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Timing Belt Break While Cranking?


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The wife has a 96 Legacy Outback 2.5 engine.  Last night she could not get it to fire while cranking the engine. 

 

A passenger standing along side the vehicle while she attempted to start it states they heard a bang sound (later further detailed to perhaps be a snap like a stick breaking) while the wife was cranking the starter. 

 

The vehicle will not start but will crank under the starter power and the cranking seems to sound as normal (not compression free) with no unusual sounds.

 

Could the timing belt have broken while the starter was cranking the engine?  If so, what's the likely extent of damage since it never started?

 

I haven't checked the ignition or anything other than cranking it under starter power yet as it's been raining outside like the great flood but will do so this afternoon.

Edited by steamin53
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You might get lucky with no bent valves.

 

Most likely a frozen up geared idler pulley.  Only way to tell is to pull the timing covers.   

 

You will need to pull all 3 to get a full picture, but pulling just the outside 2 covers will give you a hint of what happened.

 

You can fix the problem, hang a new timing belt and turn it over by hand to make sure its not significant damage.  If it checks good, start it up and listen to it.  

 

You can do a compression check and or check the exhaust for signs of bent valves or worst.

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Thanks for the reply imdew.  What you say is true.  I would have expected a report from the driver and/or passenger that there would have been some other noises if the belt broke wouldn't you?  Also, the report is that the engine never fired during the cranking.  (I wish it had happened to me then I'd be certain).  

 

I'm not sure that if it had broken and valve/piston impact occurred that perhaps it would have locked the engine as I sort of doubt that the starter would have enough torque to continue to turn it over under that condition.  What's your take?

 

Can those covers be removed without removing the AC Compressor/Alternator, etc?

 

Oh yeah... I wish I still had my Guzzi 850 Eldorado...

Edited by steamin53
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Yes, you can remove the timing covers without removing anything else.  It is a little tight in there, but should be no problem.  The biggest issue could be some of the timing cover bolts might be seized up, which means when you go to remove them, some that have captive nuts in the rear cover spin and break the plastic.

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Also, the report is that the engine never fired during the cranking.

 

it does not matter if the engine fired or not - with an intact belt things are still moving/turning over - depending on which version you have - interference, or non-interference - will determine if there is the potential for damage or not if/when the belt broke.

 

from what I have read over the years, 96 is kind of a crossover year, you may have non-interference, you may not...

The best course of action right now is to determine if the belt is indeed broken (pull outer covers to check) and if it is, why did it break, and how much other damage - if any - has been done

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OHHHHHHHHHHHHH JEEEEEEEEEEEEEZ!  I went out this afternoon and checked for ignition with a spark tester light and the danged thing started right up.  Runs Great.   I HATE INTERMITTENT PROBLEMS!!!

 

"I can't fix it if it aint broke!"

 

Thanks everyone for your replies.

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I'm not sure that if it had broken and valve/piston impact occurred that perhaps it would have locked the engine as I sort of doubt that the starter would have enough torque to continue to turn it over under that condition. What's your take?

Broken belt will almost certainly result in bent valves on that engine, and you will have a much faster cranking speed with low or no compression on multiple cylinders.

 

Don't doubt the torque of your starter. By far it has the advantage in that fight. Bending valves won't even slow it down.

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Glad to hear that you got your 96 to fire up.

 

Something to consider.............if it has been a long while since the timing belt has been replaced, then a wise move would be to replace it. On e-bay motors, timing belt kits are available that include the belt, water pump, pulleys & tensioners, and seals, at a good price. It is good insurance and peace of mind to have all that installed at the same time. I did that on my 99 OBW, and glad I did.

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