4.0 SOHC valve tapping noise

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Hi,
I have a 2002 Mazda B4000 4wd w/ the Ford SOHC 4.0 V6. The engine runs smooth, but I've noticed a dull, metallic tapping noise when the RPMs climb around 2700 and above. It is coming from the engine compartment and sounds like valves out of adjustment.

So - can the valves be adjusted on the 4.0? If not, what might be causing the noise I'm hearing?

 

[exbass94]

The valves aren't adjustable. It sounds like you have timing chain rattle, a common problem for 2002 and earlier SOHCs. The timing chain tensioners break, causing slack in the chain and it makes a rattling noise.

 

[aaaaaa]

The valves aren't adjustable. It sounds like you have timing chain rattle, a common problem for 2002 and earlier SOHCs. The timing chain tensioners break, causing slack in the chain and it makes a rattling noise.

Oh dear. What's involved in replacing the tensioners?

 

[exbass94]

It's a LOT of work. I would do some more investigating and really find out what the problem is before replacing the tensioners.

The SOHC has 3 or 4 timing chains, one of them is on the back of the engine near the firewall. Replacing that one requires removing the engine from the truck. You also need special tools. A shop would charge about 8-10 hours labor for this I believe.

This is definitely worth a read: http://www.explorerforum.com/forums/showthread.php?t=163298