4.0L Timing Chain Replacement | Ford Explorer Forums - Serious Explorations

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4.0L Timing Chain Replacement


September 20, 2012
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Year, Model & Trim Level
04 Mountaineer, 4.0l AWD
Well it has come that time where I need to start doing some thinking about my vehicle. I'm at 105k right now, and I feel like I have crested that hill on reliability. So far all I have replaced is minor things (Fuel pressure sensor, wheel bearing, balljoints, ect.)

Well now bigger things are starting to go. Obviously the trans has seen better day's. No flashing O/D or anything, just a slip here and there and a lot of clunking when shes upset. But the main problem that has recently been getting worse is the timing chain rattle. At first (2 years ago) it was very very mild, and I put it off that it was normal operation. Currently I can hear it from about a block away especially on a cold start up. Figuring it was making a racket from the cold (-20), damn Minnesota, up until recently I've started worrying. Here's a short clip I took the other night, its warmed up considerably and still sounds like a powerstroke.

Oil wise I'm on 2k for this oil change, and running full synthetic since 100k. I'd like to bounce Ideas off you guys and see what you think. When it warms up a little bit, and I have some time (probably next week) I'm going to pull the pan to check for plastic. If I find any, next will be a valve cover and the front cover to determine which tensioner has failed. As of now I will be probably be replacing the tensioner unless its a rear:eek: Then I will have to see. I will be doing a write up on both checking and replacing the tensioner, because it seems to be a very common problem now that I have researched it.


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Although at a different mileage (220000) I am getting ready to tackle the same problem. Timing chain has been rattling for about a month, found plastic in the lower pan. I am going to do the front with it in the vehicle, if its the rear....well, we all know what that entails.

Hope to see some good do's, don't and look out for's in this thread from others who have tackled this.

I am about 90% complete with replacing all the guides and most of the chains in my daughter-in-laws 2003 Explorer 4.0L. It had blown a head gasket because it overheated so i decided to do a top end rebuild. I pulled the engine although I discovered along the way that you can pull the passenger side head and replace the cassette without pulling the engine. I also discovered that the balance shaft tensioner was toast. If you are going to do all the chains and guides let me recommend a Cloyes set. They have a reputation of good quality. Good luck and happy knuckle busting. Those top motor to tranny bolts are a bear!!

Thanks guys,
I just arrived back to school after being on spring break, I should be pulling the pan in the next day or two. When you pulled the engine/heads did you find any plastic that made its way through the oil galleys and into the valvetrain? I feel like the small oil ports for the lifters would love that plastic in them :eek:

Well, this is the end

So the other day It was nice enough to be able to get some work done on the truck. First thing I needed to get done was pull the pan to see if there were any pieces of tensioner left in it.

Socket set
7,8,9,10 mm's are important
Oil catch pan
Fresh Oil
New filter
Jack, Jackstands, wheel chocks
New Oil pan gasket (Lower). Optional if yours is in good condition.
If not, its like 16 bucks at autozone.

1. First I started by getting the vehicle off the ground.

2. Next, you will need a half inch (I think) drive socket or wrench to pull the drain plug. Let drain for at least 10-15 mins to prevent a mess.

3. Use a 10mm socket to remove oil pan bolts, Leave the middle two middle bolts on each end about half way to prevent the pan from suddenly falling on your face with oil. This way you can safely pry the pan off because It will want to stick to the block/lower girdle.


4. Now you hope and pray nothings in there, but oh well. Unfortunately when I dropped mine there were pieces of the tensioner sitting in there :mad: .

So once I discovered that (even though I kinda knew it was coming) it was time to find out which tensioner went bad. So to bit the bullet, I decided to pull the passenger side valve cover off to hopefully rule out that it was the rear tensioner or guide.

I apologize in advance for lack of step by step pictures, I was having camera issues.

5. Now that you have the pan off, climb up on board and start removing the air box assembly. Upper, lower, filter and tubing to throttle must go.

6. Next comes the bracket for the A/C lines mounted to the block, behind the alternator. It was a 10mm and a 15mm I believe.

7. Now this is where the jump in photo's begins. At first I though I could get away with pulling just the throttle body and sneaking the cover off, however this became hard because of the egr tube. So I decided I was just going to pull the whole intake manifold off to make life easy. 12 torx bolts secure it to the motor, this is where it helps having an extra hand. The rear most torx bolt along the fire wall on the drivers side is a strait up *&%$#. You will also need to carefully remove the egr tube and fitting. I used a monkey wrench and a generous amount of pb blaster. Once all the lines are off the intake and the bolts are out, carefully remove it. Make sure not to drop anything in the valley for it may choose a path down the intake ports.
Important! Put rags or towels in the intake ports, or block them somehow. You don't want sockets going down there.

