I think it jumped timing. | Ford Explorer Forums - Serious Explorations

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I think it jumped timing.


New Member
September 30, 2008
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Year, Model & Trim Level
I have the 4.0 sohc which has had the timing chain tensioner rattle for quite some time (years).
The vehicle itself is in pretty crappy condition so I just figured I'd let it run its course. Its not worth the money to have the engine pulled to fix it right and I don't have the time to do it myself.
So yesterday my daughter calls me and the car just died while she was driving.
Its cranks, but is not sound like its cranking correctly. (I had a f150 with a 302 go same symptoms) I'm pretty sure the chain finally gave out.
I havent' checked anything yet, just got it back home.

SO, whats the easiest and quickest way for me to check the timing.
I'm 90% sure that its the problem and if it is, its not worth fixing.
I'm not sure where to start. Read the codes, pull the oil pan, or the valve covers and see what I see?
Its a 2004 with 210,000 miles on it.

Thanks all.

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compression test

The easiest way to check for a slipped timing chain is to pull the most accessible spark from one bank and read the compression. Then do the same thing for the other bank. Low or no compression on one bank means slipped camshaft chain on that bank. Low or no compression on both banks means slipped crankshaft to jackshaft chain.

Ok, probly trashing the vehicle.

Thanks for the reply.
After reading a few more threads I realized that should be the 1st step.
I had to buy a tester , almost 50 years old and I can't believe I haven't had to buy one yet. I got one now.
I've got zero compression on one whole bank, on the other I've got 2 cylinders with compression.
Now I've got to go find a the daughter a new beater to ride around in.

I'll research the site and see exactly what I'm dealing with and the most likely culprit before I decide what to do. If the car wasn't so dinged up I'd definately turn it into a project car.

Anybody got any handy links here for diagrams or picts of the engnine?
Save me a little leg work.


zero compression

Zero compression on all cylinders in one bank usually means piston to valve collision.

The SOHC V6 is a fairly expensive engine to rebuild and fairly complicated to time with special (expensive) tools normally needed. It's normally cheaper to replace the engine with one from a salvage yard with fairly low mileage than to rebuild the existing engine.

Thanks for that little tid bit.
It helps with the decision process.
BUT, if I got a used engine wouldn't it still have the problems with the plastic timing chain guides and have to worry about that all over again.

I'm talking after reading a few posts here. I'll bone up on it somemore before I decided. Your links in your sig are real helpful.

SOHC V6 weakness

Many hate the SOHC V6 because of its timing chain issues. The last improvements were incorporated in the 2002 and later models. I've accepted it's limitations and hope that my pre-oiler will increase the life of the engine. It will be interesting to see how the engine holds up running 6 psi of boost. Most overhead cam engines require timing belt replacement every 60K miles or so. The disadvantage with the SOHC V6 is the engine normally must be removed to replace the rear cassette.