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Why is my coolant overflow leaking from here?
Ok so in route to solving my “add coolant” light problem, I was burping the system with one of those no spill funnel systems, and after running it for seriously 30-35 minutes, the water in the funnel finally started getting about Luke warm. (30 degrees F here) so I’m like cool! The thermostat should open up here shortly, and then I noticed a leak of antifreeze coming from the Overflow tank side. I started inspecting seeing if I could find the source, because it was about 5-6 inches away from the nearest radiator connection. And it seems to be coming from a little black grommet at the base of the filler neck. https://cimg8.ibsrv.net/gimg/www.rx7...c1f5d50f2.jpeg Now this isn’t my current overflow tank that’s actually in the car, it’s a replacement that I recently bought because the whole neck of mine is broken/ disintegrated, but the part that is circled is where it is leaking from. My concern is why would the overflow tank be that full in the first place? And it takes a long time for the heat to start working in my car so I’m suspecting a heater core issue. Could this be related to that? Or why is it leaking from that specific spot? Thanks for any help! |
The overflow tank will leak if it is overfilled because it doesn't completely seal where the neck meets the tank. Theoretically you should never need to add coolant there. If you fill it past half it can leak when the car gets hot and pushes coolant into the tank. If you have a coolant seal issue or pinhole leak the car won't be able to recover coolant back from the tank as it cools and the motor will run low. Eventually it will leak at the tank.
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Typically it would leak out there if you had air in the system but it would be preceded by a boiling sound. You're using the right tool to bleed it so it's likely that it was just overfilled at the overflow like irp said.
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Ok I guess that doesn’t sound as bad put that way. I never added any coolant to the overflow tank. All I did was change the fans out which required me draining about half the coolant. I saved the coolant because it was still good and was able to add back the drained fluid. After that was added back is when my coolant light came on. I was gonna burp it first and if that didn’t work I was gonna recheck the coolant sensor lines to see if they are intact and connected. Is there a way to drain that overflow tank aside from a siphon? |
No.... taking it out is a lot more involved than it looks so dumping it isn't really an option. Just gotta siphon it out. Try bleeding it some more. This time with the heater on full blast. Let it run, once the fans come on unplug them and let it run for a couple minutes then it shut it down. The water should boil pretty good. Once it settles down, fill the funnel a little bit, plug the fans back in and let the car run until the fans turn off. Shut it down again then let it sit overnight with the funnel at less half full. You'll be 100% bled after that.
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When I turn my ignition on the fans automatically come on, is that related to the add coolant light being on? But also there looks to have been some modification with the fan wiring so idk if the owner before me wired it to do so |
The add coolant light is a system all on it's own. It's not linked to anything else on the car. If your fans are constant always then they were hard wired to do so. Not a bad thing but, it's a little annoying.
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They must have, I can see some non-oem wires within the harness. I think the cooling system is full and good if it’s fillin up in the overflow, I’ll look more into the coolant level sensor, thanks a lot you have been a big help |
I think it’s pretty unusual, but I have seen a kink in the hose between the filler neck and reservoir causing it to overflow. The pressure from the hot coolant expanding was enough to overcome the kink, but the vacuum when it cooled wasn’t. |
Originally Posted by Sgtblue
(Post 12316388)
I think it’s pretty unusual, but I have seen a kink in the hose between the filler neck and reservoir causing it to overflow. The pressure from the hot coolant expanding was enough to overcome the kink, but the vacuum when it cooled wasn’t. |
Two things, first one similar to what sgtblue described:
Way back when... I had a problem where I kept adding coolant and it would end up in the overflow. I found that the tube that goes to the bottom of the overflow tank hit the bottom of the tank and formed a seal with the gunk on bottom, acting as a check valve. When the engine cooled off the coolant wasn't pulled back into the engine like it should have been. Instead, a pinhole leak in the hose/tube/grommet was letting air in instead. I trimmed down the hard plastic tube that goes to the bottom of the overflow tank by 1/2" or so and added a slant to the end. I have had a rock solid cooling system ever since and that was 5+ years ago. For syphoning out you can use one of those mityvacs with the brake bleeder attachment. Takes a while to empty the whole tank, but it's the right way to get rid of all your old coolant during a drain/fill. |
Originally Posted by alexdimen
(Post 12316420)
Two things, first one similar to what sgtblue described:
Way back when... I had a problem where I kept adding coolant and it would end up in the overflow. I found that the tube that goes to the bottom of the overflow tank hit the bottom of the tank and formed a seal with the gunk on bottom, acting as a check valve. When the engine cooled off the coolant wasn't pulled back into the engine like it should have been. Instead, a pinhole leak in the hose/tube/grommet was letting air in instead. I trimmed down the hard plastic tube that goes to the bottom of the overflow tank by 1/2" or so and added a slant to the end. I have had a rock solid cooling system ever since and that was 5+ years ago. For syphoning out you can use one of those mityvacs with the brake bleeder attachment. Takes a while to empty the whole tank, but it's the right way to get rid of all your old coolant during a drain/fill. |
Originally Posted by ecurbd02
(Post 12316297)
Is there a way to drain that overflow tank aside from a siphon? If you go to that trouble, and your overflow is original and gunky, you may want to replace it with a new one. |
BTW new ones are like $120 or thereabouts. Will make you want to replace both that and the windshield washer tank, bright white new ones look SO good.
