How to: SOHC V6 Primary chain tensioner replacement

[2000StreetRod]

Background

There are multiple possible sources of rattle for vehicles with the 4.0L SOHC V6. See Timing chain rattle resolution process - SOHC V6 . Sometimes the location of the rattle source can be detected by using a mechanic's stethoscope or a length of flexible hose. However, internal engine sounds echo off the block walls making locating the source difficult. A frequent symptom of a failed primary (crankshaft to jackshaft) chain tensioner is rattle at mid-range (2,500 to 3,000 rpm) engine speed. Unfortunately, a failed balance shaft chain tensioner exhibits similar rattle characteristics. Normally, it is an exception for an engine with the balance shaft to be installed in a rear wheel drive vehicle. Inspection of the balance shaft and primary chain tensioners require removal of the front timing cover.

Because of high failures of the original primary chain tensioner incorporated in the 1997 thru 2001 models Ford upgraded the tensioner by increasing the base area and the number of spring leaves from three to six.

The upgraded tensioner was incorporated in 2002 and later models. Since joining the forum in May, 2009 after purchasing my 2000 Sport, I don't recall any member posting that the engine was damaged due to a failed primary chain tensioner. The primary chain is very strong and will destroy the tensioner long before the chain is significantly damaged. When my engine was dismantled to replace the timing chain components, even with no tensioner installed there was insufficient slack to slip the primary chain on either the crankshaft or jackshaft sprockets. The main concern for a failed primary chain tensioner is that broken pieces could block an oil passage resulting in bearing failure.
Replacement of the balance shaft chain tensioner additionally requires removal of the block cradle (upper oil pan).

Usually, when either tensioner fails, parts can be detected by removing the lower oil pan and inspecting. Since removing the front cover requires significant time and the replacement of the gasket, balancer retaining bolt and possibly the crankshaft oil seal, I suggest pulling the oil pan and inspecting for parts as the next diagnostic step after listening with a stethoscope or hose.

Procedure to replace the primary chain tensioner on a 2000 Explorer 4.0L SOHC V6.

Primary Chain Tensioner Removal
1. Disconnect the negative battery cable.
2. Drain the engine coolant.
3. Remove the engine appearance cover.
3.1. Disconnect the speed control cable (if equipped).
3.2. Remove the bolts.

4. Remove the air cleaner outlet tube.
4.1. Unclip the wire harness.
4.2. Disconnect the crankcase ventilation tubes.
4.3. Loosen the air cleaner outlet tube clamps and remove the air cleaner outlet tube.

 

[2000StreetRod]

Primary Chain Tensioner Removal (Continued)

5. Use the Fan Clutch Wrench and the Fan Hub Wrench to loosen and disconnect the fan blade/clutch assembly from the water pump pulley.

5.1. Insert a drive into the short section and position it to span the water pump pulley bolts.
5.2. Position the long section on the clutch hex flange (36 mm) and loosen counterclockwise.

NOTE: Fan blade not shown for clarity.
6. Remove the fan shroud bolts.

7. Lift the fan shroud out of the lower retaining clips.
8. Lift the fan shroud and the fan blade/clutch assembly together and remove from the vehicle.
NOTE: Inspect the fan for cracks.

9. Insert a 3/8 inch drive into the serpentine belt tensioner at the location identified with the red arrow shown below and rotate the tensioner counterclockwise to release the belt tension.

10. Slip belt off the pulleys and relax the belt tensioner.

 

[2000StreetRod]

Primary Chain Tensioner Removal (Continued)

11. Remove the harmonic balancer (crankshaft pulley).
11.1. Remove the balancer retaining bolt.

CAUTION: This bolt is torque to yield and cannot be reused.
NOTE: Members without access to an impact wrench that will fit in available space have difficulty releasing the bolt due to lack of a means to prevent the crankshaft from rotating. Ford uses a special strap wrench that I don't recommend because it stresses the dampening material between the outer pulley and the hub.

Some members have jammed a breaker bar against the floor or frame and then bumped the starter but that only works for loosening the bolt. I tried a fourteen inch pipe wrench but the jaws were not deep enough to hold. I also purchased a chain wrench but have not yet tried it.

If such a device is used it should be positioned so it doesn't damage the "teeth" on the damper (within red arrows below) used by the crankshaft position sensor.

Other members have used a strong board or metal plate with two holes for puller small bolts and a large hole for a socket that fits the retaining bolt.
11.2. Using special puller remove the balancer.

NOTE: 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. Many members have problems using a standard balancer puller with the Explorer balancer. That is because the diameter of the puller center shaft exceeds the diameter of the crankshaft so the puller is attempting to pull the balancer apart instead of separating the balancer from the crankshaft. My 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.

 

[2000StreetRod]

Primary Chain Tensioner Removal (Continued)

12. Remove the accessory (power steering & A/C compressor) bracket assembly and position aside.

13. Disconnect the alternator electrical connectors.

14. Remove the serpentine (accessory drive) belt tensioner retaining bolt (green arrow below).

15. Remove alternator mounting bracket and position aside.

NOTE: It is not necessary to remove the alternator from the alternator mounting bracket.
16. Disconnect the crankshaft position (CKP) sensor electrical connector.

