Leaking coolant from where? One *crazy* mystery! - Page 3 - PeachParts Mercedes-Benz Forum

5cylinder · #31 06-12-2014, 07:57 PM

Quote:

Originally Posted by uberwasser

Good stuff from the sound of it.

I certainly will be relieved if the dried coolant residue turns out to be originating from the expansion tank cap or hose.
Eliminating this leak will mean *no* leaks from my car. I've taken care of all of the rest of 'em! Not bad for a 29 year old M-B with 195,000 miles!

rscurtis · #32 06-13-2014, 10:30 AM

Another thing you could try if you haven't already is go down to a 7# pressure cap. it's a lot easier on the radiator and heater core. I run NPG in my signature car at 0 psi and it works great.

funola · #33 06-13-2014, 11:10 AM

Quote:

Originally Posted by 5cylinder

Now here's a mystery for the really brave...

My vehicle is a 1985 300CD-T (Calif.). Mileage is 195,602.
Issue: Dried residue from coolant appears on the transmission pan and the support panel for the driveshaft's intermediate bearing. I have attached three pictures.

Why do I think that this stuff is dried coolant residue? Because it has the whitish-bluish color. The new M-B coolant that I use is blue colored.

When does this residue appear?
Only after driving the vehicle on the freeway for 10-15 minutes and around 60-65 MPH.

How much coolant disappears from the coolant reservoir?
Negligible. The fluid level barely appears to drop.

All of the original cooling system hoses were replaced in July of 2011 at 178,394 miles.

I have checked the tightness of all of the cooling system's hose clamps and tightened a bit more if it seemed okay to do so.

I have used a dentist's mirror to look completely around and underneath all cooling system hoses, metal lines, and connections and have found no sign of coolant leakage anywhere.

My current guess:
Coolant is leaking from around an exterior and rear (near the firewall) portion of the head gasket from a very small spot that only leaks when there is high pressure in the cooling system (read: highway driving at highway speed). The coolant then leaks downward, blows onto the underside components (i.e., transmission pan, support panel for the driveshaft's intermediate bearing) and dries.

Other thoughts?

What kind of coolant are you using that is white? The correct Mercedes coolant is pale yellow. Those splatters looks like like white paint. Are you sure it's coolant?

Take a few drops from the expansion tank and put it on the radiator neck, let it dry and take some pics and see it it looks the same.

5cylinder · #34 06-13-2014, 11:14 AM

Quote:

Originally Posted by rscurtis

Another thing you could try if you haven't already is go down to a 7# pressure cap. it's a lot easier on the radiator and heater core. I run NPG in my signature car at 0 psi and it works great.

Hmmm, I am not that familiar with this.
So, do you just go to a McParts auto supply store with the old cap and tell them that you want a cap that fits (or is that what the 7# designation means?) that will create 0 psi in the system?

This does raise this question in my thinking:
Why would M-B use a cap that keeps the system at 1 bar (approx. 14 psi) if it would be easier on the radiator and heater core to use 0 psi?

Thanks-

5cylinder · #35 06-13-2014, 11:18 AM

Quote:

Originally Posted by funola

What kind of coolant are you using that is white? The correct Mercedes coolant is pale yellow. Those splatters looks like like white paint. Are you sure it's coolant?

Take a few drops from the expansion tank and put it on the radiator neck, let it dry and take some pics and see it it looks the same.

I am using the latest M-B "Anticorrosion/Antifreeze AGENT" (part number BQ 1 03 0004) acquired from M-B in May of 2014. It is colored blue.

funola · #36 06-13-2014, 11:21 AM

Quote:

Originally Posted by rscurtis

Another thing you could try if you haven't already is go down to a 7# pressure cap. it's a lot easier on the radiator and heater core. I run NPG in my signature car at 0 psi and it works great.

Lowering cap pressure lowers the boiling point of the coolant. I have no experience with NPG coolant. I have read NPG has serious issues in very cold climates. Is that true? I assume you live in Florida?

funola · #37 06-13-2014, 02:39 PM

Quote:

Originally Posted by 5cylinder

I am using the latest M-B "Anticorrosion/Antifreeze AGENT" (part number BQ 1 03 0004) acquired from M-B in May of 2014. It is colored blue.

Why did you change from the spec MB coolant or Zerex G-05? The newest MB coolant is for aluminum head engines and may not be the best your cast iron 617.xxx engines.

Are you 100% sure those white splatters is from the coolant? Will you do that test I suggested?

funola · #38 06-13-2014, 02:41 PM

Quote:

Originally Posted by Mxfrank

Pure glycol is flammable. Not the solution for a leak inside the passenger compartment.

How flammable is it? Anything raised to a high enough temperature will burn. If you put a wick in the antifreeze mixture and can't light it with a match or a spark, don't worry about it.

rscurtis · #39 06-13-2014, 03:13 PM

Is that true? I assume you live in Florida?

