4.6L Explorer engine timing chain ooops!

[XLRVIII]

. Haven't seen any hardcore proof in the oil either, which confuses me. I expected to see some nylon or aluminum shavings.

Chances are your just eating up Nylon at this point.

when my tensioner pad came off, it sounded like you were pedaling down the road on a bicycle and the chain comes off, hitting the rear tube..it was an AWFUL sound
using the WOT start up it made all the noise go away on start up, and once the tensioner pumped it, the chain wouldn't hit the guide.

While mine was hitting the guide it took less than 2K miles for "glitter bomb" to show up in my oil. it was kinda hard to see at first, it was just a "silver sheen" in the oil.. later it turned to full fledged glitter!

The motor was still running fine when we pulled it
I didn't want it to "saw itself in half" right in the middle of my Bracket Race Points series.

 

[ArthurJGuy]

Well the truck is all back together, she purrs like a kitten

Still would love to know what caused this.

 

[pmcronk]

I have 160k on my 1997 4.6L and want to replace the timing chains and sprockets. The Ford manual from motorcraftservice.com mentions draining the coolant and evacuating the AC while Chiltons does not. Are these necessary? Also it has a step about ensuring the intake valve on cylinder 1 is fully open when the crank is at 114 after TDC. I expected there to be keys on the sprockets to ensure proper alignment, is this (ensuring timing is correct) difficult?

 

[Pontisteve]

You have to drain the coolant in order to be able to get enough access to the front of the motor to work. It's much easier with the radiator and fan stuff out of the way. I don't think you have to evacuate the A/C. As long as you can unbolt the compressor, swing it out of the way, and support it so it doesn't bend the aluminum lines, you should be fine.

I have no idea what 114 after TDC is about. Every one I've seen, you have to have the motor at TDC on the compression stroke on cyl#1 (passenger side front cylinder). There is a tool for finding this easy in the OTC cam timing tool kit, but I use a piston TDC indicator (extra long) that I bought from Innovative Products of America, probably thru Tooltopia.com. It has graduated marks so you can see the piston rise and fall with great accuracy. Just put the #1 piston to the top, line up the black (or copper) links on the chain with the dots on the cam gears, put the crank gear dot straight down to line it up with the chain, and you should be good.

There is a "safe mode" where all the pistons are down the hole some, and it is found by turning the crank to the left of TDC, where the crankshaft KEYWAY is at the 9:00 position. Normally, the keyway is at around 11:00 if the motor is at TDC.

The only huge thing you have to remember is that you cannot rotate the motor over while you have the chains off. Also, sometimes due to valve spring pressure, the motor might want to rock the cams over in certain spots. You shouldn't have that problem at TDC, but you may not far from it. Be careful not to loosen the chains up if the motor feels like it's near rocking over the valvetrain. The camshaft holding tool would prevent this (in the otc tool kit).

 

[mstrader]

I had the same noise and had a mechanic tell me it was the timing chain. Two weeks later the noise was much worse when started like something had come loose. Rockers check out fine and mechanic says motor is bad. Havent torn into the motor, but he said sounds like wrist pin or something has broken loose. I'm looking at replacing the motor with a used one because I'm assuming there could be other damage. Any similar experiences?

 

[Pontisteve]

How many miles on it? Mod motors, for the most part, are capable of high mileage if you use the right (thin) oil in them, and change it regularly. Their only real weak link is probably the timing chain stuff, since some of it is made of plastic. Unless there is oil neglect in the motor's history, I would be very surprised if it was a wrist pin. They're not known for that.

However, a broken timing chain guide, tensioner, or tensioner arm can cause the timing chain to smack around in the cover, making a lot of noise. I heard one that sounded exactly like a main knock to me. Point is, before you condemn that motor, at least rip the timing cover off and see for yourself. In fact, if you're mechanically not up to the task, you can just take off the valve covers. That will give you access to the top of the timing chain. From there, you can probably see with a flashlight, or feel with a screwdriver, if the chain is tight or loose. If it's loose, fixing the chain problem will cure your situation for a lot less money!

