Friday, February 25, 2011

SOHC Timing Chain Replacement Procedure

4.0 SOHC Ford Explorer Timing Guide (1997 - 2005)

By Ralph McKnight Jan 4, 2007. 

Disclaimer Note: This is how i successfully did the job, but i am not a ford mechanic and don’t hold me responsible if this does not work for you.

View Picture Album of the Engine Re-Build

Technical short cut guidelines to do the entire timing job
Get Ford timing tool kit, part = otc-6488 (For about $119 USD on eBay)
4 timing chains (3 front including the optional balance shaft chain + 1 back)
2 cam guides (1 front + 1 back)
2 oil tensioners (1 front + 1 back)
1 jackshaft tensioner (1 front)
1 jackshaft guide/cassette (1 front)
1 balance shaft tensioner (1 front) (will probably be ok, so dont replace it)
1 balance shaft guide (1 front) (will probably be ok, so dont replace it)
new sprockets + bolts + gaskets etc.
new spark plugs + throttle body cleaner + lithium grease spray + oil change
head gaskets
 
some of these parts (the front stuff) can be obtained as a primary timing chain rattle noise kit Part# = 2u3e-6d256-** ab for 4*4 & bb for 2*4.
The kits also have later part numbers for us$ 76.

some good ford part sites:
http://www.carpartsdiscount.com
http://www.fordpartsonline.com

via ebay there are now kits for about $120, that have just about everything:
http://www.ebay.com.au/itm/Land-Rover-Ford-Explorer-Ranger-Mazda-B4000-4-0-SOHC-4WD-Timing-Chain-Kit-/261036586708?pt=Motors_Car_Truck_Parts_Accessories&hash=item3cc6fe36d4

Or Search ebay for: ford explorer timing chain kit
  
My parts order (without the balance shaft stuff) was:
$76.04 KIT-TENSIONER TIMING 2u3e-6d256-ab
$47.93 Engine, Camshaft and timing, Timing chain, TIMING CHAIN, Explorer, Mountaineer, Rear - 4.0L SOHC - 4.0L SOHC
$57.36 Engine, Camshaft and timing, Chain guide, CHAIN GUIDE, Explorer, Mountaineer, Jackshaft To Cam - 4.0L SOHC - 4.0L SOHC
$103.22 Engine, Overhaul gasket set, OVERHAUL GASKET SET, Explorer, Mountaineer, Upper (Valve Grind) - 4.0L SOHC - 4.0L SOHC
$28.93 Engine, Camshaft and timing, Tensioner, TENSIONER, Explorer, Mountaineer, Upper - 4.0L SOHC - 4.0L SOHC
Its worth mentioning that this procedure is not enjoyable at all and should be undertaken with at least 8 full days to completion (I recon you could do it in half the time the second time).
It is basically on entire engine re-build with both heads off and the engine out of the vehicle.
It is not possible to do the rear chain or sprocket with the engine in the car as the flywheel needs to come off + at least 1 head, but it is possible to do the front primary chain and or front cam chain with the engine in the car.
You will be a ford exploder and timing expert after you do this - the main reason should be the love of your American built vehicle. Its a solid car - except for the plastic guides!

edit: prices are somewhat inaccurate now as its been a few years.

