I have a 2002 4.0L SOHC V6 that quit going down the interstate. It still turns over but one can tell that the timing is way off so wont start. Many here say that this engine is an interference engine and when the timing jumps like this it bends some valves. I know a compression check can determine if there are valve issues but the timing problem has to be corrected first.

I came across the linked article on the Underhood Service web site in the tech topic section titled:'Exploring' Service Needs On The Ford 4.0L V6 Engine: Underhood Service
and it states in the article that: "Fortunately, the 4.0L SOHC is not an interference engine so a timing chain failure won’t bend the valves."
I want to hear back from you guys concerning this issue. Is what this article is saying true or do any of you know for sure that it is an interference engine?

Thanks for any and all replies.

 

Since posting I have talked to 3 different Ford Dealers in my area and it seems they can't give a definite answer to my question. One says it is NOT an interference engine, one says it IS an interference engine, and the other says you need a Ford rebuilt engine either way.... What gives here I keep asking myself?

I'm hoping someone here can tell me for sure or if there is someone that has fixed one that has died while driving down the interstate and would no longer start.

 

There are several things that would cause it to quit. A dead fuel pump would do it, and they are known to suddenly die. (mine did)

When it quit, did it make a lot of nasty noises with clanking and banging? Any "death smoke" out the intake or pipe? (darker gray smoke with fuel, oil and antifreeze in evidence)

AFAIK, the SOHC is interference. Timing chain failure is the main reason for replacement.

Other issues are touched on here, you have to scroll down a bit to get to post 16 regarding things little and big that can cause failures.

Valves bad and Head Gasket Bad 2005 Ranger 4.0 - Ranger-Forums - The Ultimate Ford Ranger Resource

 

Thanks for the reply and the link. Did you read the linked article I have in my first post? This is what I mean about conflicting information if it is Non-interference vs interference.

I know it had a good bit of chain noise due to its mileage and wear on the chain cassettes. Time will tell I guess because all that is left to do is to start tearing it apart and see where it takes me. :'

 

Oh and as for loud noise/clanking/banging or death smoke etc when it died on the road.... nothing at all like that. It more or less just died but it was traveling at 65 mph.

One week or so before this happened my daughter reported that she heard something sound like it fell off outside the car at her feet while she was driving it and that it lurched a bit more when she accelerated after that.

I notice a bit of shiny flakes in the oil when I wipe the dipstick but all the fluid levels are up to snuff. I am thinking the flakes are aluminum from the chain cassettes where the insulating material has worn away or through.

 

When they let go, they make a fair amount of noise.

I'd check the fuel pressure first.

Metal in the oil--not good.

One thing that will cause these engines to fail is a build up of the remains of the tensioners on the oil pickup screen. Oil starvation is the result. Again, this usually signals with noise, heat, noise, and possibly a seized rod sawing it's way out of the block.

You have to pull the engine to get the passenger side head off due to the chain for that side being in back of the engine.

correct parts #'s 4.0sohc guides & tensioners with pics... - Ford Explorer and Ranger Forums "Serious Explorations"®

The basic engine is said to interchange between all years and models, even Mustangs. I can find links to that if need be. What you have to do is transplant your intake and exhaust and accessories.

A runner out of a thrashed Explorer would be one way to go. As long as it runs, you can replace the tensioners and have a reasonably sound engine. They will run 300k in some instances, as long as the cam chains don't let go.

 

Well it is confirmed... this engine is definitely an interference engine. Had it check out at an independent shop and they are reporting that its an engine. For an engine and new chain kits all installed they quoted $3,200.

Not sure what I'll do at this point but I think I can beat that price by making it a project down the road. From all the places I have talked to around here (dealers & independents) they don't have any faith in these engines. My view of that is they don't have anyone experienced enough to work on them and that makes me want to tear it down and find out how it really ticks inside.

I'm with you 85e150xix4mtod, and I believe these engines can run a long time... being German engineered most the time is a big plus.... but nothing can hold up without good preventative maintenance. I'm sure that is what happened to this one.

 

Well, imo the cam drive design is flawed at best, and the original tensioners were flimsy. But this is not an engine to stretch the oil changes out on for sure.....

 

I don't know what you'd think about this, but you could maybe look at going to a V8 in your vehicle. You might be able to find a good running one cheaper (?) I don't know about compatibility with your transmission or other parts, however....
I agree that there are mechanics out there who don't want to mess with the 4.0 SOHC.

 

I know that this thread is sort-of old and it seems that you got your answer... but hopefully this will help someone else. Here is what happens when the timing chain guide fails and then the cam gets out of time. The piston will absolutely "interfere" with the valves.

The picture is of a 2006 4.0L engine that I worked on yesterday with the exact problem that you described in your post. The RH head was in time, but the LH head was not. It was about 150° out. I retimed it using the proper timing kit, then checked the compression. It was 0psi on all three holes. I pulled the head off, and here is what I found.

You can click on the picture for a larger view.



Unsure if the piston rod is damaged, but it may also be bent and need to be replaced. Since I am doing this myself, it only costs me parts.

Hope that helps.
K

 

You won't know until you pull the engine and check.

 

What did you find with the piston rods K? Did new intake valves fix it or did it need a a new bottom end?

 

OP,

Is it possible your getting conflicting answers because some might be getting the 4.0L OHV and OHC versions mixed up?

 

Either reworking the head with new valves or replacing the head would fix it. There was no damage to the con rod. I measured the distance from the top of the block to the top of piston at TDC and it was perfect..... thus no bent rod.

 

On the 4.0L that I have both the valves and the cam are both overhead. There is a single cam on each head.

I have seen it written both ways for these engines. Is there a difference?