SOHC V6 Timing Chain Saga | Page 12 | Ford Explorer Forums - Serious Explorations

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SOHC V6 Timing Chain Saga

Good deal. I like the illustrations myself.

I was actually supposed to be done building this motor but ran into "life", so until I can get around to it, I'll watch (and learn) from you guys building the motor. ;)
 



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The traction side is on the exhaust (outer) side of the head for the front cassette. There is very little curve to it as shown in the photo below.

Since it is fairly straight, as the guide chain contact material wears the relative timing between the jackshaft and the camshaft does not change.

The slack side is the side where the hydraulic tensioner contacts the guide and keeps the slack side of the chain from slapping.

My front guide assembly was in excellent condition until I broke off the small, curved bottom piece of the traction side trying to remove it from the head. The main reason I decided to replace it was my fear that the all plastic assembly would structurally fail into fragments like the rear assembly did. As you can see in the photo, the new one is a metal structure with attached chain contact material. Unfortunately, the plastic is not bonded to the metal. It is attached with plastic friction latches. I will possibly separate (very carefully) the plastic from the metal and reassemble the pieces with epoxy glue. My only concern is the different coefficients of expansion for metal vs plastic.

Correct me if I am wrong, but does the right rear guide have more defection on the traction side than the front left guide? That's how the parts photos look to me. Up until recently most people here have considered the front left guide to be the problematic one, and the rear guide to be more trouble free. This may be a throw-back to when Ford replaced the front left guide on the 97 & 98 SOHC engines under owner notification program TSB 01M01. If the rear guide has more defection, and combine that with fact that half of it is plastic, I would suspect it would be the first to fail in most cases...
 






injector seat

Ok, when seating the injectors, should they go in real easy (with a light coating of oil), or do they need to be forced down until flush? I installed them and they went in easily but the lower rubber o-ring seems to seal against the rubber isolators and not the head (like I originally thought). With the injector set in place, and the rail installed, this is how they sit..... I would assume that if the bracket sits flush on the head, that they are seated correctly??

injector.jpg
 






You should actually feel a little resistance when seating them. Not major but just enough to let you know it’s going in correct. I always start with one side and work my way to the other, seating each, one at a time.

Make sure the insert that’s in the head hasn't cracked. They are known to do that. And when they do, they'll spread when inserting the injector. I've actually been running one cracked for awhile now with no I'll effects but I know it's not right.
 






Improvised hex bit

. . . On the hex bit for the oil pan reinforcement. I bought the metric set from Harbor Freight and of course the 10mm was too small and the 12 mm is too big. It is either an 11 or the SAE equivalent.
Be forewarned, the only place that had the correct size was Advance Auto Parts and you have to buy the entire 46.00 kit for the right one. So I bought a set from Autozone with a 12mm and I am going to grind it to fit. . .

In the past when I needed a hex bit that I didn't have I improvised with a short bolt having a head of the needed size. Then I threaded two nuts on to the bolt and tightened the nuts against each other. I put a socket on the outer nut and used the bolt head as a bit. It works as long as the required torque is not too large. For greater required torque values a bushing of the right length is installed between the bolt head and a nut on the bolt shaft. The nut is tightened against the bushing to a torque value that exceeds that required for the bit. I may end up using the work around if my allen set doesn't have the correct size.
 






Totally agree

Correct me if I am wrong, but does the right rear guide have more deflection on the traction side than the front left guide? That's how the parts photos look to me. Up until recently most people here have considered the front left guide to be the problematic one, and the rear guide to be more trouble free. This may be a throw-back to when Ford replaced the front left guide on the 97 & 98 SOHC engines under owner notification program TSB 01M01. If the rear guide has more deflection, and combine that with fact that half of it is plastic, I would suspect it would be the first to fail in most cases...

I believe that before Ford updated the guide assemblies the front was more likely to fail from friction wear because of soft chain contact material and engine startup oil starvation. After the update, structural failure became the primary failure mode. As shown in the photo below there is considerable curvature on the traction side of the rear guide resulting in a high lateral force.
RtUpr.jpg

The upper positioning post fits in the slot at the top of the traction side. The slot is a weak point and probably the first thing to fail. Once it fails then the guide moves laterally outward allowing the chain to slap because the tensioner range is limited. As the chain slap increases the chain starts to contact the positioning post producing metal particles and accelerating chain wear. Eventually the chain will fail resulting in possible piston and valve damage.

My goal is to eliminate the traction side of the guide assembly and the positioning post. However, the chain will have to be shortened to take up the slack that would otherwise occur due to the decreased chain deflection. The timing chain is a link belt type instead of the older roller type used in my Alfa and Jaguars. I have found a link belt chain manufacturer located in the U.S. (most timing chain manufacturers are outside of the U.S.) that provide a SOHC V6 kit. I am attempting to find out if I can obtain a shorter chain either by modifying an existing one or purchasing a new custom one for evaluation purposes. I am not optimistic at this time.
 






How exactly is the Balance Shaft supposed to be timed? Do the timing marks line up with each other? In the PDF it didn't seem that way.
 






