OT: So much for Honda reliability

[A.K. Boomer]

There generally is a huge safety factor built into belt change intervals, I bought a camry and got it home and went to change the belt and it was original and the car had already logged on 225,000 miles, I think the belt was supposed to be changed @90,000

if I knew how bad the belt was I would have just towed the car,,, when I got the belt off I could just peel the teeth off effortlessly with my fingers...

much depends on how a vehicle was driven --- this was almost all highway miles and is easy on belts,

Idling is a belts worse enemy - even though it's usually 1/3 less speed than highway cruising and such camshafts have a mind of their own at idle due to the valve springs trying to speed the cam up and slow it down, lots of jossleing and hard on teeth,,,

if it's a multi-lobed cam with both intake and exhaust as in a SOHC straight 6 it's not as critical as there's not only more mass but when one valve is closing another is opening and the pulsations are all but eliminated.

if it's a DOHC subaru it's got it's work cut out for it, not only two banks but just a four cylinder to boot, so 4 camshafts with very few lobes --- now toss in roller rockers and the effect is even slightly more due to the valve springs transmitting even more friction free energy,

ahhh but don't look for premature failure from too many subies even if their used as a taxi-cab, the old wimpy twin belt design yes, but the newer subies could probably lift one end of the car up with their timing belts,,, they are one of the widest (and longest) going...

[radkins]

Ford does use a narrower belt than other makes of vehicles. I would assume because it is cheaper and ford is a cheap bastard. Porsche also used narrow timing belts for some reason, I don't understand the logic.

Subaru uses a nice wide belt as well as honda and mitsubishi.

If I had my old puter up and running yet I could show many pictures of the different motors I have built for customers and the differences in the belt widths, all the different cam setups of the different motors and all that. But unfortunately I am not and I only have pics from the last month or so on this puter..

It makes no difference if the belt was only 1/8" wide the fact remains that the replacement schedule was 60,000 miles (as was CLEARLY stated!) and they had no problem going that far with by far most of them going 100,000 miles or more, the problem was people chose to ignore the replacement and then blamed Ford when the belt failed! At the time the belt was considered a tune-up item and was expected to be replaced along with the spark plugs, etc and it was a simple inexpensive component change. Lot's of folks did get shafted by mechanics, even at dealers, due to the fact they "assumed" replacing the belt was a major task and did not question inflated replacement costs.


The early Escort interference engine had some issues, although not nearly what the Chevy Vega and Monza engines suffered, but both Ford and GM corrected these problems to turn both makers' engines into very reliable units. The belt/cylinder head problem with the first Escorts established a bad reliability reputation from which the Escort never really recovered but then like the GM Vega and Monza they were only a small part of a rather shameful list of Detroit failures that would probably take several pages to cover! All of these have come a long way and these problems are pretty much history now but the fact remains the Escort's problems were due to ignoring a clearly marked maintenance schedule far more so than using "cheap" parts! Ford's mistake in this case was to depend on owners actually taking care of their cars properly instead of driving them until they finally stop from neglect as so many owners are prone to do!


If there is one thing I learned from working on cars, especially back in the 70's/80's was that by far most owners' neglect of proper maintenance was absolutely appalling, it seems to be somewhat better today but it's still severely lacking!

[vpt]

Subi motor I built for a customer awhile ago, VVT intake cams. Subi cams don't ride on rockers, they ride on "valve lash adjusters" AKA lifters for the pushrod folks.

[vpt]

They should all be like this, no belts, no chains, just gears.

[radkins]

They should all be like this, no belts, no chains, just gears.

Ding, ding, ding, we have a winner folks!


However the gears should be made of steel or at least a good iron casting unlike those metal "up-grade" replacement sprockets for timing chains! As I mentioned before the "plastic" sprockets (or gear as it's most often mistakenly called) will easily last 100,000 miles with most going 200,000 or more while the "up-grade" replacement metal sprocket from the auto parts stores will be lucky to last 50,000 or so and it will have severely degraded even by that time! Not to even mention all the metal particles that it has shed into the oil.

[Old Hat]

They should all be like this, no belts, no chains, just gears.

I'm in no position to argue that point, but won't you admit that the "timing belt"
consigering how hard it works, and how long it lasts, (winters below zero) incuded
is a pretty impressive bit of technology?

Hey show more stuff you've done in a new thread.
I can see what life would have been had I taken the left fork in the road.
Did a Toyota dealership in 78?, went back to machining.

[vpt]

The part that sucks is it is pretty much impossible to do an overhead cam motor with gear drive. I believe we are getting close to no valvetrain drive though. Solenoids will replace chains, belts, rockers, lifters, cams, the whole bit.

[vpt]

I'm in no position to argue that point, but won't you admit that the "timing belt"
consigering how hard it works, and how long it lasts, (winters below zero) incuded
is a pretty impressive bit of technology?

Absolutely! And like I posted on the last page, if there has to be something I would take a belt over a chain any day! Gear drive is the best when it can be used but it can't with overhead cam.

