When Should I Change The Timing Belt?

The US service manual states that the timing belt should be replaced at 72 months (6 years) or 90,000 miles. The vast majority of NSXs hit 6 years well before they are anywhere near 90k miles so many owners are wondering if they really need to change the belt at 6 years.
The “safe” answer is to replace it per the maintenance schedule. However, considering the way many NSXs are pampered and the conservative nature of most timing belt replacement schedules, it is probably fairly safe for most owners to go beyond 6 years on low-mile cars.
Though one other thing to keep in mind is that Honda will have no sympathy for you if it is beyond the recommended service life and breaks, damaging your engine. Repairs for such a belt failure are likely to be a fair amount of money. But if this happens when the belt has been replaced according to the maintenance schedule there is a chance that they will help with goodwill on the repairs.
[KS – 99/12/11] I asked one of the top NSX technicians in the country about this, and here’s what he said: “Acura says 7 years or 90 k miles. Period. I have seen Integra belts break at lower miles and years, but NEVER a Legend or NSX. I have seen Legend owners go as high as 110k miles, but rarely, if ever over 8 years. Years ago I developed the quirky habit of taking every belt I remove, and twist it like wringing out a wash cloth. I listen to the number of fiberglass strands that snap and break, and predict how close to breakdown the car may have been. This sound of glass breaking is very distinctive. I have done NSX T-belts that were 7 or 8 years old with only 30 or 40 k miles, and when I twist the belt, all I get is red hands. The moral of the story is that while other cars may be in the danger zone at your cars age and miles, I would plan to do yours no later than, say, 8-9 years, or at about 50k. If this sounds arbitrary, it is based on the experience of others. If nervous, disregard [everything above] and get it replaced”
[DL – 99/12/11] The problem with a timing belt failure is that you are never again sure everything is “as new.” It bends valves, which can be replaced, as well as valve guides (sure, they can be replaced, too, but it’s a big job), stresses the heads, tappets and cams, and generally makes a mess of the top end.
I’ve always believed that the less a factory-made machine is touched by anyone away from the manufacturing process, the better. My rule when I was racing was “don’t change plugs between practice and the race,” which means for anything you touch expect side effects that will take additional time and work to recover (I won a lot of races, also blew up plenty of motors during development). It’s a lot better to do the timing belt a little early rather than a little late.
We lost a belt on our old Honda Prelude, exactly at 90K, and it’s come back OK but I don’t have the same confidence in its longevity. Just the hassle of being stuck on a freeway (if you’re quick enough to recognize what’s happened and can coast across a few lanes to safety) is a bummer. Even the tow into the dealer has some risk of tweaking something.
From what’s been posted, I’d guess 50-60K or 7 years sounds like a safe bet, but who knows? I’ve got a ’93 with 34K miles, so I guess I’ll put it off a while. On most cars, the miles match the years, but not on a special-purpose toy like our NSX’s. I’d ask around for any examples of failure, just to have some real data rather than more opinion. But it’s much better to do it when it’s just a simple belt replacement (complex though it is) rather than a full top end teardown and machine shop job.
[AT – 99/12/30] I finally had the chance to do some comparison of my old timing belt and a new one. To also check on the belt I also brought along a tool I’ve used in the past to check on spark plugs. This is a special flashlight with a magnifying lenses attached which then magnifies and illuminates any small 1 1/2″ square area in greater detail.
First I checked the old belt to see if it had stretched to any degree as compared to the new belt. I could find no difference between the two belts. This is a good sign, but considering new belt technology, I didn’t really expect this to be as much of a problem as it had been in the past. By the past I’m referring to the infamous Fiat timing belts of the 70’s. If you didn’t change these belts on the exact mileage they specified, then you could almost guarantee that it would break and total the engine. Their expected life span was no more than 30,000 miles max if I remember correctly.
Then I checked the rubber surfaces on both sides of the belt. From a normal viewing distance the main difference between the two belts was that the old one had some minor glossy areas on the outside of the belt which corresponded to the teeth on the inside of the belt. Also it was missing all markings of the belts part number and the like. On the inside of the belt it looked almost identical to the new belt. Under the magnifying lens I had a much better look at the rubber surface and texture. I fully expected to see small cracks and excessive wear on the old belt. But to my surprise it was remarkably similar to the new belt. Both surfaces looked very similar, no dry cracks, no separation, cuts or any damage. On the inside of the belt where the teeth reside, I also noticed that the surface texture exhibited on the old belt looked almost identical to the new one. The tooth pattern was very uniform, no cups, overly rounded or squared edges, either leading or trailing.
The last area I could inspect were the internal plies used to support the belt and give it a majority of it’s strength. Since I couldn’t get into this area, I can only surmise that it was probably in very good condition since it exhibited no dryness, cracking when stressed or twisted. Again this is speculation on my part so this is where the weak point of the belt would come if it were to fail. Originally my biggest concern was that the tooth shape would have changed enough along with some belt stretch to cause it to jump a few teeth on one or more of the cam sprockets. Now I think that this would be unlikely unless something else mechanical or chemical affected the belt. Possibly the belt tensioner failing to do it’s job properly or oil getting on the belt causing it to slip or break down more quickly.
All in all this is a well made part from Honda. It would be one of the parts I would least worry about on this engine.
[DD – 99/10/19] Even though most NSX’s are way under the recommended mileages for this service, owners must recognize the established time-period of the useful life for this equipment. We’ve had a few owners that “took their chances” and got burned.

