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.....

 

[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]

broken timing chain guide

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]

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]

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.

 

[Number4]

From what I've found,

9-0387SJ is for the 2002 4.6l and has the cast tensioners.
9-0387SG is for 2003-2005 4.6l and has the nylon tensioners.
According to Cloyes, Ford OE changed to the nylon style tensioner in 2003.

So Cloyes still provides the cast tensioner for the 2002 model years.
I looked at a kit the other day. The guides are molded with Ford part numbers and are stamped FOMOCO in fancy lettering. The gears and chains had markings, but nothing I could identify as Ford.
Cloyes does make a lot of OE timing components.

 

[Pontisteve]

From what I've found,

9-0387SJ is for the 2002 4.6l and has the cast tensioners.
9-0387SG is for 2003-2005 4.6l and has the nylon tensioners.
According to Cloyes, Ford OE changed to the nylon style tensioner in 2003.

So Cloyes still provides the cast tensioner for the 2002 model years.
I looked at a kit the other day. The guides are molded with Ford part numbers and are stamped FOMOCO in fancy lettering. The gears and chains had markings, but nothing I could identify as Ford.
Cloyes does make a lot of OE timing components.

The OEM Ford timing chains were high quality. The Cobra chains were fully polished. They never break, but can stretch over time. Cloyes and Trick Flow make aftermarket chains.

THere was a lot of trouble with the nylon tensioners. The older cast iron tensioners were way better, and are often used as an upgrade on the newer cars. I have seen 03 Cobras with the cast iron tensioners. I am not sure why.

 

[Moto Martin]

I'm in the middle of making this repair. This weekend I removed the timing cover and could see the damage. The passenger side guide was completely missing from it's proper location and was floating around in 4 large pieces. The plastic guides on the tensioners are also broken and worn through to some extent.
I'm pretty relieved, I thought the motor was going to be totally destroyed based upon the sounds it was making. I have looked at the cams/ cam lobes and the cylinders they look okay as it was driven for a couple of miles with low oil pressure.
I'm ordering parts at the moment, there is a kit that includes the chains, sprockets, guides, tensioners and an oil pump. I'm also going to order the timing cover gaskets, crankshaft oil seal, and a new crankshaft sensor tooth wheel. The valve cover gaskets look re-useable. Can you think of any other parts that I need?

 

[Number4]

Might consider replacing the oil pump while you are there. Mixed reviews on needing to drop the oil pan, need to make sure nothing has been left behind to get sucked up. I'd replace the valve cover gaskets myself, why risk it while you've already gone this far.
I bought the cam holding tools. Piece of mind if anything. Have yet to do the job. Let us know how it goes. Post picks.

 

[Moto Martin]

I have already dropped the oil pan, that was the first thing I did to see what kind of shrapnel was floating around in there. I think clean up of the pan and inside of the timing cover will be critical. I also plan on getting a new oil pump as there are a lot of bits of crunched up guide everywhere. Some kits come with the water pump, I don't think I want / need to replace that though. I do want to replace at least one of the chains as there is a flat spot on every link where it had been rubbing. I am planning on orienting the crank / and cams so that I hopefully do not need the holding tools - cross fingers on that one.

 

[Number4]

The cams will rotate once the chains are off. To what degree is the question. You have 2 wheel drive?

 

[CDW6212R]

I have already dropped the oil pan, that was the first thing I did to see what kind of shrapnel was floating around in there. I think clean up of the pan and inside of the timing cover will be critical. I also plan on getting a new oil pump as there are a lot of bits of crunched up guide everywhere. Some kits come with the water pump, I don't think I want / need to replace that though. I do want to replace at least one of the chains as there is a flat spot on every link where it had been rubbing. I am planning on orienting the crank / and cams so that I hopefully do not need the holding tools - cross fingers on that one.

Set the crank/timing to TDC, for all steps. That's the easiest place to reference to, in case the cams do move or get moved.

 

[Pontisteve]

Set the crank/timing to TDC, for all steps. That's the easiest place to reference to, in case the cams do move or get moved.

Actually, there is a safe zone where the motor won't rotate, and all the valves are closed or down enough to prevent bending. The factory cam tools use the crank holding tool to hold the engine at this safe zone, which is near, but not at, TDC compression.

If the valve covers are off, and the cam gears need moving around to get them back to the right position, it might be easier to remove all the rocker arms. This closes all valves, prevents any valve bending possibility, and allows for easy setup of the chains and gears. Then pop them all back on when finished.

