Timing Belt Age

Larry Bastanza

Larry Bastanza

Legendary Member
Tech Expert
Joined
9 February 2000
Messages
6,621
Location
Warwick, NY, USA
Hi Folks,

I know this is a topic we have discussed many times with varying opinions. I had an experience today that I thought was worth sharing.

I have a car in for a 60k/Timing Belt service. It is a 1991 w/17K original miles on the odometer. The car is absolutely perfect in every way, I have not even gotten dirty doing the job;).

Well before I remove the belt I get it set at TDC, and check the cams to be sure all is correct. Well with this car I set the crank to TDC EXACTLY and guess what? The cams are off, not a lot, maybe 1 degree, so the marks on each pair of cams are not where they typically should be. I make a note of it, decide I must have the crank slightly off, and move on. Remove it, do the water pump, and reinstall the new belt.

The new belt gives me a little trouble and I have to nudge the cams slightly to get it all set correctly. The timing belt I removed was stretched. Enough to have the cams marks out of time. The new belt has the cams perfectly timed.

So.....Does timing belt AGE matter? It most certianly does IMO.

First time I have seen this, but never did a 15 year old Timing Belt before:).

LarryB
 
That's a significant observation IMO. Thank you, Larry.
 
Wow, that is a great story. It should serve as a reminder to those that are looking to get early model cars will low mileage on them to have the records checked for that very thing. Just because they aren't driven doesn't mean anything it appears.
Thanks for sharing!!
 
I have had similar experiences with older japanese supercars like the FD and 300zx twin turbo. You can NOT diagnose a belt's condition visually what so ever. Obivously a worn, faded, deteriorating belt had a greater chance of failure than one that looks brand new; but new looking belts fail as well. It is slightly less common for them to stretch to this degree, but it absolutely does occur. It is a rubber part that degrades with age like any other. I'd recommend at the most to do a TB job every 12 years, regardless of mileage. The cost on a 300zx was roughly 4-5k if the belt broke, about 2-3k on the FD, but easily 10k+ on a NSX if a used engine is difficult to source.
 
The timing belt "looked" OK. The painted numbers were worn off, and when I twisted it and listened, I heard the glass reinforcements krinkling. Not a good sign. It did not look dry or cracked though.

The owner decide to flatbed it to me, since he knew the belt was old and the car had been undermaintained for it's age. After seeing this, I thought to my self he did not waste his money on the flatbed. I really feel this one was a timebomb, waiting to blow.

My $.02,
LarryB
 
Is there any advantage to replacing the hoses at the same time as the belts & pump other than saving on coolant?
 
swbatte said:
Is there any advantage to replacing the hoses at the same time as the belts & pump other than saving on coolant?
Click to expand...
I don't know whether access is easier because of things you remove while doing that service - Larry can address that. :confused: But I know one other advantage is that it makes it easy to remember when you last replaced the hoses. (And IMHO they should be replaced at the same mileage/time interval as the TB/WP, since they tend to deteriorate at roughly the same rate.)
 
Very significant post Larry!

I have also just replaced the Timing Belt and Water Pump on my '91.

Now I don't know if the TB was done before or not because the car has only done 38,000Km's. However, the water pump was the original one. Secondly, the Timing Belt was nearly out of adjustment so it was changed as a matter of caution by my very fastidous mechanic (and I wouldn't have it any other way! :wink: )
 
Larry Bastanza said:
Hi Folks,

I know this is a topic we have discussed many times with varying opinions. I had an experience today that I thought was worth sharing.

I have a car in for a 60k/Timing Belt service. It is a 1991 w/17K original miles on the odometer. The car is absolutely perfect in every way, I have not even gotten dirty doing the job;).

Well before I remove the belt I get it set at TDC, and check the cams to be sure all is correct. Well with this car I set the crank to TDC EXACTLY and guess what? The cams are off, not a lot, maybe 1 degree, so the marks on each pair of cams are not where they typically should be. I make a note of it, decide I must have the crank slightly off, and move on. Remove it, do the water pump, and reinstall the new belt.

The new belt gives me a little trouble and I have to nudge the cams slightly to get it all set correctly. The timing belt I removed was stretched. Enough to have the cams marks out of time. The new belt has the cams perfectly timed.

So.....Does timing belt AGE matter? It most certianly does IMO.

First time I have seen this, but never did a 15 year old Timing Belt before:).

LarryB
Click to expand...

I doubt when they wrote the service manual maintenance schedule they had expected 15 year old NSX's with 17K miles on them running around. By all accounts, a lot of these cars are about to qualify for historic tags.

Mileage is a secondary concern in many instances- rubber in belts, tires, bushings, gaskets, seals, hoses, and the like degrade over time- which is why many automotive products have a shelf life. Factoring in the cost of an NSX interference engine- IMO the belt should be replaced every 7 years or so as well as an older belt is definitely more prone to stretch, slip, and inconsistent performance.
 
