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So I just bought this 77 Corvette yesterday. The previous owner is a great guy was very upfront with a lot of the issues with it. His biggest issue has been the cooling system from my understanding. Car drives great. (Drove it 90 minutes of the highway to get it home.) the previous owner said the cooling system way “unhooked”. Looking at it, (picture attached) there is no overflow hose going to the expansion tank. There is a hose that connects the tank to the radiator, however the tank is almost empty. The previous owner says he has been driving the vehicle like this for years and has never had any issues with overheating. What would be the proper way to attack these? Additionally where does the overflow hose attach to?
The tanks caps nipples should face forward then you can shorten that hose a bit to the Rad Cap, away from the header.
On the other nipple I installed a short piece of clear hose and aimed it at the ground, down a ways. That second nipple is just for the unlikely event the Rez ever overflows it will not burst. I use the clear hose so I can tell at a glance if green antifreeze has been there. Never has in 12 yrs.
And you want to keep the Rez about half full. Or half empty depending on attitude.
And last but likely not least. When the P.O. said "unhooked", he was referring to the fact that there are no heater hoses. This might be a 'red flag" that the core was leaking on the carpet. So, you will have to pressure test the core to see if there is a leak and then decide to replace or ignore.
Last edited by HeadsU.P.; May 10, 2020 at 10:15 AM.
I'd be a lot more concerned about the plastic fuel filter and rubber fuel line. That's a fire waiting to happen.
(There, I said it, so the rest of you can answer the OP's question).
Does it overheat? Measure with an infrared thermometer (don't trust the gauges). You are missing the foam that goes around the radiator to force air through it.
Thank you guys for the feed back. Also this is not the original engine, he said he took the a/c compressor out when he pulled the engine and never put it back in. He gave me all the original parts for the a/c and claimed it worked before he pulled it out, but it is a t-top and he pretty much only drove it on nice days with the top off so he never felt like he needed it.
It looks like there is a hose running from below your rad cap to the top of the plastic tank on the passenger side inner fender. The other connection on that cap is for a larger diameter overflow hose directed downward toward the ground.
Your heater hoses are definitely missing, same as on my 77. I have never missed it. You are probably missing all the seals around the radiator and seals between the shroud and the radiator. All these are critical in forcing air through the rad rather than around. it. There should also be a black plastic air dam mounted under the front of the car to direct air up to the rad. The pic below is my 77. You can see some of what I'm talking about.
Depending on your climate, you may need heat or defrost once in awhile. If your heater core checks out ok, I would HIGHLY recommend a manual shut-off valve in place of the vacuum shut-off valve, which likely has been thrown away. These valves are installed in one of the heater hoses, down by the core and come in 5/8 or 3/4 at NAPA and have a simple threaded **** handle to control waterflow to the core. You can open it in the spring / fall, close in the summer. The manual valve will keep 75% of the heat out of the cockpit.
BKbroiler,
I don't believe the O.P. can use the foam rubber at the top of the Rad. Looks like when the P.O. was removing the A/C compressor & hardware, the condenser was removed along with all the foam seals. Is there a aluminum plate that would fit over that Rad gap and force the air through?
Last edited by HeadsU.P.; May 10, 2020 at 12:17 PM.
BKbroiler,
I don't believe the O.P. can use the foam rubber at the top of the Rad. Looks like when the P.O. was removing the A/C compressor & hardware, the condenser was removed along with all the foam seals. Is there a aluminum plate that would fit over that Rad gap and force the air through?
Heads UP
I see what you mean looking at his pic. Not sure why his is different than mine. My car is a 77 which originally had AC. I removed the compressor, condenser and evaporator. The light colored seal at the top of my radiator fills in the gap where the stock L48 outside air intake was.
I took a look at my car and his radiator support looks different than mine. That's what creates the big gap in front of his radiator. This really opens up a can of worms.
Last edited by BKbroiler; May 11, 2020 at 05:19 PM.
I agree. I too have a "77. (But with A/C condenser left in place, not working) His photo of the Rad support does not look like mine either.
If I had to guess, I would say maybe the Rad support was swapped out with another yr. Some model yrs seemed prone to rusting out at the bottom more than others. I believe the support is just bolted in anyway.
IDK
I don't drive my 77 in the winter but fall and spring get chilly and I have never needed the heater, the natural heat in the engine compartment keeps the cabin plenty warm. Looks like the headers on the engine may interfere with the ac compressor install, there is a brace that attaches to the engine block in that area.
Is your thermostatic fan clutch working properly? When they fail, the do not engage properly, so there is not enough airflow thru the radiator to cool the system.
There are MANY reasons for overheating of the cooling system. If you can give use some specific situations when you notice the water temp getting hotter, it might provide some clues which could point to a solution.
I drove it for an hour and a half yesterday and it didn’t overheat at all. The fan is working,(belt squeaks a little bit.) I’m working on getting an IR thermometer to check the engine temp because I’m not confident the temp. gauge is working properly. A few of the other gauges aren’t working and the low fuel light is always on, but the fuel gauge works, so I believe there may be a problem with the circuit panel behind the dash.
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
The core support does look like the one in my 77 (Late model)
The upper radiator mounts look to be missing the rubber cushions, the radiator looks to be sitting against the metal mount and the radiator is a bit far from the support.
I used pipe insulation and built a cover for the top of the radiator to hide the gap, once the radiator mount cushions are in place the gap is a lot smaller and there is a large piece of foam included with the radiator seal kit that will fill the gap.
I like the color of you car, post some pics
Neal
Last edited by chevymans 77; May 11, 2020 at 10:00 AM.
St. Jude Donor '05-'06,'11,'13-'14,'16,'18,'19,'24, '25
If its staying cool then its not that big of a deal, I would look into the radiator mount cushions just to protect the metal to metal contact, could possibly rub a whole in the radiator
The thermostatic fan will "turn" whether it works or whether it doesn't. If it is not "engaged" [temp high enough for it to lock in], it will be very quiet. If it is engaged, it will be rather noisy. To check it out, make sure you have driven the car with A/C on high for several miles at slower speeds so the engine temp is enough for it to engage. Then pull over and open the hood (engine still running) and while you are watching the action of the fan, turn the engine OFF. An 'engaged' thermostatic fan will continue to spin from 1-3 revolutions, then stop dead. If the fan is NOT engaged, it will continue to spin for more than 4 revolutions and come to a slower stop.
If you do this test and think the engine should be hot enough for the fan to come on...and it doesn't...or it spins several times before stopping, your thermostatic fan is no longer funtional and needs to be replaced.
1977 corvette cooling system question