In that race motor that broke the tensioner arm, we replaced the tensioner arm and everything was fine. No bent valves, or any other problems. Pull your valve covers, and use a long screwdriver to see and feel if the chain has any slack in it. If it does, fix the timing chain problem. An alternative to a mechanic (who probably doesn't work on mod motors all that often) is to find yourself a speed shop that deals mostly in Mustangs. These are common! The guys that work there will be plenty familiar with mod motors, and may work cheaper than a mechanic. Most of these Mustang shops know their way around a mod motor better than the Ford technicians do.

Also, don't run the motor any more until you get it fixed. If that chain throws off or jumps more than a tooth, you could be in for bent valves.

 

[mstrader]

Timing chain is tight. Can take #4 cylinder offline and cut down on some of the noise. Feel like it is in the bottom end... valve, wrist pin, or rod that has come loose.

 

[Pontisteve]

If you've narrowed the noise down to just one cylinder for sure, then I would inspect the valvetrain carefully on that cylinder. Broken valve spring? or valve head? If the motor runs funny, you could do a compression and a leakdown test. Both timing chains tight?

If its in the bottom end, it's in the bottom end. But that's not real common on mod motors. Don't let a noise fool you into thinking its something its not. You could try unhooking the ignition, and cranking it over with no spark plugs, while having somebody listen carefully with a stethoscope. That might let a bottom end noise be verified.

 

[mason197]

Mine just started making noise from the same side. But it sounds like i now have a kenne bell supercharger.Im guessing it is from warn or broken guides.It started the other day when i had to make a trip in -30 below wether. 69K on the od.
Any one have any more insite? I will soon start a teardown to find the prob.

 

[Pontisteve]

You could use a stethoscope to pinpoint the noise some. You could pull plugs to check for mechanical problems that made it inside the combustion chamber. You could drain the oil and look for telltale signs of plastic or aluminum pieces.

I saw a 4v motor recently, that had obvious chain tension problems, and ran poorly. Ultimately, the motor was torn down and broken oil pump gears were found. The lack of oil pressure most likely created a chain reaction of other parts failing.

I have noticed that typical guide problems sound like an engine knocking. I've been waiting for my "chain problem" to get worse, or verify in any way that that's my problem, and it never did get worse. Sounds like marbles in the catalytic converter to me. I now think it might be a rusty exhaust manifold shield... very hard to pinpoint.

 

[kruegern]

Just had the same thing in a 4.6 with 170,000. pieces of the guide (plastic) have ended up in the oil pan. I have 4 wheel drive so my mechanic is talking about having to drop the oil pan and it being a very big deal. Any recommendations on flushing the plastic out with out dropping pan?

 

[2000StreetRod]

flushing pieces

When the rear guide assembly failed in my SOHC V6 pieces were sucked into the oil pickup tube and trapped in the inner perimeter against the screen. I had to remove the pickup tube and work the pieces out with a bent wire. It might be possible to back flush the pickup tube from the oil filter mount thru the oil pump.

 

[Pontisteve]

Yeah, that's a good idea. The oil pickup bolts to the oil pump, which is mounted on the front of the crank, behind everything else. If you had the front cover off, you might be able to unbolt the pickup tube, I can't remember. And then flush it with solvents, air, etc. Some debris might still get caught in the covered portion of the pickup tube's pickup though. But as long as it isn't enough to clog the pickup area, you might be ok.

I don't think you can remove the entire pickup without unbolting it with the oil pan off. There is a bolt, right near where the dipstick tube ends up in the block, that holds the pickup up in the rear.

You could change the oil for something as thin as possible, 5w20 or preferably less, run the engine for a minute, shut it off, let the oil drain out for 5 minutes (backflushing the pickup), and repeat over and over. Change the oil a couple times in short intervals, like every couple days maybe.

The problem is that the oil pump uses 2 gears that are close fit, to compress the oil, and from there it goes thru the filter. So the pump gets unfiltered oil. If a big chunk gets in there, it could cause pump gear damage.

Since the alternative in a 4wd is grim, I would try it. Perhaps with a mechanical oil pressure gauge hooked up, for constant viewing. If the pump does break, you would be able to catch that right away in this process. At that point, you would still be in for pulling the pan, front cover, etc. But if you get away with it, you're only into the front cover.

