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-   -   1998 Cobra Emgine noise (https://www.allfordmustangs.com/forums/4-6l-talk/299813-1998-cobra-emgine-noise.html)

James Pickett 06-13-2011 03:30 PM

1998 Cobra Emgine noise
 
I have a strange engine noise, sounds like a knocking that speeds up with engine rpm and almost goes away at idle. I checked with a stethoscope and it appears the noise is not coming from the heads or lower block, timing chain area or waterpump. It gets very loud at the tensioner but the noise almost sounds like a rod bearing. The engine was rebuilt 6 months ago with new bearings, heads reworked, timing gears, chains and tensioners replaced. The only old items are the water pump, AC condensor, power steering pump, belt tensioner and idler bearing.Can a belt tensioner pulley make this knocking or clicking noise.

2Manystangs 06-13-2011 03:53 PM

what about the throwout bearing? Will it stop making the noise if you put the clutch in? and yes it could be a pulley or the tensioner or possibly the fan motor

Bullitt5339 06-13-2011 04:53 PM

Taking the belt off it and starting it would tell you whether the problem is accessory related really quickly.

James Pickett 06-13-2011 05:45 PM

Even with the clutch in the noise is still present. I could remove the belt to be sure.

Bullitt5339 06-13-2011 05:52 PM

It would at least tell you whether it's an accessory problem, or a timing chain problem.

James Pickett 06-13-2011 07:30 PM

I try it tonight after work. Thank you

James Pickett 06-17-2011 11:17 AM

I took off the belt and the noise is still there and progressively getting worse. So far I do not have any issues with the performance of the car. I hope its not a stupid question but with the belt off could it still be the water pump? The only other possibility i can think of is the High pressure Oil pump I installed during the overhaul. I am still hoping it is not the crank or rod bearings. The sound does not appear to be coming from this area. Anybody have any other thoughts.

Bullitt5339 06-17-2011 01:48 PM

It wouldn't be the water pump, since it's turned by the belt. It sounds like you have a timing chain/tensioner problem.

James Pickett 06-18-2011 12:15 PM

The noise got louder like a bunch of bearings in a mixer, the engine performance went down to the point of shutting down like it was hot. I cranked her up this morning, the engine sounds pretty good but the noise is very loud. My Temp gauge has a short in it so it is hard to tell the temp of the engine, so I am not sure she got hot or not, I have checked the fuses, replaced the sensors and still no temp reading on the gauge.

2Manystangs 06-18-2011 12:24 PM

can you post a video of the sound?


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