4.6L V8 - Typically how many miles before timing chain replacement?

[SyberTiger]

I have about 150K miles on my 2002 Explorer with a 4.6L V8. Curious to know when it is recommended to change the timing chains, tensioners, guide rails, etc on this type of engine.

 

[Number4]

When it starts to rattle at cold start. Mine started this around 150k.

 

[JakePSD]

Its kind of a crap shoot. I just did chains on a replacement engine for my truck. The engine had around 180k on it, no rattle at startup, but there was some spots on the guides that had worn though to the metal. No damage to the gears or chains, I reused them. I just replaced tensioners (with the metal ones) and guides.

 

[SyberTiger]

Its kind of a crap shoot. I just did chains on a replacement engine for my truck. The engine had around 180k on it, no rattle at startup, but there was some spots on the guides that had worn though to the metal. No damage to the gears or chains, I reused them. I just replaced tensioners (with the metal ones) and guides.

I thought the tensioner arms are always metal underneth but typically have a composite material on the outside as you don't want metal on metal? I assume at 180K you decided to change the timing chains because it was probably time to take a look and replace them although there wasn't any obvious problem?

 

[SyberTiger]

I'm in the process of changing the intake manifold and decided to change the valve cover gaskets as they are starting to weep. And, because I have the engine torn down to this point I thought I may as well do the timing chain job as now is the time to do it with everything torn down. Is there any specific kind of timing chain kit to avoid...like some sort of cheap made in China crap or are they all about the same?

 

[Hugh Janus]

I have about 150K miles on my 2002 Explorer with a 4.6L V8. Curious to know when it is recommended to change the timing chains, tensioners, guide rails, etc on this type of engine.

I did mine when it started to sound like a diesel on initial acceration. No rattle on startup. Here's a bunch of pics - https://sites.google.com/site/hobbyhintstricksideas/Home/ford-4-6-timing-chain-repair

 

[drdoom]

Huge those are good pictures, geez that looked bad. What a mess.

 

[imp]

Nice pics! Now if only I had the 4.6 instead of 4.0......
156K now, no sign of trouble yet. imp

 

[SyberTiger]

I did mine when it started to sound like a diesel on initial acceration. No rattle on startup. Here's a bunch of pics - https://sites.google.com/site/hobbyhintstricksideas/Home/ford-4-6-timing-chain-repair

How many miles did you say you had on the engine when you replaced the chains?

I decided I'm going to go ahead and do this job. Curious to know which camshaft holding tool you used.

 

[Hugh Janus]

How many miles did you say you had on the engine when you replaced the chains?

I decided I'm going to go ahead and do this job. Curious to know which camshaft holding tool you used.

165K miles and you don't need a tool.

 

[SyberTiger]

165K miles and you don't need a tool.

I watched THIS VIDEO and noted he used a camshaft holding tool just to make sure he didn't accidently allow the cam shafts to move.

 

[drdoom]

If you want a simple and effective holding tool get yourself a couple of the OTC 6477.

 

[SyberTiger]

If you want a simple and effective holding tool get yourself a couple of the OTC 6477.

Don't you just need one and move it from the right side to the left side as necessary?

 

[drdoom]

That's fine as long as you are just replacing hydraulic tensioners and guides, not so much for chains and sprockets.

 

[SyberTiger]

That's fine as long as you are just replacing hydraulic tensioners and guides, not so much for chains and sprockets.

My comment was based on THIS VIDEO where it looks like the one and only camshaft holding tool is moved from the right side to the left side and is only used while removing the cam shaft sprocket bolts. But...I've never done this service so I don't know for sure.

 

[imp]

My comment was based on THIS VIDEO where it looks like the one and only camshaft holding tool is moved from the right side to the left side and is only used while removing the cam shaft sprocket bolts. But...I've never done this service so I don't know for sure.

@SyberTiger
On the 4.0, as I understand it, the sprocket is not keyed in any way to the camshaft which it turns. Thus, while chain is still in place, the timing is locked in. Loosening the sprocket bolt allows those valves which happen to be exerting higher force than the others, that is, those which are open, to rotate the shaft one way or the other, putting it "out of time". Since 4.0 has two separate chains, one for each head, only one side need be locked in place.

Now, 4.6 I don't know about. I picture, though only one long chain, which drives both heads. That may be wrong, however. Nor do I know whether the sprockets are keyed to the shafts. The 4.0 sounds like a crazy design, to me. What happens if a sprocket bolt loosens in service? Ya "lunch" the engine? imp

 

[Hugh Janus]

I watched THIS VIDEO and noted he used a camshaft holding tool just to make sure he didn't accidently allow the cam shafts to move.

You don't need a tool because the 4.6 crankshaft to camshaft timing is fixed by aligning marks on the chain with marks on the sprockets. it's very easy to do. The installation instructions and YouTube videos will guide you.

 

[JakePSD]

I thought the tensioner arms are always metal underneth but typically have a composite material on the outside as you don't want metal on metal? I assume at 180K you decided to change the timing chains because it was probably time to take a look and replace them although there wasn't any obvious problem?

You are correct on the construction of the guides.

I decided to change them mainly for piece of mind and reliability. My truck had about 281,000 miles on it when I bought it for $700. I got it for that price because of a tied up engine. When I tore down the engine I quickly found out why. Something in the timing system failed which caused the right chain to slip to the point of valve/piston contact. All 4 intake valves were broke off in the cylinder. I ended up buying an entire parts truck mainly just for the engine for $600 (trans was shot). Motor ran perfectly fine with no noise, however after seeing the chaos caused from failed timing components in the first one, why not just do it now while the engine is out of a truck. It'd never be easier to change.

I'm in the process of changing the intake manifold and decided to change the valve cover gaskets as they are starting to weep. And, because I have the engine torn down to this point I thought I may as well do the timing chain job as now is the time to do it with everything torn down. Is there any specific kind of timing chain kit to avoid...like some sort of cheap made in China crap or are they all about the same?

I reused my chains and sprockets. However the new components I bought were not for our trucks. I got stuff for an older crown victoria because I liked the construction of them better. I chose a 1996 MY.