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360 Knock at Idle

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mstrcrftr View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mstrcrftr Quote  Post ReplyReply Direct Link To This Post Posted: Sep/28/2017 at 5:10pm
Originally posted by Hurst390 Hurst390 wrote:

I've had stock fuel pumps make a knocking noise years ago..use a piece of hose held to you ear as a stethoscope and try to pin point the location.
If you think it is a rod bearing I would pull the plugs and spin it over and listen to each plug hole..that will tell you if you have a bad bearing


Wow, i havent heard any speak of that method in years.  Very old school and very very effective.  ^5 Hurst390.
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Sep/28/2017 at 6:52pm
Dry fuel pump will eventually self destruct.

Has it got headers?

They can leak at one port (and often do)
resulting in a rod knock like noise.
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mixed up View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mixed up Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2017 at 12:44am
use a dowl rod or broom handle or some thing that will transfer sound hold it to he ear and to different parts of motor will help find the knock lose torq convertor bolts will knock
69 amx 290 auto
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Brynjaminjones View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brynjaminjones Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2017 at 3:28am
Cool, thanks guys. I need to find out how the LPG/gas system works and where exactly it cuts off the fuel, as I'm wondering if the pump could be running dry.

It doesn't have headers - just the original cast style manifold.
Whilst inspecting last night I noticed that the air pump has been removed, and as such it looks like any other ports on the exhaust have been plugged (although I'm not quite sure what the original setup would've been).

In case it was missed in my previous post, I've also got a video of some play in the water pump shaft. This is with the belts slackened off:


Do you think this could cause a knock that would only be audible when warm? I'm wondering if it could get worse once the viscous fan is locking-up, putting more force on the shaft?


Edited by Brynjaminjones - Sep/29/2017 at 7:19am
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2017 at 6:58am
No video, but there should be NO observable axial play.
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Brynjaminjones View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brynjaminjones Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2017 at 7:20am
Video should be sorted now - my bad!
There definitely seems to be some play.
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amcfool1 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcfool1 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2017 at 8:35am
if your water pump shaft has play in it, its bad, thats your knock. happened to my a couple of years ago. Replace water pump, no more knock. good luck, gz
george z
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Sep/29/2017 at 12:33pm
Yep, the water pump is totally screwed.
Agreed, that's your knock.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brynjaminjones Quote  Post ReplyReply Direct Link To This Post Posted: Oct/03/2017 at 3:28am
Thanks for the help guys. The cooling system needs a good flush anyway, but unfortunately I don't have the means to do so at home, so it's booked in for a replacement next week. 
I'll report back to confirm whether that was the problem!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brynjaminjones Quote  Post ReplyReply Direct Link To This Post Posted: Oct/18/2017 at 4:00am
Hi Guys,

After an eventful week in the shop (many snapped bolts), the water pump has successfully been changed.

This has got rid of the severe play in the shaft, although the viscous fan clutch has a little play too.

At first it seemed like the knock was gone, but a couple of days later I noticed that it's back. 
The Jeep drives beautifully (mechanic said the same - I forgot to ask him to listen for the knock but he evidently didn't notice it) and I've put a few hundred miles on it with no change in sound. The knock still isn't really audible when the engine is cold (this could be because of all the other noise), or at anything much above idle. 

I've not got a video of my Jeep, but the one in this video sounds the same to me in both sound and speed:



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