John@Microsoft said:
I doubt when they wrote the service manual maintenance schedule they had expected 15 year old NSX's with 17K miles on them running around.
Click to expand...
Well, the recommendation on the '91-96 NSX is to replace it at 90K miles or 6 years, whichever comes first. So their schedule does take time into account.

I just think they did a disservice by omitting a specific interval for replacing the cooling system hoses (although it does have a recommendation for inspecting them).
 
Larry, thanks for that info. I understand that timing belt and hoses should be replaced every 7 years due to age but I'm curious how do I know if the 'new' belt and hoses are newer than the ones I already have? For all I know, they might have been sitting in some warehouse aging for the last 3-4 years.
 
nsxtasy said:
Well, the recommendation on the '91-96 NSX is to replace it at 90K miles or 6 years, whichever comes first. So their schedule does take time into account.

I just think they did a disservice by omitting a specific interval for replacing the cooling system hoses (although it does have a recommendation for inspecting them).
Click to expand...

Oh, I had not noted the 6 year interval in the manual, it is good that they chose to include something along those lines. Is it not in the manual for the NA2? Curious then as to why so many wait until their 90+K service on their 91's to replace it, I'd have thought dealers would be inclined to push the timing belt change sooner at an earlier maintenance interval, but many owners might also just put it off due to expense or their low miles.
 
John@Microsoft said:
Is it not in the manual for the NA2?
Click to expand...
The NA2 has a time and mileage recommendation, but they changed it to 105K miles or 7 years beginning with the '97 model year, when the NA2 was introduced.

John@Microsoft said:
Curious then as to why so many wait until their 90+K service on their 91's to replace it, I'd have thought dealers would be inclined to push the timing belt change sooner at an earlier maintenance interval, but many owners might also just put it off due to expense or their low miles.
Click to expand...
I think it's because people hear that it's a "30K service" or a "90K service" and don't bother to read the manual or understand that those service intervals are also specified for time as well as mileage. With some of the service procedures, mileage might be a more important determinant (e.g. air filter replacement, since it builds up dirt primarily as a result of driving), but with others, time can be just as important (such as replacing parts that can deteriorate over time, such as the timing belt as well as the fluids, particularly brake fluid).
 
Well, it certainly appears that my 93 with 14,148 original owner miles is headed up to Larry's house for a TB changeout. I, too, have been reading my manual and trying to talk myself out of this, but not worth it, folks.
Good find on the TB, Larry.
 
champ19 said:
Well, it certainly appears that my 93 with 14,148 original owner miles is headed up to Larry's house for a TB changeout. I, too, have been reading my manual and trying to talk myself out of this, but not worth it, folks.
Good find on the TB, Larry.
Click to expand...



Champ, did you buy the 93 from Exeter Pa?
 
There really is no significant overlap in labor for the T/Belt service vs. the hose replacement. The only task in common is the removal of the oil filter pedestal, which is 3 bolts, easily accessible, and only takes a few minutes.

There is also an "8" shaped gasket behind the pedestal, which should be replaced for both jobs, but also this is a few dollars, not a big deal.

The hose replacement is mandatory in my mind, if you track the car. If your car is a street driver only, the risk is blowing a hose, requiring a tow, although I still recommend the hose replacement. If you loose a hose on the racetrack, it could be have very serious results. Three gallons of coolant under one of your rear tires under load will give you a whole new perspective about oversteer:eek:

HTH,
LarryB
 
It applies to all with a Timing "Belt". All the service manuals have the same Time or Mileage in the maintenance schedule.

HTH,
LarryB
 
Zennsx said:
Champ, did you buy the 93 from Exeter Pa?
Click to expand...



I did. It had 14500k miles when I bought it. Of course the 1850 mile trip home added a bit more. It seems perfect inside and out except for rusted steel parts underneath which I'm cleaning up. Definitely not a Texas car.
http://www.nsxprime.com/photopost/showphoto.php?photo=15544
Any history on this car?

JH4NA1159PT000430
 
mattd said:
I did. It had 14500k miles when I bought it. Of course the 1850 mile trip home added a bit more. It seems perfect inside and out except for rusted steel parts underneath which I'm cleaning up. Definitely not a Texas car.
http://www.nsxprime.com/photopost/showphoto.php?photo=15544
Any history on this car?

JH4NA1159PT000430
Click to expand...
I searched high and low for a NSX and eventually bought mine in NJ.
It figures 9 months later theres a cherry 93 a couple miles from my house.:mad:
I'm not sure on the history but I do know the P.o has had a host of exotics including a new Ford GT. Good luck and enjoy it :smile:
 

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