If you tried that, I would think about pouring a solvent like mineral spirits into the oil pan from the front/oil pump area. And also backflushing the pump pickup with solvent as well. The idea is you want to be able to wash all those plastic pieces out of the oil pan via the drain hole. I'm talking about a gallon of mineral spirits here.

Then once you fired it back up, any remaining mineral spirits would be mixed in with the oil. A couple quick oil changes would help to catch any plastic, as well as get rid of the solvent-thinned oil. Im actually not that worried about the bearings, as I've seen mineral spirits poured into engines and used as a motor flush, and the motor was just fine. Short term, with a quick oil change after the initial oil change, that doesn't seem like a problem to me.

If you want to send me your email address, I've got pictures of a Cobra 4v pump, pickup, etc with the oil pan removed.

 

[briggss3]

Just had mine diagnosed with a bad timing chain, guides and tensioner from a ford dealer. Plus had a check engine light (EGR). They want around $400 to replace EGR and $1600 to rebuild timing chain. Ford Dealer. EGR seems high priced, but I know nothing about cost to replace timing chain and guides. I have a 4.6L SOHC V8 in a 2004 Explorer and 118K miles.

If I do this, what else can I do (reasonable) to improve performance and MPG while the timing chain is off?

 

[Pontisteve]

Hold up, that's out of line. First of all, the guides, tensioner arms, and tensioners do occasionally go bad. But the chains rarely ever fail... unless maybe the nylon from the guide was totally ate up, and the aluminum guide started to ride directly on the chain, scratching the chain up. You need to view the carnage with the timing cover off and inspect the parts! Typically, it's just a tensioner that's bad.

And $1600? That's a boat load for that repair. If you can't get a good mechanic to work on your stuff cheap, consider taking it to a speed shop that specializes in Fords. Since these engines are in every Mustang from 96-up, all the Ford speed shops are very well versed in modular engines. They would probably do that job for 1/3 - 1/4 of that price, and are probably better at it.

As for the EGR valve, quite frankly they really hardly ever "go bad". They do occasionally get clogged up, but if you're a DIY guy, you can pull the valve off, and maybe just clean it with some carb cleaner and small brushes.

Starting in 2004, Ford uses a new type of EGR valve, often referred to as an EGR module, that incorporates the valve, the DPFE sensor, and the vacuum regulator all into one unit. I think your truck has that setup. A brand new Motorcraft EGR module is $72 at rock auto. Just unbolt the old one and bolt on the new one. Pretty straightforward on this job, if you can see it and get wrenches on it, it should be easy.

 

[briggss3]

Thanks for the advice. I will do exactly that. I am a pretty good DIY shade tree mechanic, so $400 sent up a flag for an EGR module - which I thought was pretty easy. On the timing situation - 2 seperate dealers quoted $1600 and $1800 - both stated that it was wise to replace it all while you had it tore down and that the chain really wasn't a high cost item in the rebuild kit. I'm like you - chains don;t really stretch and what little they do the tensioner should cover. It only has 118K miles on it, so fatigue should not be an issue. Barring corrosion, I would think leaving it in place is ok as long as the cost savings warrants it.

I know nothing other than my heart skipped a few beats for what seemed to me to be a striaght forward repair in my old school mechanic skills. Those same 2 dealers and another 3rd dealer said it would take a solid 1.5-2 days to do the job.

I need to find an independant Ford mechanic to give me a non-dealer quote. How do you search those and get a reputable one (I am in south Houston)?

 

[Pontisteve]

Google Ford mechanic Houston. Or try going to sctflash.com, hit the dealer search button, and find an SCT tuner in your area. SCT is predominantly a Ford tuning product, so any SCT tuners are likely to be Ford savvy, and probably are tuners/speed shop combos. If not, they will know who in your area would be a good person to turn to.

If you're a decent DIY mechanic, the job isn't that hard. It is time consuming. And you'll need a few special tools. You'll need fan clutch wrenches to get the fan off (see OTC tool co.). You'll need a Power steering pulley puller and installer, and a crank pulley puller and installer. Getting the Ford specific ones will reduce frustration. You'll need a new crankshaft bolt from Ford, as they're torque to yield. You'll also need new timing cover gaskets, some black silicone, and I think the rest is basic metric hand tools.

