Timing Chain Rattle...

[97awdx]

I have had 4 explorer over the past 8 years, all with the 4.0 sohc, every single one had a timing chain rattle on start up, and some during operation. I am currently rebuilding a 4.0 in a my 2001 Limited that the front timing chain tensioner self destructed in. Anyway, what are some things people do to help the rattle, oil weight, additives, maintenance schedule. I miss the old pushrod 4.0

 

[97awdx]

No one? The rattle is most prominent on a cold start.

 

[rumpledoll]

My 2002 V6 4WD Eddie Bauer with 61,000 that I bought new never rattles on startup. Ever.

I do hear the chain rattle during some accelerations and only at certain RPM's. When I first heard it years ago thought it was knocking and I even tried a few tankfuls of 93 octane gas and was puzzled as to why that did not eliminate the "knocking" until I finally read about the chain rattle. It happens infrequently enough to not be an issue.

Rumple

 

[Melon]

My mom had an 03 and now an 05 XLT, both with the V6's - and the times that I drove it, I've never heard the timing chain rattle. I did have an 01 Ranger with the 4.0L so I know what it sounds like. I was actually surprised to not hear it in the Explorer - although, if you think about it - the SOHC was already in the Explorer for a few years and Ford had time to fix the problem.

Just my thought

-Melon

 

[CDW6212R]

Read through the 2-3 big threads about the SOHC timing chains.

The two small external chain tensioners both have mechanical springs inside of them. Those by design naturally will weaken over time. Those springs will not be as strong after 100,000 miles as when new. Those are the one tensioning device for each cam chain. That is likely 99% the reason for any start up timing chain rattle.

The main timing chain(jackshaft chain) has a different tensioner, made with a curved piece of steel lined with a plastic. That tensioner basically will not show any symptoms, until it fails and then the jackshaft chain will be very loose.

The camshaft chains have plastic lining the guides which they ride in, those are the components that are considered poorly designed in all 97-01 SOHC 4.0 engines. Those cassettes are the big item to worry about in pre-2002 vehicles. The Ford new for 2002 part is the only replacement, and has a better design.

Any work besides the external tensioners require the special timing tools to change. I suggest changing those external tensioners on a regular basis, just like say any timing belt. Ford does not acknowledge that those mechanical springs have a limited life span, but clearly they do. Most tensioners older than say 50,000 miles will clearly be weaker than a brand new Ford part.

Considering that those parts are less than about $75, I would recommend changing those at no more than a 75k interval. Those are cheap insurance, and directly control the start up noise. Keep clean oil and air filters in the vehicle, that will help also. Regards,

 

[Russ in CT]

...and, the Jackshaft tensioner, which is the 2-3K rpm noise that sounds like ping, was redesigned, in '03 I think. The old design the plastic would fall apart, allowing the flat spring steel that backed it to fall out, resulting in virtually no chain tension. The newer part is built such that the steel springs would stay in place even if some of the pastic fell apart, and it uses a different (presumably sturdier) plastic.

So if you're rebuilding, just make sure you have the newer jackshaft tensioner (plastic is black, old part, plastic was white), and you should be good.