4.6L Explorer engine timing chain ooops!

[kworonowski]

wow looked almost exactly like mine i used the new sprockets as mine looked worn (shiny teeth) i however didn't change the crank pulley (will be doing soon damn chirp) have noticed a increase in power though even with o2 sensor code (have new sensor just haven't done yet.

[Pontisteve]

So it was the driver's side tensioner arm that wore through? I see it did a number on your tensioner too. That tensioner, by the way, IS the good cast iron one. At least, it was. These are the desirable ones to use.

Seeing as how the chain wore through the nylon and into the aluminum, one has to come to one of these conclusions:

• Factory doesn't run thick enough oil to provide adequate lubrication
• All these guides and tensioner will wear out, probably at a similar mileage
• This is a one-off rare occurance
• Using factory oil (semi-synthetic 5w20) every time would have prevented it
• The 5,000 mile oil change interval is stretching it too far
• The owner didn't use quality replacement oil
• Newer low-zinc oils are to blame

Personally, I think that if you run Motorcraft semi-synthetic 5w20 and filter, this may not have happened. But it's just a theory. My truck at 135k doesn't have an issue... yet.

[RRousta]

I have put a 5w-30 QS synthetic blend oil with more zinc content in this time, with an original motorcraft oil filter.

I tried calling about motorcraft 5w-30 blend oil and we do not carry that oil here in Canada.

I will continue to use 5w-30 oil as I still believe 5w-20 is awfully thin.

All oil change intervals were done no later than 3000 miles (5000kms) every time. It may even be done more frequently as I do not drive the truck as much

My mechanic seems to think that this wear is somewhat normal with a truck with this mileage. When you hear the noise from the front cover do the service!

[Pontisteve]

Who knows if it's dumb luck, oil, or other factors in determining why some motors fail the guides and tensioners earlier than others. But the way I figure, if the oil was slippery enough, the chain wouldn't be eating thru the guide at 100 - 140k. Or put another way, a better oil might have prevented it.

I run stock 5w20 motorcraft semi-synthetic oil in mine, with a motorcraft filter, and change the oil when the reminder comes on (which I believe happens at 5,000 mile intervals). Ford uses 6+ quarts and semi-synthetic, so it's believable that the mileage intervals could have gone up, although I'm skeptical about that... I think it has more to do with consumer ratings magazines 'cost of ownership over x miles' ratings.

Ford could have offered 10w40 or even 10w30 for a 'rough service' oil product, but they didn't. I'm sure the 5w20 oil is all about energy conservation, as the lighter weight oil weighs the crank down less, and picks up gas mileage. But remember, we have CNC machine work that allows tighter tolerances now, and the motor was built for this oil from the ground up, unlike the older motors made for 30 weight.

I've owned mine from about 80k to 135k, and so far haven't had any problems with the guides. Yet...

[yglide123]

I get to join your club of broken timing chain guides. I've got an 03 Eddie Bauer with the 4.6 at 115k miles that recently started sounding like a tractor on startup, but would then go away. This thread was great for tracking down the issue.

I pulled the valve covers and sure enough, driver's side guide is split in half and loose. Passenger side timing chain seems like it has more play than it should, but the guides appear intact from the top. I am planning to replace (hopefully) just the guides, tensioners and of course the gaskets.

Did all of you drain the coolant/engine oil as the Chilton's book suggested before removing the front cover? I will post pictures later when i get more of it apart.

Oh, and to add to your oil discussion from earlier, it's only had mobil1 5w-20 full synthetic with a mobil1 filter since 70k miles. Maybe I should switch back to motorcraft in the future?

[CDW6212R]

Originally Posted by yglide123

I get to join your club of broken timing chain guides. I've got an 03 Eddie Bauer with the 4.6 at 115k miles that recently started sounding like a tractor on startup, but would then go away. This thread was great for tracking down the issue.

I pulled the valve covers and sure enough, driver's side guide is split in half and loose. Passenger side timing chain seems like it has more play than it should, but the guides appear intact from the top. I am planning to replace (hopefully) just the guides, tensioners and of course the gaskets.

Did all of you drain the coolant/engine oil as the Chilton's book suggested before removing the front cover? I will post pictures later when i get more of it apart.

Oh, and to add to your oil discussion from earlier, it's only had mobil1 5w-20 full synthetic with a mobil1 filter since 70k miles. Maybe I should switch back to motorcraft in the future?

Your oil and filter are fine. Most likely the failure was from a collapsed external tensioner, the easy parts to change. Those have a spring inside and the tension comes from both that and oil pressure. I think those springs are going to be giving up far sooner than people think, or Ford says. I'll bet on 75-100k would be plenty of life to get from them.

[yglide123]

Driver's side guide was totally broken, but the tensioner was still alright. No noise was coming from this side (that I could tell).

Passenger side on the other hand, tensioner had completely collapsed and chain was very loose. I replaced all guides and tensioners which took up most of the slack. No more tractor noises at startup - but wish I had just gone ahead and done the chains too while I was at it for peace of mind. I think the passenger chain is still a bit looser than the driver's side....

[Pontisteve]

The tensioner will take up all the slack without much effort, and the chains are heavy duty. They'll never break. However, they could stretch some, causing the cam timing to be retarded and lose low end torque and probably gas mileage.

[RRousta]

Originally Posted by yglide123

I get to join your club of broken timing chain guides. I've got an 03 Eddie Bauer with the 4.6 at 115k miles that recently started sounding like a tractor on startup, but would then go away. This thread was great for tracking down the issue.

I pulled the valve covers and sure enough, driver's side guide is split in half and loose. Passenger side timing chain seems like it has more play than it should, but the guides appear intact from the top. I am planning to replace (hopefully) just the guides, tensioners and of course the gaskets.

Did all of you drain the coolant/engine oil as the Chilton's book suggested before removing the front cover? I will post pictures later when i get more of it apart.

Oh, and to add to your oil discussion from earlier, it's only had mobil1 5w-20 full synthetic with a mobil1 filter since 70k miles. Maybe I should switch back to motorcraft in the future?

I had the oil drained (oil change), and coolant dumped since i replaced the water pump while i was in there. I poured about 1L of cheap oil down the filler and drained out the plug to wash away any residue before I put my choice of oil in.