help asap, knocking sound
02-21-2009, 04:57 PM
#11
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
Some engines just rattle a bit when they start, my '03 has done it since I got it with 30k miles (it now has 80k). My supercharged '92 Miata did this for the 230k miles I owned it.
This is relatively common in newer (keep in mind I'm old, so "newer" means the last 20 years) because they start so rapidly, before the oil has started moving. When it's real cold (35° is real cold here in Saint Augustine) I have taken to turning the engine over 4-5 turns with a non-programmed key before starting it.
This is relatively common in newer (keep in mind I'm old, so "newer" means the last 20 years) because they start so rapidly, before the oil has started moving. When it's real cold (35° is real cold here in Saint Augustine) I have taken to turning the engine over 4-5 turns with a non-programmed key before starting it.
02-21-2009, 08:16 PM
#12
5th Gear Member
Join Date: Jul 2007
Location:
Posts: 2,363
why is piston slap out of the question? people with forged pistons have had this problem before, the piston expands as the engine builds heat and until this happens you can get minor piston slap. now with the factory hyperutectic pistons it is more uncommon but none the less cylinder wear can happen.
02-21-2009, 08:30 PM
#13
2nd Gear Member
Join Date: Sep 2008
Location: PA
Posts: 170
deff not valve tick it is metal to metal, an now appears to do it all the time, it sucks bc i have put maybe 500 miles on the car since i bought it, and it is n excellent shape has new everything. but i startin to get mad now bc i cant drive it bc i dont know what gone happen
02-21-2009, 10:34 PM
#14
aka 'Negative Nancy'
Join Date: Jul 2007
Location: Ohio
Posts: 4,839
why is piston slap out of the question? people with forged pistons have had this problem before, the piston expands as the engine builds heat and until this happens you can get minor piston slap. now with the factory hyperutectic pistons it is more uncommon but none the less cylinder wear can happen.
02-22-2009, 10:37 AM
#16
Super Moderator
Join Date: Jul 2003
Location:
Posts: 14,917
I've had a few different vehicles that ironically had horrible piston slap, most recently an 02 GT. But whatever, that doesn't matter right now - we can argue about that a different time.
Pick up a mechanics stethoscope. Or use a long screw driver. Place it over each cylinder.
Turn your car on, pull the fuel injector connector on each cylinder while it runs and see if you can isolate the sound to a particular cylinder. Your CEL light WILL come on because of the miss fire from pulling the injector, just disconnect your battery for a few and you will be all set.
If you are hearing a knocking now that is sticking around for a long time, you can rule out piston slap.
Have you done a compression test yet?
Last edited by Dan04COBRA; 02-22-2009 at 10:40 AM.
02-22-2009, 05:21 PM
#19
1st Gear Member
Join Date: Dec 2007
Location: Washington
Posts: 112
thats interesting that changing the oil had a negative effect. not very good news for u though. there is a lot of theory on what it might be, but no one is really going to be able to tell you for sure.
your valve train, and your tensioners rely on ur flow of oil to function properly. either case the dmg can get nasty fast.
i would pull the drivers side valve cover and look at the tappets, hopefully something stands out, otherwise from there i would pull the front cover and look at the tensioners.
no luck there and i would remove the cams, to see what the journals under them look like. if they dont get oil they will spin the oil holes under them shut, shutting off oil to ur valvetrain, until the pressure can send it from somewhere else.
then overnight the oil would drain until u started it again the next day.
changing your oil might have dry spun that cam and sealed more ports.
since u changed cam sprockets im wondering if u properly lubed the cams before u started it?
i did this 2 my first set of heads. and my car sounded like my tranny was almost knocking as i drove, i have no sound dampening on my shifter. i couldnt figure it out and ended up doing a pi swap and finding the problem.
drivers side bottom end knock is a pretty good description of it. first it was when my car was cold, then it was constant at certain rpms.
what weight oil are you using? when you pull the valve cover u wont see anything physically wrong, but you should see burnt oil splatters, and be able to smell it.
also the shavings the cam generated plugged one of my chain tensioners.
out of curiousity, did you overspin it recently? bang the limiter really hard or accidently miss a gear or shift down instead of up?
your valve train, and your tensioners rely on ur flow of oil to function properly. either case the dmg can get nasty fast.
i would pull the drivers side valve cover and look at the tappets, hopefully something stands out, otherwise from there i would pull the front cover and look at the tensioners.
no luck there and i would remove the cams, to see what the journals under them look like. if they dont get oil they will spin the oil holes under them shut, shutting off oil to ur valvetrain, until the pressure can send it from somewhere else.
then overnight the oil would drain until u started it again the next day.
changing your oil might have dry spun that cam and sealed more ports.
since u changed cam sprockets im wondering if u properly lubed the cams before u started it?
i did this 2 my first set of heads. and my car sounded like my tranny was almost knocking as i drove, i have no sound dampening on my shifter. i couldnt figure it out and ended up doing a pi swap and finding the problem.
drivers side bottom end knock is a pretty good description of it. first it was when my car was cold, then it was constant at certain rpms.
what weight oil are you using? when you pull the valve cover u wont see anything physically wrong, but you should see burnt oil splatters, and be able to smell it.
also the shavings the cam generated plugged one of my chain tensioners.
out of curiousity, did you overspin it recently? bang the limiter really hard or accidently miss a gear or shift down instead of up?
Last edited by ezking; 02-22-2009 at 05:32 PM.
02-23-2009, 01:45 PM
#20
Thread Starter
Join Date: Feb 2009
Location: florida
Posts: 12
Ok i just drove it about an hour away today to the best mustang shop in the south, and by the time i got there there was no noise at all the mech drove it put a steth on the bottom the oil pan nothing, the only thing he noticed is that i have a bad idler pulley, i have not revd the car or even drove it hard at all i have put less than 500 miles on it since i bought it last month, and they were just normal driveing. so now it seems if i drive it for a while it goes away completey. I have never changed the cam sprockets, and i use castrol syntec full syn 10/30 as i live in florida and its always hot. i have had 7 mustangs in the past 2 yrs and put the same oil in them all, i have never had this noise though, and have had mustangs with over 150k on them