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Discussion Starter #1 (Edited)
Okay, I will start out with saying I do not own an Xterra. My uncle recently called me and said his Xterra died on him. I told him it was probably the timing belt and he has since confirmed the timing belt snapped.

He has a 2002 with a V6 and automatic transmission, and has 170k miles on it. I don't know if this is the original timing belt or not, but I guess it really does not matter at this point.

He said he was doing about 35mph (just maintaining speed on flat ground) when it turned off, and pulled off the road as quick as possible. I know this is an interference engine, so there is a possibility that the valves made contact with the pistons, but it does seem like quite a few people get lucky. Is there any way to know if the valves are bent?

i found a link to this timing belt kit, it is supposed to be a good kit.
http://www.courtesyparts.com/nissan-timing-belt-kit-2002-2004-xterra-p-448.html?cPath=532&

I also found this kit which is $200 cheaper, what is the difference?
http://www.partsgeek.com/gbproducts/DC/6835-05239573.html?utm_source=google&utm_medium=ff&utm_content=DN&utm_campaign=PartsGeek+Google+Base&utm_term=2000-2004+Nissan+Xterra+Timing+Belt+Kit+Aisin+00-04+Nissan+Timing+Belt+Kit+03+01&gclid=CIzggP3zr7QCFUjZQgod8gcA4A

Thanks for your help
 

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In my opinion find the cheapest belt you can find or get one from nissan it doesnt matter but put it one set the timing and everything and then do a compression test. That is really the only way to know for sure. If your compression checks out than go ahead and replace the water pump and other stuff that is in the kit if not let me know I am looking for a parts truck, lol/just kidding.
 

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Discussion Starter #3
So you only have two options, replace the belt and see if it runs or pull the head and see if the valves are bent. I was hoping there would be a cheap and easy way to know with out replacing anything.

What are the chances you bent a valve if you are doing 35mph when the belt lets go?
 

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Odds are there is no damage. Replace the belt and before you put everything back together start the truck and see if it runs. You will know instantly if you have damage or not.
 

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@ Baritone Mike. I think you misunderstood.

If you did not misunderstand and you were looking for a way to test it BEFORE taking it apart then.... hmmm. There is no way that I know of if the Timing belt snapped.


Before you put the engine back together go buy a NEW belt. Put the belt on and try to turn the engine by hand using the crank pulley. (AFTER THE ENGINE IS IN TIME!!) If the engine is timed correctly and you turn it by hand it will be VERY hard to turn it by hand. Especially using a small ratchet. If you can turn the Crankshaft TWO complete Revolutions WITH it being very hard to turn(Building compression) then most likely the engine will fire up when put back together.

If you turn the motor by hand and it is very easy to turn/you can hear metal on metal sounds you have bent valves.
 

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shifting skies beat me to the punch the way he said is about the only way to test before putting everything back together
 

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Discussion Starter #8
@ Baritone Mike. I think you misunderstood.

If you did not misunderstand and you were looking for a way to test it BEFORE taking it apart then.... hmmm. There is no way that I know of if the Timing belt snapped.


Before you put the engine back together go buy a NEW belt. Put the belt on and try to turn the engine by hand using the crank pulley. (AFTER THE ENGINE IS IN TIME!!) If the engine is timed correctly and you turn it by hand it will be VERY hard to turn it by hand. Especially using a small ratchet. If you can turn the Crankshaft TWO complete Revolutions WITH it being very hard to turn(Building compression) then most likely the engine will fire up when put back together.

If you turn the motor by hand and it is very easy to turn/you can hear metal on metal sounds you have bent valves.
I was looking for a way to see if the valves were bent before putting it back together, or buying parts.

I will tell him he has to get a new timing belt before he will know if his engine is still good.

Thanks for your help.
 

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The problem with using cheap belts is they often have an extra tooth, which makes cam timing very tough.
Just go with a good belt. Get it from Courtesy parts.
The truck is worth fixing, IMHO
ps. Make sure you replace the water pump and belt tensioner bearing.
 

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"I know this is an interference engine..."

Just got off the phone with my mechanic who called Nissan because he wanted to make sure that replacing the timing belt without looking at the head was a good idea. They told him that the 3.3 isn't an interferance engine and it should be good to go. I'm guessing that's why people are getting "lucky" with broken timing belts.
 

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This is right out of the manual:
After removing timing belt, do not turn crankshaft and camshaft separately because valves will
strike piston heads.


The 3.3 V6: IS an interferance fit engine, so your information was not understood or given correctly.
 

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Sigh* This discussion happens almost EVERY time somebody gets a snapped timing and the service reps answer incorrectly.

