Replace now or wait? 4.0L hydraulic chain tensioners…

[Fwirt]

So I have a 2002 Sport, not a Sport Trac, but there is no forum for the Sport and I think the Sport shares more DNA with the Sport Trac (or even a Ranger) than Base under the hood so here goes…

Didn’t know about the infamous “death rattle” that afflicts the 4.0L SOHC until after I bought the car. Engine seems to be purring right now and according to the Carfax and previous owner it’s been really well maintained. Currently sitting at 143k miles. No chain rattle on startup or running at any RPM so far, and it’s a mid ‘02 so I might have lucked out and gotten the upgraded chain guides. However, all the reports of the tensioners wearing out have me wondering if I’m sitting on a time bomb. So I have a few questions:

- I’ve heard it’s better to change the tensioners before any rattle sets in because by the time you hear it, it indicates damage to the chain guides. But I’ve also heard that changing the tensioners can accelerate guide wear because old brittle guides can’t handle the higher tension from new tensioners. I don’t have any rattle yet, so my guides are probably in good shape and I don’t want to create an issue that doesn’t exist. Should I change them out now or wait until I hear startup rattle indicating that that the tensioners are too loose?
- Oil changes seem to have been pretty regular but I was thinking of running some Seafoam because of some quiet ticking that might be the injectors. Does anyone have experience with Seafoam making the chain guides more brittle? I would imagine that fuel additive has minimal effect but I don’t know about the intake spray since it gets into the oil. I wouldn’t want loose gunk to clog the tensioners.
- I keep seeing horror stories of people cross threading new tensioners and that scares me. But I’ve heard that’s due to incorrect procedure as well, and that after priming the new tensioners in oil you should squeeze as much oil out with a vise as you can so the new tensioners don’t put pressure on the threads as they go in. Is this true? And are there any best practices to avoid cross threading other than “carefully hand thread a few turns and hope for the best?”

I know this is my first post so I’m sorry if this is too much all at once or I picked the wrong subforum.

 

[410Fortune]

Welcome!
Valid questions!!
Yes in 02 the sport and sport trac are
just like a 02-05 ranger, the last year of the gen ii explorer was 01, so by 02-03 the sport and trac are basically identical to a ranger, on paper. The big difference is the sport and trac are spring under rear axle still whereas ranger is still pickup truck with springs outboard the frame rails

Do the tensioners now
Only use ford parts
No threat of cross threading, no need to squish the tensioner to install… I’ve done tons of them. Just clean the area, get good access, carefully thread out the old one, clean and oil the new washer, thread in the new one. It’s that simple
Now it can get more complicated if you screw something up. I nicked a head one time and caused a gushing oil leak. No amount of reseating the washer fixed it, eventually I had to flat file the head… not fun. But it worked

After install hold the fuel pedal to the floor while cranking. This will stop the engine from starting, it is called “flood
Mode” the starter will
Build oil pressure in your new tensioners before startup

Now with all that said
I highly recommend you consider manual tension chain tensioners
No hydraulics needed
They never go slack, always under tension, they stop the cold start rattle before it begins and save your cassettes and guides

Discussed in great detail on this forum
We love the manual chain tensioners
I especially do because it was my idea many years ago thanks to Polaris

The sohc engine is very good after 2000 and very very good after 03-04
We see 300-450k miles from them by owners who are religious about oil changes. Must be full synthetic and must be 3-5000 mile changes the sohc needs clean oil and changing it often is the key to long life from one of these