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  #16  
Old 03-13-2008, 10:26 AM
jayp jayp is offline
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... hmmm... so far we still haven't been able to clear up something... does the patriot and compass engines use a timing belt or timing chain...

anybody got some facts on this one??? at least this way we can clear up as to the type of maintenance that would be needed depending if it's a chain or a belt...
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  #17  
Old 03-13-2008, 10:32 AM
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Quote:
Originally Posted by Rottenbob View Post
I think I've heard this before referred to as an interference design versus a non-interference design. An interference engine will sustain major damage in the event of a broken timing belt, whereas a non-interference engine will simply stop working until the timing belt is replaced.
Correct.

Interference engines, when the belt or chain breaks, will run into major issues from the valves and pistons trying to occupy the same space at the same time. Hence the term "interference," since the valves and pistons will interfere with each other. If this happens, you're looking at a complete engine rebuild.

Noninterference engines, since there's enough room for the valves to be open and the pistons to be raised at the same time, will simply quit running. You're looking at a little more labor than a straight belt/chain replacement, but not by leaps and bounds.

Timing belts usually have replacement intervals around 80,000-100,000 miles. You want to stay on top of that, since a belt won't give any warning before it lets go. Honda is pretty notorious for using belts in interference designs- if everything holds, their engines are great, but you have to keep up on the maintenance (they usually recommend swapping the water pump at the same time).

Timing chains generally have no replacement interval- you don't worry about it going unless it begins to chatter on you. Since they are lubricated with engine oil, they last a good long time. 200,000+ miles is not unusual at all. Many automakers are going to chains for that reason; they can be noisier than belts, but I've never noticed that to be an issue.

These are separate from drive belts/serpentine belts. Those drive the engine accessories, like the power steering pump, water pump, alternator, and A/C compressor. Sometimes there is a couple belts ("drive belts"), but nowadays there's usually just one ("serpentine belt"). Generally, replacement intervals on those are 30,000 miles on the low end, and maybe over 50,000 miles. Belt quality is far better than it ever has been and they last a LONG time. Drive belts can just be watched for wear; if they squeal, it's time to change them (which can take 5 minutes in a driveway by anybody or a couple hours in a shop by a trained mechanic, depending on design; I've seen it both ways). Serpentine belts are usually easier to change out than drive belts, since there's generally an automatic tensioner that's easy to get to, and you can often thread them in from above the engine.

Hope this helps clarify things.
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  #18  
Old 03-13-2008, 10:36 AM
hunter44102 hunter44102 is offline
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Why does the 2008 Patriot owners manual schedule say "Replace the Timing Belt (2.4L engines). 102,000". (p. 394)

Is it possible that they are just calling it a belt even though it is really a chain?

Actually, does it even matter, if we have the Lifetime Drivetrain warranty, the 102k replacment should be covered, shouldn't it? Its definitely part of the drive train.

Last edited by hunter44102; 03-13-2008 at 10:39 AM.
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  #19  
Old 03-13-2008, 10:36 AM
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Quote:
Originally Posted by jayp View Post
... hmmm... so far we still haven't been able to clear up something... does the patriot and compass engines use a timing belt or timing chain...

anybody got some facts on this one??? at least this way we can clear up as to the type of maintenance that would be needed depending if it's a chain or a belt...
The GEMA 2.0 and 2.4 engines use a chain.

http://www.allpar.com/mopar/world-engine.html

There's pics of the 2.0L engine, where you can clearly see the timing chain. At the bottom are specs for the 2.4L, where it lists it as a chain driven DOHC design. I can't vouch for the 1.8L GEMA engine (which is irrelevant to the Patriot anyway), but I don't have any idea why they'd make some GEMA engines chain driven and some belt driven. Usually an automakers does only one thing throughout entire engine families (say, all 4 cylinder engines are chain driven, and so on).
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  #20  
Old 03-13-2008, 11:14 AM
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thanks for clearing that up... i did some searching around the forum and found this:http://www.jeeppatriot.com/forum/showthread.php?t=405

it only specifies the 2.4l engine though... it does say chain driven...
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  #21  
Old 03-13-2008, 12:56 PM
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Quote:
Originally Posted by hunter44102 View Post
Why does the 2008 Patriot owners manual schedule say "Replace the Timing Belt (2.4L engines). 102,000". (p. 394)

Is it possible that they are just calling it a belt even though it is really a chain?

Actually, does it even matter, if we have the Lifetime Drivetrain warranty, the 102k replacment should be covered, shouldn't it? Its definitely part of the drive train.
Because they are referring to the wrong 2.4L engine. The 2.4L used in the PT Cruiser uses a timing belt.