Timing Overview

A Small Sprocket on the crank turns a larger (2 to 1 ratio) jackshaft sprocket that is in turn connected front & back to the 2 camshafts.
Thus a 360o turn of the crank will turn both the camshafts 180o.
Firing order is 1-4 2-5 3-6, Right side numbers 1,2,3. Left Side = 4,5,6.
At TDC pistons 1 & 5 are fully raised, thus 1 is about to spark & 5 is evacuated.
The engine will turn freely (no piston to valve contact) with the cams 180o out, it will even run (roughly) with 1 out 180o, any other settings may cause major damage to the valves.
The 2 cam shafts come with timing markings, "yes" real timing marks that anyone can use (even without special tools) to ensure correct timing.
The way to time it is to ensure both the off centre cam shaft slits are level/flat with the head.
With the engine at TDC both the cams need to have the off centre slot in the same position either up and level or down and level.
It is super critical that both the camshafts are 100% in sink with each other, i.e. not a few degrees off, the engine computer can compensate for crank timing but not engineering failure.
Be warned the camshafts can turn easily fast & hard by themselves as a few springs are compressed at TDC, I got my finger jammed and its still healing + if the engine is not at TDC you may damage a valve.
Now heres the hard thing that you will need special tools for - if you need to change the timing, you will need to be able to undo the cam sprocket bolt on both cams & these are done up real tight.
There is a tool that you attach that has 2 pencil thick shafts that fit into the sprocket and prevent it from turning - then you need to put about 90Nm of force on the bolt (remember the rear one is LHT)
For the $money$, its well worth getting yourself the tool kit - it will save you hours in the long run. Search eBay for otc-6488 should be US $119 - then sell them again for say $100.
There is also a tool version of the oil tensioner in the kit that screws right in and puts the correct amount of force on the chain + guide, to enable you to do up the cam bolt with the chain and sprocket in the right spot on the cam.

