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usually a dirty MAF sensor would do it
 

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Discussion Starter · #4 ·
new member---major engine knock-thanks for info-could it be

thanks for the information something to look at, but before I pull the head is it possilbe the waterpump could be doing the knocking and the EGR making it idle bad---just trying to get as much info as possible before I go elbow deep into the engine---thanks again for the help
 

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EGR wouldn't cause knocking at idle because it brings in exhast gases into the combustion chamber to keep knocking from happening. water pump wouldn't be it cuz it's part of the cooling system. if it goes bad it will leak coolant all over ur engine.
 

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If its a dropped valve seat, the compression in at least one cylinder will be zero - usually #4. The gases blowing back into the intake manifold around the missing valve seat will also mess up the the induction for the other 3 cylinders. Its also likely the spark plug for the bad cylinder will show signs of being hit by metal bits.

Im curious how you checked that the main/rod bearings were good?

And if it -is- a dropped valve seat, it is quite possible the piston will be damaged, the compression rings caught in the squashed grooves, and the wrist pin bore distorted by the damage to the piston top.
 

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Before going too far, check the timing. I had the harmonic balancer go bad on my escort, threw the timing way off. If it fires far enough out of time you could get a bad knock. Check all the basic things that you can, compression, plugs, etc. It's amazing how badly an engine can run with one little thing not right.
 

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not sure how a dirty MAF could cause a knock... never heard that one before.

As Sparky said, check timing. If you jump a tooth, it can sound like a bad knock. It happened to me once many years ago. If the timing is good, pull the spark plugs and check them for damage.
 

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juggalo, seriously dude?

a dirty maf won't cause a knock, but it will cause a bad idle.

a water pump can make a knocking noise, there are bearings inside of it, and if they go bad, well... they knock.

and also, EGR is not to keep a motor from knocking, don't even know where you got that information. It's to keep combustion chamber temps down.
 

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I wouldnt blame the EPA; they are not a lawmaking body. The U.S. Congress passed the Clean Air Act, and the Motor Vehicle Safety Standards Act - and the many amendments thereto, & they were signed into law by presidents starting with Nixon: Not by the EPA itself. All of those legislators were elected by folks like you and I.
 

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oh yeah, dirty maf only does this a 55+ mph due to uncalculated airflow giving less gas to spray making the motor surge and ping. the EGR only works at idle or wide open throttle to keep the temps down so it would keep knocking from happening, but if the temps rise that would mean the EGR isn't working and the fuel system is leaning at idle causing pinging to happen. i got this info on here because someone wanted to take out their EGR to gain power which wouldn't be such a good idea. if it's a continuous knocking sound u probably don't have enough oil in the head which was what i ended up with. check how much oil u have.
 
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