I repeat all world engines 1.8L. 2.0L, & 2.4L use a timing chain.
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  #22  
Old 03-13-2008, 01:06 PM
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Quote:
Originally Posted by Terasec View Post
that is seperate,
...some cars are more costly hondas can cost you +$1000 to replace the Chain,...
As far as I know, the honda's don't use timing "Chains". And for sure the civic's don't use a "Chain". I would say all Honda Civic's from at least 1984 have always used Timing "Belts" and had to be checked at 100,000km's and replaced at 150,000km's.
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  #23  
Old 03-13-2008, 01:13 PM
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You are right

Quote:
Originally Posted by jeelo View Post
As far as I know, the honda's don't use timing "Chains". And for sure the civic's don't use a "Chain". I would say all Honda Civic's from at least 1984 have always used Timing "Belts" and had to be checked at 100,000km's and replaced at 150,000km's.
looks like civics do use belts,
This thread has me all confused,
going by memory,
Before i confuse myself even more(and others)
Punching out
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  #24  
Old 03-13-2008, 01:19 PM
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Quote:
Originally Posted by jeelo View Post
As far as I know, the honda's don't use timing "Chains". And for sure the civic's don't use a "Chain". I would say all Honda Civic's from at least 1984 have always used Timing "Belts" and had to be checked at 100,000km's and replaced at 150,000km's.
did some more research and it looks like the late model 2.4L's used a chain. I think Honda is starting to mix it up in the engines. Some use a belt and some use a chain. I couldn't tell you which ones exactly.

Regardless, if the vehicle uses a timing chain it should last the lifetime of the vehicle. Timing belts should be replaced at 60,000miles or 150,000kms unless specified differently in the owner manual or under the hood.
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  #25  
Old 03-13-2008, 02:13 PM
SkyBlade SkyBlade is offline
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My 2001 Neon ACR has a timing belt that needs to get replaced at the ~100K mile mark. It costs in the $100 range.

The world engines 1.8, 2.0 and 2.4 all use the chain as stated before.
This is a picture of the 2.0 from allpar.com
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  #26  
Old 03-13-2008, 02:20 PM
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2001 ACR?

Quote:
Originally Posted by SkyBlade View Post
My 2001 Neon ACR has a timing belt that needs to get replaced at the ~100K mile mark. It costs in the $100 range.

The world engines 1.8, 2.0 and 2.4 all use the chain as stated before.
This is a picture of the 2.0 from allpar.com
Didnt realize they still made the acr,
thought after SCCA deducted points for ACR's they did away with them,

Are you sure its not $100 for the part?
98 neon RT, it was 3.5 book hours for the belt,
and 2.5 book hours for the pump, (always, tried to argue that since you gotta remove the pump to get to the belt)
Hourly rate alone ranges from $262.50 if in PA at $75/hr for just the 3.5 to $570.00 NY price of $95/hr for the full 6 hrs
not including parts, tax, headache fee's etc

not counting do it yourself price
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  #27  
Old 03-13-2008, 03:00 PM
MrSensible MrSensible is offline
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Rule of thumb

My service manual says BELT. I would believe that too. According to CRX the 2.4L uses overhead cams (OHC) which means the rotating cam shaft is mounted at the top of the head. I might be wrong, but rule of thumb always was that OHC uses belts.

In OHC engines the cam shaft sits on top of the head. When it rotates, the individual cams on the shaft activate the valves directly as it turns. The cam shaft has to be turned in perfect sync with the crank shaft which means you need something that runs from the very bottom of the engine to the very top of the engine. They use a belt for two very basic reasons. One is that it is a long distance. Chains do not do well over a long distance. They have absolutely no elasticity so they can't be tightened very well so they flap causing timing jerk and noise. The other reason is that since chains are metal, they need lubrication. You can't adequately lube a chain unless you have it in a sealed housing filled with oil. That creates big problems that I won't get into.

The other design that does use a chain, places the cam shaft in the engine block right next to the crank shaft. In that case, the cams push on lifters which, in turn push on push rods which then push on tappets which activate the valves. Tappets are little fulcrums that redirect the force 180 degrees so the push rod pushing up actually then pushes down on the valve through the tappet.

The chains in that config are very short and do not require an idler for slack. Lubrication is accomplished by placing the timing chain within the crankcase so it can be lubed by the engine oil.

Both have their advantages and disadvantages.
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  #28  
Old 03-13-2008, 03:46 PM
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I have concluded that my owners manual is wrong in stating to replace the "timing belt" at 102,000 miles. It is clearly a timing chain as Akula has pointed out. It is a long chain though and does travel all the way from the crankshaft at the bottom, then all the way over both camshafts at the top. If MrSensible is right about the OHC typically using belts, I hope we don't have problems with these in the future. The longer than usual chain may be the reason it needs to be replaced at 102K and won't last the life of the engine.

It can easily be seen driving the two overhead camshafts in the pictures at:
http://www.allpar.com/mopar/world-engine.html
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  #29  
Old 03-13-2008, 03:56 PM
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Quote:
Originally Posted by hunter44102 View Post
Actually, does it even matter, if we have the Lifetime Drivetrain warranty, the 102k replacment should be covered, shouldn't it? Its definitely part of the drive train.
The 102K replacement is part of the maintenance schedule just like oil changes. They won't do anything in the maintenance schedule for free. But if you don't keep up with the schedule, you run the risk of your powertrain warranty being void if the neglected service contributes to a problem.
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  #30  
Old 03-13-2008, 04:34 PM
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Quote:
Originally Posted by hunter44102 View Post
...Actually, does it even matter, if we have the Lifetime Drivetrain warranty, the 102k replacment should be covered, shouldn't it?...
Well, it will matter to subsequent owners, who don't get the Lifetime warranty. And that will result in better resale value for the original owner when it is time to sell.
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