Setting the timing marks on a 3.5 SOHC

[nwoods]

I made a short video showing my delima related to setting the timing marks on my 1998 Gen 2.5 with the 3.5L SOHC. Opinions welcome! I'd love to get this baby back together this weekend.

https://youtu.be/NIcCTYVzsEo

 

[nckwltn]

I use a non-wratcheting wrench to get the passenger cam right on the timing mark. it should rest there, but will slip off and spin with a lot of force.


I also turn the crank back (counter clock wise) about 1 tooth, that way when you rotate clockwise, all the slack between the driver's side cam is pulled up and the timing mark aligns. You can also use this idea between the driver's and passenger cams. this will help pull in the slack under the water pump and put the driver's cam at the alignment mark.

I like your zip tie idea, to hold the belt onto the cam, will work well once you get the passenger cam at the holding spot. I usually use binder clips, they go on and off quickly.


Also... if you notice on the cam covers, they have a little bit of play where they can be installed... this means that the timing mark can move around a little as well....you'll know if you're a tooth off, but being just a little bit off seems to not cause any issues.

 

[tyty13]

Let me know if you need me to stop by

 

[jaccox23]

I'm pretty slow when setting my timing belt back on and use nckwltn process and it takes me as much as 2-3 hours to get them all lined up. It's a process of trial and error really especially if your like me and pretty new to the timing belt races lol. But I found that taking a break between failed attempts is tremendous in not breaking something out of frustration. Your back will curse you for being bent over for so long but once you start it back up and it runs perfectly again that lower back pain will disappear quickly

 

[nwoods]

Ultimately, the question is why won't the cam sprocket "stay" at TDC or whatever the position is where it aligns with the timing marks? It used to, and now it doesn't. The next uncertainty is if it's "okay" to hold the sprocket in position with a wrench while fitting the timing belt on. In theroy, having the belt in place will prevent it from turning on it's own, but I am not sure that gives me the assurance that everything is lined up properly. The third concern is just making sure I actually have the engine at TDC. I'm not confident in that.

 

[normal_dave]

You may be well past this point, but these are two very good discussions on setting the timing on Monteros.
http://www.expeditionportal.com/forum/threads/159696-Replacing-Gen-3-Heads-(Like-a-Virgin)-Any-Recommendation?p=2118043#post2118043

and a picture is worth a thousand... here's what TDC looks like on a 3.5L, dot on the tooth lines up with the raised line/slot on the engine.

Box end wrench only for the cam gear, both hands, push/pull at the same time to prevent "rolling the gear" over. It should balance/hold at the timed spot long enough to get the belt on. The ratchet wrench isn't stopping it from jumping over as your video demonstrates.

 

[snare]

I think this Timing Belt Service Kit (a rental tool at O'Reilly Auto Parts, for example) would help. It allows the cam gears to be held in place while you put the timing belt on.

 

[nwoods]

Good News! Within 5 minutes of Ty coming over, he got the cam gear to set (sit?) still in the right spot. It took 3 or 4 tries to get the timing belt on correctly where everything lined up, but it was a accomplished and Ty was super helpful in getting the AC bracket and pump back on as well. Front end is is back together and ready for me to run a compression test tomorrow. Progress!

 

[nwoods]

I should probably follow up and answer my own questions for the next guy:

1. With a solid wrench, not a ratchet, the cam sprocket will stay in the right spot. Fit the belt over the wrench first, and have someone hold the wrench while you fuss the belt into place around the other sprockets.

2. If the marks on all three gears are set to their respective positions (independanty, without the belt in place), the engine and cams should all be at top dead center for cylinder 1.

3. "Presetting" the belt a tooth or two will help. You'll know after turning the crank bolt around a few revolutions. The timing belt may be off by a tooth, due to a slight amount of slack in the belt. You should be able to turn the engine past 4 complete revolutions or so and all three timing marks should stay lined up.