2000 Montero Sport Runs Rough No Codes
 

About a year ago, I purchased this vehicle pretty cheap as it was not running. Got it back, found that the timing belt was broke, so, went ahead and put a belt on it and got it to fire up and run, but shut it off as I didn't have all the coolant stuff plumbed up. I went to add some coolant, and it just pores out from basically the front of the tube that runs down the middle of the engine and may be also coming out what I believe to be where a freeze plug would go on the passenger side of the motor. At that point I decided to pull it back apart to pinpoint the leak, with no success, and it sat for a year. Fast forward to today: I put it back together just to see how it ran because I remember it ran a little choppy and didn't want to invest more time in taking more parts off if the runability issue was major. What would it running rough and the check engine light NOT have any codes be indicative of? I'm trying to decide if I should sell it with it at least running now or fix it.
Thanks,
Chris

In order to set off the CEL you have to get through several drive cycles. Just starting it up few times and idling will not set it off.
The tough thing is - if the timing belt was broken, did it happen when the engine was running or not? That would determine if there is serious damage to the valves or not. Since it is running (even rough) it is likely that the engine is OK. I think it's worth checking further into it.
Here is what I'd check:
1. Test compression. I know it's a pain, since you have to take off the intake plenum to get to the spark plugs. But you need to do this test to confirm that all cylinders and all valves are working or not. If you have low compression on a single cylinder, you may have some issues there that will cause rough running.
2. Check timing. Absolutely do this, unless you are 100% sure that it is not off. You'd be surprised, but the engine will run with timing off by one or two teeth.
3. Check if exhaust is not plugged (back pressure)
4. Check for vacuum leaks around plenum. Use a can of starter fluid to spray around different areas after the MAF. If engine suddenly picks up RPMs - you have a vacuum leak in that area.
5. Make sure EGR valve is not stuck part open.

I hope this gives you some direction to go. Don't give up on it, unless you know it's busted completely. But even then, you can pull the head and replace couple of valves if they got damaged with the timing belt ripping.

Awesome stuff, I'll start going through your list the next couple of days and get back to you. Yeah, not looking forward to checking compression... Do my coolant leaks sound catastrophic to you? I looked at a diagram and it looks like there might be an o ring on the front of the tube that runs down the middle of the motor behind the water pump maybe and the leak on the passenger side is just gushing out where maybe a freeze plug or drain plug may have been. I can reach down and feel it but can't see it. Thanks for your help.

I would not drive with that leak. You might be able to get in there to replace the o-ring when you get the intake plenum off.