Cam Belt Replacement

[tomcouch]

I've only owned my 2000 NSX for a couple of months and it only has 43,000 miles. However there is no indication that the timing belt has ever been replaced and the manual says it should be done every 7 years. What experience do others have? Should I have it replaced ASAP since a belt failure will destroy the engine?

Thanks

 

[jwmelvin]

You are about to get a tidal wave of responses. The answer is yes.

 

[The King]

I don't feel so bad now. My 03 with under 16k hasn't been done yet, and I pretty much have been called a cheap mouth breathing loser on here. Hopefully you're not the overly sensitive type.

 

[Larry Bastanza]

Considering you have gone twice the recommended time interval, it would be a good idea to do it.

As some may say:



Regards,
LarryB

 

[JD Cross]

I don't feel so bad now. My 03 with under 16k hasn't been done yet, and I pretty much have been called a cheap mouth breathing loser on here. Hopefully you're not the overly sensitive type.

You make an interesting comment.

I'll assume you have a Canadian 03 which means it's one of only about a dozen 02+ NSX's sold in Canada.
Very rare indeed. Rare enough to keep in pristine condition I would think.

With only 16 K in 11 years the car has only seen about 1500 miles (km's?) a year.
When a car is at rest there are sections of the timing belt under constant strain against the pressure of valve springs.
In a car driven regularly these sections under strain would be pretty random and so the belt would have these stress areas pretty well spread out.

In your car these sections are under strain for months at a time.
Couple this localized strain with a belt that's 11 years old and I'd say you have sections of your timing belt that are weaker than those of a car driven many thousands of miles with random strain.
If you accept my argument then you are risking at $30K engine against at $1500 maintenance job on a very rare NSX.
More risk than an 11 year old belt with a lot more mileage.

Your decision of course as the owner, but were it me, I'm not sure I would crow about it.
Unless of course when your belt fails you are willing to report back.

 

[OLDMNSX]

......and is it the ORIGINAL coolant too???????
Brad

 

[The King]

You make an interesting point JD Cross. My car came from Florida so it has close to 16000 miles. Kaz on the British forum states that once he does a belt replacement on an NSX it doesn't need, in his opinion, to be done again for 10 years. I would hope that the people putting my engine together at the factory had similar skills to Kaz.

The car sees fairly regular use in the summer but obviously is stored away in a heated garage in the winter. Your comment on sitting in one position for extended periods of time does make some sense. Do you think it would be better to start the car now and again during the winter as opposed to leaving it to spring? I know I'm starting to run on borrowed time on this service, but I am obviously not staying awake at night worrying about it either, nor am I "crowing" about it. I am just stating a fact.

Also, when I was ripped a new one on an earlier thread, I did say that I will report back if the belt fails. That way all the experts can beat their chests and bask in the glow of their knowledge of all things automotive.

 

[Bram]

Faron,

The Timing belt on the NSX is set by a mechinical device that is locked in with a certain amount of tension on the belt, therefore the tension on the belt is the same at any point on the Engine TB. You can verify this with your Head Tech, as all Honda's made during this period have the same design.
Honda did introduce an oil Auto Tension device on some engines...prelude come to mind that may have this issue.

Bram

When a car is at rest there are sections of the timing belt under constant strain against the pressure of valve springs.
In a car driven regularly these sections under strain would be pretty random and so the belt would have these stress areas pretty well spread out.

Couple this localized strain with a belt that's 11 years old and I'd say you have sections of your timing belt that are weaker than those of a car driven many thousands of miles with random strain.
.

 

[The King]

......and is it the ORIGINAL coolant too???????
Brad

If you are referring to me, the answer is no. Just because I haven't done the belt, people immediately think I'm too cheap and stupid to do any service work to the car. I got the car with under 9500 miles. All fluids have been changed at least once and most more than that in the four years that I've had the car. The brakes are serviced yearly and the original pads have about 50% left. The rotors look brand new. The car pretty much only sees water when it gets washed and doesn't sit outside baking in the sun. When I do drive the car, I make sure that it is fully up to temperature, and then drive it as it was designed to be driven(without being arrested!) I also drive gently for awhile after a spirited drive to let things cool down before parking. I also open the glass and cover sometimes to allow it to cool, when I know it's probably a bit warm.
I try to remember to run the air conditioning at least some, every time I drive the car. Same with the windows, as it seems non use is a source of a lot of the problems with them. I keep an eye on the crank damper and plan to inspect the screws in the VVIS system when I get a chance. Don't assume that because I haven't drank the timing belt Kool-Aid, I do nothing to maintain my car.

 

[JD Cross]

The car sees fairly regular use in the summer but obviously is stored away in a heated garage in the winter. Your comment on sitting in one position for extended periods of time does make some sense. Do you think it would be better to start the car now and again during the winter as opposed to leaving it to spring?

