06 4.0L... threw a chain.

[StangsandMavs]

For the 4.0L engine guys...

I did a timing job on our 06 Explorer with a 4.0L a couple years ago... used the complete Cloyes kit... only put about 5k miles on it and the wife came home with a loud tap that sounded like a chain, again.

I tore the top of the engine off... ran a scope down the rear cassette and checked out the front cassette... everything was in tact.

I cranked the engine with it open and observed that while there was a lot of movement on the leaf spring tensioner... I didn't have anything to compare it too, just seemed like a lot... it also seemed in tact.

I did find a lot of broken insulation on wires... including the knock sensor, cam sensor, and bank 2 fuel injectors... maybe something was getting crossed?


The tensioners were all new with the kit, but I had another set of new (hydraulic) tensioners that I threw in, just in case. I addressed all the wiring and cinched it back up. I didn't have an extra leaf spring tensioner. I added some Marvel's Mystery Oil in case it was a matter of something sticking... within about 30 miles of driving, the noise quieted down substantially.

Fast forward a week, and she comes home with the engine tapping again.

I take it for a test drive the next morning... about 8 miles into the drive, the CEL comes on. At the next stop sign, I had to take a right, but it was busy 55MPH, so I had to get on it. It revved up to about 4500 RPMs and I pulled on a quick exit/shortcut to the house... the engine just completely shut off like someone flipped a switch. No noise. In total, it was probably 3/4 of a mile between the place where the CEL came on and the place the engine stopped... with that 4500 RPM rev in between.

I came to a stop and tried cranking it... no noise, but it cranked fast.

Had it towed home.

The CEL was for a camshaft position sensor.

Did a compression test, and nothing in multiple cylinders on both sides... so I figured it was something with the center Crank to Jackshaft chain.

Pulled it back apart, today... cassettes are still in tact, but the crank to jackshaft chain broke... and is laying balled up on the bank 2 side of the engine. The only thing other broken is a piece of the black plastic guide, from the side that doesn't touch the chain. that might have broke while I was cranking it.

Upon a further look, the nylon piece on the leaf spring that rubs against the mount has been worn. This would have had the effect of lessening the tension

Obviously, something was bothering this timing set before the chain flung off. Maybe the tensioner, the chain, or even the sprockets themselves... maybe it was the mechanic's (me) fault... but any suggestions would be appreciated.

Thanks, guys.

 

[Fix4Dirt]

Might jsut be me, but in the first picture, is the tensioenr where it's supposed to be? I drive a 2nd gen SOHC and IIRC the tensioner was definitely not putting that much tension on the chain. IIRC it was more like just a little bit of tension.

 

[Fix4Dirt]

Heres how I think the tensioner should be placed. If Im looking and interpreting your pic right, that must be some crazy stress on the chain.

 

[Fix4Dirt]

Do you happen to remember which way you ran your chain? Im pretty sure neither is right.

 

[Fix4Dirt]

Here it is from when i did my chain (my tensioner broke but it gives you an idea of the amoutn of tension and path of the chain.

 

[Fix4Dirt]

Sorry for so many posts, mroe thoughts came up over time...

Hold on... I see a slot at the top of where the arrow is, is the cross dowel supposed to go there? Was there anything holding both side of the leaf tensioner when you found it? It should be held at the top (arrow) and bottom (where its still held on)

 

[StangsandMavs]

Good eye and thanks for the response...

The chain looks that way because it's not tensioned any longer and the roll pin did not hold into that slot you're pointing toward. I do have pics from a few weeks ago... let me post what it looked like, prior:

 

[Fix4Dirt]

Good eye and thanks for the response...

The chain looks that way because it's not tensioned any longer and the roll pin did not hold into that slot you're pointing toward. I do have pics from a few weeks ago... let me post what it looked like, prior:

View attachment 457354

Got it, that looks normal. Then... I'm not quite sure. I understand that if the roll pin came out of the slot, it would cause a lack of tension, but I wouldn't suspect a chain snap... I will think about this more!

 

[StangsandMavs]

Got it, that looks normal. Then... I'm not quite sure. I understand that if the roll pin came out of the slot, it would cause a lack of tension, but I wouldn't suspect a chain snap... I will think about this more!

Thank you, sir. Much appreciated.

Thinking about it, myself... I believe that slot in the metal there is for the pull pin when it was installed... so the pull pin goes through the roll pin and into that slot until everything is together, and then you pull the pin and the spring tension is applied to the chain.

 

[StangsandMavs]

I like taking pictures of stuff as I'm working on them as it gives me a frame of reference should problems arise in the future... so, here's what it looked like when I installed these a couple years ago:

 

[Fix4Dirt]

Thank you, sir. Much appreciated.

Thinking about it, myself... I believe that slot in the metal there is for the pull pin when it was installed... so the pull pin goes through the roll pin and into that slot until everything is together, and then you pull the pin and the spring tension is applied to the chain.

