Weirdest cooling system leak EVER

[TheWagonator]

So I've got a '79 b310 with an A14. Picked it up super cheap off craigslist a while back, towed it home. 

 

I replaced the battery, blew out a clogged fuel line, and primed the pump and it started on the first crank and sounds like it's running great, no overheating or struggling even at higher rpm, no misfires above 6-700rpm (as long as it's got a little gas). I haven't got it to idle yet but I assume that's just a cruddy carb.

 

Anyway I thought it was a day or two and a carb rebuild from being a legit runner, and I thought I'd be proactive and change the fluids. Drained the radiator (rust-brown water...) and filled it up with a 3 day flush liquid. As I was topping up the radiator I suddenly hear a stream of water leaking, but I can't see anything under the engine bay. Finally I see a puddle at the end of the exhaust! When I stopped topping up the radiator, it stopped leaking out the exhaust. I assume that this is not part of the original design...

 

There are no leaks that I've noticed in the month or two it's been in my driveway, and theres definitely no white smoke when it runs that might indicate a blown head gasket or a crack in the jacket. (Only real issue at all is oil on the #1 spark plug would suggest a bad piston ring or valve gasket and theres a little oil burning sometimes). 

 

Is it a cracked block? Might I be hydrolocked? Should I even try and start it or will it just explode??

 

HELP

[datzenmike]

Are you saying you filled up your ehaust system with water till it ran out the tail pipe?????

 

 

Rusty water in the cooling system means the other owner didn't use antifreeze coolant, not a good idea as it prevents corrosion as well.

 

Head gaskets don't always leak water into the cylinder and make steam. They sometimes can blow out to the side too. My last gasket blew out beside the dip stick and sprayed water onto the inner fender.

[datsunaholic]

Pull the spark plugs, and try filling the radiator.  That'll tell you if you're filling a cylinder. 

[Stoffregen Motorsports]

I'm trying to think of a scenario where the coolant runs out the exhaust without making white smoke when it's running. I just cant. MAYBE the exhaust port has a crack in it through to the water jacket, but that's doubtful. It would take a hole to cause the leak to be that noticable. And it's not likely either way.

 

My money is on a head gasket and you're just not noticing the smoke or steam coming out the exhaust. That's the most likely cause, but I have seen some weird shit...

[TheWagonator]

Are you saying you filled up your ehaust system with water till it ran out the tail pipe?????

 

Looks that way? Filled the radiator up to the neck (where the overflow connects) and it kept draining down to like the first baffle and then stabilized. When it stopped draining the tailpipe stopped pouring water, so that would seem to be what's happening. 

 

Questions is, what are the chances the water's just going straight into the exhuast (the manifold is in pretty bad shape) vs. a problem with more the block/headgasket/waterjacket/etc.?

 

Got new ignition wires (the old ones are trashed, fell apart when I pulled the spark plugs) If theres no water in the cylinders that I can see I'm gonna crank it a tiny bit and see what happens.

[TheWagonator]

I'm trying to think of a scenario where the coolant runs out the exhaust without making white smoke when it's running. I just cant. 

 

Yes, hit the nail on the head. That would be why I'm a little worried/confused... 

[TheWagonator]

Sooo I went out and cranked it without spark.... more water out the tailpipe. Water in the cylinders. Lovely.

[datzenmike]

Head gasket recently blown. Compression won't allow water into the cylinder when running but when off will fill the cylinder until it runs out the open exhaust. Will only do this on the bad cylinder when it stops with an exhaust (or intake) valve open AND the rad cap off. You risk a hydro lock if left like this.

 

At the very least the head has to come off to examine the head for possible cracks. Since the gasket will be replaced this will fix it. Head should be checked for warp-age.

[TheWagonator]

Head gasket recently blown. Compression won't allow water into the cylinder when running but when off will fill the cylinder until it runs out the open exhaust. Will only do this on the bad cylinder when it stops with an exhaust (or intake) valve open AND the rad cap off. 

 

Ahhhhhh, that makes a lot of sense. Thanks man! Gotta say I'm lovin' ratsun...

 

Guess pulling the head is a good excuse to inspect the rest of the engine, head off some other potential issues, clean up a little more, etc... ahh well off to the parts store haha.

[datzenmike]

Easy fix when you don't have a timing chain to worry about. Leave the manifolds on the head, just tilt up enough to clean the surface, don't disturb the carb if possible. Check with a straight edge for level. Gaskets don't usually blow for nothing. It may be warped slightly. If so, the manifolds are a lot easier to get at OFF the motor.

 

Change oil and filter if oil looks like cafe au lait. Cappuccino in the states.

[TheWagonator]

yeah, I am definitely thanking god for A series bullet-proof simplicity right about now, I'd be scared sh*tless of trying a backyard head gasket change on any modern engine 

 

And yes indeed the oil is a very frightening color... but I was going to do an oil change anyway!

 

Also this thread will definitely also be a life saver: http://community.ratsun.net/topic/36950-a14-head-gasket-change-info-needed/

 

 

 

Hey and gonna use this as an excuse to clean up the manifolds and paint the valve cover as well, so guess you could call it a good thing