Coolant system
Thread Starter
Intermediate
Joined: May 2021
Posts: 25
Likes: 11
From: Yooper
Coolant system
So as a new owner, I asked my pops (a mechanic for 40+ years) a question about the coolant because I noticed it was an odd color when I checked my fluids and engine oil. He said it was normal because Dexcool is orange (I'm so used to green antifreeze). He took the Fill reservoir cap off to check that too and noticed some brown sludge that he assumed was "stop leak" and now he's worried that there was/is a leak somewhere and repeatedly said "I just hope there isn't a leak in the head gasket". The coolant level is a little high but looks okay otherwise, and the engine oil also looks good and is at the correct level.
My heat works fine and it was running a little hot at idle this weekend one day that it was 90 out but went back to normal as I drove and it sucked some air in.
After he left for the night I did some reading on the forums about when dexcool and the green antifreeze are mixed they great a gel, so I wonder if that's what that brown gunk was?
Thoughts?... He's having me park it until he can get it on the hoist.. so it might be parked for a few weeks of our very short summer up here
EDIT: Sorry I should mention it's a 92 C4 six speed manual, LT1, my "purple batmobile"
My heat works fine and it was running a little hot at idle this weekend one day that it was 90 out but went back to normal as I drove and it sucked some air in.
After he left for the night I did some reading on the forums about when dexcool and the green antifreeze are mixed they great a gel, so I wonder if that's what that brown gunk was?
Thoughts?... He's having me park it until he can get it on the hoist.. so it might be parked for a few weeks of our very short summer up here
EDIT: Sorry I should mention it's a 92 C4 six speed manual, LT1, my "purple batmobile"
Last edited by Famke; Jul 9, 2021 at 11:54 AM.
Team Owner
Joined: Sep 2001
Posts: 62,160
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From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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It could be stop leak, could just be gunk buildup from years and years without being changed.
Flush it out and replace with new dexcool.
Flush it out and replace with new dexcool.
Le Mans Master
Joined: Aug 2017
Posts: 6,941
Likes: 1,490
From: New Jersey
Yeah more than likely just hasn't been changed in a while. The gel is a non issue now as most all all make and model antifreeze is compatible with dex cool now. Unless it was done years ago. I'd flush and report back after that. A small amount is normal though. Pretty much all my vehicles get a little bit.
Thread Starter
Intermediate
Joined: May 2021
Posts: 25
Likes: 11
From: Yooper
Will definitely report back! Hopefully he can get it in the shop before the month is over... sigh.. I guess it will give me time to fix some other minor issues like the driver door not unlocking with the key lol
Burning Brakes
Joined: May 2002
Posts: 755
Likes: 42
From: Sierra Foothills, State of Jefferson
Don't forget to remove the knock sensors in the block when you flush it. You can get some buildup there.
Also- the factory added some 'stop leak' to the coolant systems, I seem to recall it was ground up coconuts, it was in the form of thick tablets.
I think that gunk was present the first time I did a coolant change in my '94, however that was a long time ago.
Also- the factory added some 'stop leak' to the coolant systems, I seem to recall it was ground up coconuts, it was in the form of thick tablets.
I think that gunk was present the first time I did a coolant change in my '94, however that was a long time ago.
Melting Slicks
Joined: May 2013
Posts: 2,692
Likes: 349
From: Sacramento California
I believe Dexcool in the Corvette started in 1996 and every model before 1996 got the regular green ethylene glycol coolant. Just be sure what fluid you are using when you do the flush & fill.
Safety Car
Joined: Mar 2017
Posts: 4,202
Likes: 1,323
From: LeClaire Iowa
I had exactly the same brown crud when I bought my 96. It had never been flushed. At the time I was told it was stop leak pellets put in at the factory. I gravity drained 3 times and it kept coming back. Yes, I did the knocks. I then came up with this idea and 2 years later the coolant is still clean. It requires agitation to loosen it from inside the system. Dan
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Thread Starter
Intermediate
Joined: May 2021
Posts: 25
Likes: 11
From: Yooper
Well it was deemed fine to drive and after a while the low coolant light would randomly come on and shut off on start up. Checked the coolant levels and they were all fine, some reading on here made me wonder if there was air in the system. Weeks go by and suddenly there's white smoke everywhere and I'm freaking out lol. Blew a coolant hose right at the T, big hot mess in the engine bay. So had her hauled on a flatbed to my dad's shop and he immediately put her on the hoist to take a look. (I think he was excited to work on a sports car instead of the usual rusty POS cars he has come through for work).
We (he) replaced the hoses, thermostat, flushed the coolant and put new green coolant in it. So far so good, she seems to be running fine now and the low coolant light hasn't come on yet. I wonder if there was a blockage somewhere or was there indeed air in the system and it needed to be "burped"? (The 30 year old hoses were bound to fail so that part I'm not wondering about lol)
We (he) replaced the hoses, thermostat, flushed the coolant and put new green coolant in it. So far so good, she seems to be running fine now and the low coolant light hasn't come on yet. I wonder if there was a blockage somewhere or was there indeed air in the system and it needed to be "burped"? (The 30 year old hoses were bound to fail so that part I'm not wondering about lol)