4.0L SOHC Metal Reinforced Timing Chain Guides Possible?

[swshawaii]

Posted on EF 1/27/17. Link below.



Must be a reason an aftermarket manufacturer hasn't made them. "If" the engine wasn't destroyed when the plastic tensioner guide(s) failed, seems like it would be a very lucrative business for those choosing to rebuild rather than replace their engine.

 

[Todd Z]

I think the metal on metal would be a problem..... Need something better thought...



Todd Z

 

[swshawaii]

Quote from post #1 in EF link above.

In my opinion the main deficiency with the Ford SOHC V6 4.0L design is not the use of plastic tensioner to chain wear surfaces but the use of plastic as a structural element. Due to heat cycles and mechanical stress cycles the plastic eventually fractures and then breaks.



The cassette guide assemblies should have been built of metal with plastic only used for chain to guide wear surfaces.

Quote from post #7 in EF link above.

Ford used 3 different grade plastics between all their OHC tensioner/guide designs. The grade 1 plastic was extremely lightweight and used in only a few applications. Those grade 1 pieces would absorbe the minerals and detergents in the motor oil and brake apart and fail as early as 30,000 miles.



Grade 2 was a revised version of grade 1 after Ford realized what was going on. Grade 2 suffers from the same fate but not as quickly as grade 1.



Grade 3 was what was initially used in the 4.6L and alike engines where lightweight wasnt so important. Grade 3 lasts the longest but still suffers the same fate as 1 and 2.



Ford AJV8 Family of engines used in Jaguars 1997-2008 are the best example of these cheap tensioner/guide design failures. The 4.0L was first given grade 1 and had so many failures but never issued a recall which was and still is dick on their part. They revised them with grade 2 in 2001. Then in 2003 when the 4.0L was revised into the 4.2L grade 3 plastic with metal backing plates came into production and those are the only ones that fixed this issue.

 

[EddieS'04]

Steve,

I recently found out the chain tensonors on my twin cam harley engine. Have a failure rate also. Harley recomends pulling the cover and cam plate every 17K miles, for inspection.

The problem comes when the plastic guide fails. There will be metal against the chains. The motor can trash out . This point of lubrication is after the oil filter.

The best of my motor is, hydralic tensonors. Early twin cam harley,s were spring loaded and many failures.

If I choose to keep this harley. Im looking into a gear driven cam conversion from S&S or Andrews. I have already installed hi-po lifters and adjustable pushrods.

My old harley was gear driven(74 shouvle head). Ran the crap out of it for about 80K. never broke it. Wish I never sold it. Lot of guys are turning there old shouvle heads' into stroker motors.

The new 2017 harley 8valve motor is single cam now. Still chain driven with plastic tensonors'. I would think the engineers would learn and go back to gear driven.

So with the Trac Im not sure what type of metal. Would make a good tensonor.

Ok so I got a little off..fftopic:

 

[Richard L]

I think it is probably a cost-saving issue for Ford. Plastic is probably cheaper and easier to manufacture and the plastic parts will typically outlast the warranty period/mileage. Once the vehicle is out of warranty, it's no longer Ford's problem, it's the customer's problem...and if the customer brings it to Ford for repairs, it's a Win-Win for Ford.



When timing chain rattle was a problem with some early model year Sport Trac's 4.0L V6 engines, Ford simply extended the warranty to 60K miles for the original owner. That only eased the concerns of the customer, but Ford knew that even with the extended warranty on the timing chain, they would still not see a significant increase in warranty claims due to timing chain issues. Like most other auto makers, Ford keeps very accurate records regarding vehicle repairs, repair parts and warranty claims....and know all the cost associated with those repairs. They can probably predict accurately predict, and probably have already done the analysis on just how much it will cost or save them over time, if they change the chain guides to metal rather than plastic.



As long as the initial cost-savings out weights vs warranty repair costs, they will always go for the cost-savings up front.



....Rich



...Rich

 

[EddieS'04]

Rich,

I guess that same thinking from ford. Went into the cab to frame bushings. $$$$. Most of us had to replace with something better.



I emailed the tech engineers that supplied the oem bushings , about the failures. Never heard from them. I also have a permanent clamiant with NHSTA. About safety of a loose cab.



I sometimes talk to folks in my town, that have older gen1 tracs. Many say something is wrong. I look under. Then I tell them what it is. What it cost me to repair. The kit cost and $250 labor. They dont have the $$$.

I was luckey my job was between blue collar and white collar, financely.

 

[Dean Hedin]

Even the old 2.9L had a plastic chain guide. Most chain guides on other vehicles are also plastic. In some cases there have been upgrades to the plastic guides, like early Jag XK8 that were often done under warranty. It's possible the 4.0 SOHC's guides have been improved in the aftermarket.



That's not the real problem with the SOHC.



The problem is, on the SOHC, there is "one in the back". So to replace requires an engine pull - and nobody wants to do that. Because labor wise you might as well just put a new motor in.



Let's say at 160K your guides are shot. Are you really going to pull the motor out , just put new chain guides in and put the motor back in? More than likely other things need attention, and when you add up the labor it is easier to just put a reman motor in.



The mechanic explains this to the customer and the customer wisely determines that they would rather put the money towards a new vehicle.



I don't think it is a case of direct planned obsolescence. It's just that they should have put one big timing chain on the front of the SOHC engine.



Now, in the case of my 1988 Merkur Scorpio (with the 2.9L) it is probably a Saturday job to pull the front cover off and replace the timing chain tensioner. There is something to be said for simplicity. But don't worry, my Merkur comes with it's own set of issues.

 

[swshawaii]

That's not the real problem with the SOHC.