Dale |
^Yeah....sure wish you could buy just the neck. :)
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I cleaned up my coolant tank on my recent rebuild and it looks almost brand new. Just get some glass beads and put it in the tank with soap and bleach. Plug the holes and shake outside with gloves on for your hands for about 10-15 minutes. Clean everything out with a garden hose, making sure all the glass beads are out as to not get in any of your smaller coolant lines. Clean as a whistle inside. For the outside and the neck, get hydrogen peroxide in higher concentration, if you can, and oxyclean, and put in a large pot or bucket submerged for about a week or so. The poly plastic will whiten quite a bit. Lastly, get either flex seal tape or stretchy silicone tape to reattach the neck. That's it. Almost good as new,
Mike |
Originally Posted by mikejokich
(Post 12316506)
I cleaned up my coolant tank on my recent rebuild and it looks almost brand new. Just get some glass beads and put it in the tank with soap and bleach. Plug the holes and shake outside with gloves on for your hands for about 10-15 minutes. Clean everything out with a garden hose, making sure all the glass beads are out as to not get in any of your smaller coolant lines. Clean as a whistle inside. For the outside and the neck, get hydrogen peroxide in higher concentration, if you can, and oxyclean, and put in a large pot or bucket submerged for about a week or so. The poly plastic will whiten quite a bit. Lastly, get either flex seal tape or stretchy silicone tape to reattach the neck. That's it. Almost good as new,
Mike
Originally Posted by Sgtblue
(Post 12316485)
^Yeah....sure wish you could buy just the neck. :)
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Sooo it’s probabaly not a good thing that my old antifreeze is dark green is it....(no idea how long it was in there) https://cimg8.ibsrv.net/gimg/www.rx7...e329cb457.jpeg |
Dude... distilled water or antifreeze not candy green apple juice ....
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I’m gonna venture to say it prob doesn’t taste like it 🤔 ...although.....haha |
Actually is this hole signed open?
I mean, dust may go inside? Another question: Do You seal in same way the neck on the tanks? Thanks https://cimg1.ibsrv.net/gimg/www.rx7...be0d4145eb.jpg https://cimg5.ibsrv.net/gimg/www.rx7...5b9ead6b67.jpg |
I used double sided silicone tape that stretches, seals well, and takes the heat.
Mike |
Stock, the water neck does have a tape type seal going into that tank.
The small hole is necessary, don't block it up. The tank needs to breathe or it won't function properly. It's such a small hole and in such an odd spot that the chances of significant dirt getting in there are slim. All FD's have this same tank and hole and it works just fine. Dale |
Good idea on the silicone tape, I have since got a decent used one that cleaned out pretty good. So far I haven’t had it leak again yet, but it went from half full to little over 3/4 full, it’s currenlty in storage for the winter, I haven’t had a chance to mess with it since |
What do you think about the [b=left]heat [/b][b=left]shrink [/b] tubing to seal the neck?
Silicon tape is a good idea, i will check what i find :-) |
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