ENGINE GRINDING NOISE

Ford F-250

Tiny

320hpPony?

May, 17, 2006 AT 7:50 PM

I have a 1987 Mustang GT. Freshley rebuilt T-5 trans(just over 1200 miles), Freshley rebuilt 5.0 H.O motor(rebuilt at same time as tranny), 30lb injectors, Flowmaste stage3 cat back exhaust system. This is a 2 part question. 1-The motor out of gear when revved will make a grinding noise(fast, higher pitched) at about 4500 rpms, when motor is returning to idle shakes at about 2500 rpms.I, ve almost pinpointed the sound to be coming from/around the smog pump(whic has a small hole in the top hose which is not related to the sound I think). What might the grinding noise be? Could I by-pass the smog pump(shorter belt) without affecting the performance of the engine and could it be benificial to the output of the engine?Is the shaking of the motor at lower rpms (when returning to idle after rev)related to the harmonic balancer? It doesnt seem to do niether grind or shake when driving.
2-Under hard acceleration the tranny will throw the shifter violently out of 1st and 3rd gear.I was thinking that the syncronizers were bad but a friend of mine suggested that since the tranny's still " new" it might be a bent " shifting fork". Any ideas, answers, or ways to determine what the problem is/might be would be appreciated.

1 Answer

Tiny

320hpPony?

May, 18, 2006 AT 7:18 PM

[quote=" 320hpPony?&Quot; ]I have a 1987 Mustang GT. Freshley rebuilt T-5 trans(just over 1200 miles), Freshley rebuilt 5.0 H.O motor(rebuilt at same time as tranny), 30lb injectors, Flowmaste stage3 cat back exhaust system. This is a 2 part question. 1-The motor out of gear when revved will make a grinding noise(fast, higher pitched) at about 4500 rpms, when motor is returning to idle shakes at about 2500 rpms.I, ve almost pinpointed the sound to be coming from/around the smog pump(whic has a small hole in the top hose which is not related to the sound I think). What might the grinding noise be? Could I by-pass the smog pump(shorter belt) without affecting the performance of the engine and could it be benificial to the output of the engine?Is the shaking of the motor at lower rpms (when returning to idle after rev)related to the harmonic balancer? It doesnt seem to do niether grind or shake when driving.
2-Under hard acceleration the tranny will throw the shifter violently out of 1st and 3rd gear.I was thinking that the syncronizers were bad but a friend of mine suggested that since the tranny's still " new" it might be a bent " shifting fork". Any ideas, answers, or ways to determine what the problem is/might be would be appreciated.[/Quote]

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