Is 4.0L SOHC V6 an Non-Interference Engine? | Ford Explorer - Ford Ranger Forums - Serious Explorations

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Is 4.0L SOHC V6 an Non-Interference Engine?

ajwgator

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I have a 2002 4.0L SOHC V6 that quit while going down the interstate. It still turns over but sounds like the timing is off so it wont re-start. Many say that this engine is an interference engine and when the timing jumps 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 http://www.underhoodservice.com/Art..._service_needs_on_the_ford_40l_v6_engine.aspx
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 or a non-interference engine?

Thanks for any and all replies.
 


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boominXplorer

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Yes you will bend valves, had to replace some myself before.
 




2000StreetRod

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good article - bad conclusion

The article is informative and accurate except for the statement regarding non-interference. You can see in the photo below where the exhaust valves struck the pistons when the timing chain slipped.
3Dings.jpg

It should not be necessary to time the camshafts to determine if they are damaged. Just perform a compression check. No pressure for all valves on a bank indicate the chain has slipped for that bank. No pressure for all valves indicate the primary chain has slipped. Initially just check the easiest cylinder to access on each bank. If the compression is low but not zero then the valves may not be bent.

3Dings.jpg
 




Carguy3J

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The article is informative and accurate except for the statement regarding non-interference. You can see in the photo below where the exhaust valves struck the pistons when the timing chain slipped.

It should not be necessary to time the camshafts to determine if they are damaged. Just perform a compression check. No pressure for all valves on a bank indicate the chain has slipped for that bank. No pressure for all valves indicate the primary chain has slipped. Initially just check the easiest cylinder to access on each bank. If the compression is low but not zero then the valves may not be bent.
Since you have to crank the engine for a compression test, wouldn't that be a bad idea, if slipped timing/broken chain is suspected? While cranking on the starter is much slower/less force then the engine running, it can still easily bend a previously un-bent valve(s).
 




2000StreetRod

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valid point

Since you have to crank the engine for a compression test, wouldn't that be a bad idea, if slipped timing/broken chain is suspected? While cranking on the starter is much slower/less force then the engine running, it can still easily bend a previously un-bent valve(s).

That's a valid point. I would have suggested manually rotating the engine to check for interference before cranking the starter but the OP has already attempted to start the engine using the starter. So if cranking the engine was going to cause valve damage it's probably already happened.
 




ajwgator

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Thanks 2000StreeRod. That's the kind of definitive information that can't be refuted. A picture is most definitely worth 1,000 words. Pretty much sums it all up. I too though the article I referenced was real interesting especially the history of the engine itself. Might have to back up and punt here. Thanks again!

And thanks to boominXplorer too.
 




Saik

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See my topic on this issue.
http://www.explorerforum.com/forums/showthread.php?t=401008

My chain jumped and I had to send it to a shop. They had to remove the entire engine to replace the rear chains. If you're going to go through that route you're looking at minimum $1500 labor and $800-$1000 in parts depending on what you're going to replace. I decided to have all the gaskets changed, all the chains/tensioners/guides changed, all the valves changed, and new intake manifold, and EGR valve. You will also need new coolant, power steering fluid, AC system needs to be vacuumed/refilled, and new motor oil

If you go through a Ford Dealership for this you're looking at $4000+, I went through an independent shop with a repair guarantee on their work.
 




ajwgator

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Thanks Saik. I appreciate the info and yes I checked with the Ford dealer. The one in my area will not repair this engine at all when it needs chains. I guess they have had too many bad experiences with them. They said they would only do a Ford factory remanufactured engine and quoted me a price of $5,625 "out the door". :eek:

Looking into getting a lower mileage engine (65k-80K) at a yard and doing the complete chain change myself now. If I'm lucky I might be able to do it for close to $2k max. Fingers crossed.:salute:
 




Kirka

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Thanks Saik. .... If I'm lucky I might be able to do it for close to $2k max. Fingers crossed.:salute:

Just curious how you came out on this? I am looking at the exact same problem.... chain broke while the engine was running down the road. Mine is a 2006 Explorer.

Were the valves damaged? Any piston damage?

Thanks
 




ajwgator

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Just curious how you came out on this? I am looking at the exact same problem.... chain broke while the engine was running down the road. Mine is a 2006 Explorer.

Were the valves damaged? Any piston damage?

Thanks

Yes it trashed both valves and pistons. Wasn't worth fixing in the end. So much for Ford's "Non-interference V-6" :thumbdwn:
 




jag2552

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Yes it trashed both valves and pistons. Wasn't worth fixing in the end. So much for Ford's "Non-interference V-6" :thumbdwn:
How did u find out if the valves were bent
 




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