My boyfriend and I just changed the A/C compressor today on my Z24 and now its not grinding so that is good. What isn't good is this:
When the car is started it sounds like rocks in a blender, but only when you crank it up. It will idle smooth but every 10-15 seconds it makes a clunking/chunking sound. My boyfriend got under the car and said he could her it also.
If you rev it up as the revs come down it makes a grinding in the engine somewhere. It does this with the belt off so its not an accessory causing the problem.
We were thinking rod bearing but that would make a knocking that got worse the higher the car was revved. This only makes noise when the engine changes speed rapidly, like a free rev, or when you get on it and let it rev up, then let off and it shifts it grinds if the rpm's make a major drop.
Could this be the timing chain guides or tensioner? That's what we are thinking now. How hard is it to replace the chain and guides and tensioner and can it be done with the engine in the car?
I will try to take a short video of the car starting and revving so you guys can hear what noise I'm talking about. Maybe tomorrow.
does it only happen when you crank it up after sitting overnite or after a while?? if so, my car makes the same noise. i'll crank it up in the morning and it will make same noise for a couple seconds and go away. it doesnt come back thought until the next morning. i havent looked into it cuz im sure its something internal. dont have a clue as to what it could be though.
Peace Out!!!
No it does it everytime no matter what. My A/C compressor had a bad bearing that was grinding but I put a new one on two days ago and its been fine now. So I know its not that. I also ran the engine for a few seconds with the belt off so I know its not the a/c or alternator causing the noise. I think it may be the timing chain guides or tensioner or water pump bearing? I can hear the noise in the oil pan but its not making any rod bearing symptoms.
I'm just wondering if anyone else has had this same problem and what was the fix?
If its making the noise all the time it might be a lifter tapping and carrying on in the engine.
maybe ran the belt wrong , and the tensioner is rattling
my friends rattled when it was ran wrong
It does it with the belt off.
Last night I held it in 1st and got on the gas. When I let up as the engine revved down it made that god awful grinding sound. WTF???
Well I'm about to take the motor mount and timing chain cover off in a few minutes. I just drained the cooling system and removed the resovoir. Now I have to pull the front right wheel, put it up on jackstands, remove the balancer, and then I can get the cover off. I'm thinking the chain has either broken or jumped off the sprokets and I'd bet the tensioner is shot.
The car died when Jen and I were driving home one night. It would crank very fast and only sounded like the bottom half of the engine was turning.
I pray we don't have bent valves.
Now when I get it all apart and new tensioner, guides, and chain. How do I set the timing. Just put the screws into the two cam sprockets to hold them and then put the crank to the dot facing up? Sounds simple if Chevy was smart enough to mark it. I just don't want to have it way out of time and have to tear it down again. Also if I have bent valves, how will I know till I start it? Maybe I should do a compression test before we actually fire up the engine.
Scott
2002 Audi S4, black
1996 Z24 auto, red
Don't want to scare you but sounds like the crank bearing...I just replaced the engine in my 99 Z for that same noise... I could be wrong though, but I would start there...
well i'm pretty sure it was the tensioner either making the noise, or it was keeping the chain tight enough and it was hitting the guides and making noise.
I am stuck now and can't get the motor mount bracket off the engine since its too close to the fender, the jack I have won't go high enough to get the bolts accessible from the top, and I can't go down now or the engine will fall. I might get a cherry picker from a friend and hoist the engine from above, or I guess I'll have to buy a bigger jack (a real floor jack) not the little $40.00 jack I have.
Scott
2002 Audi S4, black
1996 Z24 auto, red
disregard this post