[saltmine]

Someone mentioned the Mazda Wankel. Innovative design, low rotating mass, and lots of power. Unfortunately, for the average owner, the rotary burned copious amounts of gas and oil. The emissions were terrible. (by the time they got the exhaust emissions under control they were devoting several hundred BTU's of energy to keep that retort of a converter hot enough to incinerate all of the hydrocarbons and unburnt fuel). Short apex seal life all but doomed the rotary for American roads...BTW, Mazda never quite figured out the apex seal problem.

On the subject of overhead cam engines....Most people don't know that in order to lubricate the camshaft and all of the moving parts of the valve train, the valve stems have to be submerged in oil. What usually happens, over time, the seals harden and eventually lose their ability to seal oil. Once this happens, the car's oil consumption can become huge. In fact, back in the '70's, Chevrolet's Vega developed a serious reputation for burning oil. Truth be known, the silicon / aluminum bores and tin plated pistons were not the cause. It was the valve guide seals. Hundreds of short-blocks were replaced in a mis-guided effort to cure the problem. What's laughable is the fact that many times, the cylinder head, with the bad valve guide seals, was routinely re-installed on the new block. Once I figured this out, it became obvious to me why some OHC engines burned so much oil. A friend of mine had an F-150 Ford, with a 4.6L overhead cam engine. He was driving it five miles a day, to work and back....Once a week, his oil pressure light would illuminate, and he would be forced to add oil. He eventually had the engine overhauled.....AND.... they put the old heads back on the fresh short-block. Needless to say, the oil consumption never completely went away. He finally traded it in on an Eco-Boost V-6 F-150, which he found short on everything but fuel consumption....But that's another chapter.

[lakeside53]

I have a 1997 DOHC Subaru that I just regasketed/seals/belts/idlers/tensioner/waterpump etc. Back in '97 the belt change period was 105K or 7 years. I replaced it at 82K because I had to get in there anyhow with a crankshaft oil leak. In May I did it again at 130k (because I has the motor out and the heads off ). Both belts looked like new... I used OEM the first time then Mitsuboshi the second. Mistuboshoi (not Mitsubishi) is the oem suppler to Subaru. If you look on the Subaru forums, there is definitely a difference between brands, Gates being rated the worst, but I suspect with "ordinary driving" most decent brands will last the distance.

Life of a belt isn't just miles - it's age, environmental conditions, and DRIVING. My Outback is a pedestrian 161 hp, but the turbo WRX variant can put out 300+ hp. Mine's rarely been over 3500rpm, and never thrashed. At 130k, I could still the factory hone marks on the bore (100% coverage), and the valve actuator to cam gaps (no rockers) were effectively like they left the factory.

[A.K. Boomer]

They should all be like this, no belts, no chains, just gears.

You might get by with this type of set-up if you have a cast iron block, then the gears and the block grow at approximately the same ratio,,, but most blocks are now aluminum, so if you plan on using a design like this you better plan on running anti-backlash gears due to them being further apart when the engine reaches normal operating temps...

if not you will hear some nasty gear slop at idle when the cam is rattling around back and forth...

[radkins]

What the hell happened to my post?????? I tried to edit a spelling mistake and over half my post disappeared!!!!!!

Let's try that again.

Saltmine that's another extremely common misconception about piston ring wear and you nailed it exactly! Whenever an engine starts burning oil the first thing most people think of, including a heck of a lot of mechanics, is worn rings when almost every time it's valve guides/stem seals! Worn rings cause blow-by and oil is lost by it literally being forced out of the engine and by the fact it becomes so diluted by unburned fuel getting past the rings, by far most of that smoke coming from the tail pipe is oil getting past the valve stems not somehow getting into the combustion chamber past worn rings. People have spent tons of money rebuilding the short block or even replacing it when the real problem was worn out valve guides and stem seals. Whenever I did a rebuild, either a top overhaul or a complete rebuild, I installed bronze valve guide bushings and sometimes new valves if there was any stem wear, it made no sense to me to reassemble an engine with any detectable wear at all on the guides and stems since any life left in them would last for only a short time. Far too many mechanics however just gloss over the heads whenever doing a "rebuild" (usually just a re-ring job that's a half arsed approach anyway) and then blame improper break-in procedure when the engine continues to burn oil.


About those Vega engines, while you are correct about the heads and the fact they were all too often overlooked as a cause of the problems they were just that, usually A cause, not just THE cause! In almost every case they were only a part of the problem and the block problem was all too real, although even it was often made worse by improper repair procedures such as cylinder honing. Those engines, indeed the entire car, had multitudes of defects and in fact there is little that did not go wrong with them!

[MrSleepy]

The part that sucks is it is pretty much impossible to do an overhead cam motor with gear drive.

One of the most successful engines in F1 history was the gear driven DOHC Cosworth Double Four Valve... DFV.



Rob

[CalM]

All Gear? YES!

The part that sucks is it is pretty much impossible to do an overhead cam motor with gear drive. I believe we are getting close to no valvetrain drive though. Solenoids will replace chains, belts, rockers, lifters, cams, the whole bit.

And it's a HONDA! My 1999 VFR800Fi (That's a motorcycle ;-) has the all gear driven cam system. Including anti backlash split gears.

There is something pleasing about the sound that comes from within.

Subsequent years have gone to chain driven cams. Oh Well....

[Willy]

Two more examples.
First the Duesenburg 24 cyl.
Second image the Ferrari V-12