Timing belt question, 99 Honda Accord DX

"E. Meyer" > wrote
Elle wrote
>> Manual transmission
>> hondas also require an immobilizer (= pulley holding
>> tool)
>> to get the pulley bolt off.
>>
>
> Require is a strong word. If the clutch is in really good
> shape & the car
> is locked in gear, theoretically you should be able to
> hold it using the
> drive train as the immobilizer. That's how we did it on
> the 80's Fords &
> Mazdas.

The torque needed to free the pulley bolt on Hondas is so
large that a special crankshaft pulley holding tool is
recommended for the bolt's removal. People talk about
pushing on the brakes (and so immobilizing the drive train
and so presumably the crank pulley, in the vein of what you
are saying) while trying to free the bolt and say the pulley
still is not immobilized when torque is applied to the bolt.
I suppose a risktaker could try taking both front wheels off
and immobilizing the axles with long crowbars or similar
between the lugnut studs. From awareness of the torque
needed to free the pulley bolt on my manual drive Civics, I
personally would be mighty afraid of toppling the car off
the jackstands.

Crude calculation: Typically 400 lbs. or more of torque is
needed to free the pulley bolt. Some 400 ft-lbs applied at
the pulley bolt means something like 100 ft-lbs applied by
each of the four wheel studs involved on the two wheels. The
moment arm from wheel stud to wheel center is about 2
inches. So around (100 ft-lbs/2 in*12 in/foot =) 600 lbs. of
force is being applied to each wheel stud. This is around
1/4 of the weight of the car that is being messed with.

"Elle" > wrote in message
news
> "Dillon Pyron" > in his words "thus spake"
>> "Elle" > :
>>
>>>All one can deal with here are probabilities. Your belt is
>>>more likely to fail than one changed at seven years; less
>>>likely to fail than one driven in extreme weather over the
>>>last nine+ years. Also reports are that if a timing belt
>>>fails at lower speeds, chances are better that no engine
>>>damage will occur.
>>
>> Not true. If the cam(s) isn't/aren't spinning but the crank is, you
>> will, in all likelyhood, have a piston be introduced to a valve.
>> It's
>> the mechanics of the engine and has nothing to do with speed.
>
> I think you are envisioning a literal breaking of the TB apart, whereas I
> think many TB failures are not that extreme. With the less extreme
> failures, the cam can may still be moving somewhat in synch. The mechanics
> of the engine are also such that it comes to a stop sooner when it is
> under less load. Momentum and all.
>
> Regardless, I am going by reports. I could be talked out of the claims
> made that lower engine speed lowers the probability of engine damage but
> without knowing more about how TBs fail, I will stick with this.

I did some Googling around about Broken TBs on Hondas and the interference
vs non-interference question and found this thread. I have to agree about
the A20A engines being non-interference and that anything that is truly
interference is bound to get trashed, regardless of the speed that the belt
breaks. http://www.3geez.com/forum/showthread.php?t=35768

On 12/11/08 2:14 PM, in article , "Elle"
> wrote:

> "E. Meyer" > wrote
> Elle wrote
>>> Manual transmission
>>> hondas also require an immobilizer (= pulley holding
>>> tool)
>>> to get the pulley bolt off.
>>>
>>
>> Require is a strong word. If the clutch is in really good
>> shape & the car
>> is locked in gear, theoretically you should be able to
>> hold it using the
>> drive train as the immobilizer. That's how we did it on
>> the 80's Fords &
>> Mazdas.
>
> The torque needed to free the pulley bolt on Hondas is so
> large that a special crankshaft pulley holding tool is
> recommended for the bolt's removal. People talk about
> pushing on the brakes (and so immobilizing the drive train
> and so presumably the crank pulley, in the vein of what you
> are saying) while trying to free the bolt and say the pulley
> still is not immobilized when torque is applied to the bolt.
> I suppose a risktaker could try taking both front wheels off
> and immobilizing the axles with long crowbars or similar
> between the lugnut studs. From awareness of the torque
> needed to free the pulley bolt on my manual drive Civics, I
> personally would be mighty afraid of toppling the car off
> the jackstands.
>
> Crude calculation: Typically 400 lbs. or more of torque is
> needed to free the pulley bolt. Some 400 ft-lbs applied at
> the pulley bolt means something like 100 ft-lbs applied by
> each of the four wheel studs involved on the two wheels. The
> moment arm from wheel stud to wheel center is about 2
> inches. So around (100 ft-lbs/2 in*12 in/foot =) 600 lbs. of
> force is being applied to each wheel stud. This is around
> 1/4 of the weight of the car that is being messed with.
>
>

I did say theoretically & recommended is not the same as required. I'm
pretty sure the shops just put an impact wrench on it and spin it off.

