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1995 Mustang GT loud knocking sound Please help!

2882 Views 5 Replies 3 Participants Last post by  MustangManiac22
I have a 1995 5.0 H.O. V8 Mustang GT 5 Speed with only 90,000 miles that seems pretty much stock except apparently it had a lot of suspension work done to it so that it could take turns better and was also lowered about an Inch and a half, anyways..The PROBLEM is that it makes a loud knocking sound kind of like metal on metal whenever the car is moving and you apply the gas. Like something is spinning and hitting something else.

The sound occurs when: Car is moving. Car has warmed up for about 10 minutes. While car is pulling a light load. Higher RPM causes knock to get faster but it mostly stays fairly constant. Anywhere between 500 rpm through 2300 rpm will cause this sound as long as your not accelerating at great speeds, basically just cruising. The sound occurs even if the car is moving in nuetral and the gas is applied to keep the RPM's up around 900 to 1800. Doesn't matter the gear either as long as the RPMs are 2300 or below. The sound only happens when you use the gas pedal. As soon as your foot releases the pedal the noise stops and as soon as you tap the pedal for a light amount of thrust, noise begins.

The car will not make this sound if its: Cold, sitting still, idling, or without the use of the gas pedal.

So far the only things we can think of are: Drivetrain issue (Has an aftermarket aluminum drivetrain) maybe some sort of loose bolt or something. Something in the engine not sure valves or something. nothing too specific. I tried the EEC self test and while Cold it showed as a 116 which is a ECT (Engine Coolant Temperature Sensor) failure but next day after i drove it and tested it warm, showed just the 111 which is a system pass also tried cylinder test and code 9 or pass so yeah....The sound comes from the top drivers side like behind the dash/speedometer so it doesnt sound like the drivetrain but more like something in the top end of the engine...We are at a loss here Please help me fix my beautiful baby!!!She is clean inside and out. Got side swiped on drivers side by previous owner but just a minor dent and some paint chips as well as the drivers side blinker headlight. Recently had clutch replaced as well as battery. A new stock exhaust as well. I tried to be as specific as possible sorry and thank you!
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Hey MustangManiac22,

Sorry to hear your pony is sick. First of all, you might want to not run the car until you diagnose the problem. If you need to run it to help figure out the source, do it under light load. Get yourself an engine stethoscope. I looked at Ebay and theres some cheap ones there. You can use this to "listen" to the inside of the engine:

Cal Hawk Automotive Mechanic Stethoscope Engine Repair Diagnostic Tool CZMS | eBay

If you have isolated the sound to the top driver side of the engine, it more than likely has nothing to do with the lowered suspension. Inspect the valvetrain. '95 was the last year with the OHV pushrod 5.0 which means you have lifters. Hydralic lifters can fail over time/mileage/use causing a "collapsed" lifter. This essentially means the lifter has failed and now the pushrod that actuates the rocker arm which opens the valves is slopping around. I suggest removing the valve cover and with the engine off, negative battery cable disconnected, rotate the engine by the crank bolt until both valaves on a particular cylinder are closed. Try moving the rocker arm or pushrod of that cylinder to see if there is any "play". Check both valves of each cylinder. If you find a lifter at fault, you need to pull the intake manifold to access the lifter galley. Good Luck.

-Crazy Horse 07
Thank You so much, that is actually what my dad was thinking the problem was and if you do too its definately worth looking into, again thank you!!
If it was the lifters like you were saying, wouldnt it also do it when the car was sitting still..because the sound only happens when the car is moving atleast a few mph like 3 or so...why would a failed lifter not make that sound when the car is sitting still and the engine is on and even if i press the gas pedal it wont make that sound at all without movement of the car...?
You want a video of it? okay i can try to capture the sound
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