Well ...a little over 307,000 miles on my 4.0L SOHC and I've gotten the infamous start-up chain rattle.

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Evox

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It's coming from the passenger-side chain, which looked fine when I changed the valve covers not too long ago. It was still intact, with no wobble. I've ordered some new chain tensioners to see if that corrects the problem; I'll switch them out this weekend. Hopefully, that corrects the problem.

If it doesn't, I'll run a dry compression test; if that test is good, I'll pull the engine, replace the timing cassettes, and do a reseal. My rear main seal is weeping anyway. If the dry compression test isn't good (doubtful), I'll run a wet test and draw up a battle plan from there. Which means I'm headed for an overhaul.

Either way, the engine has to come out if the new tensioners don't fix the start-up rattle.

I can't complain; it's given me 57k miles more than its typical service life.
 

DILLARD000

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Best to do a fresh oil+filter change after changing the 2 tensioners.
Good luck & keep us updated.
 

Paul Fithian

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When starting, press the accelerator to the floor and hold it, then crank the engine. After a few seconds, oil pressure will build while cranking without starting, then let your foot off of the accelerator.

The engine will start normally with no rattle.
 

Todd Z

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Remember to prime the tensioners before installing them in a cup of oil.... pump them a few times...
 

electrician

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It's been a good truck. I've no complaints. Still, I'm hoping the new hydraulic tensioners cure the rattle. (fingers crossed).
My son has a 2002 Explorer with the 4.0. The chains started rattling about 100k. He never replaced them and kept driving. It now has 359k and still running great. No engine other routine oil, coolant, and transmision fluid changes. couldnt ask for better
 

DILLARD000

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My son has a 2002 Explorer with the 4.0. The chains started rattling about 100k. He never replaced them and kept driving. It now has 359k and still running great. No engine other routine oil, coolant, and transmision fluid changes. couldnt ask for better
Wow, don't brag too loudly; the voodoo hex God will hear you!
 

Evox

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My son has a 2002 Explorer with the 4.0. The chains started rattling about 100k. He never replaced them and kept driving. It now has 359k and still running great. No engine other routine oil, coolant, and transmision fluid changes. couldnt ask for better

"...This one time at band camp..."

Seriously, I have heard folks that have gone a long time with bad timing chain guides. Unless some of the plastic bits block off the engine's oil supply or a chain finally skips timing or breaks, the engine can run with loose chains. I guess it's kind of like playing the lotto, someone wins, but most don't.

With that said, I'm not sure it's the guides or just a bad hydraulic tensioner. I'll know this weekend; the tensioners should be here tomorrow.
 

JC2008SportTrac

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I don't mean to be a moron here, but what's the worst that happens?: you have to get a new or rebuilt V-6 put in? What do those run, $4K'ish? For a new heart to run the truck another 150-200K miles? Given the cost of buying something different, $5K to get what you know going again doesn't seem so bad, when it'll buy you another 100K+ miles.
 

JC2008SportTrac

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Oh, and, LOL, yes: My mechanic buddy said you just trash those engines when the timing chains go. Why'd Ford make them so overly-complicated, such that a, honest, mechanic doesn't want to touch them. Hopefully Ford makes a ready-to-go motor, and we just swap it in. Is that how it works? I'm hoping so, for that v-6 with timing chains/gears ready to let go.
 

Evox

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I don't mean to be a moron here, but what's the worst that happens?: you have to get a new or rebuilt V-6 put in? What do those run, $4K'ish? For a new heart to run the truck another 150-200K miles? Given the cost of buying something different, $5K to get what you know going again doesn't seem so bad, when it'll buy you another 100K+ miles.

I understand many Land Rover, Mercury, and Ford guys don't like the Ford 4.0L SOHC design, but personally, I think it's a fine engine. If it comes down to rebuilding the engine, it will probably cost me no more than $1200 - $1,500 (I haven't priced it all out), maybe less depending on what machine work I get done. I get "friend" prices in that area.

I could probably find a reman engine for $2500-$3000. But I rather enjoy doing my own work. And this isn't my first rodeo. Not even with this engine. I helped a buddy rebuild his '05 LR3 some years back, which has a Ford Cologne in it.

I should have the tensioners in hand this afternoon. I'm betting that's all it is. But even so, as I wrote above, this rarely ends with a sudden catastrophic failure as long as it's not ignored for a long period of time.
 

Ed Fenwick

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Aloha guys, I have been led to understand that these engines are not the valve hit the pistons kind. If the chain breaks, tow it home. I changed my hydraulic tensioners several times, cheep one's expensive ones Ford ones, no help. I spent $4500 having chains replaced ( also water pump and some other things while it was out). That said, it still rattles on cold start-up! Poor design but I still like the truck. Enjoy fixing it.
Ed
 

Evox

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Aloha guys, I have been led to understand that these engines are not the valve hit the pistons kind. If the chain breaks, tow it home. I changed my hydraulic tensioners several times, cheep one's expensive ones Ford ones, no help. I spent $4500 having chains replaced ( also water pump and some other things while it was out). That said, it still rattles on cold start-up! Poor design but I still like the truck. Enjoy fixing it.
Ed

It's most certainly an interference engine. If the chain skips time or breaks, you will be rebuilding or replacing it. Many folks make the mistake because, usually, broken chain guides don't result in a catastrophic engine failure.

As posted earlier, these engines can and sometimes do go a long time with bad guides. Of course, it's a gamble. As long as none of the plastic bits block off oil or the chain doesn't jump timing, it'll just rattle and run. I think that's why a lot of people think they're non-interference engines.

I think mine is the tensioner, but while trying to torque down my new tensioner, my hand slipped, and I sliced my left hand open on the brake dust cover. ...stupid mistake, I wasn't wearing gloves, and I didn't turn the wheel right before I got it on the lift. Like an idiot, I thought I'd get er done real fast. After washing it out, I used some permabond to seal the wound, but I probably could have used a few stitches. I'm kind of amazed at how deep it cut. I've banged up my hands working on cars over the years, but this one made a clean slice right through the dermis. ....wear your gloves, kids.

Before my screw up I did notice a lot of play in the old tensioner. I'm pretty sure the internal seal is toast, so I'm hoping the new one solves my problem.
 
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