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 Google Pics 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:

via ebay there are now kits for about $120, that have just about everything:

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 center cam shaft slits are level/flat with the head.
With the engine at TDC both the cams need to have the off center 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 labeling 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 tires + 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 tires 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 tires 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 @ and let me know if this was useful or need any help.

Some Pics (compressed) I have a lot more!

View Google Pics Album of the Engine Re-Build

Version History:

Sep 2016: changed Album links - because old one has stopped working.