What Else Should Be Changed With The Belt?
It is normal to replace the water pump and other engine belts (alternator and compressor) at the same time. They should not charge you labor for
replacing AC and alternator belt because they have to remove that for the timing belt anyway.
The parts costs on the other belts is minimal but the labor to get to them is substantial (mostly the same labor as replacing the timing belt). So it makes a lot of sense to change all the belts at the same time and only pay for the labor once.
The water pump is almost always replaced, but on a well-maintained (fresh coolant) car it’s not really clear how long they will actually last. A few have been disassembled and inspected after being replaced and they looked almost new inside on low-mile cars that were having the timing belt changed based on time instead of miles. But again the water pump parts cost (about $200) is less than the labor to replace it, so most owners replace it during the timing belt change as suggested.
[MBA – 99/10/29] You should always do the Timing Belt and Water Pump together. Its about 7 hours labor for one, or 7 for the other, or 7 for both. Also, the Water Pump is Timing Belt driven so a broken pump equals a broken belt.
Water Pump Note
The the vendor in Japan who was casting the pumps changed ALL the molds and can not cast the old pump any more. The weep hole was moved in the 1997 pump. The new pumps are the same price as the old pumps. The new pump will fit the 91-96 cars but one of two things must happen:
Replace the lower timing belt cover for about $100
Drill a hole in your existing lower timing belt cover so the water pump weep hole tube can stick out, then fill the old hole w/silicon glue.
If you buy a new cover you will need a grommet.
19200-PR7-A03 Water pump
11810-PR7-A02 ’97 lower timing belt cover
11816-PR7-000 Grommet
Many dealers who do not work on many NSXs are still not aware of this change. They will get halfway through the job and call to say there was a parts change and they need to get a new timing belt cover. Some owners have been able to get the dealer to give them a discount on the new belt cover when they get a call like, especially if they negotiated a flat fee for the work first.

When Have Owners Reported Changing Their Belts?
How Much Are People Paying?
[KS – 2000/3/17] Me too, on my ’91 with 39,000 miles. While they were in there, they also replaced the engine belts (the alternator belt 31110-PR7-A01 and the compressor belt 38920-PR7-A01).
[BHA – 99/2/18] The previous owner had the 30,000 done on it before I got it. Last December after I had driven it around 7000 miles (it now has 42K on it) I had the 60K AND 90K services done on it at the same time (of course, omitting duplication of parts and labor), reasoning that they were due under the 48 and 72 month side of looking at things. Timing belt, water pump, pulleys and belts, etc. I had them replaced rather than just inspected. Also had the spark plugs and fuel filter (part of the 60K). Total was around $1500. Was it overkill? Could be, but I can’t afford to blow the engine, but could afford this insurance. So now I think I am good for another 30K/60K/90K now.
From Leith Acura in Cary, NC in November 1998
Oil Filter 14.25
Washer .20
5W30 Bulk 8.75
Filter Set (I assume Fuel) 49.95
Timing Belt 149.95
Water Pump 195.42
Timing Adj 107.70
Comp Belt 13.93
Alte Belt 31.78
Spark Plugs 91.80
Parts Total 663.73
Labor* 691.20
Other* 149.53
Tax 48.80
Total 1568.26

