06 4.0L... threw a chain.

[Fix4Dirt]

Sorry to hear that... hopefully your X can be resurrected!

 

[StangsandMavs]

Sorry to hear that... hopefully your X can be resurrected!

Hey ... I've got an update on this that you might not believe... I'll write it up a bit later.

 

[StangsandMavs]

This is long, but it might save someone's engine... so here it goes:


We've had a 2004 Explorer 4.0 since 2012 with ~65k on the odometer when we bought it. I always kept the engine and transmission maintained and we never beat it, but other parts of the car started falling apart and we decided to park it and put this 2006 on the road, a year ago. So, I had this extra 4.0L with 210k miles on it, now... that I knew ran fine and knew was taken care of. I figured I'd replace the cassettes, guides, tensioners, oil pump, and front/rear seals on it and it should be a good swap.

Got everything swapped and installed into the 06... added a brass "t" so I could hook up an oil pressure gauge to it, as was discussed earlier. Cranking oil pressure hit 40... all good. I hooked up the crank sensor, but couldn't get the thing to start though.

The way it cranked didn't feel right. It seemed like an accessory was locking up, and just stopped the entire engine with thud... but then it would crank, again like nothing was wrong.

I fooled around... double checked the intake gaskets, plugs and compression... all good. burnt up a starter in the process... took off the serpentine belt to make sure it wasn't an accessory hanging up. Finally got it running. It ran a little rough, though. At first I just chalked that up to excess fuel in the system.

I put the belt back on and it started again... it idled fine... it revved fine... but was popping and carrying on as I drove it around the yard.

I tried different things, but couldn't get it to run right... after showing him the Forscan images of fuel trim and 02 sensors, my daughter's significant other suggested I double check the fuel pressure vacuum and try to swap out the MAF sensor. It was night, but I went in there and made sure the vacuum line was on and in tact and just swapped out the entire intake tube with the one from the 04.

The damn thing started up perfect. I took it for a short drive and it drove like a champ until I pulled close to my driveway, there was a shudder that I chalked up to maybe an air pocket in the transmission from some lost fluid...

Parked it for the night.

Went out to start it 10 hours later, and it wouldn't start. Cranked... the abrupt stopping during the cranking was back... but it did leave me a code, for the first time...

P0340

CRAP! Not this again!

I sent a video of the engine cranking to my daughter's significant other and he made the comment that it's almost like the engine fired on the upstroke... the belt would briefly squeal when it did that as if the engine was running backwards.

Aha!

That's not the engine timing, that's the ignition timing!

So, I swapped out the ignition coil... nothing different.

I rechecked the compression on both banks, and they were dead consistent with each other...

What's left?

The wiring.

I've had problems with the wiring on this vehicle... since we had it. The insulation just falls off of the wires at bends next to connectors. Even when the issue that I started this thread with popped up, I found some serious wire damage in the vicinity of wires that feed the fuel rail, ignition coil pack, and thermostat... right at the junction where they meet. I repaired that all, though and hadn't thought about it since.

I first cut all of the tape and covering off of the MAF wiring... since that seemed to fix it the previous night... sure enough, found some cracked insulation. Repaired all of that. Then I went and started looking at my previous repair. I was pretty confident that it was good, but I only checked the spot at that junction. I cut the cover off of the rest of the wires and finally... after days... weeks of frustration, it all made sense...

The insulation was gone and the wires were crossed. The signals from the ignition coil were all over the place and were firing when they shouldn't have been, causing the pistons to crash into a combustion... essentially pre-ignition.

So, now my mind is thinking... did this cause the engine timing chain to fail? Did the engine rev and have an unfortunately timed spark blow against its rotation and cause the chain to break in 2?

Was the noise that I originally heard with the last engine really detonation instead of noisy valves?

One of the longer term issues that I've had with this vehicle was the problem with warm starts... almost like vapor lock to those who remember that. Was that a sign, all along, that these wires were compromised?

I've taped everything up and did an old school wrap of all of the wires that I could get to. The engine starts and runs like it should.

So, this forum has ALWAYS helped me... and I thought someone might run into this issue and could use some insight about what it might be. A roll of electrical tape and an afternoon taping up the spaghetti is a lot cheaper and less frustrating than a blown engine, or in this case, almost 2 blown engines.

 

[FordFlintrock]

So the engine with the broken timing chain was swapped out with another?

 

[410Fortune]

Looks like wires were damaged when pulling and installing engines and engine parts
Ouch

Cyl 1 had 0 compression and now it’s running because you fixed wiring and changed intake tube? Help us understand what we are looking at here. Cyl 1 0’comp and piston slapped Valves and now it’s running? Some info missing

 

[StangsandMavs]

Looks like wires were damaged when pulling and installing engines and engine parts
Ouch

Cyl 1 had 0 compression and now it’s running because you fixed wiring and changed intake tube? Help us understand what we are looking at here. Cyl 1 0’comp and piston slapped Valves and now it’s running? Some info missing

This vehicle had a lot of work done to it before we ever got it... even the timing chain that I originally replaced in 2022 turned out to be aftermarket. It was supposed to be a "parts vehicle" but we decided that it was too nice for us to use it as that.

So, these wires were still wrapped in their original conduit with the original tape, as of a couple weeks ago. What likely happened is that the insulation degraded (lots of wires on this vehicle are bad) and moving the wires for maintenance and the various repairs flexed the wire and the insulation literally fell off.

I ultimately pulled the engine out with the blown timing chain and replaced it with an engine from an 04 Explorer, to which I preventively added new timing chains, cassettes, and an oil pump.

I couldn't get that engine to run right, either... so had to keep looking until I found the problem, which probably blew up the first engine. It turned out to be the wiring harnesses that extend from Bank 2's fuel injectors to the ignition coil. They were bad in multiple spots, the first of which I discussed at the beginning of this thread, but the causative problem was in a place further toward the connection to the coil that didn't outwardly look to have ever been mistreated.

 

[StangsandMavs]

So the engine with the broken timing chain was swapped out with another?

Yes. I had the spare engine and since some valves kissed the pistons, I figured it was the best way to go.