Main timing chain - OHV vs SOHC

[wow97]

:notworthythank you everybody for fyi now i think about it i have a 4.0 e.f.i vin x ohv or ohc but some crazy reason carfax said i have a SOHC FI and i have a 5-speed automatic with fulltime awd

 

[2000StreetRod]

Improved primary tensioner

. . . With regard to the Primary (jackshaft) chain tensioner, the new design incorporates a 5 leaf spring as well as a more robust mounting bracket. Not as good as an oil/spring combination unit, but still superior to the original design. I have all the parts I need to do this job on my own truck, and expect to get at in in a week or two. I expect that my primary chain tensioner is long since shot, and i am hoping my 2 cassettes are still servicable.

After having received my new primary tensioner and comparing it with my old one I agree that it is substantially improved. My new one is a 6 leaf spring which is twice as many as the old one. However, I just don't like the idea of flat pieces of spring steel that can break from fatigue and end up jamming the chain. The hydraulic design was ideal to me and is still being used in the 4.6L V8.

I wish you luck on the condition of your cassettes (especially the rear). Do you have the OTC-6488 timing tool set? You can replace your primary tensioner and guide without loosening the front jackshaft sprocket and then retiming would not be necessary. I plan to improvise and hopefully time the camshafts properly without the kit.

 

[bluestream1]

After having received my new primary tensioner and comparing it with my old one I agree that it is substantially improved. My new one is a 6 leaf spring which is twice as many as the old one. However, I just don't like the idea of flat pieces of spring steel that can break from fatigue and end up jamming the chain. The hydraulic design was ideal to me and is still being used in the 4.6L V8.

I wish you luck on the condition of your cassettes (especially the rear). Do you have the OTC-6488 timing tool set? You can replace your primary tensioner and guide without loosening the front jackshaft sprocket and then retiming would not be necessary. I plan to improvise and hopefully time the camshafts properly without the kit.

My Plan is this:

I am going to remove the valve covers and inspect the guides. If they look good, I will likely leave them alone. My Ford dealer has offered to lend me the timing tool for free; and I expect to take him up on that offer. If I have any problems getting the timing tool, I will be changing the primary chain tensioner and guide only. If the rear right guide is suspect, I have will to make a decision at that time. I don't want to bother taking the engine out for that repair as I don't have the time or patience for that job right now. I also do not want to change out the balance shaft tensioner, even though I have the new part already. I suspect the balance shaft tensioner is shot as well. I am considering just removing the chain and leaving the shaft in place. I have heard of others who have removed the shaft, and had to plug the oil passages to maintain oil pressure in the system. I think the shaft can be left in place without the chain, but I am not sure. I have followed the timing chain sage for seven years now, and the day of reckoning is now here for my truck. I will start a thread and post pics of my findings in the near future.

 

[2000StreetRod]

Camshaft timing procedure thread

My Plan is this:

I am going to remove the valve covers and inspect the guides. If they look good, I will likely leave them alone. My Ford dealer has offered to lend me the timing tool for free; and I expect to take him up on that offer. If I have any problems getting the timing tool, I will be changing the primary chain tensioner and guide only. If the rear right guide is suspect, I have will to make a decision at that time. I don't want to bother taking the engine out for that repair as I don't have the time or patience for that job right now. I also do not want to change out the balance shaft tensioner, even though I have the new part already. I suspect the balance shaft tensioner is shot as well. I am considering just removing the chain and leaving the shaft in place. I have heard of others who have removed the shaft, and had to plug the oil passages to maintain oil pressure in the system. I think the shaft can be left in place without the chain, but I am not sure. I have followed the timing chain sage for seven years now, and the day of reckoning is now here for my truck. I will start a thread and post pics of my findings in the near future.

I don't know how easy it is to remove the balance shaft chain. I think it has to be released at the balance shaft end. I'll look into it.

I'll be interested in watching your progress as it's posted on the forum.

I started a new thread (see below) that shows the timing tool kit and lists the Ford timing procedure using it. I believe that I have workarounds for the three special tools that Ford uses that are not included in the timing tool kit.

