Villager and Quest Timing Belt

Background

Is the Villager/Quest VG30E an Interference Engine?

Should I replace the Water Pump and Timing Belt Tensioner?

Disassembly

Reassembly

Another Owner's Illustrated Description

The Risk of a BROKEN CRANKSHAFT

I replaced the timing belt in my '93 Villager in December 1999, at 70,000 miles. Below are comments on the job. Here are copies of the procedure from the 1994 Quest factory shop manual:

Timing Belt 1.jpg

Timing Belt 3.jpg

Timing Belt 5.jpg

Timing Belt 7.jpg

Timing Belt 2.jpg

Timing Belt 4.jpg

Timing Belt 6.jpg

Notice the key point in the followup at the end... IF YOU OVER-TIGHTEN YOUR TIMING BELT OR YOUR ACCESSORY BELTS YOU RISK BREAKING YOUR CRANKSHAFT!!

Background

My 93 Villager had 70K miles on it. So I was 10K miles late on replacing the timing belt, according to the Mercury shop manual. I waited because I wanted to do the job in cooler weather here in Houston.

Interestingly, though, the Nissan Quest shop manual gives a replacement frequency of 105,000 miles. This is kind of odd, especially given a report I have on a Maxima VG timing belt breaking at 102,000 miles (don't know the model year, but it had to be pre-1995, because 1994 was the last year for the VG30E in the Maxima.) Ron Lockman provided a basis for the change in replacement frequency, with the following from his 1997 factory shop manual; a redesigned timing belt. Note that the belts are not interchangeable:

CAUTION: Pay special attention to the tooth shape of the timing belt. The current timing belts are not interchangeable with the timing belts from the 1993 model year. The 1993 model year uses a square or trapezoidal tooth timing belt while the current model year uses a round tooth design. The deign change was made to extend the service life of the timing belt from 60,000 miles for the square or trapezoidal toothed belt to 105,000 miles for the rounded tooth belt. If the proper timing belt is not used, the customer may complain of a "whining" noise coming from the engine compartment. If the camshaft sprocket has a square cut in the valley of the gear tooth, it will require a square or trapezoidal tooth timing belt. If the camshaft sprocket has a rounded cut in the valley of the gear tooth, it will require a rounded tooth timing belt.

I ordered the timing belt from Brown and Brown Nissan in Tempe, Arizona. 800.237.0003. I've always had excellent service from them (a long story about two bent wheels on my '96 Maxima SE when it was less than a month old...) as well as good prices.

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Is the Villager / Quest VG30E an Interference Engine?

Think about what's taking place in the combustion chamber of a running engine. The piston's going up and down and the valves are opening and closing. When a timing belt breaks, the valves stop moving. Some may be left in the open position. SO what happens when the piston comes back to the top? Well, if the engine is an Interference Engine, the piston and valves may collide. This usually results in bent valves and some significant repair cost.

All Nissan engines are designed as interference engines. So you would expect that the Nissan VG30E engine in the Villager and Quest would also be an interference engine. After all, isn't this the same engine as used in the Maxima and Nissan pickup and Pathfinder?

Well, as it turns out, it is not the same exact engine. According to Ken, an acquaintance on the internet, Ford required that Nissan make some design changes to the VG30E before they would agree to use it in the Villager / Quest. One was to modify the engine to be a non-interference, or free running engine. The only way I can think of accomplishing this is to reduce valve lift with a modified cam profile. Interestingly, this brings up the possibility of putting Maxima heads and cams on a Villager to get better breathing...

Here's the text from the design changes scan made by Ken:

(V40 is the model code for the Villager/Quest):

NEW FEATURES

Some new features to the model V40 VG30E engine include:

  1. Free running

    In the event the timing belt breaks, the pistons will not hit the valves. This feature prevents damage to both components and aids in servicing the vehicle. This feature is only on the QUEST.

    [as opposed to the Maxima and Pathfinder VG30E engines... ---Steve]

  2. Oil level sensor

    An oil level sensor mounted to the oil pan monitors the oil level in the system. With the ignition switch in the START position, the oil level sensor detects low oil levels. The sensor causes a LOW OIL light on the instrument panel to illuminate.

