I got a Ranger in disguise 2009 Mazda B4000 about 2 weeks ago. Engine has 70,000 miles on it. The only thing I have done to the engine is change the oil. 2 days ago it started making a loud peck/knock. It will still start and run smooth except for the noise. The noise will change with RPMs and is present from start up and doesn't change if the truck is warm or cold. I think the noise is coming from under the front of the driver's side valve cover, had a mechanic in the family listen and he said it sounded like it was under the intake. Both of use suspect a broken timing chain guide.

My current plan is to get a borescope and check the pistons and valves for damage. Remove the hydraulic tensioner and try to see anything through that hole. If nothing is found, then remove the valve covers for inspection. Once I find out the issue, I will then have to decide whether to fix it myself, pay to have it fixed, or drop in a low mileage replacement engine.

Also been looking around at used engines, and most sights do not show a 2009 Mazda 4.0 and a Ford 4.0 interchanging. Is there any difference at all between the Ford Ranger and Mazda B4000 as far as the engine?

Is there anything I am missing or should do instead? I have attached a video with the sound.

Thanks!

 

Welcome to the forum

2004 and up 4.0l SOHC engines had the newer designed timing chain setups so didn't have the previous problems seem in the 1997 to 2003 engines

But things still break on any engine.

Drivers side front is where timing chain is on that side.
Passenger side has the front and rear chains

Cold engine
Remove/loosen fan belt
Start engine
It is often easier to localize an engine noise when fan and accessories are quiet

Don't run engine more than 2 minutes this way as there is no water pump circulation, also Battery Light will be on because alternator is not working.
Neither is an issue for a few minutes.

If you use your current lower and upper intake and exhaust manifolds then you can use any 4.0l SOHC engine from 1997 to 2011, from Ranger, B4000, Explorer, Mountaineer, or Mustang(Mustangs used different Cams, more HP, less Torque)

So basically a Long Block swap.

As said the 2003 and earlier needed the timing chains swapped out to newer design.
Things that should also be changed while engine is apart:
Knock sensor
Heated PCV Valve, if so equipped
Rear main seal

Thermostat housing on these often cracked and leaked, judgement call

 

Thanks. I had planned to try it without the belt, haven't done it yet. Will be the first thing I do when I start on it this afternoon.

Does the Mustang block swap change fuel mileage any? I am more concerned about fuel mileage than power. Truck will be driven mostly on highway/freeway.

 

Noise is the same with the belt removed.

Removed the timing chain tensioner and still seemed stiff and did not see anything through the hole that looked out of place but could not see much. Is there any chance the tensioner is bad causing the noise. Noise is the same hot and cold though.

Pulled spark plug and looked at piston. I attached a picture. Looks like a valve shaped mark, but not sure. Is this piston normal or damaged?

Thanks

 

Can't tell from that picture

This is what it looks like if valves hit pistons: http://www.explorerforum.com/forums/...ngs-jpg.77924/

But engine will no long run at that point.

MPG is about vehicle power to weight ratio and YOUR driving habits
Different cam timing wouldn't change MPG if driving habits were the same, so mustang or truck 4.0l would be the same if everything else was the same

 

Are you saying truck would not run if valves were hitting the pistons, or saying that would not run if it was as bad as the picture you linked? Truck still starts and runs smooth except for the noise.

 

I suspect that the truck went a long time since the previous oil change. Would it be possible that some crude broke lose in the engine causing the chain tensioner to fail, or that it just wore out? It would be a lot easier to put a new tensioner in than to remove the valve covers as a next step.

 

You can remove the tensioners and then disable spark(unhook coil wire connector) and crank engine a few times, that should clear tensioner oil passages.

But a rattle is what loose tensioner sounds like, not "knock"


Yes, if valve touches piston it will bend and then not seal that cylinder, so loss of compression and that cylinder will no longer fire.
Bending 1 valve would be a long shot with overhead cam, if timing slipped then 3 valves would be effected on a V6.
Engine could run but you would know something major was wrong because it wouldn't run well and noise would be "knocks" not "a knock"

What you describe is more like 1 valve is effected not several, so valve cover needs to come off

 

If this was the problem, I'm sure Ron would have mentioned it, but I thought I would post it anyway. Watch for the first couple of minutes.
The guy in the video sure butchers up his intake manifold _ if you watch the whole thing.