How to: Rear Timing Chain Tensioner Replacement

[VWTECH]

I having been reading this thread and have a question? First off I have a 2001 Sport Trac with the V6 SOHC engine. 2 days ago I started my truck at work and started driving home. I noticed a loud rattling. At first I thought it was a idler pulling making noise. As I drove home at mid range rpm's the noise got louder and my MIL started flashing indicating a misfire fault. When I got home I pulled the codes and found that I had misfire codes for cyl 1, 2 and 3 indicating the issue is with the right bank. So now I am sure that I have an issue with my right cam. So my question is will the tensioner failing cause the misfire? If I replace the tensioner, removing the slack will the cam go back to it's correct position or does it sound like it jumped time/teeth? At idle I do not have a flashing MIL and the noise is not severe. Just hate the thought of pulling the engine!

Any help is greatly appreciated,
Lee

 

[2000StreetRod]

failed tensioner

The rotating jackshaft sprocket pulls the camshaft sprocket via the chain. I call that side the traction side. The tensioner applies pressure to the other side of the chain which I call the slack side. The tensioner merely applies enough tension to the slack side to prevent the chain from slipping a tooth on one of the sprockets. The tensioner has no impact on the valve timing when the engine is at constant rpm or accelerating. When the engine is rapidly decelerating the tensioner becomes important if the crankshaft/jackshaft is decelerating faster than the camshaft creating slack on the traction side.

You can check your tensioner spring by removing the tensioner and pressing the piston into the cylinder with your hand. I doubt that your tensioner is the problem.

I suspect that your timing chain has slipped due to failure of the rear cassette guide assembly. The rattling you hear is the slack in the chain hitting against the guide assembly upper mounting post.

In the above photo the chain is slack on the traction side because the upper section of the cassette guide assembly is missing. The chain has been hitting the post that normally secures the upper section of the guide assembly.

The tensioner piston travel is limited and is not able to compensate for missing pieces of the guide assembly. A compression test of the cylinders on Bank 1 (passenger side) will confirm the timing chain has slipped.

 

[VWTECH]

Thanks 2000streetrod. Will check it out on Sunday. I was hoping that was not the case! I hate the thought of pulling an engine for a chain guide!! If thats what it is it sucks!! I don't have the time to pull it myself! Way to go Ford!!

 

[Mebob2001]

Now you didnt use anything to hold the cams while u replaced this tensioner?

 

[2000StreetRod]

hydraulic/spring tensioner

Now you didnt use anything to hold the cams while u replaced this tensioner?

This thread is about replacing the hydraulic/spring rear tensioner only. Unscrewing the tensioner only allows a little slack in the chain so there is no need to hold the camshaft.

 

[mrau92me]

I have an '02 Mountie with 169k and I was told by a friend mechanic that I should change these tensioners as a pm measure. I'm a little confused, and the dealership doesn't seem to know what I'm talking about when I call them and they keep wanting to sell me timing chain kits. Does anyone know if there was a change for my model year with respect to these tensioners that this thread is about, or are they the same and I can order the 7U3Z6K254A and 7U3Z6K254B part number? A quick response would be appreciated...I currently have the right valve cover off and about to start on the left valve cover and think I have better access to do the rear right tensioner at this point. Thanks.

 

[2000StreetRod]

tensioners

Available online from Tascaparts or Tousleyfordparts:
7U3Z6K254A is $43.41
7U3Z6K254B is $60.49

 

[faco]

Tensioner Metal Washer orientation

First, many thanks to 2000 and this great brotherhood.

I just got both tensioners and will be changing them this weekend. She produces a slight "dieseling" noise in the mornings after the idle settles down after start. Once warm, no noise. Either way, she got 162,000 miles and I figured this is good PM.

The washers from Ford have a "cupping" to them and I am wondering if it matters which way the washer goes on.

Regards

 

[2000StreetRod]

compression ring

As I recall the inside diameter of the compression ring exceeds the outside diameter of the tensioner face. That's why it tends to slip out of position (grease will hold it in place until tightened). I doubt that the cup direction matters since it will be crushed when torqued.

 

[faco]

I oriented the ring with the "cupping" facing the engine. In this position, it was flushed with the face of the bolt almost to the point you hardly can tell it is there.

In my model (2003, 4.0 2wd), I was able to reach the tensioner by removing the intake air hose/duct (TB to air filter) and the return hose to the coolant reservoir tank (top hose small diameter). Plenty of room to get the torque wrench in there with a short extension.

I did not find much difference between the original (162,000 miles) rear tensioner's spring resistance and the new one.

When you start her up, at least put the intake air duct back into position (tighten it latter after checking for oil leaks), otherwise the noise from the air rushing into the TB will startle you (well, at least me) as it is a noise I was not expecting and immediately thought I just f'ed something up.

 

[Markaprice73]

Great thread. Thanks 2000StreetRod and everyone!
I did the rear tensioner today. Here's a few videos I shot along the way. I don't know if it will help anyone or not. But, the videos have a few observations and some before and after sounds that may be interesting none the less. Enjoy. They may be a little out of order. Also, there is a very good video(s) on youtube of replacing the rear and front tensioner. It's by DanielJaegarFilms. Search Ford Explorer Timing Chain Tenioner Replacement.
part 1 - 3:21min https://www.youtube.com/watch?v=NZfbu_RX_Xs
part 1.5 - 3:43min https://www.youtube.com/watch?v=5hKBAEsnghY
part 2 - 2:18 https://www.youtube.com/watch?v=o34wVShGcbU
part 3 - 1:08 https://www.youtube.com/watch?v=7nIa1oCzSg4
part 4 - 0:16 https://www.youtube.com/watch?v=7LWVl78e1R8
part 5 - 2:59 https://www.youtube.com/watch?v=l_sP827o_pU
part 6 - 0:36 https://www.youtube.com/watch?v=lNgSRj4mtjc
part 7 - 2:04 https://www.youtube.com/watch?v=pxAwBg_4XRY

Part 1,1.5,2, and 3 "commentary"
PART 4 and 7 are "THE RATTLE"
PART 5 and 6 are the "after"

 

[Markaprice73]

updae" rattle is back. Not as bad. But it's back none the less. Rattle is still from the rear of the block. Haven't done the front tensioner yet.