Engine out procedure - OK here we go


  1. Remove battery
  2. Remove radiator fan clutch, (note: its normal RHT. stop clutch from turning by holding one of the 4 small bolts with wire to another pulley, turn anti clockwise till its tight, attach large robogrip or equiv, extend torque by adding a large spanner to end, turn hard to left) FYI its 36mm
  3. Drain engine oil + remove the filter & remove the transmission line bracket bolt (from behind where the oil filter was).
  4. Remove clutch, fan + shroud from vehicle
  5. Drain radiator fluid - if you want to keep it - then use the tap on bottom air filter side of radiator.
  6. Remove Radiator from vehicle (as the engine needs to come out - you can leave the radiator in the vehicle for this procedure, but its a tight fit to pull the engine out - you will need to twist front up and back to the left - so better to pull the radiator out)
  7. Remove the fan belt
  8. Remove all the crap from the top of the engine, i.e. all the air intake + air filter + throttle cables + harness etc
  9. Remove the upper air intake + disconnect all vacuum lines, block the 6 lower openings with 6 rags.
  10. Relieve the fuel rail pressure - via the valve on fuel line - using a nail - like air from a type.
  11. Undo the fuel line to the injector rails (2 bolts each side) and wiggle / pull apart - there is an o ring inside, seal all fuel openings
  12. Undo the power steering pump line from middle of car - all the fluid will thus run out into a bucket
  13. Undo and label all the electrical connectors, start labelling from 01 etc - you will end up at about 30.....
  14. Undo accessory assembly (the air conditioner + others on battery side and swing into ex battery spot - the air coon does not have to be messed with as there is enough play in the cables)
  15. Remove the belt pulley tensioner and swing the entire alternator assembly bracket into the air filter box.
  16. The Front of the engine is now completely free / clear.
  17. Jack up vehicle + remove both front tyres + support 2 strong stands + remove both type/engine aprons, also put wood to support next to stands as who would trust their life to a weld?
  18. Undo Starter motor and leave connected to power cables, but place away from engine block.
  19. Remove the 4 talk converter to flywheel bolts - have helper rotate engine (always clockwise - never the other way as the plastic timing guides will destroy themselves)
  20. Put a hydraulic jack under exhaust to stop in from moving
  21. Put a hydraulic jack under the tranny front edge on a flat piece of wood to stop it from moving / turning.
  22. Remove the exhaust pipe to exhaust manifold bolts with air tools - too easy!.
  23. Undo all other bolts + lines + harnesses that you can find that prevent you from pulling the engine - such as the tranny dip stick
  24. Mark and remove the front bonnet
  25. Attach engine hoist to engine somehow - I used 4 ropes to all 4 corners of the exhaust manifold - use a good rope and good knots! - take the engine weight up.
  26. Remove the lower 4 Tranny bolts and label them
  27. Remove the upper 4 Tranny bolts and label them (through where the tyres were) - that’s all 8 bolts now (not 6 as the ford cd says!)
  28. Remove all the engine mount bolts (all 8 of them - 4 each side - not that hard with the tyres off)
  29. Undo the main firewall harness - drill out the 2 rivets - pull the harness + earth ribbon + Undo cut the small earth wire to bolt (join it up later)
  30. Pull the engine out a little - Undo the 4 back electrical harnesses + label them
  31. Pull the engine + remove the flywheel + put on engine stand via the 4 engine block bolts (Not the ladder frame etc bolts)
  32. Well done if you got here in 2 days!
  33. Engine tear down procedure:
  34. Remove spark plugs from the engine + label the leads - pull the wires from plugs but leave them on the coil
  35. Remove the harmonic balancer and ensure keyway is at 12:00 - To remove you need long screws
  36. Remove the lower air intake + all harnesses
  37. Remove the complete electrical harness & coil & wires with a helper as a complete unit
  38. Remove the engine oil dip stick - it pulls out with a twist!
  39. Remove both valve covers
  40. Remove both hydraulic / oil cam chain tensioners
  41. Clean out and loose broken cam tensioner pieces (heads still on)
  42. Remove the timing cover, you can leave the water pump housing on I think if you want - but mine was already messed with by someone - so im doing it again anyway, as I dont trust ford silicon.
  43. Clean out and loose broken crank tensioner pieces (heads still on)
  44. Turn the engine over a few times to make sure it feels smooth and get a feel for it.
  45. Again clean out any new loose plastic pieces as the guides will probably be broken.
  46. Remove the sump cover - from under the stand - dont rotate the engine as pieces of loose plastic guide may move!
  47. Remove the oil pickup pipe and check that the screen and pipe are clear - mine was full of plastic!!!!!! + clean the area and reassemble the sump.
  48. Check the engine is at TDC (keyway up or use the crank TDC tool) and the 3 drive chains are loose (dont ever rotate the engine left).
  49. Using the special ford tool, remove both the upper cam sprockets - no need to hold the shaft with the alignment tool - the shaft is not under any tension. Note: The rear cam sprocket is left hand threaded
  50. If you are going to remove the heads - do so now, I did as I also had a water leak and wanted to completely elimiate the heads but you may be able to do this job without pulling the heads as the chain + guide + sprocket will fit out the top of the head.
  51. Leave the exhaust manifolds on - they are what i used to lift the engine in and out of the car.
  52. Remove the timing cover - leave the water pump cover alone - no need to open that up.
  53. Remove jackshaft plug by flipping it over with a hammer, hold the jack shaft rear with a torx55, use powerful pneumatic tool to undo the front jackshaft bolt, if the back turns first then you need to get creative.
  54. Remove the front jackshaft metal tensioner + cassette + chain + sprockets
  55. Undo the rear cam guide holder bolts and remove the sprocket + chain + guide
  56. Undo the front cam guide holder bolts and remove the sprocket + chain + guide (may be a bit hard if the read is still on)
  57. Service the balance shaft as needed, put a new cassette in if needed, the tensioner is at the very bottom of the engine and if replacement is needed then the ladder frame will need to be removed - dont do that unless necessary
  58. The balance shaft system was not faulty on mine so i did not replace the chain or tensioner - just the cassette.
  59. I checked the balance shaft timing and found it correct, to do this align the 2 dots with the hole to the right of the sprocket and ensure TDC on the crank. You will need to rotate up to 7 times, checking each time due to the reverse gearing ratio.
  60. Clean the heads + piston tops if you pulled the heads
  61. Well done if you got here in 2 days!

