'78 280Z L28 Coolant Leak From?

[M.Bonanni]

Just picked up this '78 280Z as a new project and it has a cooling leak that I can't see the origin of so before I spend hours tearing into the top of the engine I was hoping you call could help narrow the focus of my search since I am new to this chassis and engine. The You can see in the photo where the leak, but not it's origin. It's at the back of the block on the left side and starts high up somewhere toward or at the head. I am hoping it isn't a head gasket, but I did check the oil and it isn't milky and looks in great shape. Is there something back there on that side of the engine that may be the source? It's not a terrible leak, but it looks like it's been going on for a long time.

 

 

Where you see blue is the fluid. The dark spots on the exhaust manifold are not from the leak, they're from some penetrating lube I was using on the steering column nearby. Thanks in advance!

Edited January 16, 2016 by M.Bonanni

[NewZed]

Use an editing tool to mark up your photo.  Can't really tell which dark spots are from a leak.  The Snipping Tool in Windows Accessories is a good one.

 

I had an HG leak on the passenger side, in the back.  It would leak down over the starter and transmission while the engine heated up then seal itself once everything got hot.  Stopleak helped for a while until it all extruded out of the gap.

 

There's also a core plug in the back of the head that can leak.  But external HG leaks aren't uncommon.

[M.Bonanni]

Use an editing tool to mark up your photo.  Can't really tell which dark spots are from a leak.  The Snipping Tool in Windows Accessories is a good one.

 

I had an HG leak on the passenger side, in the back.  It would leak down over the starter and transmission while the engine heated up then seal itself once everything got hot.  Stopleak helped for a while until it all extruded out of the gap.

 

There's also a core plug in the back of the head that can leak.  But external HG leaks aren't uncommon.

 

It's the blue area that is saturated with coolant, the dark spots on the exhaust manifold are from some penetrating lube overspray. The passenger side is bone dry. I will get into photoshop and clarify on the photo.

[M.Bonanni]

[NewZed]

Stick your head down on the passenger side and look across the mating surface between head and block.  You might get a better view.

[NewZed]

Here's where the coolant showed up on mine.  Flat spot on the back corner of the block deck.  No heater hoses in the way because I was removing the engine.

[M.Bonanni]

Thanks for the help again NewZed! The piece you pictured doesn't appear to be an issue on my car. I am leaning more toward head gasket the more things I rule out. All the freeze plugs seem okay as well. Really, the entire engine is so filthy I should probably clean the hell out of it as best as possible and try and see if I can spot a more defined coolant trail before I jump to any conclusions.

[Xnke]

The drain for the engine block water jacket is right above where that coolant mark is.

[TimZ]

The drain for the engine block water jacket is right above where that coolant mark is.

I was thinking that too.  Also could be the thermostat housing, with fluid running down the head/block interface surface and dripping off at the rear.

Edited January 19, 2016 by TimZ

[M.Bonanni]

I was thinking that too.  Also could be the thermostat housing, with fluid running down the head/block interface surface and dripping off at the rear.

 

Thermostat housing and gasket look relatively new and in great condition. I don't see any signs of them leaking although I wish it were the culprit as it would have been an easy fix!

 

The drain for the engine block water jacket is right above where that coolant mark is.

 

Thanks! I will look into that.