Freeze Plug Replacement
Thread Starter
Instructor
Joined: Nov 2005
Posts: 103
Likes: 0
From: Indiana
Freeze Plug Replacement
I believe the freeze plug above the starter on my 1974 L48 is leaking intermittently. Must the engine be removed to replace this freeze plug? The engine was rebuilt about 5K miles ago in 1985. Would you recommend replacement of all the freeze plugs, which I am sure would require the removal of the engine? Any idea of the labor cost to replace just the one freeze plug and the labor cost to replace all of the freeze plugs? Thanks!
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
If the plug is in fact leaking, I would remove it and examine it closely. It should reveal the reason for its leaking as well as the condition of the water jacket. If the plug has rusted from the inside and particularly if you discover lots of rusty goop behind the plug it's probably a safe assumption the other freeze plugs are in jeopardy. Especially so for those in the rear of the block.
Good luck... GUSTO
Good luck... GUSTO
Safety Car
Joined: Sep 2005
Posts: 4,226
Likes: 643
From: Orange County Ca
I have in the past, just replaced 1 leaking plug and not had problems with the others. Be sure to run the correct mix of antifreeze to stop future corrosion. Sometimes you get 1 with a thin spot or whatever.
You shouldn't have to remove the engine to replace it.
Make sure your shop actually removes it and not just punches it inside the water jacket. They can be a bear to remove sometimes.
Edit--I just read your original post. 5k miles in 30 yrs? It may be best to replace them all, especially if you plan to keep the car for another 30 yrs and can afford $200-$300, but you need to put more miles on the car to keep the fluids circulating and the seals wet.
You shouldn't have to remove the engine to replace it.
Make sure your shop actually removes it and not just punches it inside the water jacket. They can be a bear to remove sometimes.
Edit--I just read your original post. 5k miles in 30 yrs? It may be best to replace them all, especially if you plan to keep the car for another 30 yrs and can afford $200-$300, but you need to put more miles on the car to keep the fluids circulating and the seals wet.
Thread Starter
Instructor
Joined: Nov 2005
Posts: 103
Likes: 0
From: Indiana
I have in the past, just replaced 1 leaking plug and not had problems with the others. Be sure to run the correct mix of antifreeze to stop future corrosion. Sometimes you get 1 with a thin spot or whatever.
You shouldn't have to remove the engine to replace it.
Make sure your shop actually removes it and not just punches it inside the water jacket. They can be a bear to remove sometimes.
Edit--I just read your original post. 5k miles in 30 yrs? It may be best to replace them all, especially if you plan to keep the car for another 30 yrs and can afford $200-$300, but you need to put more miles on the car to keep the fluids circulating and the seals wet.
You shouldn't have to remove the engine to replace it.
Make sure your shop actually removes it and not just punches it inside the water jacket. They can be a bear to remove sometimes.
Edit--I just read your original post. 5k miles in 30 yrs? It may be best to replace them all, especially if you plan to keep the car for another 30 yrs and can afford $200-$300, but you need to put more miles on the car to keep the fluids circulating and the seals wet.
Race Director
Joined: Mar 2003
Posts: 11,608
Likes: 780
From: Eustis ( Area 51 Bat Cave ) Fl
Some people have more disposable cash than me, 
I dropped a 327 that had been sitting about 20 years in my modded 66 vette and it ran like a champ but from sitting one freeze plug had a rust spot that leaked, getting it out while the engine was in the car was a bear but no way to get the new one hammered in,
I wasn't going to give up and the parts store said we offer these rubber freeze plugs that you tighten a bolt and they get tight in the hole,
I almost laughed, I thought what a hack job POS,
I grabbed one and installed it and the car went on to be a sound daily driver, no other plug leaked even though in this case the leaking plug had rusted from neglect of sitting,
The rubber plug lasted until I sold the engine which was years of 1000's of miles, that cat used it in a mud jeep.
I am guessing the local tech would love to cha ching on this job, or you can fix it in no time for less than 10 bucks.
I dropped a 327 that had been sitting about 20 years in my modded 66 vette and it ran like a champ but from sitting one freeze plug had a rust spot that leaked, getting it out while the engine was in the car was a bear but no way to get the new one hammered in,
I wasn't going to give up and the parts store said we offer these rubber freeze plugs that you tighten a bolt and they get tight in the hole,
I almost laughed, I thought what a hack job POS,
I grabbed one and installed it and the car went on to be a sound daily driver, no other plug leaked even though in this case the leaking plug had rusted from neglect of sitting,
The rubber plug lasted until I sold the engine which was years of 1000's of miles, that cat used it in a mud jeep.
I am guessing the local tech would love to cha ching on this job, or you can fix it in no time for less than 10 bucks.
Advanced
Joined: Jul 2012
Posts: 58
Likes: 39
From: Davidson NC
Freeze Plug Replacement
I had the same freeze plug replaced on my '69 350/300 engine in Feb 2015. It was done by a local Corvette Shop for about $275.This included pulling the rusted plug out, putting a new brass plug in, draining/flushing the engine, and replacing the coolant (50/50 w/distilled water). The shop had no issues getting the old plug out which can cause the labor to go up (See this CF thread about how much of an adventure this can turn into:
https://www.corvetteforum.com/forums...eeze-plug.html). This shop warned me that getting the plug out could push the cost up. As it turned out in my case, flushing the radiator & replacing the coolant was the bigger part of the bill. As my engine was rebuilt by a previous owner about 25,000 miles ago, the other freeze plugs appeared to be in good shape and weren't changed. The engine didn't have to be pulled to do this. My engine has headers/side pipes so it was relatively a clear access to the rusted freeze plug after the starter was pulled. In addition to replacing the rusted freeze plug with a brass one ($3-5), a sealant should be used on the new plug when installed.
https://www.corvetteforum.com/forums...eeze-plug.html). This shop warned me that getting the plug out could push the cost up. As it turned out in my case, flushing the radiator & replacing the coolant was the bigger part of the bill. As my engine was rebuilt by a previous owner about 25,000 miles ago, the other freeze plugs appeared to be in good shape and weren't changed. The engine didn't have to be pulled to do this. My engine has headers/side pipes so it was relatively a clear access to the rusted freeze plug after the starter was pulled. In addition to replacing the rusted freeze plug with a brass one ($3-5), a sealant should be used on the new plug when installed.
The most correct repair.