This is a good question.
Over the winter I used to start my NSX and run it to operating temperature every month thinking that would circulate oil to the cylinder walls etc.
Then I read that something like 90 % of engine wear occurs during the starting cycle when things are cold and fresh oil hasn't had a chance to be pumped.
In older oils an additive called ZDDP (I think) was added and it apparently stuck to metal surfaces and prevented wear until oil arrived.
Then ZDDP was deemed a toxin and removed from modern oils.
So I stopped the off season starting and left the car all winter.

Others may chine in here with better info.

Bram's comment on a constant tension setup on Hondas is correct.
The belt tensioner is designed to take up any belt slack to keep it from slipping on the various gears and as the belt stretches over it's life.
However if you've had a chance to view a timing belt in action in slow motion you will see it go through a constant cycle of tension and compression as it finds resistance against the valve train and then suddenly no resistance. It appears to be vibrating like a guitar string.
The belt tensioner helps keep the belt vibration down but doesn't stop it.
It's this constant cycle of stretching and rebound that wears the belt out over time.

When the engine is stopped however the belt isn't subjected to constant tension in all areas.
The tensioner is not strong enough to cause the valve springs to open or close so uneven tension remains in various sections of the belt.
For example between the cam gears there is resistance against the belt from the valve train and it will remain until the car is restarted.

Honda has a mileage and time element to their belt life maintenance.
The mileage and time are surely conservative but I'd guess Honda decided better safe than sorry in their recommendations.
Or perhaps they assume an engine will be subject to constant high performance operation and their recommendations reflect this.
I'd bet almost all NSX timing belts are changed on time not mileage.

I think the time element while conservative is based on degradation of the fibers and rubbers in the belt.
A timing belt has a very hard life.
Hot then cold, constant stretch then rebound.

Kaz is extremely knowledgeable and if he recommends 10 years I'm sure it's a good number.
With your low mileage your belt may last 15 years or more.
I've done two timing belts in 23 years, both at 11 years, so I'm the last person who should be saying anything.

However on the last belt change, with only 37K miles, my Acura tech told me I had slipped one cam gear tooth.
No damage occurred but now I'm firmly on the 7 year bandwagon.

 

[Larry Bastanza]

The belt tensioner is designed to take up any belt slack to keep it from slipping on the various gears and as the belt stretches over it's life.

Hi JD,

I have to say I completely disagree with this statement. The tensioner is in a fixed position from the day it is installed until it is replaced. There is never a "slack adjustment" in the NSX system. You only set initial tension with the spring, then the tensioner pulley is locked in position. Did I misunderstand what you wrote?

Regards,
LarryB

 

[greenberet]

As far as I understand it, at some points in a camshaft's rotation, the valve springs are fighting against being opened and at some points, they are trying to run ahead and close. Their resistance to rotation at some degrees and trying to rotate at other degrees changes the tension of the timing belt in their segment so the tension is not the same across all points of the belt.

That's why it's important to set the timing belt tensioner spring at a certain degree of rotation. If you set the spring at a different degree, you might get too much tension overall or not enough - depending on whether the rear exhaust cam pulley is adding tension between it and the crankshaft at the moment the tensioner spring is set or taking it away. No?

 

[Larry Bastanza]

That's why it's important to set the timing belt tensioner spring at a certain degree of rotation. If you set the spring at a different degree, you might get too much tension overall or not enough - depending on whether the rear exhaust cam pulley is adding tension between it and the crankshaft at the moment the tensioner spring is set or taking it away. No?

Yes, and that is the reason you have the blue mark on the crank pulley to set the position of the crank/cams for final tension adjustment. Also remember if you follow the book you will rotate the crank pulley to the blue mark from #1 TDC. If you were to rotate the crank twice, end up on the blue mark you would have the engine(cams) in the wrong position for final tension adjustment.

Regards,
LarryB

 

[JD Cross]

Hi JD,

I have to say I completely disagree with this statement. The tensioner is in a fixed position from the day it is installed until it is replaced. There is never a "slack adjustment" in the NSX system. You only set initial tension with the spring, then the tensioner pulley is locked in position. Did I misunderstand what you wrote?

Regards,
LarryB

Larry
I should have written the tensioner is designed put the correct amount of tension on the belt which will take up any slack in the belt when it's installed.
I read somewhere the recommended tension includes an allowance for some belt stretch.
My mistake :redface:

 

[NSX9]

If those who store the cars over winter don't want to start it to change the belt, valves position you could always just put in say 4th gear and push it 1ft forward in the garage which will turn the motor over a bit.

I know some people store the cars in winter in the harsh conditions, but I loved the attitude of one of the Canadians who gave me a ride during NSXPO, his car had done about 180,000 hard miles and he frequently leaves it at motels in winter then fires it up in the morning at minus 40.......no problems at all. The car was in great condition, its a credit to the design and build quality which we admire so much.

 

[greenberet]

Yes, and that is the reason you have the blue mark on the crank pulley to set the position of the crank/cams for final tension adjustment

I wish the Service Manual were even clearer regarding the timing belt tensioning procedure for people doing it the first time. I believe you should rotate the crank pulley to the blue mark after piston #1 is at TDC on its compression stroke. Rotate the crank only once and piston #1 will be on its exhaust stroke and if you set the spring at the blue mark then, you'll get the wrong tension. I think someone did that on my NSX once.

