# How risky is it to not fix my timing belt right now? **URL:** \ **Category:** Factual Questions\ **Created:** [July 13, 2006, 10:05pm UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387 "2006-07-13T22:05:17Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![tiltypig](https://avatars.discourse-cdn.com/v4/letter/t/dbc845/32.png) [@tiltypig](https://boards.straightdope.com/u/tiltypig)\ **Post date:** [July 13, 2006, 10:05pm UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/1 "2006-07-13T22:05:17Z")
I have a 1999 Honda Civic and it was recommended that i get the timing belt and water pump replaced at 105,000 miles. My car is at 107,500 miles right now, and here’s the deal: I want to sell it ASAP, so I don’t want to throw the money into doing this major maintenance, but I also don’t want the timing belt to break and mess up the engine and completely ruin the value of the car. My friend’s husband, who worked as a used car salesman, told me I had another few thousand miles before it would go out. But then again, he was a _used car salesman_ and I don’t know how far I can trust him on this topic! How much longer is it safe to go without fixing the timing belt? (Yes, I am disclosing this to the buyer and telling them to get the work done ASAP.) Do I really have another few thousand miles? Or should I get to the mechanic posthaste and just lose a few hundred dollars on getting this maintenance work done? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [July 13, 2006, 10:11pm UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/2 "2006-07-13T22:11:10Z")
The timing belt may very well last to 150,000 miles, or it may break next week. I’ve seen both happen. Inspect the belt for obvious signs of wear and tear, and if it looks OK you _probably_ have tens of thousands of miles of safe travel left. There’s a fairly significant margin of error built into the maintenance intervals. ---
**Author:** ![diggleblop](https://avatars.discourse-cdn.com/v4/letter/d/ac91a4/32.png) [@diggleblop](https://boards.straightdope.com/u/diggleblop)\ **Post date:** [July 13, 2006, 10:17pm UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/3 "2006-07-13T22:17:47Z")
It’s very risky, it can cause all kinds of damage. And if the engine is not one that can free wheel if the timing belt snaps, your repair costs will far outweigh any savings you might have gained by getting a new belt. ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [July 13, 2006, 10:59pm UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/4 "2006-07-13T22:59:56Z")
The 1999 Civic engines are “interference” engines, wich means if the timing belt breaks, the pistons will smash the valves. The belt also drives the water pump, so what isn’t smashed will be cooked as the coolant will not be circulating. You’ve already consumed 2500 miles of borrowed time. Also, if you’ve not replaced the belt and pump, a savvy prospective buyer will take that into account and offer you that much less for what they’ll have to spend to defuse that little bomb. ---
**Author:** ![Necros](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/necros/32/11086_2.png) [@Necros](https://boards.straightdope.com/u/Necros)\ **Post date:** [July 13, 2006, 11:01pm UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/5 "2006-07-13T23:01:19Z")
The engine on this car is of the interference design, which means that, at various times in the 4 stroke cycle, the pistons and the valves occupy the same space, albeit not at the same instant. The timing belt keeps them from having an unfortunate and expensive meeting. If your belt gives way, the pistons will most likely hit the valves. This can have several consequences: 1.) nothing happens; 2.) your valves bend, requiring new valves, and head work (can be pretty expensive); 3.) the valves hit the pistons hard enough to cause damage to the pistons (will be expensive); or 4.) some combination of 2 and 3. So, it’s your gamble. The risks of something breaking if your belt is in good condition isn’t too high, but the consequences of something breaking is very high. You’ll need to plot those variables on your own personal risk matrix. Also, keep in mind that if your car is due for timing belt maintenance and you do not do it, it may have a negative impact on the amount someone else will give you for your car. I know I wouldn’t pay anywhere near as much for a car that had a due major service. ---
**Author:** ![Necros](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/necros/32/11086_2.png) [@Necros](https://boards.straightdope.com/u/Necros)\ **Post date:** [July 13, 2006, 11:02pm UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/6 "2006-07-13T23:02:20Z")
Dang that **gotpasswords** and his flying fingers! 😛 ---
**Author:** ![Airman\_Doors\_USAF](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@Airman\_Doors\_USAF](https://boards.straightdope.com/u/Airman_Doors_USAF)\ **Post date:** [July 14, 2006, 12:15am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/7 "2006-07-14T00:15:32Z")
In addition to the expense it will happen at the worst possible time, like it did for me when I was 200 miles from home. Then you’ll have to get a hotel room in addition to a major repair that they may or may not be able to do for you that day. Do it now. Save yourself a lot of potential trouble. ---
