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SOHC V6 Timing Chain Saga

2000StreetRod

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As soon as I completed the performance testing phase of my custom tune I began the possibly lengthy process of assessing my timing chain issues. The cold start up rattle has continued to increase and I know that I have been lucky that the engine has lasted this long without catastrophic failure.

I want to point out that I am disgusted with Ford for manufacturing a SOHC engine with the right timing chain located in the rear of the engine with extremely limited access. This coupled with the short life of the timing chain components reveals Ford's lack of quality, reliability and maintainability. It is indeed unfortunate for current and future owners that Ford has continued to manufacture this engine with this significant design flaw.

My first task was to remove the right valve cover to determine what damage may have occurred. I have not previously detected any rattle from the upper rear of the engine so I assumed that the timing componets in this area would be in better shape than those in the front. Also, the oil lubrication to the rear timing chain components is superior to what it is to the front timing chain components. I was surprised at how many things block access to the valve cover and its attaching bolts. Eventually I loosened all of the valve cover bolts except for the outer rear one that is under the bulge in the cover for the rear cam sprocket. I purchased a set of 1/4 inch drive metric sockets and two wobble extensions to fit around the bulge in order to loosen the bolt. The photo below shows the underside of the right valve cover.
CvrRt.jpg

I puchased the vehicle in May, 2009 with approximately 150,000 miles on the odometer. The tow truck driver I purchased it from (the vehicle was abandoned on the freeway) changed the oil just prior to selling it. I changed the oil to full synthetic after about 1,000 miles before starting the performance phase of my custom tune.
The photo below shows the buildup of sludge on the camshaft and in the head.
CamRt.jpg

It's not as bad as some I've seen on the forum but certainly nothing to be proud of. At least drainage from the top to bottom was not blocked.
The photo below is the best picture I could get of the timing chain components without using a mirror.
SlckRt.jpg

Please note the obvious lack of tension (slack) on the inner side of the camshaft sprocket as the chain drops toward the jackshaft. I could easily deflect the chain toward the center of the block more than one inch with my fingers. I did not feel the presence of a guide but my reach was very limited. My only hope is that the tensioner on the outer side of the head has a broken internal spring. I encourage every SOHC V6 owner to change the upper tensioner every 75,000 miles or less to reduce cassette damage. However, periodic replacement of the tensioner will not prevent guide wear on the traction side of the chain.
I will clean the chain area with engine flush and puchase a mirror for better visibility. I'll also remove the external tensioner and compare it with a new one I have.
The photo below shows a new rear upper cassette.
RtUpr.jpg

I suspect that most of the plastic "ladder" is missing allowing the excessive chain deflection.
 


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drothgeb

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I am definitely subscribing to this thread. Thank you for the detailed overview so far and keep up the good work.
 




2000StreetRod

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Left upper cassette

Access to the retaining bolts on the left valve cover is much better than on the right. On my 2000 model I got by with just loosening the dipstick tube mounting bracket bolt and removing the DPFE sensor bolts which allowed adequate clearance to remove the valve cover. I was glad that I did not have to loosen any of the rusty EGR valve and tube hardware. A photo of the left valve cover underside is shown below.
CvrLt.jpg

The amount of deposits in the left cover is comparable to that in the right cover. I was relieved that there were no cassette fragments stuck to the underside like one forum member found on his valve cover.
The photo below shows the buildup of sludge on the camshaft and in the head. There is considerably more sludge in the left head than in the right head but still no return oil blockage.
CamLt.jpg

The photo below shows the upper front cassette. The red arrow identifies the guide section that contacts the chain. As you can see the guide is thankfully still intact.
TnsrLt.jpg

The green arrow identifies the face of the upper front tensioner which I replaced just prior to starting my custom tune. Using my finger I did not detect any significant cassette damage. This was surprising since from the accumulation of sludge it appears that the cassette has never been replaced. Previously I have detected chain rattle coming from the front of the engine so the lower front chain must be the source of the rattle. I sprayed the sludge with engine flush to soak over night.
The photo below shows a new upper left timing chain cassette.
LftUpr.jpg

By feel I was able to verify the presence of the upper half of both sections. I will have to clean the cassette thoroughly to visually verify the presence of the lower half.
 




Opera House

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I saw an upper tensioner on ebay pretty cheap and was thinking I ought to replace it when we get some warm weather. I'm at 120K, understand the rear is easy to get at.
 




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Am i right in thinking that you will be removing the engine then as you cant replace the rear tensioner without removing the gearbox or engine. You will have to remove ladder as well to search for fragemnts of the the rear tensioner along with the oil pump strainer.
 




