engine - metal on metal knocking

swift978 · 01-09-2008, 05:46 PM

so i just took my 89 NA out for a quick test drive around the block, revved to 7k once or twice and pulled in the driveway, didn't take longer than 10 minutes. after sitting for 5 minutes idling the engine had a faint knocking sound that slowly grew louder over half a minute. it seemed to be coming from the cylinder block.

the engine was idling at around 700rpm, and the knocking was at 8~12 beats per second. considering the beats match fairly well to how often the pistons are moving, i turned the car off fearing its the push rod.

i'm going to check the push rods, is there anything else it could be check for?

and if i do have to replace them, isn't the piston and rods the only difference between a AGE and an AGZ engine?

djskorch · 01-09-2008, 05:53 PM

you could have spun a bearing in the bottem end, could be that your engine is just worn out and your pistion is bangin the walls. its very hard on the engine, especially the bottem end to go out when the car is cold and rev it up to redline. (cold engine+highrevs=spun bearings) newayz, thats just my 2 cents

swift978 · 01-09-2008, 07:14 PM

hmm well the engine was at normal running temperature by the time it was revved... but i will keep the bearings in mind when i check

DarylP · 01-13-2008, 06:17 PM

Might try this. Start the engine get it warmed up to temp. Let it idle than pull one plug wire at a time and see if the noise goes away when that cylinder is dropped. If it does than it's something with that cylinder (spin rod bearing, lose pin. etc) But would give you a idea as to which bore to look at.

djskorch · 01-13-2008, 06:57 PM

pulling the spark plug wire will not tell you what is wrong with it or where its coming from in most cases. if a bearing is spun or a wrist pin is lose, it will make the noise with or without the spark plug wire pulled because the crank is still turning (spun bearing) and the pistion and rod are still moving up and down (wrist pin or worn out engine)

DarylP · 01-13-2008, 07:01 PM

Yes but the load is reduced so the noise would either go away or be reduced. And it would give you a idea as to which bore the problem is in.

swift978 · 01-14-2008, 03:57 PM

haha well i'm glad i didn't break down the engine, i did alittle more listening using a long screwdriver to my ear to find exactly where the sound was coming from. the sound was coming from below the block.. found a broken crank pulley, also known as the harmonic balancer on the engine.

now the only hard thing to do left is take it off

, i figure wd40 or pbblaster with some brute strength will loosen it good.. thanks alot for your help guys!

DarylP · 01-14-2008, 05:22 PM

good news

MX450248 · 01-14-2008, 11:11 PM

three words for ya, air impact gun.

01-09-2008, 05:46 PM	#1 (permalink)
swift978 1st! Join Date: Aug 2007 Location: Mass Posts: 85 Thanks: 11 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	engine - metal on metal knocking so i just took my 89 NA out for a quick test drive around the block, revved to 7k once or twice and pulled in the driveway, didn't take longer than 10 minutes. after sitting for 5 minutes idling the engine had a faint knocking sound that slowly grew louder over half a minute. it seemed to be coming from the cylinder block. the engine was idling at around 700rpm, and the knocking was at 8~12 beats per second. considering the beats match fairly well to how often the pistons are moving, i turned the car off fearing its the push rod. i'm going to check the push rods, is there anything else it could be check for? and if i do have to replace them, isn't the piston and rods the only difference between a AGE and an AGZ engine?

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01-09-2008, 05:53 PM	#2 (permalink)
djskorch djskorch Join Date: Feb 2007 Location: Idaho Posts: 634 Thanks: 5 Thanked 25 Times in 23 Posts My Google Map iTrader Rating: (6/100% )	you could have spun a bearing in the bottem end, could be that your engine is just worn out and your pistion is bangin the walls. its very hard on the engine, especially the bottem end to go out when the car is cold and rev it up to redline. (cold engine+highrevs=spun bearings) newayz, thats just my 2 cents

01-09-2008, 07:14 PM	#3 (permalink)
swift978 1st! Join Date: Aug 2007 Location: Mass Posts: 85 Thanks: 11 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	hmm well the engine was at normal running temperature by the time it was revved... but i will keep the bearings in mind when i check

01-13-2008, 06:17 PM	#4 (permalink)
DarylP Cage Fighter Join Date: Aug 2007 Location: kennewick,wa Posts: 111 Thanks: 12 Thanked 4 Times in 4 Posts iTrader Rating: (0/0% )	Might try this. Start the engine get it warmed up to temp. Let it idle than pull one plug wire at a time and see if the noise goes away when that cylinder is dropped. If it does than it's something with that cylinder (spin rod bearing, lose pin. etc) But would give you a idea as to which bore to look at.

01-13-2008, 06:57 PM	#5 (permalink)
djskorch djskorch Join Date: Feb 2007 Location: Idaho Posts: 634 Thanks: 5 Thanked 25 Times in 23 Posts My Google Map iTrader Rating: (6/100% )	pulling the spark plug wire will not tell you what is wrong with it or where its coming from in most cases. if a bearing is spun or a wrist pin is lose, it will make the noise with or without the spark plug wire pulled because the crank is still turning (spun bearing) and the pistion and rod are still moving up and down (wrist pin or worn out engine)

01-13-2008, 07:01 PM	#6 (permalink)
DarylP Cage Fighter Join Date: Aug 2007 Location: kennewick,wa Posts: 111 Thanks: 12 Thanked 4 Times in 4 Posts iTrader Rating: (0/0% )	Yes but the load is reduced so the noise would either go away or be reduced. And it would give you a idea as to which bore the problem is in.

01-14-2008, 03:57 PM	#7 (permalink)
swift978 1st! Join Date: Aug 2007 Location: Mass Posts: 85 Thanks: 11 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	haha well i'm glad i didn't break down the engine, i did alittle more listening using a long screwdriver to my ear to find exactly where the sound was coming from. the sound was coming from below the block.. found a broken crank pulley, also known as the harmonic balancer on the engine. now the only hard thing to do left is take it off , i figure wd40 or pbblaster with some brute strength will loosen it good.. thanks alot for your help guys!

01-14-2008, 05:22 PM	#8 (permalink)
DarylP Cage Fighter Join Date: Aug 2007 Location: kennewick,wa Posts: 111 Thanks: 12 Thanked 4 Times in 4 Posts iTrader Rating: (0/0% )	good news

01-14-2008, 11:11 PM	#9 (permalink)
MX450248 Your Resident Welder Join Date: Nov 2006 Location: Maumee, OH Posts: 530 Thanks: 22 Thanked 21 Times in 19 Posts My Google Map iTrader Rating: (1/100% )	three words for ya, air impact gun.