Was wondering if the timing chain tensioners, were updated/improved, or just the timing chain components.Thanks

 

The 4.0l SOHC's two long chain tensioners had poorly designed springs that would fail, not 100% failure but enough to get a redesign
The 1997 to 2003 engines had the old design, by 2004 they should have the newer design

The chains and guides were never redesign to my knowledge

When the spring failed the chain would bang on the guide during start up, once engine was running oil pressure takes over so spring is not needed.
Over time it would break the guide on start up
Once guide was broken it would cause a rattle noise on start up and mid-RPM, so damage done

As said it wasn't a 100% failure rate

As far as the overall design, well 2 long timing chains will have twice the trouble of one long timing chain, lol, thats just the way it is
But you will never have timing belt issues....................yes because there is no timing belt

I recommend to most with a 4.0l SOHC to replace the two tensioners with Motorcraft brand tensioners every 100k miles or so, not 3rd party brands

 

Thanks Ron. So what you are saying the external screw in tensioners were updated. Is that correct? thanks

 

My ranger is in the shop today for the whole timing chain job. Started to hear some noise on startup, replaced the tensioners but it was too late! Haven't got the entire estimate from the shop yet but not excited

 

Yes, the two long chain screw in tensioners were redesigned with better internal springs

Yes, once you hear the rattle noise its too late, a guide is broken

 

Doesn't this require pulling the engine so you can access the chain in the back?

Thought I read somewhere that mid 2002 is when they changed the design.

 

So do you know if the part numbers, were changed.,from the old ones . If not any way to tell if you get new or old design. Mines not making any noise. thought I would order both to have on hand and change at 50k just for peace of mind. afkrejci90 if you are talking about the tensioner for the rear chain, you get to it from passenger side wheel well. thanks again

 

The tensioners screw in from the outside. The guides need the engine pulled. The rear tensioner is really easy to replace. The front one requires you to remove the throttle body and part of the thermostat housing

 

+1 ^^^

 

Thats about right, new tensioner were designed in 2001 and built in 2002, then they are sent out to the Ford Engine Building Plants where they were used to build the 4.0l SOHC engines
Engines built in 2002 would be shipped to the Ranger assembly Plants to go into 2003 models, BUT...............engines and parts in general, that are used at the Assembly Plants are suppose to be First In First Out, so if there were still 2001 built engines left at the Ranger Assembly Plant they would/should be installed in the 2003 models, once they were used up then the 2002 engines would be used
Remember this was NOT a 100% failure rate, maybe 15% so Ford didn't just trash the these engines, they redesigned a part, but no already assembled engines were pulled or redone
These are called transition years and all models have these for various changes a car maker does over the life of a model

So 2003 could have older tensioner design, 2002 would for sure, 2004 is probably safe, BUT...............someone may find a 2001 engine, or a few(in the back room, lol) that didn't get used, so they put them in the line up and its installed in a 2004

In my opinion you should change the two long chain tensioners just as service work, regardless of the year


The 4.0l SOHC engine was first used in 1997 Explorer, and the timing chain issues didn't start to show up until 1999, and it was, of course, first blamed on owners using bad oil or not changing the oil
By 2000 there were enough dealer serviced 4.0l SOHC engines having this problem, so not Owner neglect, Ford had to "find the problem", and they did, redesign and testing in 2001, then mass building of the new part in 2002 and shipping it out to engine plants

 

There were a lot of 2001 4.0 SOHC Rangers that had the timing chain problem. I watched the chain complaints on various Forums because I was concerned about what I should do. That failure rate was reduced considerably in 2002 and more so in 2003. I don't know the reason why but if Ford new there was a problem in 2001 and where redesigning the chain tensioner, it may be that they started installing the better chain tensioners in 2002 for 2002 vehicles. It would be a very easy upgrade if the engine was already built but not in the vehicle yet, especially if the throttle body had not been installed yet.

I replaced my tensioners at around 100K miles and am still running those replaced tensioners at 247K miles. Maybe I am just lucky. I do have plans to replace the guides before 300K miles. I will replace the tensioners again at that time.

 

Please excuse this unabashed, emotional dump but the decision to build the SOHC engine such that removal is necessary for these repairs is among the stupidest ever.

Honestly, with all the "hands-on" people who own trucks and all the paternalism oozed by Ford's image, you gotta wonder what they were thinking.

This board has helped immensely with tasks. I suppose everyone here should bank any money saved on DIY repairs to finance a future engine removal.

What is the benefit of the front-and-rear timing chain design? Are the heads universal?

 

I read somewhere (cant find it now) that the engine was designed to fit the factory that it was to be assembled in. Something to do with reducing the need to retool the factory and instead just design the engine around what was currently in place. Don't know if its true or not but easy enough to believe

 

The benefit of the front, and rear timing chain , was to get more hp out of the same size block for the space they had to put it in.

 

Well you don't have to pull the engine to replace the rear timing chain, you can pull the transmission, same as you would have to do if rear main seal leaked, and EVERY engine has a rear main seal

Picture of the rear of the 4.0l SOHC: https://i.ytimg.com/vi/SDLRHOM6Ru0/maxresdefault.jpg

You need access to the rear of the jack shaft(old cam shaft location on OHV), hole seen in picture

Pulling the engine makes working on it easier, of course, DUH, but isn't "required"


4.0l SOHC has a left and right head, they are not interchangeable, like most OHV engines