Timing the 4.0 SOHC (98 Explorer)

[Midwest Kid]

I have a question guys. I have Ford's process on timing this engine and the tool set on the way. I just dont understand it all. Theres no timing marks or anything so im lost as to how it is suppose to be timed. This is the first engine that didnt have marks and slots on the gears and so forth. It actually blows my mind that the bolt is the only thing that keeps it timed. Anyhow.. im replacing the front cassette and primary chain\gears and as of now.. i havent replaced anything bc i dont know where to start. i was going to just pull all the gears out so that i could have everything ready to time it when the tools came but now i dont know. Any help would be great appreciated. I searched and found all the threads about the cam cassette and tensioner issues but none that talked about how to time it. Thanks again.

 

[CDW6212R]

Welcome, and first do not unbolt any crank/cam/valvetrain parts until the engine is at TDC. There is a tool for that in the kit, get it close to TDC first, and keep it near TDC as you do the work.

The hardest parts will be dealing with the balancer(removal), and loosening/tightening the bolts for the balancer and jackshaft. A second person and/or special tools to hold the engine still would help a lot.

The timing is as you noted very different. What is done is the crank(shortblock) is set to TDC, the cams are disconnected(cams move on their own, thus TDC is critical). Then one cam is held at TDC by a tool on one end, and the cam gear is held true(straight, cannot fall off) by another tool on the other end.

The jackshaft chain and gears and tensioners have to be done/replaced before the timing is set, those connect the cams to the crank. With the tool holding the cam gear true, that's when the cam bolt holding the gear to the cam can be loosened. The tool used for setting the cam at TDC only goes on in one way(out of 360 degrees etc.).

So you do the TDC, the jackshaft items, then the cassette, then the timing. If the engine was properly worked on with it at TDC to begin with, the cam will be near TDC. You simply use the cam gear to move the cam(and crank etc.) to its TDC(the cam tool). Then you will be loosening that cam bolt to move the crank back to exactly TDC, thus making them timed(tighten the cam bolt). The second camshaft is timed in the same way, the tools work on the two ends of each cam, in turn.

Remember to start with it all at TDC(crank), then as you do something which moves the crank from its TDC, move it back after each step. It's okay for it to get moved a little as you loosen the crank bolt for the balancer, just be sure to move it back promptly. When the cams are unbolted, that's when it's critical for the crank to be at TDC.

Let me know if that makes more sense than how it is in shop manuals. Good luck,

 

[Midwest Kid]

Thanks a lot for the quick reply. I cant believe the setup Ford put into this thing but thats an on-going complaint im sure. This whole procedure is just confusing for some reason.
Now.. you said to set the engine at TDC.. then replace the jackshaft items. Are you referring to the Primary gears, chains and tensioners? If so, wouldnt that obstruct me from replacing the cassette? I have a new gears and tensioners for that front cassette. As far as the cam tools. You mentioned the side w/o the cam gear will only go on one way? Another thing is,, i noticed the only way with the OTC timing set to get the crank at TDC is with the balancer still on the crank. Well.. that means i have to re-install it...set it to TDC... and then keep installing and removing it after each step just to get it back to TDC? You would think they would just make a tool that goes on the end of the crank. Sorry if me not understanding this is aggravating but i appreciate the help.

 

[Midwest Kid]

oh and you mentioned the cams move on there own? Are you saying they will rotate where they need to be when i lossen the cam gear bolt?

 

[CDW6212R]

The jackshaft chain is the primary chain, manuals call it one or the other, it's the one that older mechanics would call the timing chain, same thing.

The jackshaft chain and front cassette(chain also) yes needs to be done as one step. I didn't mean that literally you did the one and not the other until it is finished. When you actually unbolt the jackshaft bolt, that is when the crank(shortblock) will be disconnected from the whole valvetrain, cams and valves. That's when the engine(crank) must be at TDC.

 

[CDW6212R]

The TDC crank tool does use the balancer for that, you don't install the balancer completely, just by hand to be able to use the TDC tool. That tool is the one which I think is most poorly designed. I agree that a tool that went on the crank itself would be far better. What I complain more about is that the balancer has changing depth on the timing teeth. The TDC tool will give a different indication of TDC depending on where you mount the tool on the balancer. It also is designed to rest against the block, and the timing cover. You will obtain a different TDC indication depending on which you use.

