[last update 7.07.07 all done]
May 25, 2007
My dang timing belt failed on my Nissan 2000 XTerra 4WD XE, 5 speed, VG33E V-6 with 99,300 miles. I'm the original owner and drove her very easily. I'm doing the repair myself, at least I'm going to try..... I have standard hand tools but do have a small compressor from Sears with air tools to help with the tough nuts and bolts. Air compressors rule.
A true backyard (well, it's actually my front yard) mechanics area. It's hot where I live, hence the blue shade. :-)

I took a few shots of the engine compartment, just in case I forget a few details. Not that such a thing EVER happens to me .... This is with the radiator out and the front belts and covers off. You can't see it, but the teeth near the crankshaft pulley broke off. This leaves the crankshaft spinning and the twin cams and distributor not, spinning that is. Not good.

Here is the upper intake manifold removed. Did I mention it is a beast to remove? It is.

This is one complicated engine with a butt load of parts. Not for the faint of heart. This is a shot with the timing belt removed along with the upper intake manifold. Getting that upper manifold off is not easy, it sucks. The engine is offically listed as an 'interference' engine, which mean the valves can hit the piston when the belt breaks. Which means I have to remove the heads to properly inspect the engine for damage from the belt failure.
I sincerely hope that those of you who are putting off changing the belt, as I did, will see what a large repair you will have in store.

A few ten thousand hours later, I get the driver side (left) head removed. You can finally start to see the block. After removing the old head gasket, scraping off left over pieces on the block, I put a wire wheel in my hand drill and went to town. I ran my shop vac while doing this. This keeps debris to a minimum getting in to the cylinders and water ports. Cleaned up nicely if I do say so myself. I'm going to buy one of those cylinder deburring tools that fit in to your drill to 'lightly' hone the walls. I personally think it helps keep an older bottom end ring/piston running longer without troubles - I could be wrong!
You can see that there are cutouts in the tops of the pistons for intake and exhaust valves. This usually means that the valves would NOT interfere during a timing belt failure - weird to me.
Getting the exhaust manifold/exhaust pipes off is a real PITA, the dang bolts/nuts are frozen solid and break.

Here is a shot of the left head after I wire wheeled it. I wanted to see if the valves were seated OK so I poured a little engine flush in to the intake and exhaust ports and looked for leaks. Sure enough, some did (tape). Frankly, you could probably just use it as is and it would run fine, this is no NASCAR motor. But I want to keep the truck so I'll take the heads to a machine shop to have the valves reground and seated. This way, when they do the head job, they can tell if any of the valve stems are bent. I was quoted $335 for labor only to do the head job - sounds fair to me.

Well that's about it for today. I'm going to tackle the right head removal tomorrow, that is if my back lets me - I'm old. :-)

Update May 26 I got up early and decided that the only way to get this right side head off in a reasonable manner was to remove it with the exhaust still on. Worked like a charm. Although there is one 10mm bolt in the very back that you can not see that held me up a few minutes. The other head has this too on the front right side. Seems like kind of a silly design, they hold down the edge of the head on the gead gasket.
Here is a picture of the head right after I removed it. I had to use my grinder on the bolts to get the nuts off to remove the cats. The cats are amazingly heavy. But, a glance at them indicates that they are free flowing (clear). Cats can clog up and it's a mofo to diagnose the problem. You can see my cylinder head bolts stacked in the position they came off of the engine. I place them in the old head gasket to keep them in order. I'm not sure if I am going to replace the head bolts or not yet.

And here is a shot of the engine compartment showing the block. The remnant of the head gasket can be seen. I scraped it off and wire wheeled the block top surface as I did on the left side. Again, there was no obvious indications of any collisions between the valves and pistons.

6.9.07 [update]
The good times continue. ;-)
* Machine shop tells me ALL of the valves are bent and need to be replaced. So, assuming they're giving me the straight story ( I have not seen the old ones yet), despite me not seeing any damage or scratching, apparently I do have an interference engine. I have ordered all of the parts to rebuild the heads along with all of the gaskets and water hoses from courtesyparts.com. I'm having the heads pressure tested too for cracks.
* I've been cleaning and painting parts as I wait for the parts and machine shop. There is a paint from Napa called black bumper paint. If you want a well priced paint that seems to stick to dang near anything, use this paint - it really is amazing for metal and plastic. I also highly recommend Super Clean, a water based grease remover - again great product.
* I got to cleaning the exhaust manifolds today. Gee, great big surprise. Crack in the right side (passenger) exhaust manifold. Nissan should stand up an admit this design flaw.
I may just order after market headers and cats and be done with it. Blah.