Ahhh got it. I forgot about that. It's odd that it would snap a chain though, except for age & wear? I will think more though

 

[StangsandMavs]

Ahhh got it. I forgot about that. It's odd that it would snap a chain though, except for age & wear? I will think more though

That's why I think something else is up that I'm just missing.

I've never personally seen a timing chain snap, before. I would note that it snapped right next to the "black" link... could that just be a coincidence?

I'm rotating the jackshaft without the crank and nothing feels or looks like it is interfering with the cams/valves. That wear on the round nylon part of the tensioner has a story, and I'm not sure what it is. Do these chains really move that much while they are running? I tried posting a short video of the engine cranking from a few weeks ago, but it was too large for this forum to host. Maybe it was just the lack of oil pressure in the cassette tensioners, but that center chain was really moving a lot against the leaf spring tensioner..

 

[Fix4Dirt]

That's why I think something else is up that I'm just missing.

I've never personally seen a timing chain snap, before. I would note that it snapped right next to the "black" link... could that just be a coincidence?

I'm rotating the jackshaft without the crank and nothing feels or looks like it is interfering with the cams/valves. That wear on the round nylon part of the tensioner has a story, and I'm not sure what it is. Do these chains really move that much while they are running? I tried posting a short video of the engine cranking from a few weeks ago, but it was too large for this forum to host. Maybe it was just the lack of oil pressure in the cassette tensioners, but that center chain was really moving a lot against the leaf spring tensioner..

Yes without oil (or much oil I would assume) in the the hydraulic tensioners they kind of just flail around alot at least when I used the starter. Wish I videoeed the one I did that to in the JY, haha. When they have oil pressure, they dont move much if at all I think (I have no way of confirming, but when there is low/no oil pressure I hear chain slap on alot of SOHCs but once it builds pressure, no chain slap)

 

[StangsandMavs]

Yes without oil (or much oil I would assume) in the the hydraulic tensioners they kind of just flail around alot at least when I used the starter. Wish I videoeed the one I did that to in the JY, haha. When they have oil pressure, they dont move much if at all I think (I have no way of confirming, but when there is low/no oil pressure I hear chain slap on alot of SOHCs but once it builds pressure, no chain slap)

Thanks again for the responses... and that gets to the next point.

This is an 06 Eddie Bauer... why in the hell is there no oil pressure gauge on these things? I thought for sure there would even be something in Forscan, but nothing. I think I'm going to stick a manual gauge on there before I start it up again. If oil pressure isn't getting to those tensioners, then that might explain everything.

I did change out the oil pump when I did the timing chains, a couple years ago... but according to the Youtube, apparently there's an issue with some of these 4.0L engines that eject the oil screen from the pump and cause a loss of pressure.

 

[FordFlintrock]

My guess oil pressure. Things just do not look real wet with oil in there. Anything in the valve train that heated up due to lack of lubrication will start to resist rotating which will stress the main chain. At a point the main chain gives out. When the parts cool down there would be more clearance and seem to turn okay, maybe.

 

[StangsandMavs]

I've been concerned about that since the problems popped up a few weeks ago. I'm told that the oil pressure has to go below 10 before the idiot light comes on... which probably wouldn't be helpful over 3000 RPMs. Adding the MMO wouldn't help that, either.

 

[FordFlintrock]

Top of the engine is usually first place oil pressure problems are seen.

 

[Fix4Dirt]

Thanks again for the responses... and that gets to the next point.

This is an 06 Eddie Bauer... why in the hell is there no oil pressure gauge on these things? I thought for sure there would even be something in Forscan, but nothing. I think I'm going to stick a manual gauge on there before I start it up again. If oil pressure isn't getting to those tensioners, then that might explain everything.

I did change out the oil pump when I did the timing chains, a couple years ago... but according to the Youtube, apparently there's an issue with some of these 4.0L engines that eject the oil screen from the pump and cause a loss of pressure.

Check if somethings clogging the pickup

Yes these only have the dummy lights... dummy Ford! Haha. You can at least on 2g add a real gauge in by T off where the OE switch is

 

[StangsandMavs]

I spent a long time cleaning the pickup out when I had it apart and swapped the pump a few years ago... I'm less excited about doing that with it in the vehicle, especially since it's parked in the grass at the moment.


I've done the "T" thing on my classics. You can see the oil pressure sending unit, right there... so while the front cover is off, it would certainly be the right time to do it.

 

[StangsandMavs]

Update...

I bought a Ford chain and tensioner... used the timing tool and got it timed up again. I added a 1/4" brass "T" fitting so I could run pressure gauge off of it.

I put the timing cover and balancer back on... figured I should do a compression test before going any further.

Cylinder 5 was well over 200... Cylinders 2 and 3 were just above 180... Cylinder 1 was a 0.

I ran a scope down the #1 spark plug hole and, sure enough, there are 2 crescent marks in the carbon build on the piston... so the valves are bent.

I haven't decided what I'm doing with it, yet... but wanted to check back in. I could have saved myself some time by scoping the pistons before I replaced the parts, I guess.