When we changed the belt on the '91 Mazda pickup, the solution was to simply
put a real person in the car with her foot planted firmly on the main brake
pedal. Of course, it won't work if the clutch slips.

I tried it once on the '81 Accord, but the clutch was so far gone at the
time, it just slipped. At the time, I didn't have an immobilizer & ended up
paying a shop to change it.

I am familiar with the amount of force needed to break the bolt loose. I
have the immobilizer and have done the job myself with manual tools on a '96
Odyssey and a '95 Integra (both automatic trans.). You haven't really lived
until you try the Odyssey. It's torqued about 50 lb-ft more than an Integra
or Civic. I certainly would not consider anything involving jack stands. It
would have to be either all wheels on the ground or, preferably, good sturdy
ramps to get some space under the engine.

By your calculation, I would think the drive train should be able to handle
the force. It spends its life accelerating and stopping a ton an a half of
car after all.

These days, I just sit back & bask in the glow knowing that both of my
current cars ('06 CR-V & '08 Altima) use timing chains, so with a little
luck my days of changing belts are over.

On 12/11/08 1:52 AM, in article ,
"Forrest" > wrote:

>
> "E. Meyer" > wrote in message
> ...
>>
>>
>>
>> On 12/9/08 12:35 PM, in article ,
>> "Forrest" > wrote:
>>
>>>
>>> "Elle" > wrote in message
>>> ...
>>>> "Forrest" > wrote
>>>>> 1989 Accord here, single overhead cam. I had the belt break shortly
>>>>> after
>>>>> buying it used, in around 1998 with 140,000 miles on it. No engine
>>>>> damage
>>>>> ... just put on another one. It ended up getting oil on it and broke
>>>>> again a few months ago (200,000 mi.) when my son was getting off of the
>>>>> freeway near the house.(lucky). He cranked it over trying to restart
>>>>> it.
>>>>> I didn't even know what an interference engine was and turned the cam
>>>>> and
>>>>> crankshaft over several times, trying to get things lined up. No
>>>>> damage.
>>>>> I later replaced the head gasket and saw that the valves and pistons
>>>>> were
>>>>> intact. Wonder if Honda is just playing "CYA" in case there is carbon
>>>>> build-up and things make contact.
>>>>
>>>> Pardon? What do you mean about the carbon build-up tending to promote
>>>> valves hitting piston?
>>>>
>>>> Dillon raises a good point. I do not like my explanation for why
>>>> sometimes
>>>> the engine is not damaged. When driving and the TB breaks, it's true
>>>> spark
>>>> stops pretty instantaneously, but ISTM the tranny will keep the wheels
>>>> moving and so the pistons moving for awhile, yet the cam is disconnected
>>>> from the crank, so I would expect pistons to hit valves. Unless the
>>>> valves
>>>> can halt a slow((??) moving piston?
>>>
>>> Pardon? I mean, like I don't think that the valves and pistons CAN hit
>>> each other. If anything were to make contact, it would be the carbon
>>> build-up ... not "promoting" valves hitting pistons. Talk about putting
>>> words into someone's mouth.
>>>
>>>
>>
>> The valves and pistons certainly CAN hit each other. That is the
>> definition
>> of an "interference" engine. If the timing belt snaps, the cam stops
>> turning
>> the valves instantly. If you have a manual transmission, the moving car
>> forces the crank and hence the pistons to keep moving and damage is almost
>> guaranteed. If you have an automatic, the crank MIGHT stop soon enough to
>> avoid serious damage.
>
> If it is truly an interference engine, it will almost always trash it out. I
> don't believe that the A20A3 SOHC, that is in my 1989 Accord, is. It has
> valve relief cut outs in the top of the pistons. The engine can be put at
> TDC on number 1 cyl and then have the camshaft turned all day without
> hitting the piston. I've done it and later removed the head ... not even a
> scratch on valves or pistons.
>
>

Sounds like you're in luck then. At least you don't have to fear
instantaneous catastrophic destruction.