The problem is, on the SOHC, there is "one in the back". So to replace requires an engine pull - and nobody wants to do that. Because labor wise you might as well just put a new motor in.

Wouldn't you say a broken rear plastic guide IS the problem if that's the reason you're pulling the motor?

 

[Yardsale]

That's true, in the immediate case if failure, but (I think) he means that the plastic and the location are symptoms of the bigger (design) problem. If they had gone with an "old school" (tried and true) all-in-front design, this would not be a topic of discussion - if they fail, you'd pull the cover and repair.



I think there isn't a performance improvement argument with the implemented design, considering the performance of the engine. There may have been reliability or durability goals with the design (distribute the load, etc.), but it appears those are illusions of grandeur, as I don't see these motors lasting much longer than others.



Any way ... tick-tick-tick, bang!

 

[Dean Hedin]

Yes, the 4.0L went from around 165hp to 210hp with the addition of the overhead cam. Which is very respectable.



But I probably would have been just as happy with some minor tweaks to the older OHV engine. They probably could have gotten it up to 185 or so if they bumped the compression to 9.6 like they did with the SOHC.



I pulled my "deluxe" center console out of a 2001 Explorer Sport at a junkyard. It had "timing chain bad" waxed on the inside of the windshield. Sad. Nothing wrong with it otherwise.



I just want to emphasize..Very few local shop mechanics will go deep into a high mileage engine. It's just too time consuming and risky and they don't have the specialized tools. If they are pulling it, its just easier to get a motor from a re-manufacturer. If something goes wrong with it the costs to fix are shared between the mechanic and motor re-manufacturer.



Timing chain guides & parts is what - something like $400?... and now add in the mechanics labor (motor in/out AND futzing with the guides)? Where we at? $1800-2000? and we are putting the 160k motor back in? Forget it. Fork up the extra $1000 and put the reman motor in.



Now, if you are doing the work yourself..and your on a budget..that is a different story.

 

[Dean Hedin]

Yes, the 4.0L went from around 165hp to 210hp with the addition of the overhead cam. Which is very respectable.



But I probably would have been just as happy with some minor tweaks to the older OHV engine. They probably could have gotten it up to 185 or so if they bumped the compression to 9.6 like they did with the SOHC.



I pulled my "deluxe" center console out of a 2001 Explorer Sport at a junkyard. It had "timing chain bad" waxed on the inside of the windshield. Sad. Nothing wrong with it otherwise.



I just want to emphasize..Very few local shop mechanics will go deep into a high mileage engine. It's just too time consuming and risky and they don't have the specialized tools. If they are pulling it, its just easier to get a motor from a re-manufacturer. If something goes wrong with it the costs to fix are shared between the mechanic and motor re-manufacturer.



Timing chain guides & parts is what - something like $400?... and now add in the mechanics labor (motor in/out AND futzing with the guides)? Where we at? $1800-2000? and we are putting the 160k motor back in? Forget it. Fork up the extra $1000 and put the reman motor in.



Now, if you are doing the work yourself..and your on a budget..that is a different story.

 

[Dean Hedin]

Yes, the 4.0L went from around 165hp to 210hp with the addition of the overhead cam. Which is very respectable.



But I probably would have been just as happy with some minor tweaks to the older OHV engine. They probably could have gotten it up to 185 or so if they bumped the compression to 9.6 like they did with the SOHC.



I pulled my "deluxe" center console out of a 2001 Explorer Sport at a junkyard. It had "timing chain bad" waxed on the inside of the windshield. Sad. Nothing wrong with it otherwise.



I just want to emphasize..Very few local shop mechanics will go deep into a high mileage engine. It's just too time consuming and risky and they don't have the specialized tools. If they are pulling it, its just easier to get a motor from a re-manufacturer. If something goes wrong with it the costs to fix are shared between the mechanic and motor re-manufacturer.



Timing chain guides & parts is what - something like $400?... and now add in the mechanics labor (motor in/out AND futzing with the guides)? Where we at? $1800-2000? and we are putting the 160k motor back in? Forget it. Fork up the extra $1000 and put the reman motor in.



Now, if you are doing the work yourself..and your on a budget..that is a different story.

 

[Dean Hedin]

Yes, the 4.0L went from around 165hp to 210hp with the addition of the overhead cam. Which is very respectable.



But I probably would have been just as happy with some minor tweaks to the older OHV engine. They probably could have gotten it up to 185 or so if they bumped the compression to 9.6 like they did with the SOHC.



I pulled my "deluxe" center console out of a 2001 Explorer Sport at a junkyard. It had "timing chain bad" waxed on the inside of the windshield. Sad. Nothing wrong with it otherwise.



I just want to emphasize..Very few local shop mechanics will go deep into a high mileage engine. It's just too time consuming and risky and they don't have the specialized tools. If they are pulling it, its just easier to get a motor from a re-manufacturer. If something goes wrong with it the costs to fix are shared between the mechanic and motor re-manufacturer.



Timing chain guides & parts is what - something like $400?... and now add in the mechanics labor (motor in/out AND futzing with the guides)? Where we at? $1800-2000? and we are putting the 160k motor back in? Forget it. Fork up the extra $1000 and put the reman motor in.



Now, if you are doing the work yourself..and your on a budget..that is a different story.

 

[blksn8k]

I thought the reason for the jack shaft design was that Ford chose to keep the existing OHV engine block and convert it to SOHC without designing a whole new block? That probably also allowed them to use the same basic head casting on both sides on the block. Not saying any of that was a good idea but it was probably a relatively cheap way to get more power from the same short block and they sold a ton of those engines for several years in Rangers, Explorers (including the ST) and Mustangs.