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.....

 

[bcbow1971]

Could be a broke tensioner, guide, or tensioner arm. Pop the valve cover off and have a look at the chain, and the rest of the valvetrain on that head while you're at it. If the chain has any slack in it at all, something's wrong and the timing cover has to come off.

You could also drain the oil, and look for pieces of nylon/plastic in the oil, from the guide or tensioner arm. You might try a stethoscope on that side as well, to better narrow down the noise before disassembly.

I've heard a broken guide/arm before, that sounded just like a knocking motor to me.

Thanks I plan on popping the valve cover off tonight. I am PMing you my email if you have those PDF's as well. Also found this video that gives a great idea on basics of removal. http://www.youtube.com/watch?v=HAQwkISqdGw&feature=plcp two part

Thanks again to all and I will let you all know the outcome of the inspection.

 

[Pontisteve]

My money is on the tensioner, if it's the phenolic type. But an arm wouldn't surprise me either.

You'll be able to see a loose chain with the valve cover off. DON'T try to run the engine with the cover off to see the chain move. You'll throw oil all over hell. If you do try it, build yourself a plastic bucket that goes over the bulk of the timing gear, because that's the major oil slinger. Hopefully you'll be able to see the loose chain without going thru all that.

You'll need fan clutch wrenches to get the fan off as well as the usual PS puller, harmonic balancer puller, etc.

 

[bcbow1971]

OK it was just what I suspected........Broken Timing chain guide so I just ordered a complete set of guides, Tensioners and Chains along with gaskets..

Here is video to see what I found...

 

[Pontisteve]

Dont bother replacing the chains. They never fail. The guides, tensioner arms, and tensioners do. Are your tensioners the cast iron ones or the lightweight composite ones? The cast ones are very good, but the composite ones do fail. You can take them apart and inspect them.

 

[bcbow1971]

Dont bother replacing the chains. They never fail. The guides, tensioner arms, and tensioners do. Are your tensioners the cast iron ones or the lightweight composite ones? The cast ones are very good, but the composite ones do fail. You can take them apart and inspect them.

I haven't got a chance to inspect them yet. I will wait until all the parts come in and do it all at once.

 

[bcbow1971]

OK thanks to Pontisteve and this post I replaced my chain guides and tensioners!!! All done and running great......only thing I may need to do is drop the pan and get the rest of the plastic pieces out.

 

[Pontisteve]

Which component actually failed, the guide or the tensioner arm? And how were the tensioners?

 

[bcbow1971]

Which component actually failed, the guide or the tensioner arm? And how were the tensioners?

The guides broke and the passenger side tensioner arm was wore through and some wear on the tensioners.....the factory tensioners looked like the same material, hard plastic(Polymer), as the new ones. I replaced the following:

Tensioners
Tensioner arms
Guides
Valve cover gaskets
Timing chain cover gasket
Main seal

I have a new set of chains but they looked good and as you said the old ones should be fine.

 

[Pontisteve]

Hmmm. I have the exact same truck with 130k, and no problems yet. I wonder what the difference is between yours and mine, that would cause your stuff to break earlier? I am not the original owner, but have had it since 80k and run Motorcraft 5w20 oil in it, and a Motorcraft filter (ala Walmart).

Motorcraft oil is semi-synthetic on their lighter weights. I wonder if this has an impact on longevity? I figured it can't hurt, and at Walmart, the Motorcraft oil is often one of the lower priced oils. Although recently, they've all shot thru the roof in price.

I have a couple tips for you. Make sure you get the factory specs and torque the timing chain cover properly and in order. Make sure you use black silicone to dab in all the joint areas where two different gaskets come together. And the best one... make sure you put a dab of black silicone on the keyway, or oil will leak right thru the keyway and out the front of the crank, making you think your front seal is bad.

FYI, those chains pretty much never fail. They can stretch over time some, but the tensioner takes up the slack. That does however retard the camshaft a little. Any time you do a mod motor timing chain job, you should always use the slop in the cam gear keyway to "advance" the cam as much as possible. There's about 2 crankshaft degrees worth of slop in the keyway. We want to, at the very least, advance it to compensate for timing chain stretch.

4.6 Cobra Mustangs actually use a polished version of that chain, which has less friction. I've never tried updating a 2v to that 4v polished chain, but I don't see why it wouldn't work.

 

[bcbow1971]

The previous owner used Valvoline 5w20 and standard filter....I have switched and will just use Motorcraft 5w20 Semi Synthetic and MC filter.

I used the blue silicone(better for oil resistance) on the joints as well I used it in the grooves of the chain cover and valve cover light thin line and then gasket to hold in place and creat an extra level of seal. didnt do the keyway but I pressed the bearing in about 1/32" less than factory to keep it away from key.

 

[Pontisteve]

The previous owner used Valvoline 5w20 and standard filter....I have switched and will just use Motorcraft 5w20 Semi Synthetic and MC filter.

I used the blue silicone(better for oil resistance) on the joints as well I used it in the grooves of the chain cover and valve cover light thin line and then gasket to hold in place and creat an extra level of seal. didnt do the keyway but I pressed the bearing in about 1/32" less than factory to keep it away from key.

What bearing?

Think about the front seal and timing cover by itself. Then think about the crank snout sticking thru it. Then thick of that snout having a groove cut into it. Oil goes out the groove. Only thing in it's way from coming out fast is the keyway. Only thing keeping it from coming out entirely is silicone on the keyway.

 

[bcbow1971]

What bearing?

Think about the front seal and timing cover by itself. Then think about the crank snout sticking thru it. Then thick of that snout having a groove cut into it. Oil goes out the groove. Only thing in it's way from coming out fast is the keyway. Only thing keeping it from coming out entirely is silicone on the keyway.

