1978 - Radiator Drain Plug Leaking
Thread Starter
Intermediate
Joined: Sep 2004
Posts: 35
Likes: 10
1978 - Radiator Drain Plug Leaking
I've been searching and it seems like the drain plug on the radiator can be an issue. With the car sitting for 2 weeks on the lift, this morning I noticed that the drain plug area is leaking. (on the lift waiting for new power steering lines to arrive)This new leak started sometime between last night and today. The car has not been started or touched, but this is now an issue I need to address. I'm looking for first-hand experience with the radiator drain plug and leaking. Any advice on what to do or not do would be greatly appreciated. I'd like to not replace the radiator if I can get away with just fixing or replacing the drain plug. Comments from my search make touching the drain plug seem like a very bad idea. Thanks!
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Another option is a Sacrificial Anode Rod drain plug. Much like your home hot water heater has, but smaller scale.
If you have any aluminum engine parts, heads, water pump, block, or Rad, etc there is always corrosion present with those metals.
The Anode rod will take the blunt of the chemical reaction.
Summit sells the Anode drain plug.
If you have any aluminum engine parts, heads, water pump, block, or Rad, etc there is always corrosion present with those metals.
The Anode rod will take the blunt of the chemical reaction.
Summit sells the Anode drain plug.
Thread Starter
Intermediate
Joined: Sep 2004
Posts: 35
Likes: 10
Thanks for the replies! The car has a plastic drain plug for the radiator installed with a rubber seal. I played around with it and can get it to only "drip a few drops" a day vs. a puddle under the car, but this seems like it could/will be an issue when the system is under pressure. I haven't had time to really mess with it. It's been pretty cold here in Ohio so as soon as the weather gets back to at least the 50's, I'll get back at it. I'm trying to identify the right drain plug to purchase from Summit, but that is proving to be harder than I thought it would be.
Safety Car
Joined: Oct 2007
Posts: 4,360
Likes: 1,724
From: Seattle Area Washington
It's most likely is either a 1/8" NPT or a 3/8" NPT either can be found at your local auto parts house...
Whatever you replace it with try finding one made of Brass.
About $3.00 no shipping...
Whatever you replace it with try finding one made of Brass.
About $3.00 no shipping...
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
the fact that it is plastic makes me less worried. fighting a metal plug out of a 40+ year old copper radiator could get messy. also, it may be the wrong thread plastic plug somebody forced in there. fortunately copper trumps plastic.
Thread Starter
Intermediate
Joined: Sep 2004
Posts: 35
Likes: 10
Also replaced the P/S high pressure line from the pump to the rack. That leak is also now fixed. I'm moving the car off the lift tomorrow and think it's ready for my first drive! (other than the short trip home when I bought it)
Super excited to get it on the road with the T-Tops off!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
When I bought my car, it had a NPT bolt in the bottom of the radiator for a drain plug.
Its still there. I love it. However, I have the Fluidyne Anode Rod ready to go for the next project that requires draining the Rad.
Never been a big fan of "Petcocks". They open when they shouldn't or won't close when they should. Or the little handle snaps off.
Its still there. I love it. However, I have the Fluidyne Anode Rod ready to go for the next project that requires draining the Rad.
Never been a big fan of "Petcocks". They open when they shouldn't or won't close when they should. Or the little handle snaps off.
Thread Starter
Intermediate
Joined: Sep 2004
Posts: 35
Likes: 10
To close this out: THANKS for the help! I was able to replace the plastic drain plug someone had forced into the radiator (using an O-ring) and replace it with a 1/4 NPT fitting. I ordered two things to try:
https://smile.amazon.com/dp/B07NVPR4...t_details&th=1
and
https://smile.amazon.com/dp/B0876LSX...roduct_details
I ended up cutting down the Zinc Anode piece to make sure it would fit into the radiator. Worked great. I ordered both because I wanted to make sure I could make one of them work since the car was already on the lift. Tightened right up and no more leak. I was able to take my first cruise in the car this past weekend. Just a few miles around the local back roads. Going to drive it to work tomorrow (weather depending) and that will be a 17 mile trip (one way). Car seems to do great and is a blast to drive. Thanks again for the help!
https://smile.amazon.com/dp/B07NVPR4...t_details&th=1
and
https://smile.amazon.com/dp/B0876LSX...roduct_details
I ended up cutting down the Zinc Anode piece to make sure it would fit into the radiator. Worked great. I ordered both because I wanted to make sure I could make one of them work since the car was already on the lift. Tightened right up and no more leak. I was able to take my first cruise in the car this past weekend. Just a few miles around the local back roads. Going to drive it to work tomorrow (weather depending) and that will be a 17 mile trip (one way). Car seems to do great and is a blast to drive. Thanks again for the help!