Can a coolant leak fix itself?

[Citizen]

Sounds like a newbie question, I know, but this is what happened just a while ago.

1. Took the car out for a shake-down drive before an outing tonight. Left blinker failure, so I fixed that, but then I thought the coolant was a little low, so I added a little bit (maybe 1 pint, if that). Accidently left the overflow bottle cap off, but didn't know it at the time.

2. Took the car for a second shake-down drive. When I returned home, I noticed coolant dripping from around the left front area. Thought I noticed a pin-hole spray inside around the LF tire, but when I looked again, I couldn't find it. Dripping stopped. I found that I left cap off, so replaced it (it was right there).

3. Took it out for a third shake-down, and returned home, no problem. No leak. Area around LF is dry ground.

So, did I have a pin-hole leak that somehow got plugged and is now (for the moment) not leaking? Anyone experience something like this before?

Thanks,
Thomas

...

[David T]

Probably just a loose hose and it swelled up. Anti-Freeze has some "clotting" ability to fix tiny leaks. You should see if you can tighten the hose clamp on the big hose on the radiator a little. If the radiator is original with the plastic tanks or if it is stained or leaking then you should get it replaced.

[Parzival]

Sounds like a newbie question, I know, but this is what happened just a while ago.

1. Took the car out for a shake-down drive before an outing tonight. Left blinker failure, so I fixed that, but then I thought the coolant was a little low, so I added a little bit (maybe 1 pint, if that). Accidently left the overflow bottle cap off, but didn't know it at the time.

2. Took the car for a second shake-down drive. When I returned home, I noticed coolant dripping from around the left front area. Thought I noticed a pin-hole spray inside around the LF tire, but when I looked again, I couldn't find it. Dripping stopped. I found that I left cap off, so replaced it (it was right there).

3. Took it out for a third shake-down, and returned home, no problem. No leak. Area around LF is dry ground.

So, did I have a pin-hole leak that somehow got plugged and is now (for the moment) not leaking? Anyone experience something like this before?

Thanks,
Thomas

...

With the cap off I find it hard to imagine that the system reached the pressure necessary to cause a "Spray" type of leak. If its leaking with the cap off, putting the cap on and letting the engine warm up and reach pressure will almost certainly cause that leak to be much worse. So if you've replace the cap and driven around some more with out seeing that leak, then perhaps some just spilled out of the open bottle and traveled along the pips or the frame and appeared at the front of the car?

[Josh]

Coolant leaks are very common with the rear engined - front radiator setup. Dozens of connections to leak.
I have not found any leaks to ever fix themselves, but if its not leaking it does not warrant concern (within reason)
As mentioned above the hoses swell with different tempuratures so a cold leak can go away when the coolant is warmed up.

[Jonathan]

What colour windshield wiper fluid do you use?

If it isn't just a hose clamp leaking slightly when cold (and more or less fine once warm) then maybe what you saw was wiper fluid leaking from the reservoir (front left corner as you mentioned).

[AugustneverEnds]

The draincock on your radiator might be weeping ever so slightly from where you are describing. I had to tighten it once over a year ago and never saw a drop from there again.

[mr_maxime]

I might be wrong on how it happened, but I had lots of minor leaks at the connections last winter. After driving there were no leaks, but after sitting outside in the cold I noticed drops on the ground. I suspect that this was due to the aluminum shrinking faster than the old rigid rubber in the cold weather, which made it have minor leaks. Nothing was leaking while the car was at running temp.

[Citizen]

I know I'm late responding to the questions, but I had left to go to my event (a BTTF Rolling Road Show in Houston). Thanks to everyone that provided input. As now I have time, I'll try to answer...

Probably just a loose hose and it swelled up. Anti-Freeze has some "clotting" ability to fix tiny leaks. You should see if you can tighten the hose clamp on the big hose on the radiator a little. If the radiator is original with the plastic tanks or if it is stained or leaking then you should get it replaced.

Thanks David. This is probably what it was. Even though the leak had already stopped, I did tighten the clamps nearest to the LF wheel. I didn't know Anti-Freeze had clotting ability, good to know.

With the cap off I find it hard to imagine that the system reached the pressure necessary to cause a "Spray" type of leak. If its leaking with the cap off, putting the cap on and letting the engine warm up and reach pressure will almost certainly cause that leak to be much worse. So if you've replace the cap and driven around some more with out seeing that leak, then perhaps some just spilled out of the open bottle and traveled along the pips or the frame and appeared at the front of the car?

I completely agree. I'm confused how the system had enough pressure to leak with the cap off. It's a mystery, except as David described above. And yep, I can confirm the leak did NOT return even after I put the cap on and went for a test drive.

Coolant leaks are very common with the rear engined - front radiator setup. Dozens of connections to leak.
I have not found any leaks to ever fix themselves, but if its not leaking it does not warrant concern (within reason)
As mentioned above the hoses swell with different tempuratures so a cold leak can go away when the coolant is warmed up.

Spot on. I believe it was a connection nearest to the LF wheel. I did double check the radiator and connections, and no leaks there...dry as a bone.

What colour windshield wiper fluid do you use?

If it isn't just a hose clamp leaking slightly when cold (and more or less fine once warm) then maybe what you saw was wiper fluid leaking from the reservoir (front left corner as you mentioned).

I did check the wiper fluid container, and it was dry, no leaks. The coolant on the ground was green, same as what I put in the car.

The draincock on your radiator might be weeping ever so slightly from where you are describing. I had to tighten it once over a year ago and never saw a drop from there again.

I did check the radiator specifically. It is intact an working perfectly. No indication of a leak there. All wet areas were around the LF tire.

I might be wrong on how it happened, but I had lots of minor leaks at the connections last winter. After driving there were no leaks, but after sitting outside in the cold I noticed drops on the ground. I suspect that this was due to the aluminum shrinking faster than the old rigid rubber in the cold weather, which made it have minor leaks. Nothing was leaking while the car was at running temp.

I checked the car this morning in my garage, and there is no evidence it leaked last night or this morning. Area under the car is dry.


EPILOG

It's now the next morning. I took a chance by proceeding to my event last night. I carried ample tools, fully charged cell phone and extra coolant with me. I watched the temp gauge the entire trip, to and from. The cooling system worked fine. No leaks at the event, or after. I'll continue to monitor diligently until I'm comfortable I don't have a future problem.

Thanks much to everyone who responded. I was on the fence about going, but after posting here and reading initial responses, I had the confidence to proceed. I had a good time at the outing, great food at "Fusion Eats" (home of the famous "Flux Capacitor", a Vodka drink), and catch-up conversation with the good people of the Texas DeLorean Club (six club cars attended).

IMG_20190315_181823226.jpg


Thomas

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[CFI]

I recently drove a DeLorean that leaked coolant only when the heat was on. Perhaps you experienced something similar?

[DMCMW Dave]

I've seen one problem peculiar to the OEM plastic tank radiators (most of them ought to be out of service by now - but . . . .) Where the plastic tank meets the core there is a seal. I've seen that seal leak when under pressure but not fully hot, for example as the car warms up or cools off. Since you don't usually start the car and let it idle for a long time, the warming-up phase happens as you are going down the road. You'll see the cooling-off leak a few drops on the ground in the morning after you drive the car. It won't leak any more as the car sits, and it won't leak when you warm up the car to find the leak! Look for the drip on the radiator itself at one end or the other.