Hey everyone,

I used to think that my car pulled all the way to redline with out any problems. If I bring the tach up to 5000rpm, I have no problems. A couple times a went a hair over that and got a loud knocking sound from the engine. However, after getting an ALDL cable and checking the rpm right from the engines computer, I found out that when my tach shows 5000rpm, the engine is actually at 4200-4300 rpm. That means that the knock that I heard was actually below the 5000rpm redline! The car has 142000 miles on it so I am guessing that my valvesprings are weak and they need to be replaced. Would everyone aggree with me?

Thanks
Mark Balistreri

 

Sounds about right.

 

How loud is the knock, what does it sound like? Low metallic sound? Higher pitched ping sort of noise?

 

Sounds like it might be a timing issue (too much advance - detonation)

 

I agree with the spark knock suggestion. Have you checked the timing since this has started?

Again, though, what's it sound like?

 

I dont know if its an actual knock. It makes a very loud knocking sound. Its a low pitched metal hitting metal sound. Ill have to check the timing.


I just did some math... If my car has 143,000 miles on it and I turn about 3000 RPM @ 80mph... Then if my car was driven 80mph for the entire 143,000 miles... Then each one of my valve springs have been compressed 160,875,000 times!!!! Regaurdless of what is causing my problem, I am replacing those valve springs!!!!

1500 compressions per minute @ 80mph
1500 x 60 = 90000 compressions per 80 miles
143000 / 80 = 1787.5
1787.5 x 90000 = 160,875,000

 

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Wow you have entirely to much time on your hands lol. J/p. Nice to know about the valve springs i may do the same to mine for the hell of it anyways.

 

Low metallic sound sounds like worn bearings. It may just be worn out inside.