact that much compression being lost could wen pop out the dipstick and such.

Z7What

I agree, next step is bore scope it.

Wayne

2012F-150

Thanks for the info. I also have already thought of this too but I don't own a borescope nor do I know anybody with one. Wonder if you can rent them? Depending on how much they cost, I might just buy one from the Snap-On man. I know they won't be cheap but it might be good for the long run. Just thought I could find somebody on here with some experiences in this area. I'd hate to re-invent the wheel & find out there are other folks with the same problem.

kd460

Cheapie bore scope on ebay...plugs into your computer, only about 15 to 20 bucks. YD

Northernexposure

Harbour freight (in Canada, princess auto) should have a bore scope foot cheep it not like you're gonna use it every day, just every so often.

Blown F-150

+1, get a cheap one, it will tell you what's up. being a 2012 is it out of power-train warranty?

Norhernexposure, I'm sure I'm one of the few that actually know where Arborg is! I'm from Gypsumville, lol.