You should get the OTC 4.6 2v Cam Timing Tool set (about $100), but you can very likely get along without it. Primarily, there is a cam holding tool that will stop the cam from turning on you (due to valve spring pressure turning the cam when you remove the chain).

I seriously doubt your chains are bad anyway, so you can probably just pop off the bad tensioner or guide/tensioner arm that's bad, and pop on a new one. You'll have to tear down the front of the engine before you can order the parts, but I'm sure Ford could get you the parts in 2 days. You can even save some money by finding a Ford parts dealer online that sells the parts cheaper over the internet.

As a tip, I like to put the motor at TDC on the compression stroke before I pull the chains loose. That way, if you end up having to reset cam timing from scratch, you're already there. Otherwise, you would have to pull the rocker arms off so you don't bend valves while turning the motor and cams where they need to be. This also eliminates the special tools really.

I probably have the .pdf file for Fords repair CD on this if you need it. Its easiest to pull the radiator, fan, power steering bracket, belt and other stuff on the front of the motor before you dig in. You may want to remove the front wheels and lower the front of the truck down to make reaching into the engine bay easier. Or on a lift, you can just go up and down to get to the bottom stuff when needed.

This job is not hard, but is time consuming. And requires seeing what's broke before ordering new parts. You don't really need to do everything up front, but if you do want to go above and beyond, get 2 new tensioners, 2 new guides, and 2 new tensioner arms from Ford.

Sometimes it's not any of that stuff. There's some small pins and bolts that hold some of that stuff on. I've seen little things like that break, and cause chain slack. I bet you could buy the tools and do this job yourself for under $400 including parts, if you just fixed the broken parts.

How do you know it's a chain problem?

 

[2000StreetRod]

tensioner on slack side

. . . On the timing situation - 2 seperate dealers quoted $1600 and $1800 - both stated that it was wise to replace it all while you had it tore down and that the chain really wasn't a high cost item in the rebuild kit. I'm like you - chains don;t really stretch and what little they do the tensioner should cover. It only has 118K miles on it, so fatigue should not be an issue. Barring corrosion, I would think leaving it in place is ok as long as the cost savings warrants it. . .

The tensioners are on the chain slack side and don't affect camshaft timing. The tensioners merely keep the chain taught. Timing is established by the chain traction side length. I agree that the chains should not be significantly stretched or worn in 118K miles unless there has been chain to metal contact due to guide or tensioner failure. The photo below shows a DOHC 4.6L V8. The SOHC V8 should be similar for the lower chains.

 

[Pontisteve]

The tensioners are on the chain slack side and don't affect camshaft timing. The tensioners merely keep the chain taught. Timing is established by the chain traction side length. I agree that the chains should not be significantly stretched or worn in 118K miles unless there has been chain to metal contact due to guide or tensioner failure. The photo below shows a DOHC 4.6L V8. The SOHC V8 should be similar for the lower chains.

That's not always the case. When the engine is under acceleration that's true, but when steady speed or decelerating, lack of proper chain tension can cause the cam timing to move around. This could be a problem with piston to valve clearance if it had enough slack in the chain.

Also note that the tensioners are no joke. They provide a LOT of tension, as evidenced by the sharp snap sound they make when you first release the pin and allow the tensioners to snap into position. And that's just the spring pressure. Once running, oil pressure provides even more tension to the chain via the tensioner.

Marvin Bridge once told me that they built a plexiglass timing cover for a 4v motor, and he said the chain wriggled like a snake at higher rpms. Hard to believe considering the spring tension, oil pressure tension, and the fact that the tractor effect is on under acceleration.

 

[henny496]

Hello
I am new to this forum and found this site while searching for info on an Explorer I bought last night
This thread is very informative and I am impressed with the knowledge and info from the members.
The 02, I bought has the timing chain noise, runs strong and has good oil pressure, but noise is coming from the front and is not bottom end. I am pretty handy and do my own work, and with the info supplied here I feel confident about doing the repair myself in the coming week....depending on the weather(tad cold up here right now)
I will try to see if I can find any online manuals for this repair, but with what has been posted, I am not sure if I need anymore data
take care
Tom