1988 IROC-Z ENGINE KNOCK??
08-30-2017, 07:31 PM
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1988 IROC-Z ENGINE KNOCK??
First time using this site , my last hope to figuring out this knocking issue that has developed.
So here we go...
1988 Iroc 5.7 manual ( 350 swap car ) AC deleted .... only makes the knocking sound when WARM and ONLY at IDLE .
Ive ruled out all of the flex plate issues because the noise completely goes away when you take the belt off. It sounds like it's coming from the front of the engine , so I thought for sure accessories. So I went ahead and replaced the power steering pump ( made no difference ) , replaced the water pump ( no difference again ) , and the thermostat ( no difference I read somewhere that the springs stick?) . The car has great oil pressure and runs great minus the knock. It sounds exactly like a bad rod bearing but it makes no sense as to why you pull the belt off and it totally goes away. I also just tried replacing the harmonic balancer and that made no difference either. I've run out of ideas , any suggestions ? The only time I can get the noise to change is when I put MORE tension on the belt or take the belt completely off. Could my crank be walking ??
So here we go...
1988 Iroc 5.7 manual ( 350 swap car ) AC deleted .... only makes the knocking sound when WARM and ONLY at IDLE .
Ive ruled out all of the flex plate issues because the noise completely goes away when you take the belt off. It sounds like it's coming from the front of the engine , so I thought for sure accessories. So I went ahead and replaced the power steering pump ( made no difference ) , replaced the water pump ( no difference again ) , and the thermostat ( no difference I read somewhere that the springs stick?) . The car has great oil pressure and runs great minus the knock. It sounds exactly like a bad rod bearing but it makes no sense as to why you pull the belt off and it totally goes away. I also just tried replacing the harmonic balancer and that made no difference either. I've run out of ideas , any suggestions ? The only time I can get the noise to change is when I put MORE tension on the belt or take the belt completely off. Could my crank be walking ??
08-30-2017, 07:52 PM
#2
Senior Member
Re: 1988 IROC-Z ENGINE KNOCK??
Smog pump? Belt tensioner? Does the noise follow rpms at all? If it's a true knock it will get louder with rpms.
08-30-2017, 07:56 PM
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Re: 1988 IROC-Z ENGINE KNOCK??
thanks for the reply , but no the noise does not follow RPMS at all . The noise is only at idle , and completely goes away when you rev it up to anything above idle . It only happens once it gets warm too ... the car does not have a smog pump or any emissions in fact . They have all been removed .