SOHC V6 Camshaft Timing

 

[bluestream1]

I have wondered if the balance shaft tensioner can be replaced by just changing the plastic/spring section and leaving the mounting bracket in place? The plastic shoe on my new tensioner just slides off of its stud mount. If there was room, this would mean the upper oil pan could stay in place, and therefore save a lot of labor. The bracket that holds the plastic shoe is not a part that does much other that hold the shoe., and if the old bracket is not warped or twisted, there is no reason not to use it. I have only seen pictures of the pan/balance shaft chain, so not sure if there is room for this manouver.

If I find this is not possible, and my balance shaft tensioner is shot, I would likley try and cut the chain off with a dremmel tool.

 

[CDW6212R]

I have wondered if the balance shaft tensioner can be replaced by just changing the plastic/spring section and leaving the mounting bracket in place? The plastic shoe on my new tensioner just slides off of its stud mount. If there was room, this would mean the upper oil pan could stay in place, and therefore save a lot of labor. The bracket that holds the plastic shoe is not a part that does much other that hold the shoe., and if the old bracket is not warped or twisted, there is no reason not to use it. I have only seen pictures of the pan/balance shaft chain, so not sure if there is room for this manouver.

If I find this is not possible, and my balance shaft tensioner is shot, I would likley try and cut the chain off with a dremmel tool.

That's where I was when I discovered my balance shaft out of time. There are two dots that must line up when it is timed properly. I tried to remove the tensioner without yet pulling the pan. The tensioner broke in my hand, I used no tools to get there. Try to take the guide off first, and be very very gentle with the tensioner.

If you were actually going to try it without the balance shaft, just cut it with a bolt cutter, it's very small.

 

[bluestream1]

Don, I wish your picture showed a little more to the left by the balance chain. It also looks like you have replaced the balance shaft tensioner; did you remove the oil pan ladder frame to do that?

Here is a pic of the tensioner and the plastic shoe. It just slides off the bracket by pushing in a little on the spring. You may be right that with the balance shaft guide removed, it may be possible to just slide the shoe off the old bracket, and slip on the new spring/shoe.

It is a very weak design, and only has one small leaf for a spring. I have been storing it without the spring retainer pin installed hoping that will kept the spring from becoming weaker until I get it installed. I hope that was the right thing to do...

 

[CDW6212R]

That picture was the last before finishing it completely. I took that to show the proper crank gear orientation, no dimples. I had before pulled the pans and balance shaft, oil pump and diff.
This below is a wider angle but is before I changed that tensioner. I used the two old front chain guides, they looked fine and I didn't want to wait on more ordered parts.

 

[bluestream1]

By looking at that photo, it looks as if it may be possible to just replace the balance shaft tensioner shoe/spring assemble (if you had long fingers.) I guess I will find out when I get it opened up...

 

[CDW6212R]

The pan is very close there, I didn't think of trying it. I discovered my balance shaft to be out of time, so the chain had to come off of mine.

 

[cjmedina]

I found a photo on the forum of a 1997 DOHC 4.6L engine.
View attachment 58221
The guides on the traction side are straight and do not deflect the chain. As the traction side guide wears due to chain flex the timing will not change. The tensioner on the slack side is the ratchet style combination of spring and oil pressure similar to that used on the OHV V6. Apparently chain guide wear and chain failure is also a problem with this engine. However, a design improvement over the SOHC V6 is that the chains for both banks are in the front. The chains, cassettes, tensioners and sprockets can be replaced after removing the front timing cover. Removal of the engine is not required. I would like the next vehicle I purchase to have one of these engines!

WHY DIDN'T FORD GO THIS ROUTE WITH THE 4.0l SOHC....CHAINS IN FRONT AND NO JACKSHAFT.....WHAT THE HELL WERE THEY THINKING?????

 

[mikecmax]

why the guide?

