Radiator blew up - PeachParts Mercedes-Benz Forum

Scott98 · #1 02-23-2004, 11:04 AM

Saturday I was driving to the parts store to get some replacement hose for the fuel return lines and after I left the store I noticed a little bit of steam coming from under the hood and that my temperature gauge was 3/4 of the way up. I immediately pulled over and killed the engine. The top of the radiator where the upper hose connects broke off and radiator fluid soaked the entire engine. I'm just thankful that I caught it and was able to pull over before the engine blew. I had it towed to a mechanic as I need the car soon and don't have the time or a place (I live in the city) to fix the car. The mechanic told me it is a somewhat common problem on the original plastic radiators. The new ones have extra reinforcement in that area and don't break. He said it happens because when the engine shakes, it also shakes that top raditor hose and eventually wears out that part of the radiator.

I think things could have been a lot worse so I am thankful that it is only the radiator I am replacing and not the engine too. I thought I would post this so some of you would be aware and not have the same thing happen to you.

Happy motoring,

Scott

Jim Anderson · #2 02-23-2004, 11:19 AM

I had a metal radiator do that, and heard of it happening to others too. What happened was the thermostat fails closed and the cooling system pressure climbs faster than the pressure cap can vent it, and of course the engine temperature climbs pretty fast too. It turns out the lowest pressure component in the cooling system is the radiator, I thought it would have been a hose.

I think your mechanic may or may not be right, but I'm suggesting you check/change your thermostat anyway.

My cost was just a thermostat, metal radiators are repairable.

Scott98 · #3 02-23-2004, 11:27 AM

Quote:

Originally posted by Jim Anderson
I think your mechanic may or may not be right, but I'm suggesting you check/change your thermostat anyway.

I forgot to mention that the mechanic asked when I last replaced the thermostat and said to replace it also.

Scott

psfred · #4 02-23-2004, 04:25 PM

I was lucky, the Volvo upper rad hose nipple failed in the driveway when I was setting the injection timing, not on the highway like my sister's did (740 gas turbo). Hers blew the nipple off and warped the head something fierce. New head, rad, temp sensors, thermostat (stuck open) and gasket, $700 in parts.

Very common failure, made much more likely by using green coolant.

Peter

Scott98 · #5 02-23-2004, 04:32 PM

What does green coolant have to do with it? Mine had green coolant. It was supposed to be MB coolant. I don't know because I didn't put it in myself. I had a mechanic replace the water pump some time ago and they put the coolant in.

Scott

ericnguyen · #6 02-23-2004, 07:03 PM

Dear Scott98:

The conventional American Green antifreeze tends to harden a plastic radiator and make its more brittle, which in turn causes it to be more susceptible to breakage under constant vibrations transmitted from the engine block to the upper radiator and to the radiator neck.

Various pH buffer chemicals in Mercedes coolant (or Zerex G-05) help maintain a relatively neutral pH level (actually it's more alkaline, i.e ph=7-8) during its lifetime. This stable and relatively neutral pH level over the entire lifetime of Mercedes coolant is key to the long life of plastic radiators.

Eric

leathermang · #7 02-24-2004, 08:41 AM

Eric, (or anyone with knowledge of this) Is there some way to check this with an ohm meter ?

On Ford's which have problems with heater cores rotting out... they have some test like between the negative side of the battery and the coolant in the radiator.... do we have some specs which can be used for checking our cars ?

Fredmburgess · #8 02-24-2004, 09:42 AM

Probably too late but you don't need to replace the whole radiator - just the plastic "tank" on top. I got the part for $25.00 from the company that makes radiator tanks after finding this in a search of this forum. Radiator tank on my '84 300D broke off the same way, but at 400,000 miles, it's hard to complain. If you haven't already ditched the radiator save some bucks and replace only the broken part! F

#9 02-24-2004, 10:58 AM

Hi all.

I have heard this problem before and
the guy at mercedes source actually sells
a kit for this,but it is easily duplicated.

What he came up with was:he epoxied a
piece of pipe in the opening to strenghten
the neck of this nipple.
Thus preventing it from braking.
I forgot what the pipe was made of but
I'm sure you could use a piece of stainless
or even copper.
Edit:just checked,he used a piece of copper pipe.

