Timing Chain Issues 03' Explorer 4.0

[LoneRanger89]

Hey guys I have a question about my 2003 Ford Explorer Eddie Bauer 4.0 SOHC flex fuel 4wd .. I recently purchased the vehicle but I am having regrets because of the dreaded stories of the timing chains break because of the tensioners and such. I have 135,000 miles on the motor and its been well maintained. I am wondering since there are 4 timing chains on there (3 in the front and 1 in the rear) my questions are these...

1. Will I be able to hear the timing chains rattling before they break?
2.Is there any chance they could fail without any warning?
3.Should I replace all the chains and tensioners with new updated parts right now to prevent them from ruining the motor if they should break? If so where can I find some good quality parts that are updated not to fail like the old ones?

whats the best route to take to prevent a catostrific Failer?

 

[david4451]

It's NOT the chains that break it is the plastic guides, allowing the chain to jump timing and valves hitting pistons.
The rattle if you have it is usually at cold start up, caused by the hydraulic tensioners draining of oil while standing, allowing the plastic guide to move back and forth until sufficient oil pressure is in hydraulic tensioner.
This back and forth movement fatigues the plastic guides and they break in pieces, blocking oil ways etc etc.wreaking the engine.
If your engine has no rattle at COLD start up your hydraulic tensioners are probably OK and your engines is fine.
If you have a noisy rattling sound when rpm is 2000 to 2500 it means your plastic guides have already failed and it will jump time soon.
As you may not be very familiar with this problem, get a Ford mechanic to have a look and advise you on your engine.
As for parts buy genuine Ford, you already have the latest timing parts in you ST.
With 130k on your engine timing components could be a problem, it is the luck of the draw on how long they last.

 

[LoneRanger89]

so it sounds to me like its the guides I need to watch out for. Do you think I will be able to hear the rattling sounds before it causes engine failure? or is there a chance it could just fail with no warning?

 

[david4451]

As said at cold start up, a grrrr for 1 to 5 seconds, you Will hear it. Is your first indication of pending timing guide problems.
A constant chatter at 2000 to 2500 indicates timing guide failure and you will hear it.
If you don't have above symptoms, your engine is probably fine and not likly to fail without the above indications.
I have pre lubed my ST, which has eliminated grrrr at start up, effectively protecting the plastic guides from back and fro movement at cold start by pressurising the hydraulic tensioners. It is the only effective way of protecting the plastic guides and cost me about $200.
Check out " Pre-lube and centrifugal oil filters" thread for more info.