Balance shaft alignment

How exactly is the Balance Shaft supposed to be timed? Do the timing marks line up with each other? In the PDF it didn't seem that way.

There are marks on two adjacent teeth on the balance shaft sprocket. When the marks straddle a hole on the assembly the mark on the balance shaft should be in line with the bottom of the assembly as shown in step 25. The drawing is shown with the engine inverted.
 






There are marks on two adjacent teeth on the balance shaft sprocket. When the marks straddle a hole on the assembly the mark on the balance shaft should be in line with the bottom of the assembly as shown in step 25. The drawing is shown with the engine inverted.

So it should be how it is in the drawing?

I lined it up with the mark on the balance shaft between the marks on the teeth

\ /
O

Kind of like that...I know that may not be the best description however.
 






Cleanup progress & parts

The photo below of the right valve train indicates the cleanup progress made to date using Gunk engine flush, a squirt bottle and a tooth brush.
RHead.jpg

The engine head parts are finally recognizable.

The prospects of shortening a stock rear timing chain or purchasing a shorter chain from a manufacturer seem bleak so this morning I ordered a new rear cassette and associated parts from Tousley Ford. All of the right timing chain components will be new. It will be at least a week before I receive the parts so I'll start installing the left and front timing components in a few days. The only new component on the left side will be the updated guide assembly. I'm reusing the original chain and sprocket and the tensioner has only been installed for about 1,000 miles. All of the front components are new.
 






I was under the impression that the guide is only available in a kit with the chain and sprockets. Can the left guide be bought on it's own? Please post the part number if you have it.
 






Just the guide assembly

I was under the impression that the guide is only available in a kit with the chain and sprockets. Can the left guide be bought on it's own? Please post the part number if you have it.

I was able to get just the guide assembly (PN YL2Z6M273AA) on eBay that had been laying around for a while. Now the guide assembly is part of the cassette assembly. I'm posting all the camshaft timing related part numbers I find on the following thread: SOHC V6 Camshaft Timing
 






78 to 76 links

Yesterday I received a response to my inquiry regarding shortening the length of the stock rear timing chain. An aftermarket product engineer with Cloyes Gear and Products stated that the construction of the chain requires modifications in pairs. The stock 78 link chain would have to be shortened to 76 links - a decrease of about 1.5 inches. Even if I eliminated the entire guide assembly I doubt that the shortened chain would be long enough to fit. Since my original chain is damaged from contacting the guide assembly upper positioning post it is not fit for reuse. Therefore, I will shorten it myself to confirm it would be too short to fit.
 






Help me understand what shortening the chain is going to accomplish? Not saying this in a butthead way but trying to figure out what you have up your sleeve.
 






Why shorten rear timing chain?

Help me understand what shortening the chain is going to accomplish? Not saying this in a butthead way but trying to figure out what you have up your sleeve.

The latest rear timing chain guide assembly consists of a metal bracket with plastic "shoe" on the slack side and an all plastic guide on the traction side. The plastic side suffers from structural fatigue and eventually disintegrates. Even if the plastic pieces don't jam the chain and cause it to break, the resulting slack in the chain causes it to strike the guide upper positioning post creating metal particles and eventual chain failure. Also, when the guide breaks away the timing of the camshaft relative to the crankshaft changes. My idea is to eliminate the traction side of the guide assembly and the positioning post. The chain would have to be shortened to make up for the reduced deflection because of the absent guide. The hydraulic tensioner does not have enough range to take up the slack.
 






I see now, thanks.

Have you studied how the chain and plastic parts receives oil? Is there potential for improvement?
 






Hey Guys,
I posted a week or two back about my 97 4wd sport. I opted to send it to a local mechanic and he was going to get a "used" engine and swap them out.
He's had it for a couple of weeks and finally told me today that he has looked at 4 different engines and none are the same as mine. He says the bell housing is different. Now he thinks that my 97 was built with a 96 engine (as he says the build date says 10/06.)
I looked in my Chiltons and they didn't build an E/vin engine in 96! All my numbers match.
What do you guess the problem is? (Don't say "the mechanic"! Too easy!)
 






Sludge blocking oil flow

I see now, thanks.

Have you studied how the chain and plastic parts receives oil? Is there potential for improvement?

One of the Cloyes aftermarket product engineers commented that they have received several reports of sludge blocking the oil path to the rear hydraulic tensioner and the guide assembly causing rapid wear of the chain contact material. While I had an excessive amount of sludge in my engine there was only about one tenth of the contact material worn down. Based strictly on wear the rear guide assembly could have lasted another 500,000 miles.

I believe the most guide wear occurs at engine start up. I am going to install a pre-oiler to eliminate start up oil starvation.
 






Got the motor back together and it is nice and quiet, but I still have coolant in the same cylinder. :mad:
 



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Got the motor back together and it is nice and quiet, but I still have coolant in the same cylinder. :mad:


Sorry to hear this. I'm guessing, if you just changed the head gaskets, there is only one other way water is getting in there.......

How fast is the leak?
 






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