sohc cam tensioners - how often?

[BK_89iX]

My '97 SOHC was one of the first few off the assembly line with the new motor. Had the startup diesel-like noise and later the hot-restart diesel-like noise with the conventional fixes back in about 2000. First the tensioners and then a front cassette. Now ten years later at 90k miles and everything still seems OK, and I want to keep it that way. Has the tensioner design improved since 2000, and/or is there a preventive replacement interval to assure good tension on the chains?

From my records the initial tensioner parts were:

XU3Z6K254BA
XU2Z6K254AA

On the same invoice:

XL2Z6M289AA (DRV ASY-C/SHFT LH)

I have no clue what that last part is, and a search comes up empty. Anyone have any idea on that one?

BK

 

[Carguy3J]

Yes, the later motors seem to have a lot less issues with this. Not sure exactly what year, but I think 2001 and up. Of course, I'm sure the new Mustangs have def. got it figured out by now.

Given the cost and difficulty of this repair, I wouldn't suggest doing it on a preventative maintence type schedule. It's not like a timing belt. These things will almost certainly give you fair warning before they go. If it's not making any noise yet, don't chnage them until it does. Granted, once they start getting loud, I wouldn't wait too long.

Mine was a bit noisy at startup when I got it (I think about 130K, I don't remember!) As soon as I switched to Mobil 1 5w30, it got quiet. My guess is that the "thinnner" synthetic was able to circulate up to the tensioner quicker upon startup, than convential 10w30 or 10w40.
Just keep up on proper routine maintanence/oil changes (5-7,500 miles is fine w/ goood synthetic).

 

[BK_89iX]

Thanks for the info. The tensioner parts I'm inquiring about are external and don't require opening up the motor. Relatively quick and cheap. Curious to hear if the design has improved over the years and/or if they get weak over time and benefit from preventive replacement (to avoid loose chains smashing the plastic sliders to bits).

BK

 

[2000StreetRod]

Upper tensioners

I assume that you are referring to the upper front and rear chain tensioners. As I recall one forum member (CDW6212R) who has replaced all of the timing chain components advocates replacing the upper tensioners every 75,000 miles. The springs become weak with age and there is no technology advancement that eliminates that. When I replaced my front tensioner it didn't seem to be much stronger than the one I replaced which was of the later design with the extended projection. It's fairly time consuming to remove the upper and lower intake manifolds. I haven't replaced the rear yet but I intend to soon. I've read that it's replacement is easier if you remove the inner fender flap and have a long drive extension.

 

[BK_89iX]

Yes, exactly - thanks for clarifying my terminology. I am indeed referring to the upper tensioners. That interval and logic seems sound.

BK

 

[ducrnd]

tensioniers

When did you have them replaced ? I have a 01 and am having it done now. to get to the back one, the motor has to be pulled . ( mine is a 4.0 sohc ) and I have a report from ford saying in the tech bullitian, about 120k on the older ones and there due.. they were plactic parts not nylon like now from what I have heard and have been told......but I am still thinking about a remanufactured motor. 2,399$ 3 yr 100k warrenty. If i would have saw this prior to them fixing mine, I would have bought one... its costing me 2300 to get repaired.........

 

[2000StreetRod]

tensioners vs guides

In order to change the rear guides/cassettes either the engine or the transmission must be pulled. The guides are the plastic parts that disintegrate with time. The tensioners press against the side of one of the guides and can be changed without a lot of effort. Periodically replacing the tensioners reduces the possibility of the timing chain slipping.