5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Knock at start up

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Old 05-21-2008, 07:10 PM
  #1  
stanguy306
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Default Knock at start up

Hey guys, a few days back I noticed my car only at startup would knock like 2 or 3 times then go away? Been doing itevery time I start it?Was wondering if anybody experienced something like this before? Thanks
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Old 05-21-2008, 07:59 PM
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mjr46
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Default RE: Knock at start up

could be a weak pump, wrist pin, worn bearings.. you really need to perform a mech test
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Old 05-21-2008, 08:22 PM
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droptop302
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Default RE: Knock at start up

i think its the crankshaft...when you change the oil will it sound worse?
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Old 05-21-2008, 08:27 PM
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mjr46
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Default RE: Knock at start up

ORIGINAL: droptop302

i think its the crankshaft...when you change the oil will it sound worse?
^^^i DOUBT IT..ALTHOUGH I 'm sure there is wear on it ..more so it'd be the bearings....and changing oil won't make it sound worse unless a thin grade of oil like 0w 30 or 5w 20 was used..if there is wear on bearings going to a 15w 40 or 20w 50 is first step
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Old 05-22-2008, 01:49 PM
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stanguy306
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Default RE: Knock at start up

Thanks guys...yeah that would be gay if it were the bearings....car has like 220k on it...sooooo its def. tired.....
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Old 05-22-2008, 06:34 PM
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Slo5oh
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Default RE: Knock at start up

change out the rockers at all on that one?
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Old 05-22-2008, 09:10 PM
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we b gpn
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Default RE: Knock at start up

do pending on the type of knock you have if it only does it when you start it then goes away it could be a lifter knock. if it is then add some good old engine restore at each oil change it will dissapear.
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Old 05-22-2008, 11:12 PM
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Slo5oh
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Default RE: Knock at start up

ORIGINAL: we b gpn

lifter knock.
lifter pump up.
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Old 05-23-2008, 02:27 AM
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PJC Racing
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Default RE: Knock at start up

WTF are you two talking about?!? LiftersTAP andMain andbottomends knock. Lifter tap is not caused by the lifter lifter pumping up (that's how hydraulic lifter work), lifter tap is usually cause by the lack of the lifter pumping up. And you don't change out the rockers for bad lifters.

stanguy306what oil are you using and when was it last changed? With that many miles your bearing clearances are going to getlarger, you may be able to use a thicker oil but this is just a band-aid/temp sulotion till the bearingsare replaced.


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Old 05-23-2008, 08:56 AM
  #10  
Stella94GT
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Default RE: Knock at start up

could it be a loose mount someplace? a friend of mine had a knock at startup and it was cause by engine vibration becuase he had some old weak mounts.
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