Louis.

dieseldiehard · #10 02-24-2004, 11:59 AM

When I got my first W115 (a '75 230) an experienced mechanic examined the car and said the radiator should be grounded. He said Mercedes had issued a bulletin that showed a wire from the drivers side on the upper corner of the radiator to the engine block, this supposedly prevents electrolysis. I made one up asap.
I don't know if this applies to the later Behr radiators, which are aluminum not copper and brass like the earlier rads.
I had a failure in a 300D (W123) when the rad neck cracked on a trip. I simply left the cap off and the engine didn't overheat (I watched the gauge like a hawk!) fortunately not a lot of uphill driving, and I didn't use the A/C.
I saw someone try to repair this kind of failure using epoxy, but it was futile. Iwas willing to pay say $300 for an all aluminum radiator for the W124 diesel but never found one. A specialty radiator shop wanted $650 to make one up (hey that's half the cost of a new head! I think I'll continue gambling with the stock Behr - reminds me~ HGV where are you? I need that Radiator!
DDH

Jim Anderson · #11 02-24-2004, 12:19 PM

Doctor Diesel was done in by the demons of Detroit

ericnguyen · #12 02-24-2004, 03:52 PM

Dear Leathermang:

You can get a quick measurement of the pH level of a test sample (e.g. antifreeze) by using pH Litmus Paper Strips that can be ordered online (quite inexpensively). The strip of appearing colors shows you the approximate pH level.

Regarding the electrolysis problem in radiators: by definition, electrolysis is the process in which an electric current flowing through a water solution of a chemical breaks that compound up into its components. You can easily observe the effect of electrolysis by doing this simple experiment: add some salt (sodium chloride - NaCl) to 1/2 cup of water and dip the + and - posts of a 9V battery or 12V DC power supply into the salt mixture. You will smell the pungent odor of chlorine gas emanating from the salt mixture.

Similarly, when electrolysis occurs, the various corrosion inhibitors in antifreeze are subject to breakdown and deterioration, thus partly or completely losing their anti-corrosion capability. Therefore, electrolysis is quite a serious problem when it takes place. Electrolysis occurs when electrical current routes itself through the engine's antifreeze coolant mixture in search of electrical ground. In order to test for electrolysis, try to connect the negative probe of a digital D.C. voltmeter to the battery's negative terminal, then submerge the voltmeter's positive probe into the coolant in the expansion reservoir tank without letting the positive probe to touch any metal contact. Now check the voltmeter's reading, it should be less than 0.1 V. Any higher value would indicate a serious potential difference across the antifreeze coolant mixture, because the voltage is now high enough to trigger accelerated electrolysis into action, which may destroy the anti-corrosion capability of the coolant. You know what would happen if there's no anti-corrosion stuff in your coolant system. Without corrosion inhibitors, ions such as H+, OH-, H3O+ would start ripping metal atoms from your radiator, heater core, and other metal surface within the coolant system.

In case that the reading indicates a higher voltage, try to disconnect one electrical component or accessory step by step at a time while watching the voltmeter. When the voltage reading drops to zero, the just disconnected electrical component is the culprit for the defective or missing ground.

In summary, if the electrical system and all its accessories/components are working properly, there's no concern about electrolysis in your coolant system. However, electrical gremlins are often quite a perennial problem in a modern car. If the radiator is not properly grounded and some electrical components have a defective ground, a serious potential difference may be established across the antifreeze coolant mixture, kicking the electrolysis process into high gears.

Eric

RockinWagin · #13 02-24-2004, 04:06 PM

Quote:

Originally posted by ericnguyen
Dear Leathermang:

You can get a quick measurement of the pH level of a test sample (e.g. antifreeze) by using pH Litmus Paper Strips that can be ordered online (quite inexpensively). The strip of appearing colors shows you the approximate pH level.

Regarding the electrolysis problem in radiators: by definition, electrolysis is the process in which an electric current flowing through a water solution of a chemical breaks that compound up into its components. You can easily observe the effect of electrolysis by doing this simple experiment: add some salt (sodium chloride - NaCl) to 1/2 cup of water and dip the + and - posts of a 9V battery or 12V DC power supply into the salt mixture. You will smell the pungent odor of chlorine gas emanating from the salt mixture.

Similarly, when electrolysis occurs, the various corrosion inhibitors in antifreeze are subject to breakdown and deterioration, thus partly or completely losing their anti-corrosion capability. Therefore, electrolysis is quite a serious problem when it takes place. Electrolysis occurs when electrical current routes itself through the engine's antifreeze coolant mixture in search of electrical ground. In order to test for electrolysis, try to connect the negative probe of a digital D.C. voltmeter to the battery's negative terminal, then submerge the voltmeter's positive probe into the coolant in the expansion reservoir tank without letting the positive probe to touch any metal contact. Now check the voltmeter's reading, it should be than 0.1 V. Any higher value would indicate a serious potential difference across the antifreeze coolant mixture, because the voltage is now high enough to trigger accelerated electrolysis into action, which may destroy the anti-corrosion capability of the coolant. You know what would happen if there's no anti-corrosion stuff in your coolant system. Without corrosion inhibitors, ions such as H+, OH-, H3O+ would start ripping metal atoms from your radiator, heater core, and other metal surface within the coolant system.