Valve timing


  1. re-insert the old front jackshaft bolt & hold to stop the shaft from turning, put in a new rear chain + rear sprocket + do up to 20nm + 90o. I did mine up a lot tighter + there is a tool that can hold the rear jackshaft sprocket while you do up the bolt, but its not really needed, as you can get someone to do up the front sprocket at the same time - remove the front old bolt if you used that method.  (The other method is put both sides on and do them both up at the same time).
  2. Replace everything up front (chains + cassette + tensioner & pull the pin + front cam guide, tighten up the front Jackshaft bolt to 45Nm + 90o Note: don't tighten up the cam sprocket bolts - allow free wheel.
  3. Turn the engine over a few times to ensure smooth operation with the jack shaft & tensioner etc fully tightened.
  4. Leave the engine at TDC i.e. piston 1 & 5 fully up at all times - for each side
  5. Right Side Head & Timing: (i.e. rear i.e. left hand threaded one)
  6. Position and fit the new cam guide + do it up
  7. Install cleaned head back onto the engine if you removed it, with new gasket, do them up as per ford CD order and torque
  8. Install cam sprocket onto the shaft (finger tight only - free wheel) (tighten after tools are on)
  9. Install camshaft holder tool to time the shaft, remember both slots on the cam camshaft up or both slots down - dont mismatch them!
  10. Install the timing chain tensioner tool in place of oil tensioner
  11. Install the Cam Sprocket Holding tool 303-564 (T97T-6256-B)
  12. Tighten enough that chain will turn cam, after a few crank turns ensure correct timing and then fully tighten. 61Nm with tool extension or 85Nm without
  13. Remove the timing chain tensioner tool and insert the real oil tensioner
  14. Left Side timing: (i.e. front of engine)
  15. Same as Right Side (remember engine at TDC)
  16. Install both valve covers after checking the slots are identical in both cam shafts
  17. Install timing case cover and fit harmonic balancer, use silicone at the 4 key edge points.
  18. Install the jackshaft plug

Engine Assembly tips

Install nice new spark plugs whilst the engine is out.
It is very hard to align the torque converter bolts to the flywheel for some reason? Any tips are welcome? can you use some wedges somehow?
The next time I do this job I will try and attach some string to one of the converter bolts and pull the converter into the correct alignment - there is very limited visibility through the starter motor housing.
Use a whole saw and drill out a big hole in the air filter box to allow more breathing - all the way up to 6,000+ rpm (sounds great).
This engine will run well with the air intake open (ie no resistance from the air filter etc), thus you can run the engine while spraying throttle body cleaner into the intake to clean it.
Go give the wife a hug, because she has been taking care of the kids + you for the last 6+ days!!!!!!!
email me @ mcknight.r@gmail.com and let me know if this was useful or need any help.

Some Pics (compressed) I have a lot more!

View Picture Album of the Engine Re-Build

32 comments:

Nicole Gentry said...

Thank you so much !!! The timing chain broke on my 1997 Ford Explorer about a year ago and we can't afford a mechanic! My husband 'the shade tree mechanic' has been tinkering with it and just couldn't find exact directions on how to do the repairs! THANKS SOOO MUCH!

DCL said...

I'm in them middle of doing my 2003 Explorer. I had taken the engine to a machine shop to have them set the timing but when I put the motor back in it ran really rough. I have the motor back out and noticed the slot on the cams one has the fatter side down towards the head. The the side is up facing the valve cover.. is this correct ? Or is one cam out 180 deg... ?
thanking you in advance

R.McKnight said...

both cam slots MUST face the same direction, both up or both down.

one of the cams auto rotated 180deg on them and they didnt notice. Just like i said in the article.

Pringlebandit said...

First off, want to thank you for your time in sharing this article.
Second, if the timing chain slipped on an 03 Explorer, on the left bank due to tensioner failure, is it common for the valves to be bent?
Thanks,
Jason

Cory said...

Thanks for the clear, precise notes. I got word from my mechanic that I "need a new motor for the Explorer." It's a '98 Explorer Sport with the 4.0 SOHC engine and 110k miles. I've been going over options... Donate the Explorer, ZipCar, rentals, used car, bicycle, etc. With instructions like these, and other resources, I think I can make this happen on my own.

Thank you!!!

zishancheeta said...

Thank you so much . Help a lot . I try online machenic for answer but they were unable to answer. this is graet post. I had worked on many cars but i was stuck on this explorer. with this post's help i was able to assemble this motor.
thanks deep of my heart.

zishancheeta said...

Than you so much . A great post . I got a great help to assemble my motor.
I had workded so many cars but this was some thing els.
I raely thankfull deep of my heart.
I try online mechanic to get some help but no one was able to answer my questions. Thanks again

tumbleweedtrucker said...

Thanks for posting this. It was a great help. I am a full time mechanic, and in the middle of a timing chain job on an 03 Explorer. Mitchell is not much help. Some things I have learned. Yes you can replace all 4 chains without pulling the heads. It is a little tricky but can be done. It is even possible to do this job with engine still in vehicle. You have to remove transmission and flywheel. As this was my first time I pulled the engine. Which by the way just pulling the motor is a lot easier if you pull the trans first, assuming it is only a 2wd. I had the tranny out in 45 mins. Ok i used a lift, trans jack and air tools. Thanks again.

