4.0 Timing Guide major wear spots.

[Concours.John]

I have been pouring over this issue here. Having a near 200k 4.0 2002 I know the repair is coming. Does anyone have pictures of guides prior to destruction detailing major contact points? Understanding failures are due to lack of reinforcement, plastic involved, etc. I would like to see if it is possible to reengineer this. I am not at this point trying to sell anything just have resources. It may be cost prohibitive but I have access to state of the art technology we use to replicate/improve parts for vintage Ferrari, Maseratti, and other Italian cars. There will obviously be a need for stamping of metal reinforcement and have to work on suitable composite guide surface. We have access to retired DOD liquid 3D printers and CAD welders to develop prototypes. Should something come of this I want Admin to know I will gladly pay as sponsor. I just need as much information right now as possible on these guides, break points, etc, and heavy wear points. I am in same boat and it will cost a ton to prototype this. However a guide that may wear to 150k but prevent destruction is goal or longer if preventative tensioner replacement service done.
Thanks for any information. If it has been done, tried, or failed please point me to thread.

John

Yes I may be crazy but my wife loves the truck.

 

[david4451]

The weak spot in these timing chain components started with a poor choice of the plastic used, this I believe has been addressed, along with better primary tensioners(crank to jackshaft) and balance shaft guides on 4 x 4.
All considered the improvements really add up to nought because it did not address the real problem on COLD start up, where the hydraulic tensioners are absent of oil and they rattle until the oil pressure builds up in tensioners.
You can imagine the force exerted on the plastic guides by the chain being slack for 3 to 10 seconds, on cold start up. This leads to the plastic guides fatiguing and breaking, causing jumping time and bent valves.
My Sport Trac is low mileage(41000) and this inevitable failure was grinding my brain! I live in Philippines (Brit) pushing 67 and probably this is the last vehicle I'll own, so I wanted it to survive(it had the rattle).
If I could re-engineer this set up, start with the hydraulic tensioners, stronger springs and or drill & thread centre and put limiting cushioned stop. This would probably stop the destructive rattle. This would be relatively easy to do and give the plastics more life.
What stops everyone fixing these timing components is its a big job, engine out etc etc. Even if a bullet proof fix is available, most would not do it.
As for me I'm going the change my timing components, which are now not rattling because I fitted a pre oiler(see thread"pre lube & centrifugal oil filters") but don't trust my original timing parts. The pre-oiler will of course be used with new components and out live me. Transmission next!!!

 

[Tech By Trade]

Nothing has been addressed, they are still junk. If you take a guide, and replicate everything that is plastic with steel, and then replace the running surface with a plastic or teflon runner of some sort you will have a bullet proof engine. This would also allow for increased spring pressure in the current tensionsers without fear of the plastic shattering. That and a v8 style hydraulic tensioner on the primary jackshaft chain instead of the piss poor leaf spring design. A couple of us have actually sent these ideas to dorman, without response.

 

[david4451]

If you don't address the rattle on cod start, if the metal/Teflon doesn't fatigue then it may well transfer to the chains failing.

 

[corignelson]

Unless you swap the guides with mechanically tensioned sealed roller assemblies, the issue of slapping relatively unlubricated guides will remain an issue. If they are plastic then they are prone to breaking apart. If they are steel then you have to deal with metal being worn off and forming particulates. Either way, the guide cassettes should have both been on the front of the engine for easier repair.