Serpentine belt = timing belt?

[dennis in se pa]

Is the serpentine belt the same as the timing belt? it seems to me that it should be, but I have never "been in there" so I really don't know.

[Arizona_928]

No.
Serp belt is smooth and runs the accessories (Alternator, a.c., Ect)

Timing belt has teeth.

[Dantilla]

No.
Timing belt is internal, keeping the crankshaft and camshaft properly aligned.

The serpentine belt is external, and runs auxiliary items like power steering pump, A/C compressor, water pump, yada yada...

[dennis in se pa]

OK, Thanks.

[masraum]

serpentine




vs it's predecessor




Timing belt

[Bob Kontak]

Originally Posted by Dantilla

The serpentine belt is external, and runs auxiliary items like power steering pump, A/C compressor, water pump, yada yada...

Water pump is hit or miss. It can be driven by either belt depending on engine design. I'm always happier with a WP change out if driven by the serpentine belt.

[cabmandone]

Originally Posted by Bob Kontak

Water pump is hit or miss. It can be driven by either belt depending on engine design. I'm always happier with a WP change out if driven by the serpentine belt.

Reads like the words of a man that recently did some work on a Subaru!

[asphaltgambler]

Better: Serpentine belt is ribbed longatutal, drives components with more surface area than a V- belt. Cogged belt has ' teeth' horizontally for use which no slippage is desired. Referencing engine applications: Timing belt as the cogged cam / crank gears to allow specific orientation via belt.

[svandamme]

to me, a serpentine belt is any belt that drives multiple things
and snakes around pulleys and idlers

The word says it all, serpentine..

It can be a ribbed belt
it may be used for timing

On most cars you'de have a timing belt and seperate timing belt
But it's not mutually exclusive..And there's no real law that prevents using one for timing either...or requires it to be a toothless belt.

it just needs to snake around and drive several things...
for instance on a 928, the timing belt is a serpentine belt in it's own right

It drives 2 cams, water pump, oil pump... and snakes around quite a bit.

[Bob Kontak]

Originally Posted by svandamme

to me, a serpentine belt is any belt that drives multiple things
and snakes around pulleys and idlers
The word says it all, serpentine..

No argument except that it's not common terminology in the US to call a toothed timing belt a serpentine belt even though it ends up being very serpentine when installed.

Originally Posted by cabmando

Reads like the words of a man that recently did some work on a Subaru!

Yes sir. She's still humming.

Honda and VW engines too.

[masraum]

Originally Posted by svandamme

to me, a serpentine belt is any belt that drives multiple things
and snakes around pulleys and idlers

The word says it all, serpentine..

It can be a ribbed belt
it may be used for timing

On most cars you'de have a timing belt and seperate timing belt
But it's not mutually exclusive..And there's no real law that prevents using one for timing either...or requires it to be a toothless belt.

it just needs to snake around and drive several things...
for instance on a 928, the timing belt is a serpentine belt in it's own right

It drives 2 cams, water pump, oil pump... and snakes around quite a bit.

That all seems accurate, but the common usage is that serpentine is for accessories and is what replaced having several V-belts to drive those accessories.

To me, this is one of those things where an accessory drive belt or a timing belt might be a serpentine belt, but a serpentine belt is not necessarily a timing belt or an accessory drive belt.

I'll still stick with the most common usages:

V-belt - old style accessory drive, cogged or not cogged.
Serpentine - new style longitudinally ribbed (wide, flat) accessory drive belt that also may or may not be cogged.
Timing belt - toothed belt primarily for the purpose of maintaining crank to cam timing, may also include various tensioner and idler pulleys and occassionally drive other items.

[masraum]

Originally Posted by Bob Kontak

No argument except that it's not common terminology in the US to call a toothed timing belt a serpentine belt even though it ends up being very serpentine when installed.

THe first timing belt that I ever installed looked very much like this.
THat'd be a lazy snake.


The last timing belt that I replaced, another lazy snake.

[tcar]

Many 'timing belts' are timing 'chains'.

[Zeke]

Originally Posted by tcar

Many 'timing belts' are timing 'chains'.

Really? I think I'd want to know for sure and exactly what it is. Buying an older Ferrari with actual timing belts is to keep your checking account full. Because they are not chains like on the Porsche flat engines. IDK about the V8's and other non flat motors Porsche has built.

[masraum]

Originally Posted by tcar

Many 'timing belts' are timing 'chains'.

I would consider those two different things that perform the same function, at least in common usage. A belt would normally be considered a solid, flexible loop, usually made of fiber reinforced rubber while a chain would be a flexible loop made of interlocking or interconnected, metal links. I suppose there could be some argument that a timing chain might qualify as a type of belt (like a square is to a rectangle). But most folks would probably look at you crazy if you called a timing chain a timing belt. Personally, the way that I use the terms, they are mutually exclusive.

[JackDidley]

Gilmer belts are typically used for timing and not for accessories.

[javadog]

Originally Posted by Zeke

Really? I think I'd want to know for sure and exactly what it is. Buying an older Ferrari with actual timing belts is to keep your checking account full. Because they are not chains like on the Porsche flat engines. IDK about the V8's and other non flat motors Porsche has built.

The 924, 928 and 944 all had timing belts. Porsche even made a $400 special tool for measuring the belt tension.

[stevej37]

Originally Posted by JackDidley

Gilmer belts are typically used for timing and not for accessories.

That looks exactly like my Prelude timing belt that I just had replaced.
But mine might have been a tad narrower.

[john70t]

Some camshaft timing gears.....and/or accessory drive components(WP/alternator/etc)....have ALL been run off of pure metal gears.

Belts are usually cheaper..and quiet..and make individual things easily replaceable.
They don't require precise case bearings with movable centers which is a nightmare not yet solved.
Dependable lubrication to all the "high-load" critical points makes it even worse.

[masraum]

Originally Posted by john70t

Some camshaft timing gears.....and/or accessory drive components(WP/alternator/etc)....have ALL been run off of pure metal gears.

Belts are usually cheaper..and quiet..and make individual things easily replaceable.
They don't require precise case bearings with movable centers which is a nightmare not yet solved.
Dependable lubrication to all the "high-load" critical points makes it even worse.

Yep, SBC gear drive


or a belt if you're so inclined.