4.6L Explorer engine timing chain ooops! | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

4.6L Explorer engine timing chain ooops!

Got a local customer with an Explorer who came to the shop with a noise coming from the front cover. As I suspected the timing chain guide on the pass side was broken completely and both movable guides were worn through, right down to the tensioner. Attached is some pics.....


  • 000_0180web.jpg
    56.2 KB · Views: 42,418
  • 000_0181web.jpg
    89.4 KB · Views: 94,731
  • 000_0182web.jpg
    58 KB · Views: 38,425
  • 000_0184web.jpg
    85.2 KB · Views: 86,931

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

As you can see in the 1st pic the tensioner has been "ground" down by the timing chain. This is after the chain wore through the tensioner guide. 2nd pic is the "timing wheel" which the crank sensor gets it report from. You can clearly see that the chain was really loose. Bottom pic is another pic of the tensioner guide showing the tell tale signs of being completely worn.


  • 000_0188web.jpg
    59.9 KB · Views: 35,482
  • 000_0187web.jpg
    88.1 KB · Views: 36,069
  • 000_0186web.jpg
    66.1 KB · Views: 35,783
  • 000_0185web.jpg
    48.5 KB · Views: 36,367

final pics


  • 000_0189web.jpg
    62.4 KB · Views: 35,238
  • 000_0190web.jpg
    46.2 KB · Views: 36,766
  • 000_0191web.jpg
    94.5 KB · Views: 35,162
  • 000_0192web.jpg
    88.2 KB · Views: 35,373

Wow. I ran the phooey out of my 4.6 TBird back in the day, never a problem. I guess that is a high mileage motor? Or is it on some power adder?

Interestingly enough this is a naturally aspirated 4.6L Explorer engine. Basic bolt on's (CAI,catback,underdrive pulley,HensonToon). He is considering a set of cams. I told him while it is out might as well get 'em. If he decides to go with the cams I will highlight a full installation and get video of the sound.

This is definately not a normal failure. This engine has around 107K. Alway run sythetic oil. I am around alot of Mustangs and I haven't seen this one yet. OUCH!

My 5.4 3v ran through a tensioner, destroyed the VVT unit, and completely lost compression in 1 cylinder at around 105k :)

My 02 engine failure at 82000 miles

I bought my 02 explorer used with 82k at 87k the timing chain tensioner let loose and the right side front cylinder sucked a valve through the piston. Now a new remanufactured engine is going to cost $4000.00 to install.

I am not a happy camper to say the least!

that was bad. you should c the state police cars. very common problem on those. I've been with the state police motor vehicle division for about 7 months and have done 3 or 4 and have heard about alot more. and i'm sure more of them are actually like that they just haven't broke anything yet. had one that ate both tensioners. i don't know how it was running it was so bad.

Got the parts in and got the engine timed. Will post some pics-j

What did the noise sound like??????

Chatter,chatter,rattle,rattle, pop,pop.- Kinda like a rod bearing let loose but the harmony wasn't perfect with the rpm's.-j

Replace them.

How hard is it to replace the chain tensioners?

I suspect my 03 Explorer 4.6 may have the same thing starting to happen at 100k. It's made noise since I bought it at 85k. My noise sounds like a piece of broken catalytic converter rattling around in the cat, or maybe like a torque converter problem of some sort. It's load-sensative, and seems to mostly do it while accelerating from 0 to 60. The noise always lets off as the tranny shifts (I'm thinking due to lack of load), and goes away as the truck enters 5th gear, especially with the converter locked up.

An ex Ford tech told me he recognized the noise, it was a common problem, and was the timing chain guides. Once he told me that, the symptoms seemed to fit. There's no rod-knock type of noise. Just a SHHHHHHH noise when accelerating. It doesn't seem to be getting any worse, oil changes don't affect it, and it goes away above maybe 2500 rpm.

Can you change tensioners or guides without having to retime the motor? I'm hoping to not have to buy the 2v cam timing kit. How much work is it on an 03 explorer? I've done this job on 4v Mustangs, but I'm guessing the explorer chassis is a bit tougher to work on, due to it's height and size. Couldn't you just paint the chain links and the timing gear before you disassemble that tensioner, so you don't have to retime the motor from scratch?

I would recommend retiming the engine for the insurance of knowing the engine is timed correctly. This would only ensure (if the tensioner was broken) that the engine hasn't jumped a tooth. I would not replace just the tensioner anyway. Usually the sprockets get wear and the chain has surface damage from not being tight. I would recommend replacing the entire timing setup- chain,tensioners,guides,etc.

Do my symptoms and noises match up with what your customer had?

Without being present it will be hard to tell. It actually sounded like a wrist pin rattle except it came from the front of the engine.-j

Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!

My noise doesn't sound like a knock at all. Just sounds like a lot of small pebbles being spun around in a coffee can (but it's nothing like detonation). It's not really there at idle, which makes it hard to diagnose. It's only evident under load at acceleration. Once it gets up into overdrive or converter lockup, the noise is gone. And it also goes away during each shift of the auto tranny. I'm assuming that's from a temporary lack of load.

I thought it was broken catalytic converter pieces or a rattling cat heat shield at first, but close inspection of the cats showed no problems there. The noise does sort of sound like a chain being dragged over something metal though, so a failed chain guide seemed feasible.