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Unread 08-26-2003, 02:36 PM   #1
daveleau
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4.0L Timing belt question

I have symptoms (I think) of a going timing belt. The engine seems to sound faster and higher pitched when starting and the idle has dropped a bit, which has not been the case in the past. IF the timing belt goes before I can get it replaced, will it destroy the engine? I had a Honda Civic when I was in college and the timing belt went. It belt rods and tore the engine up to the point where I had to get rid of the car. The same happened 3 months later with my replacement car (Toyota Celica), but the engine damage was not there.

So, is the 4.0L engine designed to be able to handle a timing belt failure without destroying other parts of the engine?

Thanks
Dave

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Unread 08-26-2003, 03:51 PM   #2
ChrisinVA
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The 4.0 doesn't have a timing belt. It's not an overhead cam engine like you're used to. It just has a plain 'ol timing chain, at the bottom of the engine. They generally last the life of the engine.

I seriously doubt that would be your 'problem'. More than likely it's your idle air motor gummed up.
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Unread 08-27-2003, 11:48 AM   #3
TampaXJ
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Im thinking your problem is something with intake. LIke an idle air controller or something to that nature....as far as the engine and serious damage only interference engines cause serious damage when the timing belts let loose...toyotas and hondas(non interference) generally do damage with the water pump goes and seizes the timing belt causing the car to overhead and things inside to warp due to extreme heat...
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Unread 08-27-2003, 12:49 PM   #4
FourthGenHatch
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If the 4.0 isn't OHC than does that mean its a Pushrod engine?

So if that chain broke (if that is even possible?) I heard that on a pushrod engine the pushrods just break but they are easy to fix. Is that true? Do I have the right idea?
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Last edited by FourthGenHatch; 08-27-2003 at 01:02 PM..
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Unread 08-27-2003, 02:52 PM   #5
TampaXJ
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no not really...ok with our engines if the timing chain goes, as long as you stop within a minute or so and shut the car off you'll be fine. now with a cam engine...what happens is the valves open and close, hence the term interference, sowhen the timing belt goes the valves dont get out of the way of the uprising pustons and presto your piston just crushed your still opened valves....
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Unread 08-27-2003, 04:23 PM   #6
JTruel
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Almost all engines are "interference" motors

whether it has a belt or a chain it all works the same. If the belt or gear or chain breaks or jumps (which DOES happen with a timing chain) You have the possibility of busting a few valves. Pushrods are not the weakest link in your engine.. look at a pushrod, most are a little over 5/16 in diameter.. now look at a valve stem.. about 1/8 give or take, which will bend first? You be the judge.
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Unread 08-27-2003, 08:26 PM   #7
ChrisinVA
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Fourth, please don't worry about it. Probably just your idle motor.

And yes...it is a pushrod/overhead VALVE motor. It's a modified version of those inline sixes you see in mail jeeps/CJ's.
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