when should the timing chain get replaced?

[mixwhit]

I'm looking at purchasing an '03 with a 4.0L V6 and 158k miles. I'm guessing it's probably due for a timing chain replacement if I buy it, although I haven't been able to find a maintenance schedule online. Anyone know what the maintenance interval is for it?

Also, is there anything else big like that that is probably about due?

thanks!

[exbass94]

The timing chain is supposed to last the life of the engine, no replacement necessary.

[reginald fairfield]

Replacing the timing chain at that mileage is a good idea, but I don't know if it is completely necessary. I would change all the fluids and oils including axles, flush the radiator, etc. I would also check things like the universal joints and wheel bearings for wear. Some motors will get completely destroyed if the timing chain snaps, I know that. I don't know if the 4.0 L is one of them.

[Will]

Forget about it. If it is running and the chains are quiet it's probably fine. If it isn't in a vehicle I would be suspicious, even if my mother were selling it to me. It's an overhead cam motor and it has a regular timing chain that goes from the crank to where the camshaft would be in a pushrod motor--but it's just a blank called a jackshaft in the 'cammer. Then, there is a timing chain in the rear for the right side cam and one in the front for the left side. If it is a 4x4 there is another chain that drives a balance shaft in the crankcase. All of those chains have nylon tensioners and guides. In earlier motors the guides dissolved and the motors started getting loud. In about 2001 or so I replaced a motor in a '98 Explorer that had finally had a chain fail. The owner of that truck could not get Ford to touch it out of warranty--the dealership mechanics did not know how to set up the timing at that time. So he drove it to failure and I put in a rebuild from one of those cheap places that paints over nasty shit with silver paint. At some point Ford had fixed the problem I would guess, but I wouldn't spend much money to find out if this motor is a quiet one unless you know first hand. There are no timing marks to line up and the chains sprockets on the cams are held with bolt tension: if you loosen one, the cam jumps and you'll never get it to run again. It takes special proceedures--probably involving a piston stop and a pair of degree wheels and a dial indicator or some neato kit that Ford developed for the techs.

[Muddycowboy]

check your local dealer for a maintance schedule they will be happy to print one out for you im sure

[07rangersport]

Originally Posted by exbass94

The timing chain is supposed to last the life of the engine, no replacement necessary.

I second that. If it was a timing belt......

[Bruce]

I have a friend who has a relative that works for FORD and when i bought my 2002 Ranger with the 4.0 he said that they have seen the chains fail at 70,000 miles. I dont know what year that was may of been an earlier model like 1 of the first years of the motor and he had a 1999 with 138,000 miles on it in his shop that he just got done changing the engine because of chain failure. I know of another 2000 4.0 that has150.000 on it and chains rattling and need changing and motor has to come out to change them from what i hear. Im not trying to scare anyone only stating what i have heard. The KEY factor of the whole deal is maintenance regular oil changes because of the ones i have heard of failing they had said where neglected and not maintained . I bought my truck with 43,000 miles on it and i have 71,000 on it now. Im not easy on a vehicle but i do change my oil every 6,000 miles and use nothing but full synthetic oil and i dont use the cheap filters either, most of my driving is highway

[Wicked_Sludge]

Originally Posted by Bruce

I have a friend who has a relative that works for FORD and when i bought my 2002 Ranger with the 4.0 he said that they have seen the chains fail at 70,000 miles.

the timing chain almost never fails....the 4.0 SOHC's weak link is the hydraulic timing chain tensioners. these fail quite a lot and cause the chain to fall off.

[reginald fairfield]

Originally Posted by Will

If it isn't in a vehicle I would be suspicious, even if my mother were selling it to me.

What kind of noise do they make?

[Will]

Chain rattling from the tensioners failing. I've never heard it--just cleaned up the mess afterwards. No worries with a 3.0 though.

This doesn't mean the 4.0 Cammer is a bad motor--far from it. It's a better motor than a pushrod 4.0. It just sucked while they were figuring out the correct receipe for the tensioner material. I drove that Explorer after I installed the new motor and it is a great motor. If you are used to a pushrod 4.0--it feels just like it, but it doesn't fall on its ass seconds after each shift. Those heads have huge ports that shoot straight down into the chambers--it's a hotrod motor and if someone told me the Mustangs were getting 250hp out of it, I would not be suprised. The only thing about it is it's size--it's HUGE compared to a pushrod 4.0. One thing I like about the pushrod 4.0 is the displacement density--a lot of cubes for such a compact size and it's a heavy-duty little bugger too. they don't fail from structural issues. They are big inside and tought for such a small package. The Cammer takes up a lot of space.

[Will]

These are the parts required--