I have not had any issues even at 2* F. I'm not worried about the boiling point, it boils at 370* F. The original racing formula did have some viscosity issues.

5cylinder, sorry for the confusion. The 7# cap reduces the pressure on the system. I run mine at 0 PSI by leaving the cap loose. The reason for the higher pressure from the factory is to guard against the most extreme temperature situations. There is no benefit to pressurizing a cooling system more than necessary. All that extra boiling point won't be doing you any good when you're stuck in traffic with a blown hose or a split radiator tank.

uberwasser · #40 06-13-2014, 03:19 PM

PG is NOT flammable. It was easy to do a bit of research. Per the NFPA, a liquid needs a flash point temperature below 100°F to be considered flammable. Anything above that is simply combustible.

Gasoline is, obviously, flammable. It has a flash point of -45°F.

Diesel is not considered flammable. The MSDS for D2 refined by BP says it has a flash point of 100.4°F. So it's considered combustible, just over the edge. How many of us have D2 leaking on our hot engines, without stressing?

The MSDS for PG shows a flash point of 228°F. And it doesn't auto-ignite until 700°F.

So, will PG burn? Of course. Anything that is combustible has the potential. But I'd suggest that having a leak of PG in to your car's cabin or even on to the engine is not a fire hazard. If your car caught on fire for other reasons then sure, the PG would ignite given enough energy/heat from said fire and perhaps make it worse but it's moot, then, as your car was already burning down!

funola · #41 06-13-2014, 03:38 PM

Quote:

Originally Posted by rscurtis

Is that true? I assume you live in Florida?

I have not had any issues even at 2* F. I'm not worried about the boiling point, it boils at 370* F. The original racing formula did have some viscosity issues.

5cylinder, sorry for the confusion. The 7# cap reduces the pressure on the system. I run mine at 0 PSI by leaving the cap loose. The reason for the higher pressure from the factory is to guard against the most extreme temperature situations. There is no benefit to pressurizing a cooling system more than necessary. All that extra boiling point won't be doing you any good when you're stuck in traffic with a blown hose or a split radiator tank.

Wouldn't leaving the cap loose allow air (oxygen) to enter? Oxygen promotes oxidation (rust). Isn't that not good for cast iron engines?

5cylinder · #42 06-13-2014, 03:54 PM

Quote:

Originally Posted by rscurtis

Is that true? I assume you live in Florida?
5cylinder, sorry for the confusion. The 7# cap reduces the pressure on the system. I run mine at 0 PSI by leaving the cap loose. The reason for the higher pressure from the factory is to guard against the most extreme temperature situations. There is no benefit to pressurizing a cooling system more than necessary. All that extra boiling point won't be doing you any good when you're stuck in traffic with a blown hose or a split radiator tank.

Got it. Thanks for clarifications. The coldest environment that my car experiences is, say, 30 degrees. Rather mild. And that is inside a garage.

dieselbenz1 · #43 06-13-2014, 04:30 PM

Quote:

Originally Posted by funola

Why did you change from the spec MB coolant or Zerex G-05? The newest MB coolant is for aluminum head engines and may not be the best your cast iron 617.xxx engines.

Are you 100% sure those white splatters is from the coolant? Will you do that test I suggested?

Ok I have a 602 engine with an aluminum head am I to believe g-05 is not what I should be using?

uberwasser · #44 06-13-2014, 07:12 PM

Indeed, NPG+ from Evan's has a flash point of 233*F or 111*C. Again, WAY higher than diesel fuel. I don't know anyone here who stresses about a diesel leak on their engine. I've had a return hose that broke in half an was pissing diesel all over the side of the block. Nothing even remotely problematic.

I know that a diesel leak CAN be dangerous, I'm not saying it isn't.

However I would say it's much more dangerous than a waterless coolant leak.

You would need both that temperature, and an ignition source. That's usually lacking.

My point is that NPG is safer than many of the other fluids we use in our engines and my initial response was to point out that it's in no way "flammable" per the definition.

uberwasser · #45 06-13-2014, 07:25 PM

And by the way, I don't use NPG, don't plan to, not even really interested in it. But 10 minutes of research debunked the claim that it was in the flammable category, much less even as ignitable as diesel fuel. You're acting like it's the same as running gasoline in the cooling system.

I think the key here is being more clear and honest with the language used. You keep saying it's flammable. NOT true.

What it is, is IGNITABLE. I.E. when all factors come together it can ignite.

In case you're interested, PG is also ignitable at concentrations over 40% in a PG/water solution. Most people run higher concentrations, maybe 50/50. The NFPA banned this practice in fire sprinklers after a case where anti-freeze in the water from a fire sprinkler made a grease fire worse. That's a situation where all factors came together and the PG in the water burned.

Are you going to stop using antifreeze and just run plain water? Or take a calculated risk?