Even though Explorers from 1991 thru 2001 were powered by the OHV V6 I was not able to find any photos of it's main timing chain on the forum. There were hardly any threads that even discussed it. However, there are numerous threads posted on the forum about the SOHC V6 timing chains. I'm confident that the reason for the lack of OHV threads is because it has proven to be very reliable. I have been unable to find a photo of the timing components mounted on the engine with the timing cover removed. However, the photo below shows an OHV crankshaft sprocket, camshaft sprocket, timing chain, guide, and tensioner.
View attachment 57957
Please notice that the chain guide has a straight slot for the chain. When the guide is mounted on the block it does not tension the chain. It merely restricts the chain from deviating from a straight line as the crankshaft sprocket pulls the chain to rotate the camshaft sprocket. Also notice the length and thickness of the chain contact surface on the tensioner. While you can't see it in the photo, under the temporary installation keeper is a plunger that pushes the contact surface against the chain.

The photo below shows the crankshaft to jackshaft chain installed on a SOHC V6.
View attachment 57958
Please notice how the guide deflects the chain inward toward the other half. One problem with this design is the deflection results in significant guide wear. As the guide wears away the distance from the crankshaft sprocket to the jackshaft sprocket decreases resulting in a change in crankshaft to camshaft timing. Also notice the absence of the chain contact surface on the tensioner. It appears to have been completely worn away. The photo below shows a worn and new tensioner.
View attachment 57959
The method of tensioning and the robustness of the tensioner is obviously inferior to that of the OHV tensioner. Ford's redesign of the SOHC tensioner can be seen in the photo. It appears to be limited to enlarging the mounting base and possibly changing the composition of the contact material. I am concerned about spending the time to tear down my engine to replace the tensioner with such a flimsy component of questionable reliability. My first thought was to try and use the OHV tensioner and guide but there are significant differences in the mounting bolt holes on the two blocks.

Does anyone know of an aftermarket tensioner that is more robust?

 

[Hitchhikingmike]

2000StreetRod, thank you for your documentation of the SOHC engine. I have tracked most of your threads and enjoy brushing up my knowledge of the working of the engine. I have a SOHC in my 3rd gen sitting at 73k mi. Hopefully it will be quite a while until I will ever have to do this job.

 

[mikecmax]

To Hitchikingmike:
I think you made a wrong turn I'm mikecmax and 2000streetrod has given me some invaluable info on how to find out what is wrong with the 98 explorer I just bought with a blown engine.

 

[srt_hubcap]

not trying , to bring to life an old thread but i got the DEATH RADDLE coming from my Y2K sport ohv .
i got the timing chain kit . and i'm changing it Saturday . but till then i'm having to drive it to work , scary trying not to kill it . but i'm shifting before 2krpm trying not to strain it ... i'll have a full spread of pics on here sunday for everyone ....

 

[wow97]

hello i have a 1997 ford explorer XL/XLT EDDIE BAUER LIMITED 4.0 SFI SOHC V-6 WHEN I DRIVE AND GO FAST i got the DEATH RADDLE TIMING CHAIN
HELP ME DID I HAVE ONE TIMING CHAIN OR THREE TIMING CHAIN

 

[wow97]

Death raddle timing chain

hello i have a 1997 ford explorer xl/xlt eddie bauer limited 4.0 sfi sohc v-6 with 5-speed automatic vin x i have cologne sohc v-6
when i drive and go fast i got the death raddle timing chain
help me did i have one timing chain or three timing chain

vin x with 5-speed automatic it has to be sohc to get 5-speed automatic

 

[Glen4X4]

Vin E is the SOHC

 

[srt_hubcap]

ok , here ya go people
the start , the fan clutch puller wrench from autozone didn't fit so i had to pull off the water pump .

after shot

sorry for the pics all i had was my cheap cell phone to take them with

oh someone could have told me about all the star drive bolts , lol
got it all put together and runs perfect again .
if this can help anyone , then my job here is done

 

[CDW6212R]

That is a unique jack shaft bolt, yours takes a Torx bit. Mine and the others I know of all used a Torx bolt, meaning they take a Torx socket to remove. It was an odd large size too, about a T17 or T18.