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Login to post Forums » Grassroots Motorsports » Coolant leaks out AFTER shutting car off?

May 26, 2008 6:35 p.m. Jay HalfDork

So this past weekend I took the Lotus out for a small cruise (around 100 km) with the German Lotus Club. It was the first time I'd really had the car out for a good boot, and it was mostly behaving well.

After parking it (warm) for a while I came back and found a big puddle underneath. Maybe a litre of coolant had come out from somewhere after I'd shut the car off. First time I'd ever seen it happen. I couldn't find anything immediately wrong so I drove it an hour back home where it did the same thing. (It's not condensation from the A/C before anyone asks - it's antifreeze.)

There are no drips or squirts when the motor is running and I stayed and watched for a few minutes after I'd shut it down, but I didn't see it come out right immediately. It looks like it all came out in one big go because the whole crossmember was wet underneath.

The temperature is fine when driving (according to the gauge which may or may not be accurate - some of my other gauges aren't working right at the moment), the fans come on normally, I don't HEAR the coolant boiling or anything to indicate I'm overheating. No idea what's going on here.

Some suggestions of things to look at would be much appreciated!

: J
May 26, 2008 6:54 p.m. wlkelley3 Reader

Check the hose clamps. Orginal spring type? I had a leak there when the coolant warmed up (pressure in the system?). A real hose clamp fixed it.
May 26, 2008 7:58 p.m. porksboy HalfDork

Check the water pump. some times they leak when they are not turning or only in certaim positions. Try this, pressurize the system with a tester. Remove or at the least loosen the belt til you can turn the pump shaft. As you turn the shaft move it side to side and see if it leaks. try it with the engine warm if you can get in there without frying your arm. :nice:
May 26, 2008 8:15 p.m. internetautomart SuperDork

my gut is saying it's something with the radiator cap, but i forgot what the problem was. I had the issue once before
May 26, 2008 10:10 p.m. Jack SuperDork

Is there an overflow tank? Was it completely full?

Coolant gets much hotter after stopping and will expand. If I fill my TR3 radiator up (no overflow tank) it'll dump coolant the first few times out. Even with an overflow tank, if there isn't enough room for the expansion, it's going to overflow.

Then again, it could be another issue.

Jack
May 26, 2008 10:51 p.m. joshx99 New Reader

Maybe there's a crack in your radiator that is swollen shut while the system is under pressure.
May 27, 2008 7:35 a.m. amaff Reader

I'm with porksboy. About a year ago I had coolant leaking from the front of the engine. Replacing the water pump fixed it.
May 27, 2008 8:30 a.m. mad_machine SuperDork

I have to ask the same question as Jack. I have dealt with cars that do not have an overflow tank. Hate those cars as they always seem to "barf" coolant after a run.
May 27, 2008 9:07 a.m. iceracer New Reader

Radiator cap would be the first thing to check. I asume it doesn't have a catch can/overflow tank.
May 27, 2008 9:58 a.m. Jay HalfDork

It does actually have an overflow tank, which has a sealer cap and pressurizes. In fact, it doesn't have a rad cap as the normal way to top off the coolant is to fill it up through the overflow tank.

> J
May 27, 2008 10:47 a.m. joshx99 New Reader

My rx7 did this for awhile. It turned out to be a crack in the radiator that would start to drip after the car was shut off.
May 27, 2008 10:48 a.m. Jack SuperDork

Now I think you need to drive it a bit, pop open the bonnet and watch for a drip. It could be a lot of different things. Then again, since it's British, isn't it supposed to leak something?

Jack TR's 3 & 8
May 27, 2008 2:01 p.m. mad_machine SuperDork

just so long as it is not leaking smoke from the wires
May 18, 2010 1:35 p.m. rahul

Hi, Did you come to know the cause i have exactly same issue in my car.
May 18, 2010 1:44 p.m. Powar Dork

rahul... My girlfriend's '93 900S did this last weekend. The coolant reservoir cap was bad. Hasn't lost a drop since. I can't speak for the OP, but that fixed the similar (same?) issue for me.
May 18, 2010 2:29 p.m. Jay Dork

Woah, back from the dead thread. Nope, never did find any obvious problem. It's been forever since the car's done that, but I still have to top up the coolant once every couple months, no idea where it's going. Overflow cap seals well (I have a pressurized reservoir anyway, no rad cap, like a 944.) I did replace a couple dodgy hoses but they weren't bad over the spot where I'd occasionally find water. I dunno.
May 18, 2010 4:46 p.m. kb58 Reader

I had that happen... it was a pinhole leak in a hose, which would leak only after it sat turned off for a minute or so.
May 18, 2010 8:34 p.m. NGTD HalfDork

My Passat is doing this now. Appears to be coming from the water pump. Only happens once in a while.
May 18, 2010 9:11 p.m. Jensenman SuperDork

The Trooper's water pump did this recently. It would only puke coolant when the ambient temp was below about 50 degrees and the car sat overnight. I'd wak into the garage and there would be a 4 or 5 inch puddle. The worst part: onthat engine the T belt drives the water pump and it was damn near impossible to see exactly where the leak was coming from because of all the covers etc.

I have also seen hoses do this. The Oetiker and spring type clamps were designed to fix that; as the hoses heat cycle they swell and shrink along with the nipple (heh heh he said nipple) meaning the clamp needs to be able to do the same to hold the hose tight. Screw type clamps have to be retorqued, spring and Oetiker do not.

Oetiker clamp and installation tool:

Spring clamps:

Plastic and aluminum radiators have been known to do this as well. The plastic tanks have a gasket, then there are tabs on the radiator core which are crimped to hold the tank to the core. Over time, the gasket will extrude away from the seam area and the result is a cold coolant leak.

VW had problems with hoses that had a porous inner liner; coolant would wick its way through the liner then follow the reinforcing threads to the end of the hose and drip out. No amount of clamp torquing would fix this, only new hoses. The funny thing: VW knew about it for a while because the crappy hoses had a yellow paint dot and the good hoses had a white one.

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