SOHC Timing Chain Tensioners

[engine]

I'm going to heed the advice I have seen from several contributors and replace the tensioners on my 140K mile 2002 to reduce the possibility of the "death rattle". There are actually four tensioners for the four chain-driven shafts: one for the right camshaft, one for the left camshaft, and one also for the jackshaft, and another for the balance shaft. The only discussions about the tensioners on the forum I have seen regard the camshaft chains, mainly I suppose because of the difficulty involved in accessing the rear chain. What about the other two? Should they be replaced as well? They are not expensive but how hard are they to replace? Advice appreciated.

 

[DILLARD000]

You're correct there are 3 or 4 total TimingTensioners in the V6~4.0L~SOHC:
* LeafSpring TimingTensioner on the front Jack TimingChain
* LeafSpring TimingTensioner on the front Balance TimingChain (if your engine has a Balance TimingShaft, most after ~2003 do not)
* OilPressurized TimingTensioner on the left Cam TimingChain
* OilPressurized TimingTensioner on the right Cam TimingChain

The right can be changed relatively easily.
The left requires removing some external parts.
The two LeafSpring Tensioners require removing the CoolantPump & front TimingCover.
The concensus is to change the left & right every 75k~100kMiles.

 

[sgtsandman]

The tensioners of prime concern are accessible from the right wheel well at the back of the head. The left tensioner is under the intake in the valley. You need to remove the thermostat housing. There are a few videos on youtube for the job that will give you a better idea what you are looking at. It’s too hard to properly describe it with just words.

 

[RonD]

+1 ^^^

The only tensioners that were failure prone were the two Long Chain tensioners, as described above, passenger side of block toward the rear and drivers side top front near lower intake
Only use Motorcraft brand for replacements

And prime them or after they are installed disconnect coil packs 4 wire connector and crank the engine over for 5 seconds 2 or 3 times to pump oil into the tensioners

To prime them put them in a container of oil so oil covers the threads then push down on each until they are very stiff, i..e full of oil

 

[gw33gp]

I replaced my hydraulic tensioners at 100K miles and they were still in good condition. I thought the rear (right side) tensioner was easier than the front (left ) tensioner.

At 250K miles I did a full timing chain rebuild. Most everything was still in good condition but the guides were getting brittle. The one thing that was broken was the mechanical tensioner between the crankshaft and jack shaft. It was completely broken off and looked to be that way a while. I think at 140K miles you should not need to replace that one. I think mine was a fluke and is not a common failure.

My engine did not have the balance shaft but I did buy all the stuff for it. Fortunately, I was able to return for a refund. It is my understanding that by 2002, Ford was not installing the balance shaft anymore, but that does not mean all 2002 4.0 SOHC engines have no balance shaft.

 

[RonD]

The balancer was only used in 4x4 4.0l SOHC engines, it was there to prevent a vibration when 4WD Rangers got Live Axles(2001) and the always rotating front drive shaft, but there was no vibration, except on paper, so yes it was dropped after a few years

 

[engine]

Thank you all. I will only replace the left and right camshaft tensioners. I purchased my ranger three years and 20K miles ago. I do not know the history but it appears to have been well cared for. The fluids are clear. The oil was not dirty. I change every 5K with full synthetic. I think it was used for light towing of boats because of all the misc. electric connections in the back of the truck. All I know is that it came from Maryland and the body is rust free. The engine runs so well I do not want to risk losing it because of the tensioners. It is well equipped and came with the original sticker in the glove compartment. 25K in 2002 dollars! Again thanks.

 

[600$04Ranger]

Fordtechmakuloco on YouTube has an excellent 4 video series on the entire timing job. It's the best one I found and it helped me to successfully rebuild and time mine.

 

[DILLARD000]

 

[Broosedamoose]

Your thinking of the plastic guides. The only tensioners you should replace are the ones mentioned above. Relatively simple job. While your at it, replace the thermostat housing with the aluminum one. The plastic one will eventually start to leak.

 

[NIGERIAN RANGER]

I keep wondering why Ford engineers placed timing chain at the back..

 

[Uncle Gump]

They didn't want to cast two different cylinder heads.

 

[gw33gp]

Also, running a very long chain on the front to run both cams is not a good idea either. If you keep the rpm low it is not bad but the higher you run the rpm the more the chain stretches and the cam timing changes. Back in the very late 60 when they were running the overhead cams on the 428CJ at drag strips, they had to come up with some unique ideas to overcome the chain stretch and very few were able to do that.

They also had the holes and the bearings already in the block where the cam was on the push rod block. They just replaced the cam with the jackshaft to run the rear chain. It works well but but it make working on it difficult. OHC engines are more difficult to work on anyway, but I think the extra performance is worth it.

 

[engine]

Also, running a very long chain on the front to run both cams is not a good idea either. If you keep the rpm low it is not bad but the higher you run the rpm the more the chain stretches and the cam timing changes. Back in the very late 60 when they were running the overhead cams on the 428CJ at drag strips, they had to come up with some unique ideas to overcome the chain stretch and very few were able to do that.

They also had the holes and the bearings already in the block where the cam was on the push rod block. They just replaced the cam with the jackshaft to run the rear chain. It works well but but it make working on it difficult. OHC engines are more difficult to work on anyway, but I think the extra performance is worth it.

In my BMW, rather than a long chain to run both camshafts, there is a moderately long chain to one camshaft and a shorter chain from that camshaft to the other.