NEED HELP Boiling sound from radiator overflow

Rick

Original poster
Member
Jul 18, 2016
21
S. Arizona
Trying to fix a few issues on my wife TB before giving it back to her. She told me and I have witnessed, after getting it heated up from driving, when we stop and turn it off, there is bubbling and steam coming into the radiator overflow container. Already changed the thermostat due to overheating issue a couple weeks ago. Any idea what would cause the gurgling/boiling scenario I'm having?
 

TJBaker57

Member
Aug 16, 2015
2,897
Colorado
Trying to fix a few issues on my wife TB before giving it back to her. She told me and I have witnessed, after getting it heated up from driving, when we stop and turn it off, there is bubbling and steam coming into the radiator overflow container. Already changed the thermostat due to overheating issue a couple weeks ago. Any idea what would cause the gurgling/boiling scenario I'm having?


You need a new radiator cap. The current one is not able to hold pressure. Lower pressure means lower boiling point. I had the same issue, I bought a new one at Napa. That one leaked at the radiator neck seal. Grabbed one at a Upull yard, tested with a coolant system & cap tester, installed and we were good to go.
 

mrrsm

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Oct 22, 2015
7,641
Tampa Bay Area
Don't be insulted by this suggestion... but there have been some instances where Water from a Garden Hose has been used to make up for the loss of Coolant on the road after an Over-Heating Boil Over. If this is the case, a full Coolant System Drain Down and replacement of same by the GM DexCool Product would be wise. Which Coolant are you using?
 
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Rick

Original poster
Member
Jul 18, 2016
21
S. Arizona
You need a new radiator cap. The current one is not able to hold pressure. Lower pressure means lower boiling point. I had the same issue, I bought a new one at Napa. That one leaked at the radiator neck seal. Grabbed one at a Upull yard, tested with a coolant system & cap tester, installed and we were good to go.
Thanks! That's an easy fix. Got one on its way.
 

Rick

Original poster
Member
Jul 18, 2016
21
S. Arizona
Don't be insulted by this suggestion... but there have been some instances where Water from a Garden Hose has been used to make up for the loss of Coolant on the road after an Over-Heating Boil Over. If this is the case, a full Coolant System Drain Down and replacement of same by the GM DexCool Product would be wise. Which Coolant are you using?
No insult received! Always need to check the "obvious" stuff and keep learning. We bought this vehicle a few years ago used. When I changed the thermostat there was some rusty-colored sludge in thermostat. I drained it all out and refilled it with All Vehicle coolant as I was told it wasn't until 2007 and beyond that it had to be DexCool. Are you telling me that it does have to be GM DexCool?
 

mrrsm

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Supporting Donor
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Oct 22, 2015
7,641
Tampa Bay Area
I'm a "Dyed In The Wool" ACDelco and GM OEM Parts & Products 'Maven' ...so using DexCool is always my expensive preference. But many other Members will give you good reasons to use alternative parts and less expensive products that WILL also function just as well.

One other Cautionary Tale... involves the remote possibility that someone... perhaps the prior owner... worked on replacing the Water Pump or Radiator Hoses and forgot that they left a Red Shop Rag or a Wad of Paper Towels stuffed deep inside of the Lower Hose to prevent inconvenient spillage on them during any said maintenance. Just an afterthought and something to remember.
 
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Mooseman

Moderator
Dec 4, 2011
25,260
Ottawa, ON
Are you telling me that it does have to be GM DexCool?
Yes. Has been since the 80's. It's Dexron VI trans fluid that has been around since 2006, which replaced Dexron III.
 
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