Sorry front seal. The keyway stops before the seal area but now I see what you are talking about.

 

[kworonowski]

I am having this done got the full kit chains gears tensioners (cast) guides casettes and whatnot. I have seen alot of people say these engines rarely have this issue. But after 3 different mechanics all saying the same thing prolly best to get it fixed. 1900 is a bit pricey but will i have any other issues that may arise ill have to save up for. Transmission is running good had flushed several times and no issue (now that ive said it it'll prolly break). Will be going to amsoil after this issue is fixed.

 

[Pontisteve]

For a V6, thats probably an ok price. For a 4.6 V8, thats too much money. I hate the sohc v6 with the rear timing chain, but the v8 explorer engine is good. The timing chain guides and tensioners and tensioner arms are about the only issue they have, and not all of them have that problem.

Im at 130k and so far no trans or timing chain issues. Slop in both the front and rear axle gears annoys me though. Wheel bearings suck, especially in the rear. And at some point, you'll be in for 8 ball joints.

I think at around 10 years old or 120k is a good time to say goodbye to these trucks. Or hunker down and be prepared to spend some serious money.

 

[kworonowski]

I am at 129k first real issue. Was quoted 2400-3000 at one dealership 2200 at 2nd and 1885 at a performance racing place. Mostly mustangs but has done several 4.6 timing chain issue replacement. This is including replacing the gears chains and everything. Ford quoted 15 hrs plus parts around here that $120+ hr. We have discussed leaving the chains and gears so no issue with timing only if there is no damage to gear or to much stretch to chain. Also i am having the water pump replaced while there as a "prevetitive maintence". Didn't have it done at dealership as when they checked the engine they put the belt on wrong and i shredded it and covered all the pulleys with rubber.(105 degree 2 hr waiting on tow) The guy that working on it now did say he thought 15 hrs was high and would only charge the actual hrs.

 

[Pontisteve]

Getting a speed shop familiar with Mustang 4.6 2v engines is a good choice. They probably know more about those engines than most shops do, short of Ford maybe.

15 hours doesn't sound unrealistic. But try to find a shop that works cheaper per hour maybe. Or find a Mustang enthusiast that's really good at working on engines and pay him. The chains may stretch some, but it's not an issue. They never break. The worst thing that can happen is that the cam timing gets "retarded" some compared to stock. Put another way, reusing the chain would put you right where you were before. In fact, a sharp installer could use the slop in the cam gear keyway to "advance" the cam a little bit to compensate for that. I would do that.

The chains are completely reusable without issue. The gears are also usually just fine. They're hardened on the surface, and as long as they look good, reuse them and save money. Where to spend money: tensioners, guides, and tensioner arms. You should consider buying these new from Ford. I wouldn't bother with the water pump if it's not leaking out the weep hole, and if the fan seems tight (pump bearing good). But the water pump should be relatively cheap anyway($60 maybe?), so if you want to put one on, it's not the end of the world.

I say 15 hrs x $75/hr = 1,125 + parts. Parts might total $300. Some Mustang shop would be a good choice for doing the labor.

 

[Pontisteve]

FYI, I spent 2 years with my 4V Cobra motor on an engine stand, working on how to degree the cams on 4v engines. I've gotten to know them real well. Here's a pic of my 4v on the stand. Your motor looks the same, except it doesn't have that extra "short chain" at the top, or the extra cams.

 

[kworonowski]

well got to the root of the problem the guides weren't broke and the cassettes weren't bad. However the chain did stretch and both sides cut thru the guides down into the tensioners. So pretty much replacing all of it water pump i could prolly leave alone but for the $80 and no extra time not worried. The kit was 300 and only 1300 labor. which around Denver is pretty good. Fluids and gaskets cover the difference of the 500. If i could figure out how to post the pics i can show how little of the guides are left. I probably could have shopped around some more but i liked what i had seen of his shop and some of his work. But my explorer might have become an exploder.

http://www.facebook.com/media/set/?set=a.438434052856360.105022.100000693086248&type=1

hope that works

http://www.oreillyauto.com/site/c/d...71_2630&keyword=timing+kit&pt=04806&ppt=C0141

 

[Pontisteve]

The failure you're looking at is the tensioner arms. They're so worn out that the plastic is just worn thru. Once the chain eats thru the plastic, it starts in on the metal and eventually into the tensioner piston.

To some degree, it's just a matter of time before this happens to every mod motor. But I believe the reason some die prematurely has to do with oil. First of all, oil doesnt have as much zinc in it as it used to. Second, all of the Motorcraft brand of thin oils like 5w20 are semi-synthetic (while the thicker oils are not). Aftermarket oil brands are typically not synthetic or semi-synthetic, except the expensive ones. Even worse, the oil change intervals are up to 5k miles now if you use the in-dash oil change reminder, just adding to the problem.

Much less likely, but possible, is that the motor at some point backfired and kicked back, causing the tensioner ratchet to tighten up one notch too tight. I experimented with this some, and it can happen in the right scenario. And if that does happen, it puts huge pressure on the tensioner arm, and causes massive drag on the engine.

 

[Pontisteve]

I haven't found the chains to stretch very much, but even if they do, the tensioner arm just extends its ratchet more to take up the slack. On the down side, it does slightly retard cam timing when that happens, losing low end torque and increasing top end power.

If you get a chance, take the old chain and the new chains, fold them in half, and compare their length.

FYI, those are the old, cast tensioners. They were the good ones. Darn shame they got damaged. The replacements available are composite, and aren't nearly as durable. They also no longer have the ratcheting ladder that continually keeps the chain somewhat tight until the oil pressure builds up.