Mystery coolant leak **PICS** (formerly Hole Corroded in Head)

[suprarx7nut]

So I have had a very slow coolant leak since I've owned my car. (5 months) It has seemed to stop, but I found a red trail of something and I use Toyota red coolant... The plot thickens.

This week i had some time to take of the exhaust shied and take a look.

Follow me as we journey underneath my exhaust mani and inspect the culprit:

Does it look like a hole has made its way through my head?! If not, what the hell is that gory looking thing leaking my red coolant? Perhaps a rodent bled profusely on my engine? :dunno:

 

[willfish]

dam man,


at first,
I thought you did a PT test ( liquid) on it to show all the cracks.....


Will

 

[suprabad]

Block test it for exhaust gasses in the radiator. Something tells me this is a BHG or cracked head. I'd be surprised if there wasn't some coolant getting into the combustion chamber.

On a cheerful note, you'll have one piston that's real clean.

 

[johnathan1]

Wow, that's pretty scary looking...

I suppose it COULD be the head gasket...but that would be pretty unlikely...

Maybe there is a pinhole leak on the other side of the coolant hardpipe that you can't see...and it's spraying coolant onto the engine while at operating temp? :dunno:

 

[MK3Brent]

I'll play the completely random card:

Electrolysis.


Good luck figuring it out.

 

[willfish]

either way, , you better start saving some money....

Will

 

[suprarx7nut]

Block test it for exhaust gasses in the radiator. Something tells me this is a BHG or cracked head. I'd be surprised if there wasn't some coolant getting into the combustion chamber.

On a cheerful note, you'll have one piston that's real clean.

Haha.

Block tested 2 months ago, after the leak was noticed and it was negative. No gases detected.

I'm planning on doing the head gasket this summer anyways, so if it is a bhg, as long as it holds until then, its no biggie. If it goes before then though....

 

[Dirgle]

I'll play the completely random card:

Electrolysis.


Good luck figuring it out.

More then likely Brent is right, and it isn't done. Electrolysis is very destructive, you'll be amazingly luckly to make it to summer

 

[suprarx7nut]

More then likely Brent is right, and it isn't done. Electrolysis is very destructive, you'll be amazingly luckly to make it to summer

How would that piece of the block get any voltage? I would think that would be ground?

Or am I not grasping the concept? :dunno:

 

[suprabad]

How would that piece of the block get any voltage? I would think that would be ground?

Or am I not grasping the concept? :dunno:

Electrolosis is the process of an electrical charge being created by two different kinds of metals touching or being in the proximity of eachother.

 

[suprarx7nut]

Electrolosis is the process of an electrical charge being created by two different kinds of metals touching or being in the proximity of eachother.

I thought electrolysis was where you send current through an aqueous solution (water, perhaps) and the current causes the solution to split into smaller compounds. Water -> Hydrogen and Oxygen. With water, those compounds can act to oxidize metal at a very accelerated rate.

 

[johnathan1]

I thought electrolysis was where you send current through an aqueous solution (water, perhaps) and the current causes the solution to split into smaller compounds. Water -> Hydrogen and Oxygen. With water, those compounds can act to oxidize metal at a very accelerated rate.

DING DING DING!

Electrolosis is the process of an electrical charge being created by two different kinds of metals touching or being in the proximity of eachother.

That one, not so much... :biglaugh:

Although when certain metals are put together, reactions can occur...

 

[Dirgle]

How would that piece of the block get any voltage? I would think that would be ground?

Or am I not grasping the concept? :dunno:

Poorly grounded accessories can use the coolant as a better current path, things like the starter or A/C clutch can really dump the voltage in there, causing accelerated erosion. You need to check if there is any stray voltage in your cooling system.

To do this, remove the radiator cap(I shouldn't have to tell you to make sure the radiator isn't under pressure before you take the cap off), start the car and have all your accessories running(A/C, head lights stereo, wipers, ect) place the negative terminal of a voltage meter on the chassis ground, and stick the other probe into the coolant at the radiator cap. Check to make sure you don't show more than .05 volts(some sources say no more than .10 volt) If you do, and I'd guess you do, have someone shut off the different accessories until the voltage drops to acceptable levels, once you have isolated the problem system check the grounds on it, more than likely they are in need of repair.

Also some have said to try and use an analog voltage meter because some of the more generic digitals don't work well. However my digital worked fine for me.

There was actually thread about this a few days ago.

http://www.supramania.com/forums/showthread.php?t=60596

There are other forms of chemical corrosion that can cause this but since you said that you already did the exhaust gas test thought we would jump to this test.

 

[CRE]

Brent's referring to what's more commonly called dielectric erosion. Electrolysis is applicable though, you've got your cathode and a sacrificial anode.

Personally, I'm with Johnathan as far as most likely cause of the leak.

 

[csnow]

Great info...


Good luck on the repair.

 

[suprarx7nut]

Well I'm off try to find the problem area. I only have a digital MM, so I'll be using that as of now. If it doesn't give any consistent reading, then I'll buy an analog.

Thank you Dirgle for the info and link I'll report back with my findings in a few hours.

 

[lagged]

did you try pressure testing the cooling system to find the exact location of the actual leak? (ie: the first thing you should do whenever you have a hard to find water leak...)

those pictures really tell us nothing. it could be a hole, it might not be. but its impossible to say based off of looking at those pictures over the internet.

 

[SupraMario]

Holy hell, your 7m is bleeding!!!!

 

[IJ.]

Another cause "stray current"

I'd grab a pick or a small screwdriver and poke it to see if it is an actual hole and not a leak higher up before jumping to conclusions.

 

[GrimJack]

Personally, I'm with Johnathan as far as most likely cause of the leak.

x2.

I've had this exact problem. I lost the head gasket seal between the water jacket and the EXTERIOR of the head. At operating temp, it would leak a bit. Leakdown test passed, block test passed, compression was fine.

Eventually the task of adding a bit more coolant every 2000 miles got annoying, and I tore the head off and replaced the gasket anyway.