Mitsubishi Montero & Montero Sport This sport utility vehicle offers more size than the other Mitsubishi SUVs, but manages to keep a sporty look and comfortable feel, unlike many larger SUVs.

How to Adjust Tension on Timing Belt-1999 Montero

  #1  
Old 06-09-2019, 08:10 AM
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Default How to Adjust Tension on Timing Belt-1999 Montero

Here are a few pics of the front of the engine to a 1999 Montero (not the Sport). Has all the options like the SR's models did, including rear diff. air locker.






In this picture you can better see the timing belt tensioner pulley with the two holes accross the top. When adjusting, you are supposed to set it so you can easily pull a "grenaide pin" in/out of the long silver cylinder (to the lower left of the pulley). After torquing the pulley bolt, the pin should pull in/out w/o binding. The hard part is torquing the bolt down without causing the pulley to rotate to the right, which makes it too tight. How does everyone else hold the pulley from turning as you tighten the pulley bolt?
We ultimately used a vice grip plyiers and "lightly" locked it between the bolt to the left of the pulley and to the inner flange of the pulley......but you cant lock it on "tight" as it could bend the pulley out-of-round. This helped, but was not perfect.



Here is a pic of the tension spring cylinder with the "grenade pin" in place:



Thanks.
Hope this info also helps others.
 
  #2  
Old 06-09-2019, 01:08 PM
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You need one of these little tools:
Amazon Amazon
It holds the center of the pulley from rotating when tightening the bolt to required torque. In a pinch a pair of needlenose pliers work.
 
  #3  
Old 06-09-2019, 04:25 PM
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Hunter.....Thanks for the info. I need to snag me one of those special tools....not bad for $12.
It was real frustrating trying to get enough torque on the pulley bolt without the pulley rotating clockwise and getting the tension too tight. Finally we basically compensated for the "slid action" and started the bolt tightening with alot of extra play, knowing it would slip clockwise when tigtening the bolt. We got it real close.

The idea spot is when the "grenade pin" will slip in and out of that spring-loaded cylinder, and not have much friction on it when goint in/out. After torqing the pulley bolt, you are supposed to pull the grenade pin out, and wait an hour or so and then try to put the pin back in the holes. Any explanation as to why the spring tension would change after a bit of time? Is this tension that darn critical, or do most mechanics just slap the timing belt on, and guess at the right tightness and close up the incisions with stitches and go on to the next patient?
 
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Old 06-09-2019, 10:18 PM
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Don't know why you'd have to wait an hour to make sure the tension is still good. I'd think once you pull the pin the tensioner does its' job and keeps pressure on the belt. On my 2001 Monty, you just pull the pin out (after proper pre-set) and you are done. I've done preload the way you described - with pulley starting further back and then moving into the right place when tensioning. After I got the little tool it is much easier to get everything into the "sweet" spot.

I've been thinking - why do you even need to deal with the grenade pin? Why not just tension the pulley and pull the grenade pin and let the tensioner put the right pressure on the belt? What I figured is the following: if you get just a little too low preload (grenade pin comes out with some effort) the tensioner by itself will put the right pressure on the belt. However, it may reach the full extension later in life before its time to change the belt again. If on the other hand, you put too much preload on the pulley right away (the pin is also jammed), you initially putting too much stress on the belt and stretching it unnecessarily before the tensioner has a chance to extend and put the required pressure on the belt. Using the grenade pin ensures that the preload is in the sweet spot right away and it will give you the longest life on the tensioner and the belt.
 
  #5  
Old 06-10-2019, 06:43 AM
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Hunter........I also think that this design is way over-engineered and unnecessarily complicated. Why not just have a plain pulley (w/o the cam feature), and just let the spring tensioner apply the proper pressure. I guess I can see that with time the spring tensioner will lessen as the belt ages/stretches, but something could have been done to make it simplier.

I think the directions on the new parts said to pull the grenade pin and wait, and then go back and see if it still goes in/out easily, and if not you must re-do it. We gave up with that fine-tuning, and got it right finally and let it be.

Im thinking about my ole riding lawnmower.......with a simple idler pulley with a grease fitting on the top, and it is forced into the right spot/right amount of push on the deck belt with a large spring.......no pulley cams, no grenades, no special tools, no runs, no drips, no errors........now, thats the type of timing belt tensioner Id like to see on these Monties.

Ka-BOOOOOOOOOOOOOOOM.......I pulled the pin, and fogot to toss out the grenade.
Ooooops. DOHHHHHHHH!
 
  #6  
Old 06-13-2019, 01:56 AM
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I hear what you are saying about simple designs. However, I feel that there are both such things at "too simple" and "too complicated". I think Montero timing belt falls firmly right in between those two extremes. On some of the modern I4 engines you have to time the camshaft AND time the balancing shaft at the same time. Talk about two timing jobs at the same time. That system approaches "too complicated" without getting into the Red Zone. Check out this video to see engineers calling your "too complicated' and cranking it up to 11...
 
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Old 06-13-2019, 06:57 AM
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Hunter......I watched that video......Mannnnnn! No way in hell I would buy one of those GMC Canyons. You are right.....this Mitsubishi timing belt tensioner is a cake walk compared to changing the timing chain on that Canyon.....totally unbelievable. He had a lift and said it took 20 hrs to pull the tranny, and all the other major steps needed to do the timing chain, but it would have taken me a month, and I probably would have thrown in the towell. If you took it to the dealer for the work, the bill would probably be close to $5,000.

With this fresh perspective, the Montero's timing belt replacement is much better now.
 
  #8  
Old 06-13-2019, 07:28 PM
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It's all a matter of perspective Like you said - relative to that Canyon Mitsubishi timing belt is easy as pie
 
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