I was only responding to what read to me like confusion about what an
interference engine is.

"E. Meyer" > wrote
snip but all comments noted
> I am familiar with the amount of force needed to break the
> bolt loose.

Yes, pardon. I know you are one of the experienced, well
seasoned regulars here. I did not give enough credit to your
qualification "theoretically... "

> By your calculation, I would think the drive train should
> be able to handle
> the force. It spends its life accelerating and stopping a
> ton an a half of
> car after all.

I too thought about the drive train (relative to my numbers
and also normal operating conditions) and also think the
gears yada would not be limiting. That is, they would hold
just fine while freeing the pulley bolt.

> These days, I just sit back & bask in the glow knowing
> that both of my
> current cars ('06 CR-V & '08 Altima) use timing chains, so
> with a little
> luck my days of changing belts are over.

It is a lot of work for me, but learning how to do it was a
great education, meaning wealth itself.

A person at Honda-tech.com a few years back tossed out that,
when a TB breaks, it is possible for the cam to be in a
position such that all the valves are shut.

"Elle" > wrote in message
...
>A person at Honda-tech.com a few years back tossed out that, when a TB
>breaks, it is possible for the cam to be in a position such that all the
>valves are shut.

I'm no expert on any of this stuff but that doesn't sound possible. I would
think that at any one time, the only cylinder with the valves closed would
be the cylinder on the compression stroke. While it's doing that, the
opposite cylinder, on a 4 cyl engine, is on the exhaust stroke with the
exhaust valves open. Check out this video.
http://www.youtube.com/watch?v=Hhc6x...eature=related

"Forrest" > wrote in message
...
>
> "Elle" > wrote in message
> ...
>>A person at Honda-tech.com a few years back tossed out that, when a TB
>>breaks, it is possible for the cam to be in a position such that all the
>>valves are shut.
>
> I'm no expert on any of this stuff but that doesn't sound possible. I
> would think that at any one time, the only cylinder with the valves closed
> would be the cylinder on the compression stroke. While it's doing that,
> the opposite cylinder, on a 4 cyl engine, is on the exhaust stroke with
> the exhaust valves open. Check out this video.
> http://www.youtube.com/watch?v=Hhc6x...eature=related

This video shows the operation of the four cylinder better. Easier to see
what's doing what, when.
http://www.youtube.com/watch?v=4vWoS...eature=related

"Elle" > wrote in news:gRC%k.19135$yB4.17638
@newsfe07.iad:

> Dillon, four folks reporting personal experiences where
> their broken timing belt did not damage the engine:
> http://www.honda-tech.com/showthread.php?t=2201848 .
>
> (For newbies, note the thread emphasizes that luck is a
> factor in not damaging the engine. If your TB is due, change
> it now.)
>
>



My boss's old '94 CR-V had its belt break (he was WAAAY overdue!!!). No
damage. And he was going highway speed at the time.

Still, the downside of an unlucky break is /extremely/ expensive, so it's
very, very unwise to try and save a few bucks stretching the belt's life.

--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

Tegger wrote:
> "Elle" > wrote in news:gRC%k.19135$yB4.17638
> @newsfe07.iad:
>
>> Dillon, four folks reporting personal experiences where
>> their broken timing belt did not damage the engine:
>> http://www.honda-tech.com/showthread.php?t=2201848 .
>>
>> (For newbies, note the thread emphasizes that luck is a
>> factor in not damaging the engine. If your TB is due, change
>> it now.)
>>
>>
>
>
>
> My boss's old '94 CR-V had its belt break (he was WAAAY overdue!!!). No
> damage. And he was going highway speed at the time.
>
> Still, the downside of an unlucky break is /extremely/ expensive, so it's
> very, very unwise to try and save a few bucks stretching the belt's life.
>

I agree.

Since my '88 Accord had it's water pump explode at an early age, I tend
to think that replacing the TB, Water Pump and Tensioners, as well as
any rubber belts you have to remove to access said parts is the most
economical way to deal with the Honda engine.

dan