Broken Timing Belt

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  #1  
Old 11-03-05, 08:54 AM
hotwire58
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Broken Timing Belt

1995 Dodge Intrepid 3.5 V6 Does this cause engine damage or is there a possiblity replacing the belt will fix the problem. I'm getting ready to use as a tradein and without it running it probably has no value? Don't know my options at this point. Belt broke on the freeway and I pulled over ASAP. The car had quit running immediately after I heard the pop, when I stopped I noticed collant coming from the overflow but the car had also overheated that quick.
 
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  #2  
Old 11-03-05, 10:23 AM
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Some cars, mostly imported, have an interference fit, where the piston can run into an open valve. Yours should be okay. If you D.Y.I. it, make certain that you get the timing marks properly aligned.
 
  #3  
Old 11-03-05, 11:24 AM
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I had a cylinder compression test done on a car I had with a broken timing belt. If the cylinders hold compression, your enigine is still good.
 
  #4  
Old 11-03-05, 11:50 AM
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Originally Posted by J.M.C.
I had a cylinder compression test done on a car I had with a broken timing belt. If the cylinders hold compression, your enigine is still good.
This is incorrect if you are talking about a compression check before the belt is replaced. And it is too much work to change the belt and then do a comp check. If it was a bent valve then the belt would have to come back off to pull the head.
If the belt is broken then the cam will not turn and if a valve is in the open position on any cylinder then that cylinder will have no compression. The dealer and some shops have a simple book that list all types of cars and if they DO or DO NOT bend valves when the belt breaks. Give them the vehicle make and engine size and if they have the chart they can tell you YES or NO if you have a bent valve.
 
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Old 11-03-05, 05:00 PM
dabirdzR?T
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3.5's are a non interference engine, and i have never hear of one bending a valve when the belt breaks, but just an FYI, replace the water pump when you are in there, since its right there.
 
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Old 11-03-05, 09:33 PM
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So does this mean the mechanic who told me my engine was scrambled because of the results of a compression test didn't know what he was doing?
 
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Old 11-03-05, 09:44 PM
Ramrod48
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scrambled

well if he tryed to do a compression test on a engine that the cam is belt driven , an the belt is off the engine -- theres no way for the valves to open an close, hence the cylinder compression readings will not be correct,,, he didnt buy the car off you did he ??
 
  #8  
Old 11-04-05, 05:39 AM
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No, he didn't buy the car and the book said it did bend valves when the belt broke, so it probably was still junk. I hate it when you are given bad info like this and then look like an idiot passing it on. Gonna have to have a talk with this guy....
 
  #9  
Old 11-05-05, 08:12 PM
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Actually if you take the time to manually move the pistons, and cams, a compression test can be done..Piston TDC, move cam so valves are closed...
 
  #10  
Old 11-05-05, 11:57 PM
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Originally Posted by msargent
Actually if you take the time to manually move the pistons, and cams, a compression test can be done..Piston TDC, move cam so valves are closed...
BUT if that type engine bends the valves then if you attempt to do the above you will bend ALL the valves and have to remove the head or BOTH heads on a V-6 or V-8 engine.
Say you get #1 piston at TDC to check that cyl, well another cyl will have a valve that is full open which will bend that vaive. Then when # 2 piston is up the next cyl in order will have a valve open and it will bend and so on. Once you were finished checking each cyl you would have sucsessfully bent a valve in every cyl.

And you have to have a timed valve sequence to get compression, if the valves are closed it will not show compression. As the piston travels down with the valves closed it will put a vaccum on the cyl chamber and when the piston comes back up it will return to regular pressure. You have to have the intake stroke to allow the cyl to fill with air. Then the intake valve closes to give you compression on the compression stroke.

You have to have a couple of revolutions to get a full compression check not just one up. The timming belt has to be on and in time to get a good compression check.
 

Last edited by chevydrivin; 11-06-05 at 12:58 AM.
  #11  
Old 11-06-05, 05:54 AM
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The 3.5 will not bend valves when a timing belt fails. The usual cause of timing belt failure is a seized water pump. The timing belt idler pulley should also be replaced.
 
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