I have a montero and I have not driven it for about a year because I thought the engine blew on it… What happend was it was given to me because my brother in law thought the motor was bad, it was knocking really hard and blowing out smoke pretty bad…you had to keep on the throttle just for it to run, well he gave it to me and i went over to drive it home, and it fired right up no problem at all, then about a thousand miles later that problem came back so i left it sit in my driveway for a few days and fired it up…no problems with it, then i have since put about a thousand miles on it, but then that problem happened again and now it wont turn over (i think the starter went out on it…not worried about that), do you think it may just be a head gasket problem? any help would be great 
thanks
I suppose it’s possible, but you’ve driven it many times with an unknown, severe problem, and so has your BIY, so it’s likely the engine is in worse shape than it was at the first sign of a problem. Why didn’t someone get it checked out instead of guessing?
There’s no way to tell what’s going on here from the info you’ve given. What condition is the oil in–does it look normal, or does it look like a milkshake? Is there coolant in the vehicle, and what does that look like? Was it blowing out smoke or steam? What color? From the exhaust or elsewhere?
Why don’t you just take it (preferably tow it) to a mechanic and have it checked out instead of hoping that someone here will tell you what you want to hear. Surely it’s worth $50-100 to find out if it’s fixable/worth fixing…
It has been taken to 4 mechanics…no one could figure it out.
With all due respect, if 4 mechanics who had a chance to examine the vehicle directly were unable to figure out the nature of the problem, how could any of us–separated by cyberspace–have a better chance of correctly diagnosing the problem?
We can all give you possibilities, but those possibilities would still need to be confirmed by a mechanic.
Anyway–
What can you tell us about the condition/appearance/level of the motor oil and the coolant?
Has a compression test been done? If so, what were the results–cylinder by cylinder?
Has a leak-down test been done? If so, what was the result of that test?
everything checks perfect on it, two of the mechanics said it was a thrown rod? but how could that be if it started running fine again? could it be a cracked distributor cap?