 

[2000StreetRod]

Primary Chain Tensioner Removal (Continued)

17. Remove the fuel vapor tube retaining nut and position aside.

18. Remove the water bypass hose.

19. Remove the lower heater water hose.
19.1. Squeeze the hose clamp.
19.2. Remove the hose.

20. Disconnect the lower radiator hose.
20.1. Squeeze the hose clamp.
20.2. Disconnect the hose.

21. On A/C-equipped vehicles, remove the A/C line bracket and position aside.

 

[2000StreetRod]

Primary Chain Tensioner Removal (Continued)

22. Remove the wiring harness retainer and position aside.

23. Remove the crankshaft front oil seal.
NOTE: It is possible (but risky) to leave the crankshaft front oil seal in place. However, if left in place the front cover must be installed in the same position as it was when removed or the seal may leak. A seal puller may be used to remove the oil seal. Note the depth of the original seal in the cover.

CAUTION: Avoid scratching the crankshaft or the seal bore in the cover.
24. Remove the five bolts (red arrows below) attaching the block cradle to the front cover.

25. Remove the five stud bolts and five bolts (red circles below) that attach the engine front cover to the block.

NOTE: It is not necessary to remove the water pump from the front cover saving time and a gasket.
26. Starting at the top separate the front cover from the block. Even if you are very careful you will probably damage the gasket between the bottom of the front cover and the block cradle.
27. Remove the two bolts retaining the chain tensioner (orange arrows below).
28. Extract the chain tensioner.

29. Remove the two bolts retaining the primary chain guide (yellow arrows above) if replacement desired.
30. Pull guide forward to extract.

 

[2000StreetRod]

Primary Chain Tensioner Installation

1. Remove the front cover gasket remains from the block and clean the sealing surface.
2. If previously removed install the primary chain guide.
2.1. Align the pin on the rear of the guide with the oil port (green arrow below) and press the guide against the block to seal the port.

2.2. Install the bolts (green arrows below) and torque to 19 Nm (14 lb-ft).

3. Install the primary chain tensioner and torque the two bolts (blue arrows above) to 9 Nm (80 lb-in).
NOTE: Torque the original style tensioner bolts to 10 Nm (89 lb-in).
4. Pull the pin (yellow arrow above) to tension the chain.
5. Apply gasket sealer to a new front cover gasket and position on the block.

6. Apply silicone sealant in the two corners where the block meets the block cradle, the two places where the curved rubber gasket meets the block cradle, and along the exposed top of the old paper gasket that seals the bottom of the front cover to the block cradle.

7. Apply thread lock to the block threads of the five stud bolts.
8. Position the front cover and loosely install the stud bolts in their original positions.

9. Loosely install the five front cover to block bolts.
10. Align the front cover to its original position.
NOTE: Ford uses a special tool to align the bore axis of the crankshaft seal with the crankshaft axis. Since I did not remove the old crankshaft seal I loosely installed the crankshaft pulley to align the cover.
11. Torgue the cover to block bolts and stud bolts to 19 Nm (14 lb-ft).
12. Install the five block cradle to front cover bolts and torque to 9 Nm (80 lb-in).
13. If the crankshaft front oil seal was previously removed, lubricate the new seal lip with clean engine oil and install it.
NOTE: Ford uses a special tool that screws into the crankshaft threads to install the seal. However, it can be driven in with a suitably sized socket and hammer.

 

[2000StreetRod]

Primary Chain Tensioner Installation (Continued)

14. Install the wiring harness retainer.

15. On A/C equipped vehicles, install the A/C line bracket nut.

16. Connect the lower radiator hose.
16.1. Position the hose
16.2. Install the clamp.
17. Connect the lower heater water hose.
17.1. Position the hose.
17.2. Install the hose clamp.
18. Install the water bypass hose.
19. Position the fuel vapor tube and bracket, and install the nut.

20. Connect the crankshaft position (CKP) sensor electrical connector.
21. Install the alternator mounting bracket.

22. Install the accessory drive belt tensioner.

Torque the bolt (green arrow above) to 40-55 Nm (30-40 Lb ft).

 

[2000StreetRod]

Primary Chain Tensioner Installation (Continued)

23. Connect the alternator electrical connectors.

24. Install the accessory (power steering & A/C compressor) bracket.

25. Install the harmonic balancer (crankshaft pulley).
NOTE: The new crankshaft damper retaining bolt is not long enough to reach the crankshaft when the damper is first positioned on the crank. Ford uses a special tool to install the damper. The photo below shows my "special tool" consisting of an on hand 36mm 6 point socket and a 4 lb hand sledge hammer.

The socket is larger in diameter than the damper retaining bolt head and it's round seat. I "tapped" the socket with the hammer until the damper was far enough onto the crankshaft that the new retaining bolt could screw in at least a half inch to eliminate the possibility of stripping its threads. I continued tapping and screwing until the damper was seated on the crank.
26. Install crankshaft holding tool (see removal instructions) and torque the harmonic balancer new retaining bolt to 60 Nm (44 lb-ft) plus 90 degrees.
27. Route the serpentine belt.

