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Rod knock or something else? Need Help please

 
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Old 28 Jul 2018, 02:02 pm
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Exclamation Rod knock or something else? Need Help please

Hi all it's been forever since I posted something on the forums LOL
Usually when I do it's not even my question..
Anyways a buddy of mine owns a 2003 GT he has the stage one in it.
Only 111,000 km on it brand new transmission maeby 300km on it.
Recently he heard a knocking sound...He was at a gas station and started his car, it made a minor knocking sound...He asked the guy beside him if he could hear it and what he thinks it would be. He thought and the guy at gas pump thought it might be a loose muffler. He drove straight to the Muffler place and they checked it out and said everything was tight. The car stopped making the noise. Then a few days later when he turned the air conditioning on he heard that knock again only this time it sounded like a hammer banging on a piece of metal. He took it to a few mechanics but could not get it to make the noise.
Finally one of them got it to make the noise so they used a stethoscope and said it is definitely a rod bearing or something major going on down there.
But it only makes that loud knocking when the air conditioning is turned on and not all the time. I heard it yesterday and we got it to make the noise and it was loud..I figured it's something major. It doesn't do it when he starts it and it runs normal no knocking at all. He drove it like normal and then pounded on it and went a bat outta hell..He is still running it and he seriously been pounding on it. Still no banging. But only hears it once in awhile when air is turned on at idle, not all the time though..He has been driving it as normally he would. No knock when started, no knock when he steps on it after he starts it.
I still think it a serious bottom end problem. It is so loud when he can get it to make the sound but starts normal and runs normal all gauges normal. No metal filing in oil. Any ideas?
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Old 28 Jul 2018, 02:21 pm
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Default Re: Rod knock or something else? Need Help please

I would check the torque converter to flexplate bolts for tightness first before tearing into the motor. It may be the flexplate cracked where it bolts to the crankshaft too?!
I'm just guessing , but with the transmission being replaced recently, there is a possibility
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Old 28 Jul 2018, 04:20 pm
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Default Re: Rod knock or something else? Need Help please

Quote:
Originally Posted by SPLNeon View Post
I would check the torque converter to flexplate bolts for tightness first before tearing into the motor. It may be the flexplate cracked where it bolts to the crankshaft too?!
I'm just guessing , but with the transmission being replaced recently, there is a possibility
Good diagnosis... definitely worth checking out.
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Old 28 Jul 2018, 05:28 pm
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Default Re: Rod knock or something else? Need Help please

I would suggest checking to make sure the freon level in the A/C is not low.
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Last edited by ptcruisersteve; 28 Jul 2018 at 05:32 pm.
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Old 28 Jul 2018, 05:37 pm
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Default Re: Rod knock or something else? Need Help please

Quote:
Originally Posted by SPLNeon View Post
I would check the torque converter to flexplate bolts for tightness first before tearing into the motor. It may be the flexplate cracked where it bolts to the crankshaft too?!
I'm just guessing , but with the transmission being replaced recently, there is a possibility
+1

My thoughts as well since the tranny has been changed out.

I had the same thing happen on a Ford some years back after a warranty engine replacement at the dealership.
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Old 28 Jul 2018, 11:26 pm
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Default Re: Rod knock or something else? Need Help please

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Originally Posted by Handy_Cruiser View Post
+1

My thoughts as well since the tranny has been changed out.

I had the same thing happen on a Ford some years back after a warranty engine replacement at the dealership.
Years ago my buddies dad's Ford Taurus developed what everyone thought was a rod knock. When he brought it over it turns out it was a cracked flex plate.

I have also seen engine to transmission bolts loosen. If it is a auto the torque converter bolts loose?

If it really sounds like it is in the bottom end it could be the counter balance chain slop?

Hopefully it's not a bearing.
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Old 29 Jul 2018, 07:23 am
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Default Re: Rod knock or something else? Need Help please

The big question is whether or not he ever heard the noise before the transmission swap. If not, then that's where he needs to start. Loose torque converter bolts will do this. And as they get looser, it's going to become louder and more frequent. I had an 87 Horizon that did the same thing. Drove me nuts, so I sold it to a guy that needed a car. He took it to a garage and they found what it was.
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Old 29 Jul 2018, 02:44 pm
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Default Re: Rod knock or something else? Need Help please

Sorry for the long posts but I am trying to be as clear as I can.
So thanks guys..I passed all the comments to him. Just as most of you said..
He said when the muffler shop did a analysis on it with a stethoscope 2 mechanics had a listen and both said it's coming from the tranny more then likely a torque converter or flex plate bolt. They charged him $45 for that
So off to the tranny shop he went. The tranny has a 3 year warranty. When he got there he said it barley had done it but just enough to hear it for a second or two.They told him it's highly unluckily it's that and said they could check it but it would cost him around $600 to check it out because they would have to drop the tranny. They said that the flex plate and torque converter isn't a tranny problem so it's not covered? They said they can't be sure if that's what it is? So he would be $600.00 out if it's not. The air works as normal and the car did not make a knocking sound before or after they installed the brand new tranny straight from Chrysler. Tranny and install was $4200 and the knocking started at about 420km later...
So he went and got a third opinion from a high end mechanics shop where they fix corvettes and porche ect. Again he could not get it to do it..so he left it with them anyways and they finally got it to do it..So after they diagnosed it they called him and they said it sounds like a deeper engine problem maybe a rod bearing or? They charged him $138 for that.

I have heard it and it is LOUD and sounds like a hammer beating a pot.
He drives it like a bat outta hell still and it seems to be running as normal and not a sound at idle or when he pounds it..He checked the oil and it is clean as a whistle, no metal filings.
He is bewildered as am I I think he just wants to drive it until something happens cause he so pissed..Lol I told him to take it easy in case he makes it worse...He is very grateful of you guys opinions!
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Old 29 Jul 2018, 05:59 pm
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Default Re: Rod knock or something else? Need Help please

Quote:
Originally Posted by ptcruisersteve View Post
I would suggest checking to make sure the freon level in the A/C is not low.
I am suggesting that after doing repairs to the engine or in the engine compartment that the A/C lines get moved around and start leaking. The A/C compressor can be sensitive to low pressure and I have seen some articles of the A/C compressor knocking.
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Old 03 Aug 2018, 01:59 pm
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Default Re: Rod knock or something else? Need Help please

I suspect, like others, the flex plate bolts are loose or something transmission related. Rod knock is consistent, it does not come and go. Not to say, you might have a loose piece getting knocked around in the oil pan but removing that pan is relatively easy to do as well. Balance shaft guides or chain is a possibility but I have learned to suspect the most recent maintenance action lots of times reveals the issue, especially, if it didn't do it before that specific repair action.
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