How to: - SOHC V6 Timing Chain Parts Removal Procedure | Ford Explorer Forums - Serious Explorations

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How to: SOHC V6 Timing Chain Parts Removal Procedure

Prefix for threads which are instructional.


Moderator Emeritus
May 26, 2009
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City, State
Greenville, SC
Year, Model & Trim Level
00 Sport FI, 03 Ltd V8

The Ford 4.0L single overhead camshaft (SOHC) V6 engine manufactured in Cologne, Germany was available in the 1997 thru 2010 Ford Explorer and Mercury Mountaineer, 2001 thru 2011 Ford Ranger and Mazda B4000, 2005 thru 2010 Ford Mustang and 2004 thru 2008 Land Rover LR3/Discovery 3. Any SOHC engine requires periodic replacement of the camshaft timing mechanism. The possible mechanisms used to enable the crankshaft to rotate the camshafts are gears, chains and belts. Metal gears would be the most reliable but are not practical due to the distance between the crankshaft and the camshafts. Early dual overhead cam engines incorporated dual row roller chains with tensioner(s) to connect a sprocket mounted on the crankshaft to sprockets mounted on the camshafts. Many modern SOHC engines utilize a timing belt that must be replaced every 70,000 to 100,000 miles. High performance engines incorporate increased valve lift and higher compression ratios. Failure to replace the camshaft timing mechanism at the recommended interval risks timing chain/belt slip or total failure resulting in the pistons colliding with the valves.

The Cologne SOHC V6 replaced the overhead valve (OHV) V6 camshaft with a jackshaft that transfers crankshaft rotational forces to the left camshaft sprocket at the front of the engine and the right camshaft sprocket at the rear of the engine via multiple chains and tensioners. The primary (crankshaft to jackshaft) timing chain components consist of crankshaft sprocket, jackshaft sprocket, connecting chain, and a chain guide and tensioner as shown in the photo below by White98.

The above photo shows the original style tensioner that has failed.

An assembly consisting of a jackshaft sprocket, camshaft sprocket, connecting chain and chain guide constitute a cassette. The camshaft chain is kept taught by a spring loaded hydraulic tensioner utilizing engine oil pressure. A photo of the left cassette is shown below.

A photo of the right cassette with the metal reinforced tensioner (slack) side is shown below.

The engines in the 4 wheel drive models and a relative few number of 2 wheel drive models incorporated a balance shaft driven by a chain connected to an additional crankshaft sprocket. There is also an associated chain guide and tensioner.

Normally, chain driven overhead camshafts would be more reliable than belt driven overhead camshafts. However, many failures occurred during the first few years of the SOHC V6 engine production. Ford implemented a series of tensioner and guide improvements to increase reliability and recalls to install them. All of the timing chain related improvements were incorporated in the 2002 and later production models. The base of the primary tensioner was strengthened and the number of leaf springs was increased from 3 to 6. The photo below compares the improved and original primary tensioners.

The spring loaded hydraulic tensioners were modified. The camshaft guides constructed of a plastic type material were reinforced with metal. Unfortunately, the traction side of the right guide assembly was never reinforced with metal and can break due to heat and vibration fatigue. Replacement of the right guide requires removal of the engine or the transmission since the guide lower mounting bolt is under the transmission bellhousing between the rear of the engine block and the flywheel/flexplate. Removal of the engine, replacement of the timing chain components, timing of the camshafts and the reinstallation of the engine is a complicated and labor intensive process which performed by a dealer or repair shop may cost more than the market value of the vehicle after repair. A special camshaft timing tool set (OTC 6488) reduces the complexity of the process but is normally not available on a rental basis.

There are well documented procedures available for assembly of the SOHC V6 engine. If anyone needs one just PM me your e-mail address and I will send you a copy. However, I have not found an adequate description of how to remove the timing chain related components. This thread will attempt to provide a SOHC V6 timing chain components removal procedure. It is based on my experience from replacing the timing components in my 2000 Explorer Sport engine and information I have obtained from my Haynes Repair Manual, the Explorer Forum, and other internet resources. The procedure has not been validated and I caution you to use it at your own risk. Some steps should be performed in the order indicated while for others the order may not matter. I will add text and photos as time permits and will attempt to give credit when photos are not my own. I am no expert on this engine and make mistakes like anyone else. I would like to improve the quality of this procedure over time by incorporating your constructive comments/corrections.





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Remove engine & position #1 piston at TDC

Using a crane remove the engine from the vehicle.