**Author:** ![nivlac](https://avatars.discourse-cdn.com/v4/letter/n/3bc359/32.png) [@nivlac](https://boards.straightdope.com/u/nivlac)\ **Post date:** [July 14, 2006, 12:24am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/8 "2006-07-14T00:24:21Z")
**tiltypig,** I think your operative words were “I want to sell it ASAP, so I don’t want to throw the money into doing this major maintenance.” If this is indeed true, sell it as is. I wouldn’t throw money into a timing belt, then sell it. For a 6 or 7 year old car, you’re not likely to recover the cost of the maintenance in the selling price. OTOH, if you plan to drive the car some more, say thousands of more miles, then do the maintenance or you may not have a running car to sell. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [July 14, 2006, 12:25am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/9 "2006-07-14T00:25:30Z")
The other side of the coin is that Honda gives itself a hell of a lot of leeway in its recommended timing belt changes. After all, it’s not like there’s any magical thing about reaching the recommended mileage that suddenly makes the timing belt susceptible to breaking. You’ve got a pretty good chance of making it to double the recommended mileage with no issue. The thing is, the downside of a timing belt breaking is so serious that it’s just not worth taking any chances with it whatsoever. ---
**Author:** ![Angel\_of\_the\_Lord](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/angel_of_the_lord/32/2949_2.png) [@Angel\_of\_the\_Lord](https://boards.straightdope.com/u/Angel_of_the_Lord)\ **Post date:** [July 14, 2006, 12:58am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/10 "2006-07-14T00:58:07Z")
My timing belt died about a year ago (actually, to be technical, one of the pulleys holding the timing belt died). My car died in the left lane on the freaking interstate while I was going 75 mph. I lucked out in that A.) I didn’t get killed by having some idiot plow into me, and B.) my pistons and valves weren’t damaged. Even so, having my car towed and stuff still set me back a bit. If you’re planning on driving it, replace the belt. If you’re planning on selling it, let the people know you haven’t changed the belt. ---
**Author:** ![Enter\_the\_Flagon](https://avatars.discourse-cdn.com/v4/letter/e/b9bd4f/32.png) [@Enter\_the\_Flagon](https://boards.straightdope.com/u/Enter_the_Flagon)\ **Post date:** [July 14, 2006, 1:12am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/11 "2006-07-14T01:12:32Z")
And if you do replace the belt, please just go ahead and replace the water pump, if recommended. It’s not uncommon for a new timing belt, with it’s high tension, to kill an old water pump, with it’s worn-out moving parts. I’ve seen the water pump fail within a day after replacement of the belt, resulting in the customer having to pay for the labor of replacing the belt again, along with the water pump. Next, of course, the customer blames the mechanic for the water pump failure, even though he declined to replace the water pump with the belt. It’s enough to make you wish for legalized murder. :mad: ---
**Author:** ![tiltypig](https://avatars.discourse-cdn.com/v4/letter/t/dbc845/32.png) [@tiltypig](https://boards.straightdope.com/u/tiltypig)\ **Post date:** [July 14, 2006, 1:30am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/12 "2006-07-14T01:30:20Z")
argh, now I’m scared! I figured there would be a good amount of leeway built into the recommended 105k… Also, “ASAP” means “I’m moving cross-country on the 23rd of this month” so there is really a limited number of days/miles for things to go wrong. Do you think there is a risk of the belt breaking within the next two weeks? What would you do if it was your car? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [July 14, 2006, 2:19am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/13 "2006-07-14T02:19:28Z")
> [@tiltypig](#): > > Do you think there is a risk of the belt breaking within the next two weeks? > > What would you do if it was your car? Yes, there is a small but finite probability that it will break tomorrow, but there was a small but finite probability that it would break 50,000 miles ago. If a visible inspection of the belt shows it in good shape, you _probably_ will make it through the next few weeks without problem. The risk is low, but the resulting damage can be catastrophic. If I was selling the car in two weeks I wouldn’t give it a second thought, assuming a visual inspection showed nothing. 105K vs 115K is really not a big deal. I’d be very clear to the buyer that I hadn’t done the work yet and let them decide to do the work. ---
**Author:** ![Schuyler](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Schuyler](https://boards.straightdope.com/u/Schuyler)\ **Post date:** [July 14, 2006, 2:41am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/14 "2006-07-14T02:41:25Z")
Contrary to popular belief, there isn’t a mileage sensor in the timing belt that tells it to break when you reach 105,001 miles (nor is there a warranty sensor that detects when you run over 3 years/36,000 miles). 🙂 If belts failed at exactly (or near abouts) 105,000 miles, Honda reliability engineers would have specified an early replacement schedule. And anyway, the belt responds to crankshaft revolutions not wheel miles - how does the reliability engineer know if you’ve been on the highway the whole time, or tooling around in first gear. I would expect that belt breakage is unlikely at 105,000 miles, but the probability of failure has reached a threshold where, when averaged over fleets of cars, this is where replacement should be done. I am not a failure analyst, but one can chime in here. Also, there’s no warranty on opinions that you get from a message board. One last thought - since you are going to sell the car, let the new owner worry about this maintenance. You’ll for sure lose money getting this done yourself (you won’t recoup it in sale price), and since you are right at that mileage there is an excuse for not having gotten around to it yet. (It does make your potential claim of “religiously maintained” harded to prove.) Good luck. ---
