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engine makes loud metallic knocking sound


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tarbender
Novice

Jun 24, 2013, 1:34 PM

Post #1 of 5 (2218 views)
engine makes loud metallic knocking sound Sign In

93 olds 88 royalle 3.8ltr 114,000 mi. car over heated almost to red on temp gauge. put water in brought temp back to normal. car started but drove poorly for about half mile.then power returned drove about 2mi. stopped at light,engine was making a low knocking noise.checked oil it was quart low added oil.drove home after increasing speed to 40mph noise from engine stops.but still there at idle speed.the engine still seems to have normal power at this point? metallic knocking sound at start up and idle seems to have incresed but driving at 40mph or above sound stops?


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jun 24, 2013, 1:55 PM

Post #2 of 5 (2207 views)
Re: engine makes loud metallic knocking sound Sign In

Did you find out where the coolant is going? Where does the knocking noise sound like it is originating from?

Can you record the noise and upload it to a video hosting site and then send us the link?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jun 24, 2013, 1:56 PM)


tarbender
Novice

Jun 24, 2013, 5:51 PM

Post #3 of 5 (2170 views)
Re: engine makes loud metallic knocking sound Sign In

the car is in san antonio and im in austin. however it sounds like it is coming from the engine- firewall passenger side- also i omitted a pretty important detail-turning the serpentine belt by hand it will move 3 to four inches and will get the metallic noise going clockwise but not counter clockwise.so i know the problem is in the bottom end,just don't know what it is. thanks for your intrest


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Jun 24, 2013, 6:00 PM

Post #4 of 5 (2167 views)
Re: engine makes loud metallic knocking sound Sign In

One possiblity is you have a bad harmonic balancer. The older 3.8L had a common problem with the rubber coming apart in the balancer causing the hub to chuck and make rattling banging noises. It really would make the noise at idle, but revving the engine would make it go away.

Here's is an example of that:

http://www.youtube.com/watch?v=lwugNhAwNgg





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


tarbender
Novice

Jun 24, 2013, 7:02 PM

Post #5 of 5 (2155 views)
Re: engine makes loud metallic knocking sound Sign In

hey thanks for the video. and the harmonic balancer makes sense...i was worried rod or crank...but couldn't understand no loss of power and noise stopping at 40mph. it will be a week before i get back to S.A and work on the car.but i will let you know for sure when i get it on the road. thanks alot for your insight it's really appreciated






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