For instructions on removing the engine from the vehicle see my helpful thread: SOHC V6 Engine Removal Procedure
Using breaker bar with 19mm socket installed on balancer bolt position #1 piston at TDC as shown below.

The red arrow indicates the mark next to the "0". There is another mark next to "10". Make sure that the #1 cylinder is on the compression stroke by placing a finger over the removed #1 spark plug opening and feeling for pressure as the piston approaches TDC.

Loosen harmonic balancer retaining bolt

The Ford camshaft timing procedure utilizes a special tool strap wrench 303-D055 (D85L-6000-A) (not included in the timing tool kit) to prevent the crankshaft harmonic balancer/damper from rotating when loosening the harmonic balancer retaining bolt prior to removing the front timing cover. If using a strap wrench or chain wrench to prevent the balancer from rotating attach it to the inner section of the balancer in the region identified by the green arrows in the photo below.

Avoid the area identified with the red arrows because of the indentations for the crankshaft position sensor. If these are damaged by the wrench the engine may not start or run properly.

While the flexplate/flywheel is still attached, the improvised tool shown in the photo below is suitable for preventing rotation of the crankshaft while loosening the balancer retaining bolt.

A scrap bolt with washers on both sides of the chain link is screwed into the head. Another scrap bolt with washers is passed thru one of the torque converter/clutch mounting holes and a chain link is secured with a nut.

Using a breaker bar with 19mm socket loosen (counter-clockwise) the harmonic balancer retaining bolt.

Remove flexplate/flywheel, spacer & spacer plate

The Ford engine assembly procedure utilizes a special tool crankshaft holder 303-674 (not included in the timing tool kit) to prevent the crankshaft from rotating when loosening the flexplate/flywheel to crankshaft bolts. The improvised tool shown below can be used to prevent the crankshaft from rotating.

Make alignment marks for reassembly on the flexplate and spacer or the flywheel and the crankshaft.

If the spacer plate (shown below) has not already fallen off remove it.

Remove (counter-clockwise) the 8 flexplate/flywheel to crankshaft bolts.
Remove the flexplate with spacer or flywheel.

Since the flexplate is thinner than the flywheel there is a spacer (shown below) between the flexplate and the crankshaft to make up the difference.

Mount engine on stand

Mount engine on stand as shown below.

This is my engine after being cleaned and painted. Attach the stand mounts in a manner that allows access to the jackshaft rear cover and the right cassette lower mounting bolt as shown below.

Do not attach the stand mounts to the reinforcement section/upper oil pan since it may be necessary to remove it.

Remove harmonic balancer

A crankshaft balancer puller is required to remove the balancer. Do not attempt to use a gear puller. A gear puller will damage the rubber like material between the inner and outer sections of the balancer. Crankshaft balancer pullers usually come in a kit that includes various diameter and length bolts to attach the puller to the balancer. Because of the depth of the balancer the standard puller kit bolts will be too short. They may be long enough to engage but will strip when force is applied to the center puller bolt. Suitable bolts are M8-1.25 of 90mm or 100mm (preferred) length. Some members use the stud bolts that attach the A/C compressor to its mount.

In order to remove the balancer the large bolt on the puller has to press against something contacting the crankshaft while the two smaller bolts pull against the balancer. See photo below by cjmedina.

The normal process is to loosen the balancer retaining bolt about a half inch. Then install the puller with the center bolt pushing against the head of the balancer retaining bolt and the long side bolts attached to the balancer. The puller center bolt head is then alternately tightened with a wrench and hit with a hammer until the balancer is extracted far enough to reach the head of the balancer retaining bolt. Then the puller is removed, the balancer retaining bolt is loosened another half inch and the puller is reinstalled and the puller center bolt is tightened and hammered until the balancer once again reaches the head. The process is repeated until the balancer is free of the crankshaft or there are only a few balancer retaining bolt threads still engaged with the crankshaft. Then the balancer retaining bolt is completely removed and a longer bolt inserted. The longer bolt can be the same thread as the balancer retaining bolt but those are hard to find and expensive. Instead, I use a smaller diameter (3/8 inch) bolt that does not engage the female threads on the crankshaft and is long enough (5.5 inch) to seat in the bottom of the bore for the crankshaft threads. By this point there is little force required to complete the extraction of the balancer because there is only a small amount of surface in contact with the crankshaft.

It is hammering the puller center bolt head (impulse) that results in extraction of the balancer. The side bolts just apply the tension determined by how much the center bolt is turned.