2000StreetRod

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Repair approach

Am i right in thinking that you will be removing the engine then as you cant replace the rear tensioner without removing the gearbox or engine. You will have to remove ladder as well to search for fragemnts of the the rear tensioner along with the oil pump strainer.

I haven't decided yet on what to do. I'm going to continue my assessment by removing the front timing cover. Then I'll be able to generate a complete list of replacement parts required. I'll then decide (based on cost) whether to order a complete timing chain kit or just the failed components.

I agree that as a minimum the lower oil pan and probably the upper support ladder will have to be removed to check for fragments. Especially if the front lower tensioner and guide has deteriorated.
 




jonlax

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looking to do the same.

as of right now 2001 sport with 75k. Light rattle during stating. Valve covers are clean since its well taken care of with synthetic oil and frequent changes the passenger side rear chain is loose but no fragments found. I am just trying to figure out if i should do it or have the dealership do it. (they quoted me at 2100 USD). Parts for a full rebuild are 310 USD but my time is the most valuable thing since i do not have much of it. I have a garage that i can use but no lift.

Good luck with your assesment for i will be watching to see how the swap of parts goes. The last time i changed a timing belt its was on an acura integra and the engine had to come out. I do not want to go threw that again with out a proper garage.

Jon
 




2000StreetRod

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Cassette Deficient Design Rant

The photo below shows the components of a SOHC timing chain repair kit.
ChainKet.jpg

The rear cassette is located in the upper right of the photo. The "ladder" portion of the guide contacts the chain on the traction side. The side where the rotating jackshaft sprocket pulls the camshaft sprocket via the chain to rotate. The curved shape of the "ladder" indicates the amount of deflection forced on the chain by the guide.

In my opinion the configuration of the guide is the result of either incompetent design engineering or planned failure by Ford for future repair work. Chain deflection on the traction side is unecessary and results in designed friction wear. Chain deflection is only necessary on the slack side where the tensioner is located. The guide does not prevent damage to the rest of the engine if the chain should break because the guide wears away well before the chain can fail. There is no head component obstruction that requires the chain path deviation and there is no need for symmetrical chain deflection of the traction and slack sides. It's almost as if Ford didn't have access to the proper length of chain and used the guides to take up the slack. As the guide wears the chain length from the jackshaft sprocket to the camshaft sprocket decreases. This results in mechanical camshaft to crankshaft timing changes that negatively impact engine performance.

I plan to investigate the possibility of shortening the chain by removing a link and eliminating the traction side of the guide assembly for the rear cassette. This would reduce friction, wear, rotating mass and ensure correct mechanical timing. It's a shame that Ford hasn't done the same thing after all of the past years of customer dissatisfaction.
 




Carguy3J

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Very interesting concept. Just be very careful here. You would definitely be "playing with fire" here. Also, wouldn't removing a link change the relationship between the crank/cam? I know "jumping" even a single tooth, with a loose/sloppy chain, can have severe consequences on these engines. Wouldn't you basically be doing the same, just with a tight chain? Maybe it would require a fabricated means of adjusting the cam timing reliably and accurately?

As far as friction reduction, if you're willing to go such extremes as reengineering the timing components, have you considered the possibility of using "coatings" on the timing components? I'm referring to, essentially, the same anti-friction, oil retention, and/or heat rejection coatings that can be used on internal engine components (pistons/bearings/etc...) As long as the components can withstand the "curing" process, it might be very beneficial. I believe coated parts ar baked at about 300deg. I would think that even the "plastic" parts fo the timing system should be able to withstand this, given that they are routinely exposed to engine temps not far below this. Even if you can only apply it to the chain itself, there would probably still be a worthwhile advantage.

I seriously doubt that Ford intentionally designed these timing cassettes to fail in order to make money on repairs. After all, they must have spent millions on the recall repairs, and they redesigned the components/materials on later engines to prevent the problem. Which also brings me to my next point. Once the cassettes/components have been replaced with the updated components, I don't think that wear is nearly as much an issue. I think planning on 75,000mile or less change intervals is probably excessive. Given that there is usually ample warning before a catastrophic failure, I would not replace them again unless/until the vehicle began exhibiting symptoms again. (rattling). Further, now that the "problem" is known, and given that the you will have the components from "new", you can use good quality synthetics, of the proper grade and changed at appropriate intervals, right from the start, further extending the life of these new parts, vs the originals.
 




2000StreetRod

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cam/crank timing

Very interesting concept. Just be very careful here. You would definitely be "playing with fire" here. Also, wouldn't removing a link change the relationship between the crank/cam? I know "jumping" even a single tooth, with a loose/sloppy chain, can have severe consequences on these engines. Wouldn't you basically be doing the same, just with a tight chain? Maybe it would require a fabricated means of adjusting the cam timing reliably and accurately?

