2003 Ford Exploder timing chain.

I have no idea what is wrong with me some days... My dad called me the other day, and I thought he told me the chain(s) in my uncles 03 exploder had exploded. He asked me if I was interested in the damn thing, and I said no.

Yesterday we were all out at dad's place, and I got suckered into checking the thing out. The problem is my uncle has taken GREAT care of the thing. It has always been garage kept and pampered its whole life. Then I find out it hasn't exploded yet, but is only noisy. It starts right up and runs fine. So no bent valves.. ect..

Apparently this engine has some wacky design... What on earth could the chain at the back of the engine be driving??? Is there any way to inspect the guides on the rear chain without pulling the engine? Or do you have to pull the engine to do the front chains anyway?

How should I attack this?

The rear chain drives the passenger side cam. Ford used the same head on both banks, as an expedient for shoehorning OHC design on a pushrod engine first produced in 1950. The cam drive nestles neatly in the dead space formed by cylinder bank offset, you see, and each end is driven by the shaft that goes where the OHV camshaft went.

You can replace the timing chain tensioners in-chassis (they just thread in, but some models require removal of intake manifold for driver's side bank) but replacement of the chains/guides themselves requires removal of the engine or transmission because of the eay the rear cassette is formed. Engine would make it easier.

You will want to do all four chains at the same time. Don't get aftermarket parts, use Ford only. Many iATN hits for chain noise with aftermarket chains.

Aahhhhh... that makes... uhh... sense?

Can you inspect the guides without pulling the engine?

Sort of. If you remove the valve covers you can see down in there. You won't be able to see very much, though.

Of course, removing the valve covers is like a 15 second task, right? Easier than blinking. Took more time to type.

Hey... I don't have the truck in front of me at the moment, just trying to put a plan together, and hoping their is some magic trick I can use to make it fix itself.

I assume you could do the front chains with the engine still in the truck? and then see if it will go a little longer before the rear one fails? (assuming it doesn't make any noise after doing the front ones)

To be honest, I don't know. The only time I've personally had to deal with those engines were a failed head gasket, which we repaired by putting a reman engine in (the cost was remarkably similar), and one where the timing chains were noisy after a head gasket repair by someone else... and the vehicle's owner opted for a used engine instead of tearing into it to find out why the tensioners were not getting oil pressure.

Those 4.0 litre engines are scary. Lots of special tools, rear chain needs engine removal, which is a cast iron bitch anyway. I'm not sure there is an Exploder left in the world that is worth fixing if its serious.

There is a ratcheting screw in tensioner that can fail, and it does cause the startup rattle situation you describe. The right side is easy, the left is not, IIRC.

We sell ~2 4.0 SOHC engines a year and ~4 timing chain sets for the same motor. 100% of the shops/DIY'ers who buy the chain set follow it with the whole motor. I love Ford OHC V-motors, I make lots of money on them.

The number 1 issue on those is using the incorrect oil (has to be 5W20, and a real ACEA 100% full synthetic) and/or long OCI's. Gums up the hydraulic tensioners, kills the guides.

The shop manual instructs you to pull the engine. It can be done without pulling the engine, but it will probably take more time.

Also... due diligence is required. Timing marks don't exist. Find a way to lock the cams in position at TDC, otherwise you will be semi-screwed. One of my techs didn't do that, and even Ford doesn't have a tool to set the cams. I don't even know how my tech figured it out but he finally did... a week later.

walk away!

-J0N

Not worth the hassle to end up with... an 03 explorer. This is coming from somebody who is not afraid of the repair. It just isn't worth it!