Sludge in Coolant Reservoir
Thread Starter
8th Gear
Joined: Jun 2007
Posts: 8
Likes: 0
Sludge in Coolant Reservoir
I'm hoping someone can point me in the right direction on this.
I noticed some dark goo-y stuff in the coolant reservoir of my '87 vette(automatic - 110k miles). The coolant in the radiator is clear and there is no evidence of foaming in the oil.
As suggested in other threads, I suspected head gasket/cracked head/cracked block (
).
I took it to the dealer and they did a "37 point check" and (surprisingly) they found nothing to fix! There is a bit of blue smoke when I start the car which I believe is valve stem seals. But that is the only thing they came up with. Anybody else ever been to a dealer shop that didn't find something they want to repair?
Anyway, back to the sludge... any thoughts?
Thanks for any ideas!
I noticed some dark goo-y stuff in the coolant reservoir of my '87 vette(automatic - 110k miles). The coolant in the radiator is clear and there is no evidence of foaming in the oil.
As suggested in other threads, I suspected head gasket/cracked head/cracked block (
). I took it to the dealer and they did a "37 point check" and (surprisingly) they found nothing to fix! There is a bit of blue smoke when I start the car which I believe is valve stem seals. But that is the only thing they came up with. Anybody else ever been to a dealer shop that didn't find something they want to repair?
Anyway, back to the sludge... any thoughts?
Thanks for any ideas!
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
It's probably just old coolant residue.
I removed my coolant resevoir, emptied it out then put in a handful of nuts and bolts and swished them around in water. That cleaned it out really well. It's been over a year later and it's still clean.
I removed my coolant resevoir, emptied it out then put in a handful of nuts and bolts and swished them around in water. That cleaned it out really well. It's been over a year later and it's still clean.
Racer
Joined: Jul 2007
Posts: 281
Likes: 2
From: Mount Vernon Indiana
Team Owner
Joined: Sep 2001
Posts: 62,164
Likes: 1,734
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Old coolant residue probably, assuming you have no other problems that would indicate a head gasket failure.
Flush the system.
Flush the system.
Advanced
Joined: Nov 2004
Posts: 79
Likes: 0
From: Richmond VA
Won't mixing green and orange antifreeze cause the antifreeze to turn into sludge? If I am not mistaken, at least the early C4's had orange antifreeze. It would be easy enough to overlook when topping off coolant.
Phillip
Phillip
Team Owner
Joined: Sep 2001
Posts: 62,164
Likes: 1,734
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Now they make them compatible with both, but the stuff is green.
Team Owner
Joined: Oct 2004
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From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
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Racer
Joined: Jul 2007
Posts: 281
Likes: 2
From: Mount Vernon Indiana
I'll vote with the dealer mechanic you do not have an issue. It's completely normal if the radiator hasn't been properly maintained. It's "rust" from the radiator and engine that is making the sludge. Flush the rad and block completely until the radiator runs clear, then go about your day.