Tyrel said...

Great info. Pulled my engine to replace the chains but found out its just the front lower tensioner. Will i still have to re time the motor? and if so, will i have to have the special tools? Thanks

maria said...

So do any of you work in Ca! I need a good mechanic that knows what's up like you guys.

sleepyhead416 said...

GREAT POST Just started putting mine back together. In the kit for the new parts for the balance shaft it has 1 small pipe plug. Do they want u to block oil passage? Thank u so much

BOB said...

Is the rear jackshaft bolt reverse thread? it is the #55 torx head one. please reply to enderton2000@yahoo.com or call me direct at 208-940-2454 thanks for the great article, i need to finish this by next week!

BOB said...

Thanks for calling the other day. I have 1 more question. on the right side timing chain, as you rotate the crankshaft, the tensioner moves in and out "snapping" the tensioner arm then re-extending. is this normal? left side goes in and out but no snapping. let me know if you can. Bob 208-940-2454 or enderton2000@yahoo.com thanks again

theTIMguy said...

just checked out an explorer family member was told spun /broken rod after listening to it didn't sound like lower end, checked oil drain plug with no debris showing. after reading this post thinking I am looking at timing issue, noise is up front but passenger side compression is lower than driver side by 60 psi consistently. I will check it out further in the morning hope n pray in fla.

theTIMguy said...

I forgot to say thanks for this post just thinking of the work ahead, hope n pray I can do this with the tools i have. plus rentals of course!!! any comments please call 478-442-3123

bfsjr said...

This is a truly awesome documentary of your work and I'm sure many have benefitted from your dedication for doing this. I am about to embark on pulling the engine in my 98 Ford Explorer XLT SOHC in order to replace those nasty stock tensioners and guides. I will follow your directions and hope I can accomplish this feat. You mentioned that you may have some more pics which I would like to have if at all possible. Again, thanks for your hard work in preparing this excellent overview of just how to replace the timing chains, tensioners, and guides.

B said...

Just want to let everyone know that needs to preform this that the rear timing chain can replaced without removing the motor. You can drop the transmission to gain access the rear timing chain bolts. Just helped a friend do this on his 2004. Still sucks though.

R.McKnight said...

Some answers:

Yes, transmission can come out instead of engine. but then you need to be able to get it out of the way.

The chains should NOT chatter or snap, everything runs smooth once tensioned correctly.

Even without the tensioners, the valves will not hit anything, so there is quite a bit of room (but it is still an interferance engine).

yes the "1 small pipe plug", (stick looking thing) is to restrict the oil from getting out of the front oil tensioner, and goes in the torx screw area near the tensioner.

diy-master said...

Good job!. After reading through R Mcnight's presentation I mustered courage to work on my 199 v6 4.0SOHC Eddie Baurer. I replaced the front tensioner becuase it was all stripped to metal (plastics all gone). The front left cassette and the balance guide/tensioner looked ok from my inspections - no cracked or stripped plastic guides. I just assumed that the rear right tensioner/guide will also be ok since much of the clunking noise I was hearing seemed to come from front of the engine. I did not even bother to open the right valve cover to check the right cassette anymore. Kind of stretching my luck that I have solved this dreadful issue without having to go through the costly engine removal process for the balance shaft and right rear cassette repairs. NO! NO!! NO!!!. After puttng everything back again the noise reduced a bit but the big mettaliic noise was still present, and now is evidently coming from the rear of the engine. It seems after eliminating the front noise the rear was now more distinct. Also some noise seemed to be the kind due to low oil lubricating noise. Next day I took down the oil pan to investigate if the oil strainer is blocked. I found a load of plastic pieces in the pan and the strainer was practically blocked with plastics. I cleaned out all the debris and the sound improved and a lot more oil was now visible from the top oil filler cover lubricating the valves and chain when the engine is running. It is advisable to stop using the truck when the noise starts because the plastic pieces blocks the strainer and reduces engine lubrication and cause a lot more damage. The amount of plastic debris I removed from the oil pan and strainer indicated and confirmed to me that the right cassette was terribly gone. When I opened the right valve cover to inspect it was a terrible sight to behold. Everything in the cassette was gone - both tensioner and guide were stripped out. The chain was now riding on top of the tensioner mettalic spring strips below, and at the top was flapping on the top cassette securing bolt and had worn it down to a quarter of the bolt diameter. So, no luck. I am now re-reading Mcnights presentation again to muster courage to bring the engine down and do the rear chain/cassette.
Some questions! Will the 1-ton floor engine hoist do the job or a 2-ton hoist is needed? What size of hoist did you use as seen in your pics? How reliable are the cheaper Autozone (made-in-Taiwan) tensioner kits? Has anyone used them? Your replies will be appreciated.