**Author:** ![Schuyler](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Schuyler](https://boards.straightdope.com/u/Schuyler)\ **Post date:** [July 14, 2006, 2:47am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/15 "2006-07-14T02:47:00Z")
> [@tiltypig](#): > > argh, now I’m scared! > > I figured there would be a good amount of leeway built into the recommended 105k… > > Also, “ASAP” means “I’m moving cross-country on the 23rd of this month” so there is really a limited number of days/miles for things to go wrong. Do you think there is a risk of the belt breaking within the next two weeks? There is a risk, but it is a small one (I would expect small here to mean that it’s just not going to break). > [@tiltypig](#): > > What would you do if it was your car? If it were my car, it wouldn’t bother me at all to inform the buyer that the belt is due for a replacement (and maybe expect them to use that as a bargaining point). If I were keeping the car, or if I were the new owner, then I would get the belt replaced soon. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [July 14, 2006, 3:40am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/16 "2006-07-14T03:40:03Z")
My advice: don’t replace it. But be sure you understand that there’s a calculated risk involved. Back in the days when typical timing belt intervals were 60,000 miles, I saw some belts that broke at 61K and some that went past 100K. The problem is, there’s no way to predict when your particular belt will break. As **Telemark** said, it may last to 150K (or longer) or it may break next week (or tomorrow). There’s no way to know. What is extremely rare is for a belt to break before its recommended replacement interval. The suggested interval is essentially a reliable minimum mileage you can expect (barring freakishly bad luck or something actively shortening the belt’s life). Your talking about selling the car within 10 days (selling before you move, right?). The odds of the belt breaking within that period, while not zero, are very very low - problably less than a 0.1% chance. It’s rather like the lottery - terribly small chance, very large consequence. In Russian Roulette there’s only a 15% chance of getting the bullet, but if you’re in that unlucky 15%, you’re 100% dead. Likewise, if you’re in the unlucky 0.1%, you’ll have 100% of a problem (big repair bill). This is the calculated risk. If you take it, you must be prepared to face that bill. But given the statistically tiny risk factor, it’s not a bad choice. Just be aware it’s not a sure bet. It’s generally not feasible to inspect a timing belt. Just to get a look at it requires removing a dust cover, and then what can be seen - the outside surface of the belt, a few teeth - usually doesn’t tell much. If you really want to meaingfully inspect a timing belt, you need to take it off so you can bend it backwards and see if the teeth are starting to separate from the body of the belt. The labor charge for taking it off is probably about 80% of the cost of replacing the belt. It doesn’t make sense to pay that much just to inspect it - if you take it off, replace it. If it were my car, I would not replace the belt. ---
**Author:** ![ombre3](https://avatars.discourse-cdn.com/v4/letter/o/da6949/32.png) [@ombre3](https://boards.straightdope.com/u/ombre3)\ **Post date:** [July 14, 2006, 4:00am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/17 "2006-07-14T04:00:09Z")
Not to mean to sidetrack this but---------- Is there any particularly good reason to make engines that can self destruct if the timing belt breaks? Does it have something to do with saving a few bucks in manufacture? Does it have something to do with efficiency? There are so many motors out there that are non interfering. Why does Honda choose to make an interfering one? ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [July 14, 2006, 4:10am UTC](https://boards.straightdope.com/t/how-risky-is-it-to-not-fix-my-timing-belt-right-now/364387/18 "2006-07-14T04:10:13Z")
> [@ombre3](#): > > Not to mean to sidetrack this but---------- > > Is there any particularly good reason to make engines that can self destruct if the timing belt breaks? > > Does it have something to do with saving a few bucks in manufacture? > > Does it have something to do with efficiency? > > There are so many motors out there that are non interfering. > > Why does Honda choose to make an interfering one? Many manufacturers have interference engines. These engines might use timing belts or timing chains. To have a non-iterference engine requires more space in the combustion chamber. This limits the compression ratio and results in a less powerful, less efficient engine. It can also make it tougher to achieve fuel mileage and emissions goals. In designing an engine, making it non-iterference is generally not a high priority. The only disadvantage to an interference engine is the possibility of bending valves, and that can almost always be avoided by good maintenance.