8. Once the intake manifolds out of the way, there's like a whole acre of space to work under there. Next I removed the fuel rail, you might be able to get away with not pulling it but I felt it was faster to just remove it. You will need a fuel line disconnect tool for the part of the rail that runs above the valve cover. Have some extra rags on hand to clean up the bit of fuel that comes apourin' out. Some explorer's might not have that fitting over the valve cover? Not 100% sure on that, but if you can, disconnect it. If you choose to remove the rail completely, be very careful. You want to pull the rail off the top of the injectors, not the injectors out of the head. There are two bolts holding the fuel rail in place. Have a buddy hold the injectors in place while you pull up on the rail. There a blue o-rings sealing the top of the injector to the fuel rail, make sure not to damage or loose these.
Injectors (RED)
Fuel Rail (GREEN)
Fuel Rail Fitting (BLUE)


9. Now you can unbolt the valve cover from the head. Some of the studs for the valve cover are hidden under the spark plug wires, just use a pliers to yank the plastic holders off the top of the studs. Now remove the valve cover. You will need to slightly bend the egr tube back to make clearance for the cover.

10. And now this is where it gets sad. As soon as the cover came off I saw the problem. Turns out the read guide had come apart:mad: . And the chain was now riding on the mounting bolt for the guide, it had worn pretty well into it.

11. Taking a peak down into the head, I found a large chunk of the guide sitting down in there. With a set of very long straight, and bend needle nose pliers and a mirror we got the chunk out.


And here she is:

12. After we got the pieces out, I decided pulling the other valve cover is a good Idea. It comes off the exact same way as the passenger side. There's no need to remove the fuel rail on the drivers side. The drivers side tesnioner and guide were both in good condition and all in one piece. Once you're finished, everything goes back together the way it came apart. Just give the fuel injector o-rings a good cleaning before you put the rail back on.

I decided to pull this bolt out so the chain wouldn't cut into it anymore, its a bit tricky to get out, but if you use a pry bar to slightly push the A/C lines back, you can sneak a 1/4in drive with a torx to get it out.

Now I have a good deal of thinking to do. Should I fix? Should I sell? Should I swap? Fixing can be an option, however if the motor every leaves this vehicle its never going back in :D. Either a 4.6l or a 5.4l would be going in. And as for the trans which is starting to give me trouble, I wouldn't want to keep that either. I've done some late night craigslist and ebay browsing and thinking about swaps, but being realistic, I don't have the time or $ to do either being a college student. I've been oogling over OBS powerstrokes and 80's k10's. However I do feel a connection to this mountaineer, its been in my family its whole life and the memory's I've had in it I don't want to loose.
Adam :usa:

Some of the pieces in the oil pan look to be metal. If they are they are probably the flat spring plate to the balance shaft chain tensioner. Mine was toast. You have to remove the ladder skirt to replace that tensioner. You may want to pull the front cover off and check out everything.

Sorry to hear about the problem but just wanted to say thanks for a very helpful and informative write up and photos.

Thanks guys! I'm still trying to decided where this is going, but once I make a decision ill fire up another How To post.

Did you notice any oil pressure anomalies before you tore it down? My guides failed, like yours, but some pieces got sucked up into the pump (guessing), and within a minute of starting it after sitting overnight the oil pressure would just drop to zero.

Keep every piece of the tensioner and guide that you can find, and try to put it back together. If you're confident you got every piece of it out of the engine, then make your decision. If you didn't, you're looking at a complete overhaul to make sure you haven't blocked on oil port with a tiny piece of plastic.

I got $900 for my ST.

I have not (knock on wood). However I pulled out whatever I could when I had it apart, most likely got only half of it considering I'm still missing pieces on that guide alone. I cleaned the oil pickup screen, but that grate filters only the big stuff. At this point anything can go, engines hate particles floating around in them.

What did you get $900 for?

I 5.4L swap is seeming the best option right now for that a friend of a friend rolled his 99 Superduty, (lucky hes okay). Only issue is $, as a college student there isn't a lot lol. After some research on the forums,
Seems that I can go the route of hooking the 5.4L with the 6.8's flex plate to the trans I have now, and trying to figure out computers and wiring harnesses I need. Which most likely would be a complete 4.6l harness and computers. I wish the 4.0l computers would work with the 5.4 :(
Taking 5.4L+trans+transfer case and all the harnesses involved and squeezing them into the mountaineer. Only foreseeable issues are fitment issues, drive shafts, and integrating the SD dash into the mountaineer's location. Fab work is relatively cheap compared to buying 4.6l harnesses/intake manifolds.

Its really a shame that these vehicles don't hold any value. I still have the window sticker and its sad that $32000 can decline to somewhere under 4k.

Looks like all my plans are on hold, rear wheel bearing went out. What a pain...