In case that the reading indicates a higher voltage, try to disconnect one electrical component or accessory step by step at a time while watching the voltmeter. When the voltage reading drops to zero, the just disconnected electrical component is the culprit for the defective or missing ground.

In summary, if the electrical system and all its accessories/components are working properly, there's no concern about electrolysis in your coolant system. However, electrical gremlins are often quite a perennial problem in a modern car. If the radiator is not properly grounded and some electrical components have a defective ground, a serious potential difference may be established across the antifreeze coolant mixture, kicking the electrolysis process into high gears.

ric

So, does this have anything to do with the use of green antifreeze? Alll recent antifreese that I have purchased have looked more orange than green. I have never gone back to MB to get antifreeze.

ericnguyen · #14 02-24-2004, 04:36 PM

Dear RockinWagin:

The color (dye) has nothing to do with any capability of an antifreeze solution. It's just used to distinguish between various kinds of antifreeze.

You can read my posts in the following threads to understand why distilled/deionized water is the best for mixing with antifreeze, and the actual differences between various kinds of antifreeze such as conventional green antifreeze, Japanese (green | orange | purple) antifreeze, European antifreeze (Clear, Blue, Yellowish, Orange) G-05, G11, G12, G48 etc...

Antifreeze changed..

AntiFreeze Use in Large Diesels

Eric

RockinWagin · #15 02-24-2004, 05:19 PM

You-all should be happy that I am starting a new job on Monday.............

First, let me state that I am color blind. Here is a pic of PEAK AF and coolant (it is probably green) so I take back my earlier............uh, statement about color.

Ok I have read this:

Quote:

dieseldiehard: "Atomic core" should be "atomic nucleus".

P.E.Haiges: Evans waterless coolant requires a near complete removal of all water in the cooling system. Doing this on an old Mercedes would be quite a big chore and may be very time-consuming (several days to dry with a hair dryer etc..)

In pure water, the following 2 reactions constantly occur in both directions, and they are in an equilibrium state.

1) H20 <-> H(+) + OH(-)

2) H2O + H20 < -> H3O(+) + OH(-)

H(+) is a positive hydrogen ion, OH(-) is a negative hydroxide ion, and H3O(+) is a positive hydronium ion.

In tap water, the existence of minerals (and salts) such as NaCl, KCl, Na2CO3, NaHCO3, NaNO3, CaCO3, MgCO3 etc... means that there is an abundance of other ions such as Na(+), Ca(2+), Mg(2+), Cl(-), CO3(-2), NO3(-) .... besides the above-mentioned water-derived ions.

We generally have 3 different terms for "purified water".

1) De-mineralized water (pure), also called "softened water"

2) Distilled water (purer)

3) Deionized water (purest)

Deionized water, de-mineralized water, distilled water are called "purified water" because the extra minerals and salt ions are removed thanks to chemical precipitation/resin ion exchanges, and steam distillation/condensation (for distilled water only). So most of the extra ions (besides the water-derived ions) are extracted, but the water-derived ions (hydrogen ions, hydroxide ions, hydronium ions) are always there, because that's how water molecules and their ions exist in constant equilibrium.

In a nutshell, the strength of an acid is represented by the concentration of hydrogen ions H(+) it can create, and the strength of a base (alkaline) by the concentration of hydroxide ions (OH-).

The pH of a solution is calculated from the formula: pH = -log[H+]
Remember that this "log" stands for decimal logarithm (base 10), not the natural (or Napierian) logarithm (base e=2.7182818..)

For the purest water, the concentrations of H(+), OH(-), H3O(+)
are equal, so [H(+)] = [OH(-)] = [H3O(+)] = 10^(-7). Therefore, the pH of purest water is:

pH = -log[H+] = -log(10^-7) = - (-7)log(10) = 7x1 = 7

For real acids, [H+] is definitely greater than 10^(-7), i.e. it should
be 10^(-n) where n < 7. This means that the pH of an acid is always less than 7:

pH = -log[H+] = -log(10^-n) = -(-n)log(10) = nx1 = n < 7

For real bases, [H+] is less than 10^(-7), i.e. it should be 10^(-m) where m > 7. This means that the pH of an acid is always greater than 7:

pH = -log[H+] = -log(10^-m) = -(-m)log(10) = mx1 = m > 7

For tap water (H+, OH-, H30+, Na+, Cl-, NO3-, etc....), the mineral or salt ions react with water-derived H+, H30(+) ions and prevent them from acting like an acid (which are very corrosive to metals). De-mineralized/deionized/distilled water don't have or have very little mineral/salt ions, so the water-derived H+, H3O(+) are free to attack metal atoms by sucking the low valence electrons from the outer orbital shell of metal atoms (note that H+ and H3O+ have positive charge and electrons have negative charge, so they have high affinity for each other)

The chemical ingredients in the antifreeze coolants such as Dexcool and Mercedes/Zerex G-05 produce lots of other ions that help neutralize the effect of H+, H3O(+) in de mineralized/deionized/distiller water (purified water), so it is OK to mix purified water with antifreeze without any problem. Keep in mind that you MUST use at least 50% antifreeze in your antifreeze/water solution (but less than 70%)! If you follow the proper mixture ratio, purified water is always better than tap water. No minerals/salts = No scaling/deposits/blocking...