  3. Oil filter relocation

    The oil filter assembly has been relocated to provide easy access. The filter is now mounted next to the oil pan, at the front of the engine.

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Replace the Water Pump and the Timing Belt Tensioner?

It is common for your mechanic to recommend that you replace your water pump and your timing belt tensioner when you have your timing belt replaced. If you are paying someone to do this work, I think it is a good idea. These parts are cheap. The added labor for both should not be more than one hour's charge. And if you don't have them replaced and they subsequently fail, you'll have to pay basically the same labor charge as required for the timing belt so that the mechanic can tear it down to the same point. Big bucks.

That said, I did not replace my tensioner or water pump. The way I looked at it was that neither of these devices normally fail catastrophically. So I'm not worried about being stranded away from home. And if they fail, I'm out the same parts cost and another Saturday of my own time. I'm not out the labor cost to pay a mechanic to replace them. There is a finite risk associated with installing new parts (the water pump more than the tensioner) that they could fail early. Also, I'm a member of the Maxima mailing list, and there is no history reported there of water pump failures on the VG engine. As a result, I chose not to replace these parts and take the risk. If I still own the van at the next timing belt change (130K miles), I'll replace them at that time, symptoms or not.

Two other items that deserve checking for leaks are the camshaft seals and the steel coolant plug located below the camshaft seal on the firewall side of the head. These are both very tricky to repair. It is very easy to booger up the sealing surface on the camshaft seal. And removal of a leaking, corroded plug can be very difficult.

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Disassembly

I began the replacement Friday morning. The steps in the Villager factory shop manual were clear and proper. One thing I tried for the first time was wearing latex surgical-style gloves to keep my hands clean. I went through about 5 pairs over the job as they ripped or as I removed them to go do something like go to the parts store. They were great. No black circles around my fingernails.

When I removed the drive belts I found that they were in bad shape. A lot of cracks on the underside. These are original belts, so it is no surprise that they needed replacement. But it meant a trip to the parts store. I also found a leaking oil pressure sender which I replaced.

The first real trouble I had was removing the bypass hose that goes from the thermostat housing to the intake manifold. It lies in front of the upper timing belt cover on the firewall side, and thus has to come off. Well, it, like a lot of OEM hoses, has those DAMN spring clamps. The ones where you have to get pliers on both ears, squeeze the ears together to increase the diameter of the clamp, and then slide it down. Well in the confined spaces where these hoses are it is nearly impossible to get any type of pliers in there to squeeze the clamp. I really had problems with the lower clamp. I bet it took me 1-1/2 hours to get this hose off. I put it back on with normal worm screw hose clamps, and it was a piece of cake. GGGGRRRRR.

Carl Haines replaced his water pump (and timing belt, etc.) in 2002 and had the following cool idea to help get to these spring clamps:

Coolant hose spring clamps. When working with the coolant hose clamps I recalled what Steve Cutchen wrote on his web page about his trouble and dislike with the spring type hose clamps and replacing it with the worm screw type clamps. This caused the light bulb over my head to light up. Can you see it above my head? The problem is that the position of the spring type clamp does not give adequate access with a set of pliers or channel locks to remove the clamp. My idea was to use a worm screw type clamp to loosen the spring type clamp to release the spring type clamp far enough so that the clamp can be repositioned so that I could gain access with a set of pliers to actually remove the clamp. (The worm screw clamp I used was an old one from a heater hose and could only tighten it far enough to be able to rotate the spring clamp. The clamp did not release far enough for me to clear ridge on the fitting, so I just rotated the clamp so that I could get better access to the ears and then squeeze and remove the clamp with a pair of channel locks.) I actually prefer using the spring type clamps because they provide a constant clamping force and don't tend to leak when the metal fittings contract on cold mornings.

As I understnad this, he's using a small screw clamp on the spring clamp's ears to squeeze them. Then, with the ears squoozen (!) the clamp can be moved off the hose and rotated out of the way. Cool idea!