 

[Bram]

Scott,
You should know a thing or two about us Canadian eh.

Since the Lil Guy (Dean) is a full blown Canadian.

Back to the Topic... I have always recommend that people don't start their NSX during the storage months, because most of the ware happen during the first couple of seconds after starting.

Bram

 

[OLDMNSX]

Something else to remember referencing running your car in the winter. One of the byproducts of the internal combustion engine is H2O. The water that is produced during the engine running will remain in the engine and the exhaust unless the engine and exhaust system gets warm enough to evaporate the water. People wonder why in the winter time that all of the cars seem to have a lot of steam coming out of the exhaust.......This same steam is present in the summer months it's just not visible.

My solution to the timing belt static position, along with the valve train, is to rotate the crankshaft 120 degrees each month. In effect, rotate the crank with a 17mm deep socket and a couple long extensions in a clockwise direction, normal rotation of the crankshaft, until resistance is present. This is where the next piston is coming up on the compression stroke. Over time the pressure will dissipate past the rings / valves and next month the resistance of this cylinder is gone and the next one will pressurize and give you resistance.
Brad

 

[ftuhy]

Hmm. Having also owned a few older Corvettes, a trick with them was to remove the distributor (remember those things!), which gave you access to the oil pump shaft. One could then lower what was essentially a fat screwdriver blade into there, connect it to an electric drill, and circulate oil through the engine in the winter without starting the engine. Unfortunately, the NSX oil pump is direct driven from the crank.

I thought about unplugging the igniter so the NSX doesn't start, then cranking the engine. The problem there is you also need to turn off the fuel pump and release the fuel pressure first, or you'll be spraying raw gas into the cylinders. So, I think Brad's suggestion of cranking the engine 120 degrees by hand is a good idea.

I agree with Kaz and have my NSX timing belt replacement on a 10 year schedule. But, that is highly dependent on the car's use/storage/mileage/age, I know my car, and so that is my very personal decision. With parts availability a concern, I think the belt will be available for a long time. But I'll be ordering all the hoses this year, possibly the tensioner pulley, and some other specialized parts this year for use in 2016.

 

[greenberet]

Rotating the crankshaft 120 degrees by hand is good idea. When I want to rotate the engine without starting it, I unplug the fuel injector resistor (very easily accessible on the right side of the engine bay) and twist the key in the ignition. The engine cranks but since it gets no fuel, it doesn't start.

 

[Larry Bastanza]

Something else to remember referencing running your car in the winter. One of the byproducts of the internal combustion engine is H2O. The water that is produced during the engine running will remain in the engine and the exhaust unless the engine and exhaust system gets warm enough to evaporate the water. People wonder why in the winter time that all of the cars seem to have a lot of steam coming out of the exhaust.......This same steam is present in the summer months it's just not visible.

My solution to the timing belt static position, along with the valve train, is to rotate the crankshaft 120 degrees each month. In effect, rotate the crank with a 17mm deep socket and a couple long extensions in a clockwise direction, normal rotation of the crankshaft, until resistance is present. This is where the next piston is coming up on the compression stroke. Over time the pressure will dissipate past the rings / valves and next month the resistance of this cylinder is gone and the next one will pressurize and give you resistance.
Brad

I know you really meant a 19mm socket......

Regards,
LarryB

 

[N-Wing]

So funny, I have a 2000 and it had 43k miles and I asked the same question. It took me a year to get it done but it was done at about 54k this year. Thanks Larry...

 

[ftuhy]

Rotating the crankshaft 120 degrees by hand is good idea. When I want to rotate the engine without starting it, I unplug the fuel injector resistor (very easily accessible on the right side of the engine bay) and twist the key in the ignition. The engine cranks but since it gets no fuel, it doesn't start.

Great tip. Thanks!

 

[Larry Bastanza]

Rotating the crankshaft 120 degrees by hand is good idea. When I want to rotate the engine without starting it, I unplug the fuel injector resistor (very easily accessible on the right side of the engine bay) and twist the key in the ignition. The engine cranks but since it gets no fuel, it doesn't start.

Exactly!!

 

[The King]

Rotating the crankshaft 120 degrees by hand is good idea. When I want to rotate the engine without starting it, I unplug the fuel injector resistor (very easily accessible on the right side of the engine bay) and twist the key in the ignition. The engine cranks but since it gets no fuel, it doesn't start.

By doing this, aren't you just causing wear by having everything moving around with little or no lubrication? I've used Molyslip in my S2000 from early on, as it sometimes sits for extended periods of time. This type of product is supposed to leave a film on everything so less wear occurs on startup and at high rpms. I have used it in several Hondas over the years, and seems to work as advertised. I've never used it in the NSX though.

My service department used to give me a hard time about using Molyslip, as Honda in general, doesn't recommend using additives. Years later I was told by a Honda parts and service rep that Hondas actually have, or at least had at that time, Molyslip in their engines when delivered, as part of the package that made it "break in oil". Anybody else ever hear this?