I have a 2006 mark lt I bought from bank, runs great when cold as soon as it warms up it runs bad and spark knocks loudly. displays knock sensor and cam position sensor codes. I changed the position sensors, crank sensor, both phaser solenoids, spark plugs and all of the coil packs. all of that didn't change anything. had garage look at it they said the guides were bad, so I took apart nothing looked bad (except for wear on block and case by the left chain) but was out of time so I replaced chains sprockets phasers, guides and tensioners. I started it up it ran fine until warm then stared running bad and eventually broke down, I took apart and the new left side timing chain broke. so I replaced that chain got marks all aligned put new tensioner on that side and reassembled started it up. it ran fine until warm then started running bad again so after all of this I am still at square 1...… help!!

 

I'm very curious about --- "the new left side timing chain broke. so I replaced that chain got marks all aligned put new tensioner on that side and reassembled started it up. ..."

Without personally experiencing such - I would think THAT would tear HELL out of a lot of stuff. (Maybe Not. I've read "Conflicting" reports about these engines being 'interference engines'. And I never wanted to TEST that).

You didn't mention replacing the oil pump - which leads to the next point.

More to your point. Have you 'removed' the oil pan and checked the Oil Pump pickup tube. Broken chain guide 'debris' CAN & WILL sink to the bottom right below the pickup screen. As oil thins from heating up and oil flows more freely, the junk gets sucked up into and clogs the pickup screen causing "cavitation" (or air bubbles in the oil galleys). Air compresses (is spungy) - where oil does not. This results in poor cam phaser operation when one warms up.

 

The chain breaking doesn't seem to have effected anything. I have not removed the oil pan. Can it be done on a 06 Mark lt 4x4 in the truck?

 

Yea, but it is more trouble. I have no experience there as my F150 is 2WD. But I've seen posts on here about it and it is definitely do-able. If you had BROKEN guides, you have junk in the pan --- for sure.

 

There was no broken guides or anything to suggest any loose pieces in the motor but it's probably my next step.

 

You might (meanwhile) put an aftermarket Oil Pressure Gauge on it to 'verify' idle Oil Pressure. Even if temporary. You can pick up a cheap OP gauge, Brass "T", and a length of 1/8 copper tubing for a few bucks and temporarily hang it under the hood somewhere. Reasonably cheap and easy diagnostic effort.

If it will not maintain > 15 to 17 lbs pressure at FULL HOT IDLE, it is in the borderline region of having trouble keeping phasers at full advance. Somewhere down there, the CPS signal (which is a component of Ignition timing) begin to jump all over the place, resulting in VERY RAGGED Idle. This might be caused by oil pump cavitation or just plain ole ware degrading idle oil pressure. Attempting to avoid this un-pleasant situation is what leads many to include HV oil pumps in their timing job parts list.

 

"I took apart and the new left side timing chain broke."
Lets get on the same page -is this a 4 valve Lincoln with a double overhead cam which could be a second chain between cams .
Next when you say left is that the drivers side or passenger side .
Breaking a chain is very serious and unusual,do you think chain was aftermarket and defective . We have seen seized cams wring clean in two for lack of oil . Worse other condition is valve to piston contact and you would be lucky if it just broke the chain it would be a miracle if no other damage .
You may need an inspection camera for a cell phone they are cheap now to look in cyl. Unless you can find a obstruction in timing area . like maybe a bad guide -- it does sound like a poor chain .
To me its a given to pull head on that side if no hole in piston.

 

I agree completely --- up to, but not crossing, the red-line of disbelieving the OP as the engine running fine afterwards until warm. As for piston damage, I remember reading, on this forum I think, a post swearing intentionally rotating both cams and the crank with heads on and timing chains OFF - just to see if interference would occur. Other than that I cannot say, except if it runs fine cold, I guess I wouldn't worry about heads or pistons.

But if there is a position a cam can stop turning with no valves open far enough to touch pistons --- the OP is damn lucky. Additionally, I cannot imagine a chain breaking and NOT sliding down and piling up around the Crank gear. The teeth on that thing grinding around on bunched up chain links looks like would destroy timing cover, oil pump - if not bottom of block.

 

This could be very interesting ,hope he gives feedback.

 

I just replaced heads, timing set and oil pump on my 4.6 1997. The truck ran fine for 4 miles. I shut it off and upon restarting ran rough. I pulled valve covers to find a broken cloyes timing chain. Clean break. Ill run a borescope to see damage at crank. Not sure if i did something wrong or just bad luck?

 

Breaking a chain is serious , we were hoping to get some feed back experience . It makes me think of a lack of oil circulation or perhaps bad cam bearings -seizing ,not putting on a new crank gear would be bad also . I have heard of cams being wrung in two pieces .The chances of bent valves and holes in pistons go way up for a break .