The A/C drive belt tensioner and the water pump pulley came off next. Then I had access to the upper timing belt cover bolts. Tough to get to, but not too bad. 8mm heads. You'll need a small socket set for this. The difficult part is that the A/C drier and the A/C hoses all run right up against this cover and limit access. I took the speed control actuator loose and then removed the three bolts holding the drier in place, just to give me some push room. It is not easy to get the timing belt cover out from the engine compartment, but it can be done.

On the lower part of the engine, the key was removing the vibration dampner. I have an air wrench, and it had enough power to loosen the big (1-1/16") bolt. Otherwise, I would have had to buy a strap wrench to hold the vibration dampner while removing the bolt. I then used a big wheel puller to remove the dampner from the end of the crankshaft. From this point, removal of the lower timing belt cover was straightforward.

I lined up the timing marks on the cam gears with their marks on the engine and was ready to remove the old belt. (Before loosening the timing belt tensioner, read the section below on Reassembly. Be sure to notice exactly how the 6mm hex hole on the tensioner is clocked. You will want to put it back in the same relative location.) Loosening the timing belt tensioner was easy, and the belt came off no sweat. It looked used, but there were really no bad spots that I could notice visually. I've heard that a visual inspection seldom reveals a timing belt about to fail.

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Reassembly

I was really impressed with Nissan's design of the timing belt. There are three white lines across the belt, each of which correspond to a white mark on either the crankshaft or the two timing gears. Make sure the marks line up with the lines and you are guaranteed to have the right number of cogs between each pulley.

Setting the timing belt tension was odd. In a greatly simplified version, the manual says to set the tensioner 70-80 degrees from its spring loaded position. Then use a 0.35mm feeler gauge between the belt and tensioner to finalize the setting. It's like cut it with an ax and then measure it with a micrometer. I set it to 70-80 degrees and then checked the deflection by the book. I had to go another 10 degrees or so to get a deflection I was satisfied with. I am probably between 75-85 degrees from the spring-rest position.

Since I did my timing belt, I ran across the April 1999 issue of Motor magazine, which had an article on the VG engine. On timing belt tension adjustment, they wrote:

Adjust the VG30 belt tensioner by turning its 6mm hex bolt. Always note the clock position the hex hole is in before loosening the tensioner to remove the original belt. Experienced Nissan specialists report that 99% of the time, the factory's adjustment puts the hex hole exactly in the 5:30 position. For consistent results, they also use a genuine Nissan timing belt and reset the tensioner bolt to its original clock position.

The rest of the car went back together without too much trouble. Getting a few of the timing belt cover bolts to start was a pain, but not too bad.

All together, not too bad of a job. Harder than the timing belt change on my old TBird TCoupe, but easier than my Mercury Tracer. It took about 9 clock hours, including the other work I did and the trip to the parts store.

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Another Owner's Illustrated Description

Villager/Quest mailing list member Dale Wadding has also changed his timing belt. And he took some wonderful pictures. I've included his text and pictures on a seperate page.

Followup: The Risk of a Broken Crankshaft

Shortly after I completed my timing belt replacement, I ran across the following posts on alt.autos.nissan:

Magary wrote:

Has anyone heard anything about the crankshaft breaking on the 3.0 liter Nissan engine at the crankshaft pulley? I have a 93 Villager and last week the crankshaft pulley just broke off. I am looking at a $4000 engine replacement and my mechanic says it is a defective crankshaft. If you have had this happen to you let me know. A defective crankshaft should be the responsibility of the manufacturer. Makes you think twice about the Villager.

Bryan

"NissTech" replied:

Nissan has a TSB on this issue. It states that improper drive belt tension can cause this problem and improper tension of the timing belt.

The 93 Quest / Villager came with a 25mm crank , they have since changed it to a 27mm crank, the larger crank is available for your van

This is not a defect , when the Quest first came out we saw a lot of broken cranks , and 99% of the time the customer just had belts put on at a shop other that the dealership and they set them too tight, I hope that is not the case with you .

You do not need a "new" engine just a new crank

Igor N. Hue posted to alt.autos.nissan that the issue was not just a REPLACEMENT issue... The crankshaft could break even as the van comes from the factory:

As a matter of fact the mechanic pointed out to me that there was a lot of corrosion inside on half of the break indicating that it probably was cracked for a long time before it finally broke. The initial factory belt tensioning is the main cause as acknowledged in the OASIS report. That's why Ford 1) made the revised crank 2mm thicker. and 2) revised the 1996 shop manual with a new tensioning procedure.