First of all let me show you my table of parts. You can see how I kept the old head bolts in order along with the rocker arm assemblies.
Amazing how many there are really. This next shot shows some parts before and after cleaning them and painting them. They really look new after only a little work. It also gives you a chance to inspect them for cracks or whatever. I also grease up the parts that need it too. The intake rubber pieces and air box, which is shown dirty here, really came out nice.
It took awhile to get all of the parts I needed from Courtesy. I ended up getting a new exhaust manifold too. And yes I painted it and those metal exhaust covers too. I bought all new studs and nuts for all of the exhaust attachments. Totally worth the few bucks to keep sane.
Oh, let me show you what the underside of the intake manifold looks like. Holy crap the space shuttle has less plumbing than these babies! For those of you who tremble and whine like little girls just to do an oil change on your car, you may want to look away - you've been warned!
Got my heads and cats back from the machine shop yesterday and I was hoping to get this b$tch back together this weekend - no such luck. I started with the right side-passenger head. Attached my new spiffy manifold and oh so shiny heat shields with newly painted cats.
I cleaned and cleaned the block cylinder walls and wire wheeled the surface again. I bought a tap from NAPA and cleaned out all of the thread holes for the head bolts. This is a big deal on my engine, tons of carbon and crap build up. Shop vac helped me keep it as clean as possible. Last night I soaked the old head bolts in oil, I wire wheeled the threads again - clean. I also soaked the hydralic lifters in motor oil. I had really cleaned these out with solvent and compressed air, inspected them and lightly sand papered the surfaces. Same for the rocker assemblies, clean as a whistle. Turns out they are actually aluminun in color not petina brown! I was reading my repair book and I read that the lifters need to be presoaked in oil. I had not thought about that, so I am glad I caught that.
I then layed my new head gasket in place and with my son aligning the exhaust pipe under the car, positioned the head. The head bolts were placed in their original order and because of the clean thread and holes, they easily went in hand tight. Be sure and place the washers on correctly, one side has a camfer, this goes towards the head of the bolt. The head bolts are tightened in four steps. The second step calls for about 84 foot-pounds. (<--- this is wrong! see below) as i was just about to finish up with the sequence when, one of the longer head bolts broke in two, twisted - Oh fudge me. One of the earlier long bolts did not tighten up either, but I stopped before it broke.
Luckily the remnant of the bolt in the block unscrewed easily with just my hand - I already had my extractor tool out!
I had new head bolts on my original order, Nissan doesn't call for them to be replaced so I cancelled them - mistake. So ... if you are doing a similar repair, buy new bolts and washers. I now get to wait another week or so for new head bolts and a new head gasket and try it all over again. Boo hoo.
A Hui Ho.

7.2.07 [update]
Man oh man I fudged up. I was reading the wrong torque readings for my head bolts. The correct number is around 47 foot-pounds. I was reading the sequence numbers, which are inch-pounds for the lower intake manifold. So it was I who broke that head bolt.

I received my new head bolts, washers and head gasket and started my install yesterday, Sunday. Thank goodness I reviewed the repair manual and discovered my error. It also points out that you should do your own research and homework if you're doing a repair such as this and not rely on retards who post repairs on line. :-(
Heads on, rocker assemblies and lower intake manifold. Before torqing up the rocker arms, be sure that the pistons are set at Top-Dead Center! (or you might bend the valves) I temporarily put on the cam gears and upper timing belt cover and rotated each cam to its TDC alignment marks too. After getting the rest of the engine back together, this leaves you all setup to replace the timing belt.

7.6.07 [update]
Good progress today! Hooked up the exhaust pipes to the cats. Screwed in the two 10mm bolts that go through each head in to the block. Yes, I almost forgot about them. :-) Attached the exhaust plates and the myriad of hoses and electrical connectors. Attached the upper intake. The back small water hose by the fire wall gave me fits and some bloody forearms, torqued it down after feeding the bundle of electrical wires for the injectors, used new tie downs for these. These pictures below does not show it, but attached my throttle body, alternator and air conditioner, smog hoses and connectors. Basically all of the driver side compoments. Amazingly enough, found all of the hoses connecting points, man what a mess!
I am almost at the point where you would start to replace the timing belt. All that's left to begin this process is to install my power steering bracket and pump. LOL, at this point replacing the timing belt seems like taking candy from a baby! I am hoping to start her up tomorrow or Sunday ...
My previous pictures were taken in the day, but here is how I finished up today, took a snap at night. She's now starting to look like snarling mess of my starting point. :-)

7.7.07 [update]
Got up nice and early this morning, started around 6AM. By 2:00PM, I was driving around the neighborhood - success! Started right up the first time, always a good sign. So hopefully, I can drive her for another 100k .....
The timing belt install was straight forward. I did it twice just to make sure all of my timing marks were correct. I used a Nissan belt and tensioner. The belt really can only go on correctly one way. The instructions I had to set the tensioner were a bit vague, at least to me it seemed that way. I just tightened it so the top center deflects about 1/2 inch.
Of course I installed all new drive belts, fresh oil and filter, coolant, new radiator hoses, air filter and platinum spark plugs. Checked the ignition timing and I could probably use a new rotor and cap - another day.
My truck motor has always been a bit noisy. I was hoping all of this work would eliminate it, no such luck. Maybe the noise is from the drive belt pulleys, another day maybe. I need a break from the grease. Man oh man, 6 weeks to finish! It was fun, sort of, I'm a bit sore but it sure is good to know 'I still got it'. :-) Aloha.

9.29.07 [update]
Just an update on a few minor things. I did replace both drive belt pulleys and my noises went away - yippee! I drove with this silly noise for years, stupid it's a simple fix. One member on the Xterra site asked me about the blue intake gaskets you see on my table in a few shots. Those are not for the Xterra, but my '84 Vette (Fel-Pro). The Nissan upper and lower intake manifold gaskets are metal. Truck is running great!