 

[Robman]

If my sohc has the cold start rattle, is this normally the rear tensioner?

 

[rewind1]

I have completed the repair on all timing components and reassembled my motor. I have a concern however with the right/rear chain's camshaft bolt. When I tighten it to the specified ~63 ft lbs, it slips (turns what seems like 1/8th turn).
I am using a beam style torque wrench and my arm does shake trying while trying to approach the proper torque slowly. Just when it seems I have reached the proper torque, the bolt rotates!
I reassembled first using the original bolt (I understand that this is not TTY). However, I later found that there were 2 new cam sprocket bolts included with the primary chain kit.
Given the behavior above, I removed the original bolt and replaced with the brand new one. It did the same thing and slipped as I approached the 63 ft lbs! Is this normal? Is this ok?
I also tried going to 45 ft lbs with the adapter and a click style torque wrench and it clicked. But this "slipping" has me concerned, I have never experienced this while torquing any other bolts.

 

[Tech By Trade]

I have completed the repair on all timing components and reassembled my motor. I have a concern however with the right/rear chain's camshaft bolt. When I tighten it to the specified ~63 ft lbs, it slips (turns what seems like 1/8th turn).
I am using a beam style torque wrench and my arm does shake trying while trying to approach the proper torque slowly. Just when it seems I have reached the proper torque, the bolt rotates!
I reassembled first using the original bolt (I understand that this is not TTY). However, I later found that there were 2 new cam sprocket bolts included with the primary chain kit.
Given the behavior above, I removed the original bolt and replaced with the brand new one. It did the same thing and slipped as I approached the 63 ft lbs! Is this normal? Is this ok?
I also tried going to 45 ft lbs with the adapter and a click style torque wrench and it clicked. But this "slipping" has me concerned, I have never experienced this while torquing any other bolts.

Stop now! either your threads are shot on the bolt, or your threads are shot on the cam. If you put it back together all its going to do is spin and bend valves. You need to find out what the issue is.

 

[rewind1]

So if I tried 2 bolts, that means cam threads are shot?
How could/would that happen? Is there some other way to test that everything is ok?

 

[Tech By Trade]

So if I tried 2 bolts, that means cam threads are shot?
How could/would that happen? Is there some other way to test that everything is ok?

I'm not sure but if I were a betting man I would bet you are probably going to have to pull the cam and take it to a machine shop and have the threads repaired. Either that or get a new cam.

 

[rewind1]

If I must replace the cam, what are your thoughts on using cams from a blown motor (lost rear tensioner and guides).
The particular motor I have available was lifted by the cams with fabric straps. Would that have caused any irreparable damage to the cams (ie. bent them)?

In any case, Can I just replace a single cam with a new one? Or do they both need to be replaced at the same time due to wear?

 

[2000StreetRod]

Unfortunately, there are no camshaft bearing inserts on the SOHC V6 - another significant design deficiency. The heads are bored to match the camshaft journal diameters.

The bolts that come in the primary tensioner kit are shown below.

Some people don't realize that the rear sprocket retaining bolt tool is a lever arm that multiplies the torque being applied. That's why the specification is 63 lb-ft with a torque wrench or 45 lb-ft with the adapter. If the 63 lb-ft is applied to the adapter then 88 lb-ft is being applied to the bolt which may strip the threads in either the bolt or the camshaft.

I would not be comfortable running the engine without the proper torque being applied since that is the only thing that guarantees proper camshaft timing - another design deficiency. I suggest seeking the advice of a local cylinder head shop and preferably one experienced with the head design. It may be possible to reliably repair the camshaft but that may cost more than purchasing a used head.

 

[rewind1]

Unfortunately, there are no camshaft bearing inserts on the SOHC V6 - another significant design deficiency. The heads are bored to match the camshaft journal diameters.

Just so I understand you. So I cannot simply remove the cam with potentially bad threads and replace it with a brand new part from ford because every head is specially machined to match the specific cam?

The bolts that come in the primary tensioner kit are shown below.
View attachment 97021
Some people don't realize that the rear sprocket retaining bolt tool is a lever arm that multiplies the torque being applied. That's why the specification is 63 lb-ft with a torque wrench or 45 lb-ft with the adapter. If the 63 lb-ft is applied to the adapter then 88 lb-ft is being applied to the bolt which may strip the threads in either the bolt or the camshaft.

I did realize that and read your torque specs carefully (thank you). I only applied 45 ft lbs while using the adapter. and I only used the adapter because my click-type torque wrench only works in the on position which doesn't work directly on the LH-threaded bolt.

I would not be comfortable running the engine without the proper torque being applied since that is the only thing that guarantees proper camshaft timing - another design deficiency. I suggest seeking the advice of a local cylinder head shop and preferably one experienced with the head design. It may be possible to reliably repair the camshaft but that may cost more than purchasing a used head.

Why would i need a used head, because it comes with a matching cam?

Thank you for all your help, very greatly appreciated.
-Ray