28. Insert a 3/8 inch drive into the serpentine belt tensioner at the location identified with the red arrow shown below and rotate the tensioner counterclockwise.

29. Slip the belt over the tensioner pulley and extract the drive to tension the belt.

 

[2000StreetRod]

Primary Chain Tensioner Installation (Continued)

30. Lower the fan shroud and the fan blade/clutch assembly together into position.
31. Push the fan shroud down into the lower retaining clips.
32. Install the fan shroud bolts.

33. Screw the fan blade/clutch assembly unto the water pump pulley.
34. Use the Fan Clutch Wrench and the Fan Hub Wrench to tighten the fan blade/clutch assembly to the water pump pulley. Torque to 43-63 Nm (34-46 lb ft).
35. Install the air cleaner outlet tube.
35.1. Install the air cleaner outlet tube and tighten the air cleaner outlet tube clamps.
35.2. Connect the crankcase ventilation tubes.
35.3. Clip the wire harness.

36. Install the engine appearance cover.
36.1. Install the bolts.
36.2. Connect the speed control cable (if equipped).

37. Drain the engine oil.
NOTE: When the front cover is separated from the block coolant in the block drains into the oil pan.
38. Fill the engine with SAE 5W-30 motor oil.
39. Fill the radiator with coolant and the coolant recovery reservoir to the cold fill line.
40. Connect the negative battery cable.
NOTE: The engine will have air in the block and will easily overheat if driven and possibly blow a head gasket.
41. Purge the cooling system.
41.1. Run the engine until it warms enough for the thermostat to open (the coolant level will drop in the radiator).
41.2. Fill the radiator with coolant and install and tighten the radiator cap.
41.3. Run the engine until it reaches operating temperature.
41.4. Turn off the engine and allow the cooling system to cool.
41.5. Release the pressure in the cooling system by slowly turning the radiator cap one half to one turn counterclockwise to the first stop on the filler neck. When the pressure has been released, remove the radiator cap.
41.6. Fill the radiator with coolant and the coolant recovery reservoir to the cold fill line.
41.7. Install and tighten the radiator cap.
NOTE: Carry extra coolant in the vehicle on the first drive and monitor the engine temperature gauge for overheating. If engine starts to overheat repeat steps 41.4. thru 41.7.

 

[allmyEXes]

What was your source for the Primary Chain Tensioner, Chain Guide and the new "Torque to yield" Harmonic Balancer Bolt ? BTW, you have a very good "write up" here. I am to the point of aligning the engine to TDC before removing the HB or do I have to if the engine still runs? Even though I don't have the timing cover off yet, I am pretty sure that my issue is a broken tensioner because the engine still runs enough that I was able to drive it up on a trailer. If the left head secondary chain had the issue I assume that it wouldn't have the power that it has. All of the "slappy" sound is coming from the front of the 1997 4.0 SOHC. I'm really hoping it is a Primary Timing Chain issue. Thanks for the information.

 

[2000StreetRod]

I purchased my parts from Ford: www.tascaparts.com
I recommend the crankshaft be at TDC on cylinder 1 before disconnecting any timing chains. That way you won't have to rotate the camshafts relative to the crankshaft on the interference engine.
I suggest removing the valve covers and inspecting the cassettes before removing the front cover. If the rear cassette is broken you'll probably end up pulling the engine to replace it. Its easier to replace components with the engine out.

 

[allmyEXes]

Thanks 2KSR. So the '97 SOHC is an interference engine ? I'm finding conflicting information. I would not have run it more than a few seconds if it is. I will pull the valve covers during the next work session. Number one cylinder appears to be on the right front according to the internet. Removing the HB too. I should have Metric bolts in my kit.

 

[2000StreetRod]

The photo below shows what can happen when the valves are too far out of time.

Here's the cylinder numbering.

Make sure cylinder 1 is on the compression stroke before disconnecting any timing. The engine will start and run (but not well) with the camshafts off by 180 degrees. Also note cylinders 5 and 6 connections on the coil pack.

 

[donalds]

Thanks 2KSR. So the '97 SOHC is an interference engine ? I'm finding conflicting information. I would not have run it more than a few seconds if it is. I will pull the valve covers during the next work session. Number one cylinder appears to be on the right front according to the internet. Removing the HB too. I should have Metric bolts in my kit.

I'm pretty sure the bolts to remove the HB are m8/1.25/110mm long my HB puller did not have long enough bolts I went to ace hardware to get them

A few years back my primary tensioner broke it sounded like keys jingle ing and it was louder when cold

 

[donalds]

17. Remove the fuel vapor tube retaining nut and position aside.

I think this bracket may be missing in my engine can you tell me more of where it's location is?

 

[2000StreetRod]

I think this bracket may be missing in my engine can you tell me more of where it's location is?

Should be at yellow arrow shown below.