I recently bought my first vette, a 77 L48 with 69,000 miles on it. I have discovered that there is a small coolant leak coming from under the engine, about between the front 2 wheels. I do get some coolant smoke sometimes on a hot start as well. Should I be concerned about this? When running there is no smoke nor has the engine has never been close to overheating. It runs very well and just got tuned 1 month ago. Just looking for some advice.

 

I would be concerned but I do not have enough info to gauge the problem, for all I know your puke tank is overflowing a little...or something really nasty waiting just waiting to attack at the worse possible moment.

 

My wild *** guess is you have a water pump that is failing as it's located right where you describe. If the pump is failing it will leak coolant out of a small weep hole in the bottom of the pump. If coolant is dripping off the bottom of your harmonic balancer it's probably coming from the weep hole or a bad hose connection to the water pump. Either way that's what you need to fix.

The good news is water pumps are cheap (about $35) and easy to install (about 2 or 3 hours) with basic hand tools. The pumps can be replaced by anyone pretty easily after watching a couple of YouTube video's.

While your at it now is also a good time to replace all your drive belts since they all have to come off anyways and to replace your anti-freeze because it has to be drained. All of that will cost you about $100 and a couple of hours.

 

And if it is the water pump weeping you should be very concerned as failure is imminent.

 

Ok, one more observation about it, it only seems to let's out 1 drop after turning off the engine, none in between. Does that change anything?

 

With the motor turned off, reach under the front of the car and touch the bottom of the harmonic balancer (the big solid round thing on the front of the motor) after it drips. If it's wet the problem is the water pump. If the water pump is leaking it can fail at anytime.

It's probably leaking at other times but the fluid is spinning off into space when it drops on the harmonic balancer with the engine running.

 

Maybe not much out of a weep hole, although I've only experienced that a couple times before. Only seen slow dripping anyway.

I found my coolant to be like muddy water when I drained it, apparently when I checked that before buying the car I was only thinking of the level inside and not looking for a good clean green color. Was sunny and in shadow of hood too.

Took an hour of flushing out sudsy cleaner to get good water in there.

Check and replace coolant hoses (and heater hoses or bypass hose) if they seem old at all. You could probably squeeze on them to feel if they're crunchy inside from a coating of rusty crud, if like mine were.

I had been trying to seal the overflow hose at the radiator fill neck ever since I broke it off when checking the petrified hose there. Really needs a new nipple brazed or soldered on.
Was thinking it kept losing coolant there every time I shut the engine off because there was a small puddle within a few minutes of parking.

While my car was on a lift a few weeks ago a mechanic pointed out the lower radiator hose had a rusty stain at the WP clamp.

Was going to replace the hoses later on and shouldn't have waited, but I was only needing to top the radiator up by about a quart after every hundred miles or so, and suddenly lost too much coolant taking my car for the Memorial Day holiday only 15 miles from home. Somehow the lower radiator hose let loose where the leak was, a break at the clamp.

Anyway, that was obviously always dripping down near the middle and close to the passenger side tire.

Side note: if you replace the hoses yourself without removing the fan shroud be careful to make sure that doesn't dislodge from the bottom like mine did as I struggled to pull that lower hose out from above.
When starting the car to circulate and top up coolant my fan was clattering on something, was the bottom of shroud. It pulled out at the bottom right corner from the metal bar going across under it. Simple fix by prying it back into place with a screwdriver.

Also, the lower hose had a metal coil inside. My replacement AC Delco hose didn't. Chose not to attempt removing and cramming that into the new hose (bend makes that idea next to impossible I would guess) and it seems to be okay without one.

 

OP, yes you should be concerned about any coolant leak. it will only get worse with potentially overheating and damaging the engine, especially if you are getting coolant smoke out of the tailpipe (you did not specify where the smoke was coming from).

if you don't have the tools, take it to a shop to do a pressure test. they can determine if it is something as simple as a hose, or a water pump, radiator, head gasket, heater core, etc.

 

HMMM.dry out everthing carefully, heater hose connections, rad hose connections and water pump area.Radiator bottom and sides and drain plug--petcock.
Check coolant level cold as well as overflow jug. Overflow jug cold has a recommended level of fluid..Checking it hot should show a different level..)Add..proper rad coolant if level is low..

Of course a decent shop can pressure test the system, verify rad cap is correct and find leaks or hose drips for you..They can also test the coolant for proper mix and determine if the T stat is functioning.

IF you are doing the initial checking:
Then start the car and let it come up to running temp with t stat opened so to rad hose is firm..Open hood..
you can do this over newspaper spread out on the floor and lay beside the car and if when you see the first drip of water-coolant..stop car and investigate to almost certainly find the source..
NEWVER Never add any of the stop leak stuff to your cooling systemm. Jim

 

Ditto on going ahead and getting the belts, hoses water pump, t stat, coolant all examined and replaced..without service records..all of the items could be original 70K MILES and 38 years is a long time..
Properly working, dependable Cooling, lubrication and fuul-vacuum systems are the very base requisites for any car vintage or otherwise..Start with those isses and you will have a relaible baseline on the care and condition of your ne corvette..Jim