The Nissan Path

I think I am coming out of a bad experience incredibly lucky and I would like to get any thoughts about what might lay ahead. I own a 99 pathfinder 4x4 220,000 miles and a 2003 frontier kingcab 166,000 miles, both have the same basic 3.3L V-6.

About 15,000 miles ago I did the timing belt and water pump on the pickup myself when the water pump developed a leak. This kept with the appropriate service interval since the belt had been changed early in the life of the truck at the garage due to a failing tensioner.

So last week I was travelling probably about 50-60 mph on the highway, just getting ready to get into the fast lane after merging. Applying the gas pedal all power killed without warning and I coasted it to an exit and did the tow truck deal. Towed to Nissan, hoping for a quick albeit expensive fix the next day....I thought maybe fuel pump failure in my wisdom since I could not hear it when I turned the key (too loud in parking lot). Nissan could nto get to it for days so towed to the AAA suggested garage....they said the cam shaft was not moving, quoted such a high price for a used engine swap that I think they may have jst wanted me to leave and or did not do that kind of work too often, and thanked me for my 100 buck diagnostic fee....towed home...

Out of desperation....I bought a new timing belt, tension pulley, water pump and took about 8-9 hours slowly replacing all. Cranked it....thought I heard a little tapping but it went away and truck seems to drive well enough.....I think I got some grace and did not get bent valves....


.note: the day before I replaced the fuel filter (it was long overdue) when I got a code at the auto parts store for cylinder #1 misfire, bad enough to get a backfire once when driving, after the fuel filter change the ride smoothed out and the engine light disappeared. cleaned off spark plug as well...thent he next day the belt broke...unrelated I think....

Questions: The old belt appeared torn and was separated down by the crankshaft gear.....also that water pump was leaking probably from my installation 15K ago....it was leaking for about the last 1k miles. Belt looked great except for the tear. Any ideas why the catastrauphic failure??

I can not hear any new noises and motor runs as smooth as before, meaning occasional hiccup but overall smooth....can I expect good service life so long as I installed well...ie can valves seem ok but leak a small bit and thus "burn" or otherwise shorted life??

To be fair this car has been though a lot over the years and has oil leaks etc, but I am hoping to keep it for about another year while I am in school and considering what other money to spend on repairs that come up.

I know this was a length diatribe but if anyone has any thoughts that might be useful as I consider the future of the car and what I spend on it over the next year or two....I appreciate it.

In my experience with these engines (16 years as a Nissan tech), when they fail due to age it is usually because of dry rot and splitting at the base of the cogs, resulting (when they do fail) in stripping the cogs off on the belt at the crankshaft sprocket.
In your situation, the belt tore (by your words) in 15,000 miles, if I read your post correctly. Now, it's tough to assess the cause of the problem when I can't see the parts, but, usually when a timing belt tears, it's because something got stuck between the belt and another object. Coolant or oil contamination would definitely damage a belt over time, but if that were the case, you would have noticed the evidence of contamination on the belt in an oily film. The other possibility was that, perhaps, the belt was installed too tight, which isn't hard to do.
When I install these belts, I tension them like this after the belt is installed: Loosen the tensioner nut. Turn the right bank (or, passenger side) cam sprocket about 3-4 teeth counter-clockwise, which pulls the slack out of the belt and the spring on the tensioner should allow it to take up the slack. Then, I torque the tensioner nut to 35 lb/ft. Then, I'll turn the right bank cam sprocket about 3-4 teeth clockwise. This puts any slack in the belt in the top span, the span between the two cam sprocket. I'll take my thumb and forefinger and will twist the timing belt in the middle of that span. If I can turn it 90 degrees, the tension is good. If I can't turn it 90 degrees, it's too tight. If I turn it more than 90 degrees, then too loose. If too loose or too tight, I'll repeat the procedure. I've done well over a hundred timing belt jobs on VG engines, including my own, and this has worked for me for over 20 years.

I really appreciate the pro-tip you shared about how you test to see if you have installed the timing belt with appropriate tension. I probably should have looked for advice on here before fixing my truck since this fix is only the second timing belt I have ever done.

Looking back at this experience, I tend to grudgingly think that my prior install about 15k ago must have been too tight or something wrong to lead to this failure....I know that I had overtorqued the waterpump when using an old torque wrench that was given to me and I just went with it....bad choice that led to leaking after about 14k miles.

I snapped some photos of the belt to show the rip but I see that the image must reside on an http: or such not direct from my computer to share if I understand correctly. If you would like to see let me know and I will email.

Right now I consider myself fortunate that the valves do not "sound" as though they bent as I was on the highway and I may reopen the timing cover this Summer to examine my work and the tension.

When I was looking at the torn belt today I would say it had a slight tackiness to it....is this the coolant residue from the leaking water pump? Would this have made the belt weak after 15,000 miles but show no damage other than the tear/break. From what I see there is not wear at least like what is shown on p93 of the factory serivce manual that shows tooth wear and cracking.

Tackiness is likely due to the coolant contamination. It's a 105,000 mile timing belt, so you shouldn't be able to see any wear at 15,000 miles. I have seen a few last over 150,000 miles, but I wouldn't recommend letting them go that far.