HOWEVER, if you use too little antifreeze or just simply use purified water in your cooling system (such as in racing cars), you will kill your engine/radiator IN NO TIME FLAT because of the attacking H+, H3O+ from purified water.

Eric

and this:

Quote:

A proper antifreeze coolant is a mixture of 4 major components:

1) Ethylene Glycol HO-CH2-CH2-OH

Ethylene Glycol is used because it provides 2 important advantages.

- In a proper mixture of ethylene glycol and water, ethylene glycol
helps lower the FREEZING point and raise the BOILING point of the mixture at the same time. This will protect a cooling system in either very cold weather or under extreme heat conditions generated by engine combustion.

- It is very stable, non corrosive, and does not degrade under highly variable and harsh conditions of a cooling system.

A mixture of 70% (by volume) ethylene glycol and 30% (by volume) water provides the LOWEST freezing point and HIGHEST boiling point, and it's the most desirable combination if freezing and overheating problems are critical. Higher concentrations (by volume) of ethylene glycol will actually raise the freezing point and lower the boiling point of the mixture. Also, the most important reason why a higher concentration of antifreeze is not recommended is because pure ethylene glycol has extremely high surface tension and heat specificity. These properties tend to cause ethylene glycol to retain its heat, and its heat transfer ability to be very low. Water must be present to "wet" the metal surface (e.g. radiator) by lowering the surface tension in order to increase the heat transfer ability of the mixture.

Ethylene Glycol does raise the boiling point of a water/antifreeze mixture, but not quite a lot. Therefore, a cooling system needs to be under pressure (about 15 PSI, not enough to blow up a radiator or coolant hoses) when it's hot because higher pressure means that water/ethylene glycol molecules must have higher average kinetic energy in order to jump out of the mixture's surface to trigger the boiling process. Average kinetic energy of molecules/atoms is proportional to the temperature via the relation E(k) = (3/2) * k * T , where k = Boltzmann constant = 1.38065 * 10^(-23) J/K, and T = absolute temperate in Kelvin = 273.15 + C = 273.15 + (5/9)*(F - 32)

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2) Water H2O

Water alone only provides freezing and overheating protection at 0 degree Celcius and 100 degree Celcius respectively, so antifreeze (mostly ethylene glycol) is required. The most important reason for the presence of water is to help increase the heat transfer ability of the mixture, so that the radiator can easily dissipate heat from the coolant mixture. This is accomplished by lowering the surface tension of the mixture molecules against metal surfaces.

Some coolant additive such as Redline WaterWetter may actually increase the heat transfer efficiency by reducing the surface tension even further. Redline WaterWetter also comes with some proprietary corrosion inhibitors.

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3) Corrosion inhibitors

These substances are designed specifically to protect the metal surface of radiator, engine etc... Because an optimal mixture
requires both water (corrosive) and ethylene glycol (non-corrosive, almost non-reactive), corrosion inhibitors must be present to counter the corrosive effect of water.

The reason why you have to change antifreeze coolant every few years is to replenish the proper amount of corrosion inhibitors. Corrosion inhibitors usually start to deteriorate after several years.

The only difference between different kinds of antifreeze is the corrosion inhibitor package and water pump lubricant. The corrosion inhibitor packages in various kinds of antifreeze are:

- Conventional American Green antifreeze = silicate, phosphate

- GM-spec Dexcool (orange) = organic acids only (no silicate/phosphate)

- Japanese antifreeze (green, purple, red ...) = no silicate but high phosphate, plus some other proprietary inhibitors.

- European antifreeze (G-05, G-11,G-12, G48) = very little silicate (no phosphate) to be backward compatible, organic acids (different from Dexcool)

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4) Water pump lubricant

It's used to lubricate a water pump's seals.

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Some new less toxic antifreezes use Propylene Glycol (OH-CH2-CH2-CH2-OH) instead of Ethylene Glycol (OH-CH2-CH2-OH). However, antifreezes using Propylene Glycol are not as efficient as those using Ethylene Glycol, because the heat capacity of Ethylene Glycol is higher at 0.85 Cal/g*K as compared to Propylene Glycol at 0.6 Cal/g*K

Hope this helps.

Eric