I recently bought this 03 explorer with 4.0 sohc motor in it. the owner told me it needed a new engine at 103k ??? his mechanic told him the timing chains were going out and the engine would need replaced.
he started it up for me and i really couldnt hear anything other than a brief rattle at cold start which went away quickly. he told me you dont really notice it till you get up to 2500 or 2700 rpm then it sounds like a pinging noise. I bought it that way and frankly other than the rattle at start up it ran quite nice.
I got new tensioners and that didnt help.
I pulled the valve covers and the front was cassette and guides were in place and looked fine with good tension on the chain.
The rear guide was in million pieces so bad that the chain had been hitting the top guide bolt was worn flat on one area.
I pulled the motor, knowing how these timing gears lose their timing once you loosen them. I made a camshaft retaining plate, kinda like you see for sale that mounts to the head and slides in the camshaft cutouts.
I also made a flywheel bracket that did not let flywheel turn in either direction.
So after making sure of top dead on cylinder one in the compression stroke. i locked everything down. I got a new cassette from ford.
I put it all back together using the old tensioner i welded the stub to the housing..an improvise a tensioner tool.
after torquing everything up i rotated it 3 or 4 times just to be sure of marks. left and right bank perfect at top dead compression.
I fired her up tonight. to my dismay it has horrible knocking at the rear chain. I tore down the top end to double check my work. timing is dead on. chains are tight. tensioners are new. the front is quite as a mouse but the back one sounds like crap!
did i miss something? also i checked my firing order and they are right .
Im thinking my new tensioner may be not building the correct pressure.
The car runs good except for the knocking noise..cant deal with that heck its worse now that i put the new cassette in. thanks all

 

wow! im glad see to im not the only one stumped
ok upon going bed last night you know how we all have the moments of brilliance or clarity just before dozing off that makes us wanna get up and put pants back on and head to the shop?
that was me.. i was backtracking my method of camgear install..
now i had the front of the camshaft engaged with my tool to keep the slots parallel to the head (slots on lowside).
I had the flywheel locked with a 1/4 bar fastened to block and one hole on the flywheel.
after installing the cassette everything finger tight. I installed my dummy tensioner. its the old tensioner welded at joint full extension.
I screwed it in till the tension on the chain seemed tight enough to slack out. then i tightened the camshaft.
now bear in mind i did not have the dummy screwed in the whole way i still had a 1/4 or 3/8 of threads showing. when i locked it down.
could this be the problem. maybe i should have threaded it in the whole way by doing that it would have rotated the camgear clockwise thus changing the cam relationship to the jackshaft.
I never did this job before and now that i think about it the dummy should have been seated at full position like the tensioner at full pressure. Im heading to the shop now.. will let you all know

 

Ok.. i get up this morning after i posted my moment of clarity....lol
i went down and ground the weld off the old tensioner and freed it up. of course i did a nice job and polished up the grindmarks...worked nice so as im removing the old rear tensioner i see alot of oil on the garage floor around the tire...hmmm
well in one of my moments of brilliance last night i decided that the little steel oring that seats on the tensioner was such a pain keeping in place (that is really important) i been using cup grease to hold it in place till the tensioner is in. well i decides that locktite super glue would hold it nicely.. well it held it nicely but did not provide a good sealing surface and she must have been leaking like stuck hog. the ex manifold was saturated with oil.
Anyway back to my story... after thoroughly cleaning the super glue off the washer and using 1500 grit wet sand and polished. i reinstalled the original tensioner. and fired her up.. still got the chain knock at the right rear.
So now im suspecting that i messed up when i did not install the dummy tensioner the whole way in tight. that would definately change things with camshaft to jackshaft so im fixing to pull the intake and get back to square one. im assuming i can just lock the engine at top dead #1 compression and loosen the camshaft gear a smidge to free it . and reinstall dummy tensioner the whole way. set my camshaft with tool i made. and tighten down. oh yeah folks remember the camshaft bolt is lefty tighty righty loosey. I will post back to yall.. pray for me please.. I am loving these sohc motors already.