• The other charge had to do with two parts which were partially goodwilled by Acura (rear taillight cover which contained water and the windshield

molding which was shrinking from the drivers edge) and might have influenced the overall labor charge.
[JWI – 99/2/28] I just asked a dealer in Santa Monica and they said it would be $1,100 (including the water pump) and added that was the same price as for a Legend. I have not yet tried to confirm this elsewhere. The recommended service interval is 90,000 miles or 72 months, but I asked the service manager 1) have they ever seen an NSX belt go before 90K, and 2) after how many years from new would they recommend a precautionary replacement. They said they saw ONE car’s belt go early, but that guy was racing his car. They then asked how I drive my car, and I said I babied it. They recommenced doing it in the next year or two. I have a ’91 with 32K miles.
[GW – 99/10/18] I had my timing belt, water pump and all other belts replaced for $800.
[RA – 99/10/18] I just had my ’92 timing belt replaced at Stevens Creek Acura, Santa Clara CA. Costs:
Labor 547.
Belt, Timing 151
Adj, Timing Belt 109
Water Pump Assy 206
Belt, Alternator 28
Belt, Compressor 14
CVR, Timing Belt 148
misc …
total parts: 676
total labor: 547
[RLI – 99/10/18] I just had my timing belt replaced. Cost of belt only was $700. I did not have the water pump replaced.
[MCS – 99/10/18] Davis Acura quoted me a timing belt for $889. This includes: 1) Timing belt, 2) All other belts, 3) H2O pump, 4) Labor
[DD – 99/10/19] In regards to the general inquiry about the parts and costs involved in a timing belt replacement, we (Davis Acura) are running a special on that service until Christmas since this is traditionally our slowest time of the year. The service includes an new timing belt, water-pump, alternator belt, power steering belt, A/C compressor belt, and Honda coolant. The price for this maintenance is normally $1003 plus tax but our sale price is now $795 plus tax.
[TSC – 99/11/14] Timing belt was $795 for all at Ann Arbor Acura.
[AWL – 99/11/11] $795 for timing belt and related work at Ann Arbor Acura. They were matching Davis Acura’s “winter special” price…

Should I Try This Myself?
[MBA – 99/11/13] It is one job definitely left to a pro. There are so many chances for something to go wrong, on a job where going very wrong
is very dangerous (read- expensive). If you have air tools, and a manual, and lots of time, you could probably do it if your skills were at least a little above average. But it is one of those jobs that requires all the little ‘tricks’ you learn over years of practice. The knowing exactly which wrench for which impossible looking bolt. How not to snap a water pump bolt that is almost certainly threaded into 20 mm of sheer corrosion. How much tension for the belt and many other ‘feels’ that come with time. Setting the cam timing, splitting teeth, seal replacement, surface prep, I could go on, but I have already put you to sleep, I’d bet. Give it to a qualified tech, you’ll sleep better.
Can I Save By Doing Other Maintenance At The Same Time?
[MBA – 99/7/20] There is overlap in the time for adjusting the valves which is also part of a 60, 75, 90 k svc. There is also overlap for the time it takes to fill and bleed the cooling system after replacing the water pump which is also done as part of a major. When I do a t-belt / w-pump at the same time as a major, I deduct 2.0 hrs from the total time. (14.0 total).

How To Save Big $$$
If your car is covered under the water pump recall and you haven’t had that work done, you should be able to have the belts and water pump replaced with no labor charge at the same time the recall work is done.
[TEC – 99/10/18] I had my car done by South Coast Acura when they did my coolant hose recall because the recall had the dealer replace the water pump. They charged me $190 to replace all of the belts. No labor was charged.
[PY – 2000/3/3] There is a recall that they replace water pump and hoses. While they were doing that he suggested I replace the timing belt. It only cost me $300 for a $1300 job.

Failed Belt Reports
[DG – 99/10/20] At this year’s River Run club event, I was being chased by an NSX driven by club member Buzz Clark. After a burst up to about 80 or 90, he disappeared from my rear view mirror. Turns out his t-belt had disintegrated, causing the usual related engine nastiness.
Upon inspection, it appeared as if a piece of road debris had entered the belt housing, contributing to its failure. His car was also supercharged, but the mechanics at Davis Acura don’t believe that was a contributing factor.
Maintenance