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Knocking in cold start


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well awhile back my motor spun a rod bearing (happened at about 36,000 miles, i currently have 40,000 miles)..the dealer rebulit it under warrenty. when the bearing was spun, the motor would knock indefinatly at idle and through the powerband. well it started this again, it only does it at startup and between 3000 and 4000 RPMs you can kinda hear it. the dealer is trying to tell me that its just because its cold outside.

they said, and i quote, "its just the pistons slapping against the cylinder walls"

"once it warms up they will expand, and the knocking should stop"

well, that was the most regoddamndiculus thing i have ever heard.

beware of the shrinking piston!!

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The phase II motor are notorious for piston slap. It should only happen when the engine is cold. If it happens when the motor is warm, after 10 minutes or so, odds are it is something else. A bad belt tensioner will give you a knock also. It will usually sound more like a tick than a knock and I do not think it will go away when it warms up. Someone else may chime in with more info on that one.

 

As for one thump, maybe the parking brake is sticking? If its an auto are you on level ground? The car maybe rocking and putting pressure against the detent in the trans. If it's an auto and it happens when you first start moving, not putting it in gear, something is binding somewhere. Don't really know?

 

Legacy2.5R did the dealer rebuild your short bolck or put in a rebuilt short block. If he rebuilt yours you shuldn't be having any knock when cold from pistons. If you have 36K on those pistons without slap you should not have it now. If they honed your cylinders for some reason you could get it but, why would they honed your cylinders?? Do you have the break-down of all they did to your motor? If he put in a rebuilt one from Subbie, that new short block could have a piston slap problem.

 

Peace,

 

Greg

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its my motor they rebuilt, not another one.

 

the startup is not what bothers me as much as when im driving the car after the motor is running at normal temperature, it still does it.

 

im still pissed the dealer blamed it on "expanding pistons"

bababababullshit.

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its my motor they rebuilt, not another one.

 

the startup is not what bothers me as much as when im driving the car after the motor is running at normal temperature, it still does it.

 

im still pissed the dealer blamed it on "expanding pistons"

bababababullshit.

 

 

Bad Motor:(

"Belief does not make truth. Evidence makes truth. And belief does not make evidence."
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negative degree weather = a very unhappy my car

 

my car sounds horrible at startup, whining, knocking any problem i'm sure its happened during some cold startup, i get very worried, but i do have to deliver the school newspapers every monday and tuesday at 5am so that doesn't help either.

 

i definitely don't believe in expanding pistons, but hey, i've been wrong before (not often though!)

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