2000 nissan quest

can someone please help with a problem with my 2000 nissan quest going 75 miles on freeway it was about to dark so i open the lights soon after i started looseing the speed and finally stop.Now the mechnic said needs to change timing belt, waterpump, sparkplugs and some other thing please help with opinions.thanks

How can we give opinions when you have left out vital details?
We need to you tell us:

What is the odometer mileage of the vehicle?
Has the timing belt has ever been replaced?
When were the spark plugs last replaced?

However, in the absence of that important information, I will give my opinion that this vehicle has likely NOT been maintained as it should have been. For instance, the timing belt in this engine is supposed to be replaced at 105,000 miles or 7 years, whichever comes first. I suspect that you did not do this, and if this is the case, then you only have yourself to blame for this type of neglect.

This engine is of the “interference” type, meaning that when the timing belt snaps, valves and pistons collide with great force. The result is that the engine has to be disassembled to replace bent valves and possibly to replace damaged pistons. The cost of this can easily run into the $1,500 range–in addition to the cost of the timing belt.

When a timing belt is replaced, the water pump, the serpentine belt, and all belt tensioners should be replaced at the same time. Are these the “other things” that were mentioned by your mechanic?

If you had replaced the timing belt when it should have been done, your total bill would likely have been in the range of $600-$800. Now, you will have to pay that cost, plus $1,500-$2,000 for repair of engine damage. Throw in the new spark plugs, and your total bill will likely be around $2,500. As you can see, timely maintenance is far cheaper than the cost of the repairs that result from lack of maintenance.

If you have previously changed the timing belt, then I apologize for the assumptions that I have made.
Anyway, I and others await the answers to the questions that I posed, above.

First I would want to know if the alternator/battery/alternator belt checked out OK. What did the mechanic say about that? The other items listed may be needed, but don’t seem to address the loss of power to the car after turning on headlights.

I would not invest in timing belt and water pump until I actually knew the car would start and run. What is the “some other thing” mentioned?

Jayhawkroy makes a good point, and it is possible that the mechanic is “overreaching” in his diagnosis of what led to the loss of power.

Then again, the “opening” of the lights and loss of power could be merely coincidental, and it could be that the timing belt just happened to snap shortly after he/she turned on the lights.

Then again, maybe it is just a broken serpentine belt currently, but the mechanic also knows that the timing belt is overdue for replacement and is adding that to the repair list. There are lots of possibilities here, but until the OP begins to give us better information, we are all just shooting in the dark, so to speak.

Below are the questions we need to see if you can answer. We now know the car was purchased at 132K miles and it now has 140K miles on it. Did the mechanic diagnose and interpret any diagnostic codes he retrieved? Did he rule out alternator/batttery,alternator belt as a possibility? Did he say that the engine timing belt had broken?
What you listed as the intended repair may or may not repair the car, with the symptoms you gave. These are maintenance items that probably need to be one, but they may or may not fix the issue as you presented it to us.

“We now know the car was purchased at 132K miles and it now has 140K miles on it.”

We do?
How did you learn this detail?

I too was mystified by that. Then I found a whole separate thread:
http://community.cartalk.com/posts/list/2142299.page

Here is what was in it:
“Sorry i forget to mention the mileage in my previous post currently about 140000 miles i purchased at 132000 miles i do not know wheather the timing belt changed or not sparkplug ,oilpump and air sensor changed recently my question is wheather is it electical problem or mech problem.”

Sim - you have to stay in the same thread!

There is a good chance that your timing belt was never changed and that it has now broken. Even if it that was not the cause of this event you should have it done anyway. Not doing it, as you may have learned from VDCdriver’s original post, would be very bad.

If the timing belt did break, do not let someone just charge you to put a new belt on. If you want to save the van it will probably need major engine work as noted above.

…Sigh…

The OP is yet another person who spends thousands of dollars on a vehicle, and then fails to have it maintained properly, thus potentially squandering their hard-earned money. I am an extremely thrifty person by nature, and I know that skipping maintenance will inevitably cost more than performing maintenance.

Sim–I know that it is a bit late for this advice, but when you buy a used vehicle that does not come with maintenance records, you have to assume that NO MAINTENANCE has ever been done. What you should have done was to refer to the 90k, 105k, and 120k maintenance schedules in the Owner’s Manual, and performed everything that was listed. By not doing that, and by trusting that vital maintenance had been done by the previous stranger who owned the vehicle, you may have added a huge amount to your cost of owning this vehicle.