There are two Motors in the Xterra the 3.3 V6 Vg33e which IS an interferance motor. If the Pistons CAN contact the valves at ANY TIME and BEND/BREAK either then YES it is an interference motor but people do get LUCKY and get away scott free.

The Other Motor is the 2.4L4 KA24DE which if memory serves me is MOST DEFINANTLY an interference motor. If the belt breaks there is a darn good chance of those pistons touching those valves. So They Did not know what they are talking about.

They probably see sooo many cars and engines they cannot keep which engine is interference or not straight. The testament to whether an engine is interference or not is "google" My timing belt snapped. If you see a bunch of sob stories where they all did engine damage. It is an Interference motor. If you see no stories and return almost nothing then it is a Non-Interferance.


From Soccerbrace-
The term interference engine is not limited to a timing belt vs. a chain. When a piston travels upward, it had a top dead center. This is the furthest UP the piston will travel. Valves had a BDC or bottom dead center (although that term is usually reserved for pistons). When timing is on, piston is traveling downward while the valves are too. The same can be said about upwards travel. Since valves and piston are contained within the same cylinder, they operate within one enclosed space. If the bottom dead center of valves are within the same space as the top dead center of the piston, then that is considered an interference engine. This is not a problem as long as the timing is on.

I hope this has helped. If you do contact them and they give you evidance supporting them being Non-interference Please Share.

With Non-Interferance there is no Lucky because there is a .01% chance to hit the valves unless something freaky happens.
X2 on ITS ME Right out of the Manual. Good thinking.
 

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If the manual says so, then I guess it is. We all know that we can believe what we read on google all the time, lol. I was talking to my mechanic about it when I picked the truck up and he said it would eat itself regardless if it was an interferance engine. Regardless, I'm just glad that it was fixable. $838 later including a much needed battery, so I guess that's not too bad.
 

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@scottybones
By "eating itself" was your mechanic talking about the chain/Belt eating the engine or the Valves and pistons Making Freinds? Two Totally different things.

Im just curious because the point of a non interference motor is well... Non interference between the valves and the pistons. Now what the tensioner and the belt that get slung off do to the engine thats another story.

Anywho Glad that you found your answer and that you got it fixed.
What was the $838 dollars for in labour? Just putting a new Timing belt back on it?

Ye sometimes google can lead you astray; however it also is a treasure trove of answers if you know where and how to look.
 

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$838 sounds good compared to the $1,130 that the Nissan dealership wants to charge me to do my belt, water pump, and plugs & wires in the spring.
 

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The ONLY non-interference Nissan engine is in the old Quest/Mercury Villager and this was done solely for Ford's sake with different pistons. Otherwise, EVERY NISSAN ENGINE IS INTERFERENCE! Sorry for the yelling, but other than the Quest, they all have the chance of the valves hitting the pistons.

If you had a borescope, then you could take the spark plugs out and inspect each piston to see if there are any smiley faces on the top of the piston where the valves hit. Turn the engine over by hand, slowly, while looking at the borescope to inspect the piston face thoroughly.

If you put a timing belt on it and started it without putting it all together, you'll find out quickly. No need to turn it over slowly by hand to see if it builds compression. Either it will fire and run smoothly or it will fire and run like crap. If it runs good, excellent! If not, then something hit and you'll need to take the heads off and get it fixed (or get a rebuilt motor).

You can run the engine without the tin on for a little bit, around a minute or so, so you'll know it's running good. I like to put the crank pulley on at least with the slinger to guide the belt on, but I'm paranoid like that.
 

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Excellent read you guys. I had a belt break last weekend ... or so I have been told. However, I have not seen the belt with my own eyes. I have a second opinion appointment on Tuesday at another shop. I am considering having them put another belt on and try all the stuff you suggested above. That borescope sure makes a lot of sense. Will call the shop Monday to get a plan together. Just didn't have the heart to let this truck go yet as it has been great and I have done a bunch of work to it. If the valves are good, I am going to get it fixed.
 

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The boroscope could be time consuming and possibly inconclusive. You’d have to look at every piston to be totally sure. If I was paying the labor, I’d just have the belt installed and hope for the best.

There is also other ways to check for valvetrain damage without a timing belt installed. For instance, one could remove the camshafts, which would cause all of the valves to be in the closed position, then perform a leak down test. This would also be very time consuming and I’d recommend installing a belt and hoping for the best in almost any situation.
 

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You don't have to remove the camshafts, just the rockers to get the valves in the closed position. If you do this make sure that you follow the bolt removal and installation pattern and instructions exactly as the FSM dictates. Doint it incorrectly can result in warped parts and stripped threads in the head.
 
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