The balancer retaining bolt is torque-to-yield and should not be reused.

Remove valve covers

Remove the right valve cover.

The bolts on the later model valve covers have retainers to keep them from falling out.

Remove the left valve cover.

Make sure #1 cylinder is on the compression stroke by checking the camshaft position sensor "nub" on the left camshaft identified by the green arrow in the photo below by shelbygt.

The nub should be above the axis of the camshaft. If it is below the axis then rotate the crankshaft clockwise 360 degrees to TDC.

Remove lower oil pan

Remove (counter-clockwise) the 10 bolts that attach the lower oil pan to the block cradle.

Separate the oil pan from the block cradle by prying. Do not damage gasket sealing surface.
Remove any guide and tensioner fragments from the pan. Try to find all broken pieces since any overlooked might block an oil passageway.

Remove oil pump pickup tube

Remove the two bolts securing the oil pump pickup tube to the oil pump. I was careful not to damage the gasket (shown below) since I did not have a replacement.

I used gasket sealer when reassembling. Extract guide fragments from the screen. I used a wire to dislodge guide fragments at the inside diameter of the screen. The oil pump pickup tube must be removed in order to remove the block cradle.

Remove block cradle

If you have the balance shaft and want to replace the balance shaft chain tensioner it will be necessary to remove the block cradle (upper oil pan) in order to remove the balance shaft chain tensioner mounting bolts shown in the photo below by janolsson.

Remove the eight Allen head 11mm hex bolt inserts. There are six accessible thru the lower oil pan opening and two accessible near the front bottom of the block cradle.

Remove the two block cradle to block Torx bolts at the rear of the block cradle as shown below.

One bolt is long and the other is short.
Remove the remaining block cradle to block nuts (2) and bolts (20) on the perimeter of the block cradle. When separating the block cradle from the block do not pry between gasket sealing surfaces.

If you don't have the balance shaft, it is not necessary to remove the block cradle. Just remove the front bolts (5) that attach the block cradle to the front timing cover.

Remove front timing cover & gasket

Remove front timing cover with water pump attached unless you plan to replace the water pump.

Remove the front timing cover gasket making sure no pieces fall into the block cradle if still attached. Be careful not to damage sealing surface when removing the gasket. Clean the sealing surface with solvent making sure all old gasket remnants are removed.

Remove jackshaft rear plug

Rotate engine on stand to position right camshaft axis vertically above jackshaft cover.

The left head should be lowered more than shown for the correct position.
The engine with the heads is very top heavy. Be very careful when rotating the engine to be off balance (left head nearly horizontal). Since I work alone I used the crane to support the off balance weight as I gradually lowered the left head while the stand holding pin was removed.

Hammer the plug on one side near the edge with a punch being careful not to score the plug bore. As the one side is driven inward the other side rotates slightly outward as shown below.

It is very important to only hammer in one side so that the plug does not go into the opening. Next hammer the protruding lip with a large screw driver from the side to force the plug enough outward (see photo below) that it can be grasped with locking pliers.

Loosen jackshaft rear sprocket bolt

Loosen (counterclockwise) jackshaft rear sprocket retaining bolt (shown below) while preventing crankshaft or jackshaft from rotating (the jackshaft front sprocket retaining bolt can be used to prevent the jackshaft from rotating)

If the jackshaft front sprocket retaining bolt has already been loosened or removed then the jackshaft rear sprocket can be prevented from rotating by immobilizing the right camshaft sprocket using tools described in the following post.

Loosen right camshaft sprocket bolt

Loosen (clockwise) right camshaft sprocket retaining bolt. A universal sprocket holder similar the one shown below may be used to prevent the sprocket from rotating.

If you have the OTC 6488 timing tool kit camshaft gear holding tool (6478) and camshaft gear holding tool adapter (6482) can be used to prevent the sprocket from rotating.

Remove right hydraulic/spring tensioner

Remove (counter-clockwise) the right hydraulic/spring tensioner identified by the red arrow in the photo below by CDW6212R.

Use a 27 mm shallow 6 point socket and a long breaker bar or torque wrench. The force required may exceed 75 ft-lbs. A new right tensioner is shown below.

Remove right guide assembly upper mounting bolt

Remove the right guide assembly upper mounting bolt identified by the red arrow in the photo below.

You may notice that the entire upper section of the guide is missing due to breakage. Also, the positioning bolt has been worn flat on one side by the chain slapping against it. The accumulation of sludge shown is probably due to infrequent oil changes by the previous owner or a defective thermostat.

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