As far as friction reduction, if you're willing to go such extremes as reengineering the timing components, have you considered the possibility of using "coatings" on the timing components? I'm referring to, essentially, the same anti-friction, oil retention, and/or heat rejection coatings that can be used on internal engine components (pistons/bearings/etc...) As long as the components can withstand the "curing" process, it might be very beneficial. I believe coated parts ar baked at about 300deg. I would think that even the "plastic" parts fo the timing system should be able to withstand this, given that they are routinely exposed to engine temps not far below this. Even if you can only apply it to the chain itself, there would probably still be a worthwhile advantage.

I'm not familiar with the friction reduction coatings but I'll look into them. Thanks for the idea.

The actual length of the chain from the jackshaft sprocket to the camshaft sprocket does not matter as long as it doesn't change after the cam/crank is timed. One of the only good things about the keyless overhead cam is that it's timing is adjustable to any position. On my 2600 DOHC Alfa Spider there were inner and outer splines on the camshaft sprocket that allowed user settable relative timing of the intake and exhaust valves and crank. It was also an interference engine.

. . .Once the cassettes/components have been replaced with the updated components, I don't think that wear is nearly as much an issue. I think planning on 75,000mile or less change intervals is probably excessive. . . .

To my knowledge the rear cassette and tensioner has never been redesigned. I'm only recommending periodic replacement of the spring loaded piston tensioner since the spring weakens with age. Replacing it is not much more difficult than replacing the right rear spark plug.

I believe the best way to improve the longevity of the timing chain system is by adding a pre-oiler.
 




2000StreetRod

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Rear main seal

While I was under my Sport to drain the engine oil I noticed that the rear main seal is leaking more since I switched to full synthetic oil. I was hoping to own my Sport for at least a year before having to pull the engine. However, Harbor Freight is having a sale on 1 ton capacity foldable shop cranes so I'll be picking one up in the morning.
 




jonlax

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While I was under my Sport to drain the engine oil I noticed that the rear main seal is leaking more since I switched to full synthetic oil. I was hoping to own my Sport for at least a year before having to pull the engine. However, Harbor Freight is having a sale on 1 ton capacity foldable shop cranes so I'll be picking one up in the morning.


I used a harbor freight 1 ton shop crane about 6 years ago when i did an engine swap on my acura. BE VERY CAREFUL! It would not hold pressure so it would release it self and actually ruined an oil pan. The fill point actually burst off causing all of the fluid out of the jack to go everywhere the 3 times i tried to use it.
 








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jonlax

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Good links!

I Cryogenicly treated the internals of my rotory and its still has not failed.

Teflon coatings might be good for the guides and will actually adhear better to the pastics.

This is the company i used when i rebuilt my wankel

http://www.calicocoatings.com/

Great people and really helped me out with the right coating to rid heat and reduce friction. They have expanded quite a bit over the years too.

Jon
 




2000StreetRod

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Coatings very interesting!

Thanks for the very interesting links on coatings Carguy3J. The maximum performance gained doesn't seem to justify the cost for my infrequent daily driver. However, some coating applications may be warranted from a longevity or fuel economy standpoint. I will continue to investigate as I remove and tear my engine apart.
 




jonlax

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Teflon coating is inexpensive and can be done yourself but most plastic peices already have it.

I can contest to the price of the coatings because it was well over 400 dollars just for my rotors to be coated. Its not very practical for a DD since the costs are not easily offset like you posted.
 




ranger7ltr

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Did the coating apply to the apex seals?

Teflon coating is inexpensive and can be done yourself but most plastic peices already have it.

I can contest to the price of the coatings because it was well over 400 dollars just for my rotors to be coated. Its not very practical for a DD since the costs are not easily offset like you posted.

Sorry to thread-jack but I have built and re-built more than a few rotary engines and always wondered if the seals life could be extended by some type of coating...

Most of the rotaries were endurance engines and would see higher rpm and the best solution was to redesign the lubrication system to help them last...

I have even had fellow engineers design the seals out of different materials just to experiment with...
 




2000StreetRod

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rotary engine

I designed a rotary engine on paper in 1954. My design did not incorporate eccentric rotation. I started working on a patent application and a prototype but gave it up because among other things I could not think of any way to reduce the friction between the rotor and the cylinder wall. I really kicked myself when the Wankel was announced with it's Teflon seals.
 


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2000StreetRod

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1st Transformation

$50 plus tax at Harbor Freight buys what's in the photo below:
StndBox.jpg

After about an hour of unpacking and assembly it transforms to this:
Stand.jpg

Does anyone know what size bolts I need to mount an SOHC V6 on the stand?
 




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