Thus the actual TDC obtained is very dependent on how you set up the tool, each time. I suggest that it only really matters when you do the final cam timing. Each time that you set the tool against the block or timing cover, be very slow about that. Be very comfortable in where you have it set, make the tool tight, fit snugly and squarely on the balancer. That is the timing of the cams, if you alter that, you will have altered cam timing.

 

[CDW6212R]

With overhead camshafts, the valves and valve springs affect where they will settle. They will have a few locations along a 360 rotation where they will want to be, equalizing the springs being compressed. If you let the cams go away from those points, the unequal pressures will move the cams/valves to the nearest happy point.

The bottom line is that, when the crank and each cam is at TDC, each head and its cam/valves will not move far at all, if at all. But if you had the engine too far away from TDC when they are disconnected, one or more of the heads could spin on their own farther away from TDC(away from instead of towards TDC). That's why you want it at TDC to start with. There it will cause no problems or drama. If you unbolt it far far away from TDC, once the crank and cams are not connected, you would have to move them individually, to TDC without valves contacting pistons. It's not easy to move the crank, and the left head, and the right head, together when they are not connected.

Thus it's much better to start at TDC, and never get far from TDC during the work. Regards,

 

[Midwest Kid]

Is it correct to say that i definately have to time the RH cam too? I was hoping i wouldnt have to mess with it since the cam gear is at the rear of the engine.
If i understand you correctly, im going to set the engine at TDC, remove the balancer, lock the cam on either side, remove the jackshaft chain and gears, remove the front cassette gears, chain, tensioner & guide, replace everything in the front cassette (leaving the gear bolt loose, make sure the crank is still at TDC, install the new jackshaft chain and gears, loosen the hold down bolts that are locking the cam in place.... this is where im lost.. you had mentioned that the cam tool only fits in one way. Does that mean that when I install it, ill have to turn the cam until the tool actually mounts onto the cam? If so, when it does, is that the indication that the cam is where it needs to be? That being the case, thats when ill lock the cam in place again, verify TDC and torque the cam gear bolt down?

 

[CDW6212R]

Yes you have to both cams, the jackshaft is the connection for each cam to the crank. When that bolt is loosened, the timing for both is lost. If the timing was perfect to start with, and the jackshaft parts were not changed, then you would be fine to leave the right cam alone. But anyone who goes in there needs to do the jackshaft chain etc, and machining tolerances could have the result off for the right cam.

You do not need to install the cam tools until you actually are ready to unbolt the cam bolt. I'm remembering... you can unbolt the left cam while the jack shaft is all still together, crank at TDC. That would let you do that without the cam tool to hold the cam, but I didn't do that. The jackshaft bolt is not easy to loosen or tighten, I did that bolt first. With everything together, there was a lot more holding the parts, it made loosening that easier than if you have other things unbolted.

So by unbolting the jackshaft first, the left cam needs to be held by the cam tool on the back end. That cam tool is the one which engages the end at TDC. There is a slot in the cam, which the special tool engages. The tool outer section holds the cam tool in place, which is holding the cam. That is the very easy tool to use, it only goes in one way, perfectly. Thus you only need that one tool on then to be hold the cam, to unbolt the cam gear bolt at the front. Then you can do the cassette etc.

The timing of the left head is much easier than the right one. The cam tool which engages the cam gear is hard to attached in the back of the right head. Pay close attention to doing the front of the left head, that tool has two pins in it which must line up with the many holes in the cam gear. It simply engages the cam gear for the purpose of holding it upright, true to the cam. The cam gear spins infinitely around the cam, there are no splines etc. Watch how that tool slips into the holes of the cam gear, because you have to do that with the right head, by feel alone.

 

[Midwest Kid]

thanks for all the info. Ill post back next week when i start it.

 

[CDW6212R]

You are welcome, look through the threads just before you start, and your shop manual. It's more time consuming than people think, take your time. Regards,

 

[iceman7329]

Some good info here...