diy-master said...

Finally brought down my engine and replaced everything (left and right cassettes including hydaulic tensioners, front chain and guide/tensioner, balancer shaft tensioner). I can't believe my truck could run this smooth and quietly. Also found out that my cold-starting ueneven run has been taken care of, I guess it was the replacement of the upper intake manifold gasket that did it.
It took me five 18-hour days. Could have been shorter if I did not take one full day trying to get the engine to align onto trans pins. Not until I installed a load leveler on the hoist since I was working without a helper. The top 4trans bolts are best handled through the wheel well. Also buy a cheap ratchet (say from a cheap set, check Harborfrieght) and cut the handle to say 4 inches and use it with short 1/2" socket inside those tight spots. (You may need dremmel/or high speed wheel cutter to cut the handle). When the bolts are snug insert an appropriately sized custom made pipe extension (say 12" long) to torque the bolts. Another handy tool that helped was air wrench. This helps with pulley bolt loosening and tightening without turning the crankshaft, helps with exhaust bolts, timing shaft bolts without tuning the shaft (just grip the shaft with good grip plier and let it bear on the appropriate block face just to be on safe side to provide additional resistance to turning. The turning force the air wrench exerts on the shaft is surpringly minimal since it loosens the bolt by short knock-shocks on a tight bolt or nut).
Thanks to this forum and McNight.

diy-master said...

In addition remember before you pull the engine to place bright paint mark on one (immediately reachable through the starter opening) torque converter bolt-stud tip and the surrounding area around the flywheel hole. (Use glossy white paint that could stick well). This will let you know when you have flywheel/torque converter alignment during reinstallation of the engine. Note that the torque converter studs are not symmetrically placed and can only align in one relative postion on the flywheel.

plastic stanchions said...
This comment has been removed by a blog administrator.
steph menard said...

I found a really good hd video it's in spanish but you could use it with the volume down.I will bring my laptop in the garage.It's on you tube
Sincronizacion motorfor ford 4.0


hope it helps

Rikki Burn said...

Thanks for the post, it is very helpful. We had to get the head gasket repair in our vehicle. The post helped out a lot, thanks.

Christian Hernandez said...

This was very helpful my car runs like new!!! I spend 3 days to fix it. I think is not to complicated as it looks like. And i didnt use any special tools.If any body need a help around orlando just contact me! I became expert!!! :-)

Steve O said...

This was very helpful knowledge wise but i need to know more specifically if the chain tensioners were to break would they fall into the oil pan and if so would this cause my oil pressure to decrease and my car thus to be immobile? If you would please email or call me at 573-747-9093 Or sogden1318@gmail.com it would be very much appreciated.

R.McKnight said...

yes, the pieces should eventually fall into the sump. No you will not loose oil pressure, unless they get caught in the pickup.

kevin chambers said...

Does any one know if I can remove the balance shaft chain or do I have to replace it? I just pulled the engine and its a 4wd engine in a 2wd Explorer?

Christian Hernandez said...

Yes you have to change everything in same time, and don't forget guide can break very easy never turn crank backwards

mark frank said...

2 pin black female plug back of motor driver side, where does it go?

NathannKelly Newman said...

my 99 explorer is in the shop, the timing chain guides broke, now they are saying there is an issue with the back timing chain.....Does the SOHC even have a back timing chain???

Christian Hernandez said...

Yes!! Has 4 chain!