Otherwise, the chains have to be on as the motor is turned, or the pistons will be moving while the valves stay the same. If you put the motor at the safe zone before you take the chains off, it resolves the issue of how to rotate the engine without some pistons hitting some valves.

 

[CDW6212R]

Actually, there is a safe zone where the motor won't rotate, and all the valves are closed or down enough to prevent bending. The factory cam tools use the crank holding tool to hold the engine at this safe zone, which is near, but not at, TDC compression.

If the valve covers are off, and the cam gears need moving around to get them back to the right position, it might be easier to remove all the rocker arms. This closes all valves, prevents any valve bending possibility, and allows for easy setup of the chains and gears. Then pop them all back on when finished.

Otherwise, the chains have to be on as the motor is turned, or the pistons will be moving while the valves stay the same. If you put the motor at the safe zone before you take the chains off, it resolves the issue of how to rotate the engine without some pistons hitting some valves.

That is all true. I suggested the TDC because anyone can identify it, and the TDC location for each cam if needed. The cams and valvetrain will move to that neutral point you mentioned, from TDC, a short distance away. The key is that it's not a large rotation away, and the person working on it can figure out which way is needed easily, to locate the TDC a short distance away, to line them all up.

I found out the hard way with the 4.0 V6, having first loosened the front jack shaft bolt, before realizing that it's not splined or geared in any way. I was a long way from TDC, about 200 degrees.

The 4.0 jack shaft and its gears are held together in position by the bolt pressure only. When the bolt is loosened, the shaft(both cams) can immediately move if the valve springs are wanting to. I had to carefully and slowly figure out which way each cam moved, and move all three assemblies(crank/cam/cam) very slowly together in short steps. Placing the engine at TDC is super easy compared to figuring it all out after letting the parts get happy.

 

[Pontisteve]

That's right. And you could do that at TDC, and be a world better off than doing it anywhere other than TDC compression. The only reason the safe zone is not right at TDC must be that there is some uneven valve spring pressures at that point, causing the cam to want to "spring" in one direction if you let pressure off.

The safe zone also makes sure all valves are not open their full amount, which would completely prevent valve to piston contact. If you have the cam timing tools (which are only about $100 from amazon, ebay, usatoolwarehouse, tooltopia), then its easiest to just put the crank right where it will line up with the tool.

The crank holding tool slides over the keyed crank, and has a hole in the end of it's lever that lines up with one of the dowel pins that holds the timing cover on, as I recall. If I remember correctly, this is at around 11:00 where TDC was at 10:00... but it's been a while so don't quote me on that. It is very close to TDC.

If you don't have the cam timing tools, I would say the easiest way might be to put it at TDC and then take off any rocker arms that have valves open. Or take all of them off. This way, you could put the motor at TDC and line up the dots.

When degreeing 4v camshafts in for racing (which is a far more precise method than just timing them like these stock engines), we found that Sean Hyland recommended removing the intake cam keys, and then degreeing the cams in and using the intake gear bolts torqued down extra hard to hold the cam gear on and the cam timing in place. We found that this sucked, and would lead to cam gears slipping on the cams, despite much extra torque (and using ARP hardware).

Offset keyways or adjustable gears of some sort were the better way to fly. Cloyes makes some stuff that seems to be working for that. The point is, I agree about your V6 gears not being keyed. If the parts were all removable, you could always have them keyed by a machine shop.

Our 4v engines have a cam holding tool that holds the two intake cams on each side of the engine against eachother, preventing rotation. I believe the 2v cam timing tool kit has a tool like this as well, that holds the cam from moving relative to the head. But you kind of need one for the other side unless you are doing just one side, I would think. Unless you are in a position like the safe zone, where there is no valve spring pressure rotating the cams on the side you don't have the holding tool for.

 

[CDW6212R]

...

I believe the 2v cam timing tool kit has a tool like this as well, that holds the cam from moving relative to the head. But you kind of need one for the other side unless you are doing just one side, I would think. Unless you are in a position like the safe zone, where there is no valve spring pressure rotating the cams on the side you don't have the holding tool for.

Yeah, the V6 tools hold just one cam in place. So you set each cam to match the TDC crank tool, separately. I like that the V8 evidently has a stable position where the crank tool will set it all to, and not move more etc.

The V6 TDC/crank tool is not very accurate. If I ever do another one, I plan to skip that tool and use the more method of locating actual TDC with a piston stop tool. Then with a degree wheel attached you can easily set the TDC accurately. That may or may not differ from how the cams were designed to run, but it makes more sense than the cheap tool that slips around a bit on the balancer grooves. Every movement is a change of the crank position. I see that coming soon for my 99 4.0 again, when I do the trans rebuild.