Cooling Problem
Thread Starter
1st Gear
Joined: Sep 2024
Posts: 1
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Cooling Problem
So I've been chasing a cooling problem on my stock 2000 C5 Z51. There was a crack in the nipple of the coolant reservoir that was leaking coolant. so I changed that but didn't fix it. The coolant seems to be flowing and the fans are turning on. Coolant isn't turning brown or any dirty color.
I also noticed a decently loud hissing noise has developed recently coming from the front of the engine around the front of the intake area that I didn't hear before, or at least wasn't loud enough for me to notice. Another new noise I'm hearing is a rattling coming from what sounds like the pulley system on the passenger side. The harmonic balancer was changed about 2 years ago with a summit racing balancer. Doesn't seem to be wobbling or look out of sorts. Any suggestions would be greatly appreciated!
I also noticed a decently loud hissing noise has developed recently coming from the front of the engine around the front of the intake area that I didn't hear before, or at least wasn't loud enough for me to notice. Another new noise I'm hearing is a rattling coming from what sounds like the pulley system on the passenger side. The harmonic balancer was changed about 2 years ago with a summit racing balancer. Doesn't seem to be wobbling or look out of sorts. Any suggestions would be greatly appreciated!
Tech Contributor
Joined: Jan 2007
Posts: 19,398
Likes: 1,139
From: Dyer, IN
So I've been chasing a cooling problem on my stock 2000 C5 Z51. There was a crack in the nipple of the coolant reservoir that was leaking coolant. so I changed that but didn't fix it. The coolant seems to be flowing and the fans are turning on. Coolant isn't turning brown or any dirty color.
I also noticed a decently loud hissing noise has developed recently coming from the front of the engine around the front of the intake area that I didn't hear before, or at least wasn't loud enough for me to notice. Another new noise I'm hearing is a rattling coming from what sounds like the pulley system on the passenger side. The harmonic balancer was changed about 2 years ago with a summit racing balancer. Doesn't seem to be wobbling or look out of sorts. Any suggestions would be greatly appreciated!
I also noticed a decently loud hissing noise has developed recently coming from the front of the engine around the front of the intake area that I didn't hear before, or at least wasn't loud enough for me to notice. Another new noise I'm hearing is a rattling coming from what sounds like the pulley system on the passenger side. The harmonic balancer was changed about 2 years ago with a summit racing balancer. Doesn't seem to be wobbling or look out of sorts. Any suggestions would be greatly appreciated!
The hissing noise you have to locate yourself, no one can do that for you. Did you follow the service manual procedure to get the air out after changing the coolant reservoir? What temp do the fans turn on at? Rattling in center of motor could be water pump....but troubleshooting will reveal that.
Last edited by lucky131969; Sep 27, 2024 at 08:29 AM.
Safety Car
Joined: Mar 2017
Posts: 3,767
Likes: 938
From: Orlando Florida
The radiator is known to have a tendency to crack the driver’s side tank in the immediate area of the inlet hose fitting. Difficult to see, look for coolant residue on the surrounding rail after a drive. Took me days to figure out where my coolant was going.
Melting Slicks
Joined: Feb 2001
Posts: 2,803
Likes: 357
From: Northville, MI
IS the car over heating? If not it is probably in the serpentine belt pully area, if it is also overheating look for a pinhole crack in the coolant reservoir area by the engine. That will make a hissing sound as it hits the engine block and when checking the coolant level is will sloly go down each check.
