Mysterious coolant leak 94 3.4L DOHC

[GnatGoSplat]

The 94 convertible seems to have sprung a mysterious coolant leak while it's been sitting, waiting for a new starter. It's dripping coolant off of the front edge of the transaxle oil pan, behind the engine oil drain plug. It doesn't have to be running, it's a constant drip drip drip like a leaky faucet just sitting there cold, not having been driven for a week. Any guesses where it could be coming from? I can't get a visual on the source of the leak from the top side of the engine. I'm really worried it could be an external head gasket leak.

[GOT2B GM]

A few possibilities that arent quite as serious:

the LIM to plenum coolant port o-ring

the front coolant bypass pipe to plenum connection (the 3" piece of 3/4 hose below the TB)

The coolant quick connector going into the LIM

[GnatGoSplat]

I can't visualize where the LIM to plenum coolant port O-ring is. I've changed out the LIM before, but not really remembering any O-rings. Where's the best spot to see it?

I think the hoses below the TB were dry, but hard to tell because it's oily there from the oil pump drive O-ring leak. I'll have to double-check.

It was dry at the coolant quick connector.

[GOT2B GM]

The plenum seals onto top of the LIM right beside where that 3" hose connects. There is a port there sealed only by an oring. Part of the TB heater circuit.

[GnatGoSplat]

Thanks, I'll be sure to check it out. It's definitely greasy looking in the valley from the oil pump drive, but I didn't see anything resembling coolant anywhere in the valley area, but it's worth double, triple, quadruple checking. This may be the end of the road for the vert if it's the head gasket as that's a bigger job than I want to tackle.

[GOT2B GM]

If its a HG, sell it to Nunzi, he needs a vert, he just doesn't know it yet.

[GnatGoSplat]

LIM to plenum under the TB, dry.
T-stat housing, dry.
Heater pipe quick disconnect, dry.
All dry up there. Time for panic? Or any other ideas?

I guess it's not really worse. The dripping is significantly less now that my wife is driving it again. I think it started dripping because it'd been pooling up on top of the transaxle housing for a week while waiting for a new starter.

[GEN1Z34]

Try checking heater core connects and lines for cracks/leaks..

Also maybe check the LM gaskets, specificly where the cylinder head coolant port is near the T-stat housing..

Here:

[GnatGoSplat]

Thanks, I'll take a look when I get home, but I didn't remember seeing anything that looks like coolant in the whole valley area. That is one nice looking 3.4 DOHC!

[GEN1Z34]

Thanks, I'll take a look when I get home, but I didn't remember seeing anything that looks like coolant in the whole valley area. That is one nice looking 3.4 DOHC!

Thanks!

The thing is, there's a step in the block casting in that area..

Could be that the leak is dripping below the step and running down the back side of the block.

If you suspect a head gasket issue you could try a compression test..

But being the bank against the firewall you know how fun that would be..lol

[GEN1Z34]

Oh yeah, could also be the freeze plug in the head there, but I think you'd see that fairly easily..

But definetly check the heater core lines..

Especially where the hard coolant line runs along the passenger fender well..

It makes a turn back in there where you can't see..

A couple of years ago I had a coolant leak down while my 92 z34 was parked too..

Pulled the fender well and uncliped the line from the chassy and it just crumbled in my hands..

[GnatGoSplat]

Thanks, I could be wrong, but I don't think a compression test would find a head gasket crack that runs from cooling passage to the outside. I think it would only show up if the crack runs into the combustion chamber. I'll be sure to check the other stuff when I get motivated to get under the car.

[GOT2B GM]

If you have the cooling system pressure tested the external leak will show.

[GEN1Z34]

If you have the cooling system pressure tested the external leak will show.

This, is what I should have said...my bad..

[GnatGoSplat]

Think this would work?
http://cgi.ebay.com/ebaymotors/Mityv...item20b64b8e1d
Like everything else, if I have to pay someone else to do it, I'll procrastinate and it'll never get done so any DIY solution is preferable.
I may procrastinate on this anyway, it seems the leak isn't as bad as I initially thought. It had just been pooling for a week so it was around a week's worth spilling off the tranny all once.