I posted the issue of overtightened belts to the Villager / Quest mailing list, and list admin Carl Haines replied:

I have recently received an email from another person who has mentioned that this problem is listed in the 1998 Consumer Reports Buyers Guide. I have not yet looked at the Buyers guide but was told that the problem is the result of over tightened drive belts. I would take the CR information into consideration, but I wonder what CR's source of information is on this. Maybe I should right them a letter to find out. It is certainly a good idea to check the belt tension regardless of whether this can cause the crankshaft to break. Overtightened belts can cause premature bearing failure in the accessories and seal failure. One thing to consider is that since this is an overhead cam engine there is some extra machining in this area that may weaken the crankshaft. A couple months ago I went through the NHTSA complaint database to see what I could find. I did find a number of reports about broken crankshafts for 93'-95' Villagers. This confirms that the problem is real. The real question is how to avoid a broken crankshaft.

Concerning the repair of the broken crankshaft. Unless it is covered by warranty I wouldn't replace the engine. The engine is most likely to be perfectly fine with the exception of the broken crankshaft. In this case I would find a shop that does engine rebuilds and have them replace the crankshaft. A replacement crankshaft will not be cheap but it will certainly be cheaper than replacing the engine.

Carl has since received another email about this problem and Ford's response:

Speaking of broken crankshafts... Below is an exerpt from a mail I received recently. If the information is accurate, I am a bit relieved about the possibility of breaking the crank on my '96.

Mine broke at 50,000 miles (right at the front of the engine just behind crankshaft pulley). After talking to several mechanics I discovered it was a known problem and they said they had seen them before. My dealer and Ford customer service refused to do anything about it (car was out of warranty). A friend got me a Ford OASIS report (SSM 04925) which acknowledges the problem.

It states that "Engineering determined the cause was the initial tensile force set on the engine accessory belts during assembly." In Feb. 1995 a new crankshaft that is 2mm thicker at front was implemented. For the older crankshafts Ford recommends using the revised belt tension adjustment found in the 1996 service manual.

A Quest owner, and member of the Viillager/Quest mailing list also was fortunate enough to have the dealer pay for her new engine. Here's her story:

After getting the initial $4800 estimate to put in a re-manufactured engine, I called Nissan Consumer Affairs (1-800-647-7261). I told the rep that the van had fewer than 68,000 miles and had always been serviced at the dealer. After consulting with the local Nissan service guy, the rep said Nissan would pay at least half. In the meantime I found this list and other information about the problem and called the local guy telling him it was a known problem. When the repair was made, the Nissan rep called me to see whether I had decided to buy a new vehicle or keep the Quest. I didn't want another Quest and the Pathfinder is pricey. Then she said they would pay for all of the new engine!! I wouldn't hesitate to get a Pathfinder when I get some funds together.

 

Setting the Accessory Belt Tension

I did not have an accessory belt tensioner. And the way these belts are tightened lends to easy overtightening. You ratchet a bolt to tighten and loosen them, and the torque required to turn these bolts is quite light, even when the belt is overtightened.

After reading these posts, I loosened my belts until I felt confident from the belt deflection between pulleys that they were not overtightened.

Since then, I came across the following "rule of thumb" method for setting the accessory belt tension on rec.autos.nissan:

The question was:

Any idea where I can get a belt tensioning gauge?

Daniel B. Martin replied:

Don't bother. They are surprisingly expensive and difficult to use because of limited accessibility of the belt.

I use my thumb as the belt tensioning gauge. Paraphrasing from the Haynes Maxima manual, page 1-16 ...

Push the belt firmly with your thumb and observe the distance the belt moves.

  • If the distance between adjacent pulley centers is 7 - 11 inches, the belt should deflect 1/4 inch.
  • If the distance is 12 - 16 inches, the belt should deflect 1/4 to 1/2 inch.

I prefer to run a belt on the loose side. If it squeals, tighten it a bit. This is so easy to do on your '97 Maxima that trial-and-error adjustment won't take much time.

 

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