2002 Explorer 4.0 SOHC cam chain tensioners

[tedmc1]

Hi EV1 Just joined the website today and thought I would make my first post. It goes something like this:
The 4.0 SOHC uses a cam chain tensioner on each bank. It's at the front on the drivers side and the rear on the pass side. Without looking back too far in the prev threads I didn't see any mention of these parts (and how they will fail) and how your tensioning cassettes will get wiped out in the process.And if you lose your upper timing chains you will most likely be looking at a new engine.
My 02 4.0 SOHC has 120K miles since new (And I bought it new). Also bought a Premium care warranty along with the car. At 66K lost the transmission due to bad servos+ more and got a new trans for the $100 deductable.My dealership also put new L+R upper cam chain tensioners on my engine at this time since the deductable covered the whole invoice.
I've started noticing the slight noise on cold start and the increased noise level from the cam chain area.
So I pulled them out and as there was very little resistance pressure from either of them, I submerged them in 5W30 and started depressing them. Out came air bubbles and finally a few faint wisps of very dirty oil. After about 15-20 depressings in the submerged oil they finally started to gain resistance pressure until they finally both got pumped up so tightly that I could barely depress them at all. Reinstalled them and chains are quiet again and no extra noise at cold start at all. I have about 350 miles on the car and plan to pull them both out after 1K miles and check them again.
I ordered a new Cloyes tensioner and submerged it and pumped and pumped ......it never got as
strong as the Ford parts with 55K on them. There are quite a few youtube vids on this. Watch them. So rather than spending $120 on a pair of new tensioners why not try to service the old ones first.
Don't have a clue as to why the tensioners ran partially dry as my car has good oil pressure.

 

[imp]

Hi EV1 Just joined the website today and thought I would make my first post. It goes something like this:
The 4.0 SOHC uses a cam chain tensioner on each bank. It's at the front on the drivers side and the rear on the pass side. Without looking back too far in the prev threads I didn't see any mention of these parts (and how they will fail) and how your tensioning cassettes will get wiped out in the process.And if you lose your upper timing chains you will most likely be looking at a new engine.
My 02 4.0 SOHC has 120K miles since new (And I bought it new). Also bought a Premium care warranty along with the car. At 66K lost the transmission due to bad servos+ more and got a new trans for the $100 deductable.My dealership also put new L+R upper cam chain tensioners on my engine at this time since the deductable covered the whole invoice.
I've started noticing the slight noise on cold start and the increased noise level from the cam chain area.
So I pulled them out and as there was very little resistance pressure from either of them, I submerged them in 5W30 and started depressing them. Out came air bubbles and finally a few faint wisps of very dirty oil. After about 15-20 depressings in the submerged oil they finally started to gain resistance pressure until they finally both got pumped up so tightly that I could barely depress them at all. Reinstalled them and chains are quiet again and no extra noise at cold start at all. I have about 350 miles on the car and plan to pull them both out after 1K miles and check them again.
I ordered a new Cloyes tensioner and submerged it and pumped and pumped ......it never got as
strong as the Ford parts with 55K on them. There are quite a few youtube vids on this. Watch them. So rather than spending $120 on a pair of new tensioners why not try to service the old ones first.
Don't have a clue as to why the tensioners ran partially dry as my car has good oil pressure.

@tedmc1 @Tech By Trade
FYI, quite a bit has been written in the past here about the tensioners. Your post is most appreciated, as it points out something I neverr thought about: hydraulically operated tensioners provide no tension until oil pressure rises at start-up. So, it seems reasonable that if the designers' heads were not buried in their a$$e$, the tensioners would be provided with inlet check valves, like hydraulic lifters, to keep the oil in them, not necessarily at pressure (bound to leak away), so that time is not wasted in filling them back up upon starting. Dirt and crud build-up could certainly foul up the check valve allowing the oil to back out when shut down. Confirmed by your cleaning one, filling it with oil, and finding it held force when applied.

Now my thought: Why not design a replacement tensioner powered by mechanical means, a spring, like the 4.6L uses? Easy enough to figure out what force the designers were after in the hydraulic units, eng. oil pressure X piston area. This would be subject to limitations imposed by the space available. If I built one, would anyone here try it? imp

 

[tedmc1]

Hi imp, thx for the reply.
You said:"hydraulically operated tensioners provide no tension until oil pressure rises at start-up"
My apologies for not fully explaining the operation of these tensioner thingies that are on the 4.0. They do have a "weak ass spring" in them. This was to provide some tensioning effect until the oil pressure came up and then the main hydraulic tensioning took over. The reasoning could only be that the engine would only be idling until full oil pressure developed so a weak spring would work.
I have not seen the Ford tech manual but am pretty sure that replacement of these tensioners includes the "priming" steps outlined in my first post.
OK here is the rub.....the driver side tensioner is installed on the inside of the cylinder head and is slightly oriented in a downward position. Hence this tensioner has a fluid reservoir built into it. I can only surmise that the designers thought that the downward angle of this tensioner was slight enough that gravity could not allow complete drainage of all the oil in the reservoir through the weep hole at the tip
unless the engine was not started for a long time
The passenger side tensioner is mounted on the outside of the head and is slightly pointing up toward the chain/cassette. Since there wont be any weeping through the front hole due to the upward tilt there is no reservoir on this tensioner.
When I pulled the pass side tensioner it wasn't as dry as the drivers side but did need priming as it was not full.This reinforces my assesment the the seals in the tensioner have not gone bad and there is another reason these things fail so often.
insuficcent oiling? Planned obsolecence?
My car has good oil pressure on the guage,and comes up rather quickly.

 

[tedmc1]

Imp said:
"the tensioners would be provided with inlet check valves, like hydraulic lifters, to keep the oil in them"
And that is EXACTLY what they DON'T HAVE!!!!!!!!
These same tensioners are in a LOT of other overhead cam engines GM,Toyota to name just a few. So these things were already a part that Ford could buy and use without specifications and a new part to be designed and oem supplier contracts to be haggled over etc.

 

[imp]

Imp said:
"the tensioners would be provided with inlet check valves, like hydraulic lifters, to keep the oil in them"
And that is EXACTLY what they DON'T HAVE!!!!!!!!
These same tensioners are in a LOT of other overhead cam engines GM,Toyota to name just a few. So these things were already a part that Ford could buy and use without specifications and a new part to be designed and oem supplier contracts to be haggled over etc.

@tedmc1
Really interesting post! I have no real experience with chain tensioners, but can easily evaluate various design techniques based on my background. To do so, I need more than heresay info, which is what I often see here. Again, I see a spring-engaged tensioner as superior in design, as well as simpler, more reliable, than the hydraulic bullshit used in the 4.0L.

This whole quandary of if's and but's would be resolved if the frigging engine used GEARS to drive the cams. Guess why the best industrial engines do that. imp