 

guess im on my own here. lol
hey it was sunday i didnt push too hard on the explorer.
i did manage to get the rear camgear loosened and ran the dummy tensioner in tight, I had marked the the camgear and the shaft with a sharpie to see how much i gained by tightning the tensioner clear up. it amounted to about 1/8 inch of movement. thats big in cam timing. i buttoned everything tonight and called it a day at midnight i will start it in the morning and see if the knocking is still there. if it is then something else is causing the knocking. it could be one of the front chains or tensioners. i know the front cassette is in good shape. but i dont know how the lower crank to jackshaft chain looks. perhaps if that one has slack it could be messing with the rear chain setup. hmmm we will see.

 

Update:
found the front jackshaft tensioner gone. well the glider was gone the metal attachment plate was still there but that chain was just kinda dangling.
also the balancer shaft tensioner was absent as well.

I fixed them, that got rid of my 2500 - 2700 rpm pinging i was hearing.
But..... i still have the nasty knocking coming from the right rear area.

Im almost convinced it might be a lifter. im gonna look at tomorrow.

 

ITS TIME FOR A BEER!!!!!!!!!!!!!!!

yall aint gonna believe what i found today..
I need to make a new thread on this cause this can happen sooooo easy to someone else...

I pride myself in mechanical ability. OK? as im sure alot of you do as well.
I keep things neat and precise. heck ive been know to get frustrated and just start wiping all my tools down and organizing my snap on roll stand.

well get this... after all the sweat and worry and about my inability to make this 4.0 sohc run right and my putting new cassette in the back and having this STUPID knocking noise drive me crazy. I pulled it back apart this morning only took 25 minutes ( i timed myself) thats intake, to valve covers. Here it comes... if your familiar with the 4.0 sohc you know there is a hollow oil line that runs overhead of the camshaft.. that has little oil holes in it and keeps the lobes oiled... WELL apparently during my engine removal and install i must have leaned or otherwise bowed the hollow tube down to the point where #2 intake and exhaust lobes were striking this tube, now you dont notice this during assembly and rotating over by hand unless your checking hard for clearance issues.

 

Great story and glad you kept up with the thread. I have one of these motors with just shy 200K on it. Never know...

 

Actually they are good little motor with alot of power for a v-6.
Too bad Ford didnt have a ( BETTER IDEA) remember that slogan? in regards to the plastic/composite cam guide materials. Heck i had 1987 chrysler conquest with 2.6 Japanese mitsubishi motor and it had an overhead cam too. with 150k i rebuilt the motor and the guides were fine.
its not really too hard to replace these cassettes, but i would advise the correct tool kit to hold the cams and crankshaft still while tightening up.

 

Hey boots, if you're out there, I just had to replace a long block in my '08 Explorer 4.0 with 74,000 miles on it. Don't know exactly what caused timing chain and sundry associated damage as I don't have the time of facility to pull the motor myself. You referenced some recalls and/or service bulletins. How or where do I go to find these things. The car was bought new and all service was completed by the dealer. Any help would be appreciated.

 

Boots last posted in Nov '14 so stand by.

Poor design is the reason yours let go. These are not a very robust tensioner system, even with the "upgraded" parts starting in '03 or '04. Clean oil is your only defense. Some go past 200k, one maybe into the 300s. Others die young.

One good thing about them is they seem to interchange--all years, all models, including Mustang engines, can be retrofitted with the intake etc from whatever you're driving.

 

Ours is a 98 that just rolled over 237K. Runs fine.

 

Hi Yall! im still around, its hard to believe that you had issues with your 08 engine...I surely thought Ford would have worked out the issues by then.
I am not real familiar with TSBs on the 4.0 sohc but im sure they are out there. Like the other poster said frequent oil changes and definitely use synthetic oil in 5-20 is going to go a long way to preventing issues.
I have not owned a 4.0 sohc since getting that explorer on the road. I do know the new owner still drives it daily and has put on 100k since I did the cassettes and chains. (using synthetics) Great little motor just take care of oil changes frequently.