E-Class S210, 1999, Radiator burst

A friend is having the following problem:

Mercedes E-Class S210, year 1999, 3.2-liter V6 gasoline engine with LPG conversion.

Monday:

Because something needed to be tested with the gas, but it's quite cold here AND the engine is signaling an error, causing the radiator fan to run at full speed constantly, the fan motor was temporarily disconnected from the radiator to achieve the desired temperature.
(No, it wasn't me.)
Of course, the trailer was first pulled across the yard until the coolant started gushing out from underneath.
Diagnosis: The radiator is completely ruptured on both sides, and the mounting brackets are completely bent.
You brought it on yourself!!!
Um, the radiator was quite new.
Replaced 6 months ago:
Radiator, water pump, thermostat valve, pressure relief valve on the expansion tank, and the temperature sensor located at the front, in the middle, above the water pump.

Einstein said that stupidity is limitless, but he wasn't quite so sure about the universe.

Tuesday:

Yesterday, the colleague mentioned above removed the old cooler, and this morning, on WEDNESDAY, he installed the new cooler.
Please take a deep breath.
The coolant was filled with sufficient antifreeze.
The engine was started and allowed to run until the UPPER radiator hose became warm.
Hat off and let's go.
A distance of approximately 2 kilometers was covered.
At the gas station, they checked it again briefly, and the radiator hoses were rock-hard and COLD.
The lid of the storage container was briefly opened to release the pressure.
Then, they drove another 1.5 to 2 kilometers.
Result:
Cooler cracked on both sides.

The pressure vessel's closure is freezing up!!!
When antifreeze escapes from a cold, pressurized system, it can cause a drop in temperature.
Therefore, it's even logical.

For some reason, the engine built up a tremendous amount of pressure.
This weekend, I'm going to take my time and really focus on it.

I have a simple question regarding this chaos:
Does the pressure relief valve not have to function reliably in all cases?

I'm talking about the Monday when the radiator fan was disconnected.
On Wednesday, the antifreeze was refilled, and the valve worked, but it froze.
I mean Monday.
A working cooling system where the fan was disconnected, causing pressure to build up to the point where it ripped the cooler apart.
Until then, the engine was still running on all cylinders and seemed to be okay, except for the engine check light.
Until then, there were absolutely no air bubbles in the cooling system.
And no, the error code was not read.

I know.
It almost sounds unbelievable, but look at Einstein.

I won't be able to take a closer look at this until the weekend.
Best regards, Frank.

Hello!
Well, I've experienced a lot, including some of the most unbelievable things, and frankly, without a more detailed explanation, most people wouldn't believe me.

Something doesn't seem right when I read what was exchanged six months ago.

I've never actually seen a radiator burst; at most, I've seen one that was frozen.

I find it very unlikely that the container's lid is frozen shut. The typical antifreeze coolant isn't actually that prone to evaporation.
Even if windshield washer fluid containing alcohol, instead of Glysantin, was added, I find it absolutely impossible given the current temperatures. And especially with short distances.

According to my colleague, the issue with the frozen valve is a confirmed fact.
Although it has a large air bubble in the cooling system, its observations and the way it presents them are accurate.
Best regards, Frank.

So, in order to move forward here, it seems that different approaches are needed than arguing about whether a valve is frozen or not.

I can't think of anything else right now.
I have absolutely no knowledge about gas systems.
Could there be a heat exchanger there that warms/vaporizes the gas using the cooling water?
Is it possible that, in the event of a defect, some of the gas is being forced into the coolant circuit?
I can't really picture it right now, being so late, but something like that might be possible.

I find it practically impossible for conventional diesel and gasoline engines to achieve what is described.
But, I've actually experienced a lot of things that seemed impossible, there is no such thing, I've stopped using that saying.

Butane evaporates at atmospheric pressure at 0.5°C and has a pressure of approximately 3 bar at the roughly 20°C inside the refrigeration system. Propane evaporates at -40°C and has a pressure of 8 bar at 20°C. LPG consists of both.

Therefore, if LPG enters the cooling system, it will reliably activate the pressure relief valve of the engine. Propane will escape through the valve, causing ice to form there. If not enough propane can escape, the pressure will eventually rise to a point where something in the cooling system will burst (at 90°C, this would be 36 bar). It makes perfect sense.

Question: Could the upcoming engine error message possibly be related to a lack of LPG pressure?

Sure, here's the translation:

"Note:"
LPG is known to be flammable and explosive. If I imagine a fan motor running at full speed (with the corresponding sparking at the brushes) and the LPG-filled radiator right in front of it, then someone here has been incredibly lucky.

Further troubleshooting should be carried out with appropriate caution and expertise.

Greetings.
Guste.

As I already mentioned, the radiator and the car won't arrive until the weekend, and nothing will happen before then.
The idea of using gas in the coolant might be a possibility.
There was definitely a smell of gas when switching from gasoline to gas.

I will proceed with caution, and if in doubt:
Go to the Mercedes-Benz workshop.

Thank you for the feedback.
Best regards, Frank.

Sure, I'd appreciate it if you could take some photos and also post the solution here at the end.

Hi.

Sure, here's the translation:

'Quick update:'
I initially installed a transparent hose instead of the radiator and turned off the gas supply.

No excessive pressure, no additional air/gas in the cooling system.
The error code in the MSG was read, but I don't have the error numbers here.
Anyway, I started by welding a torn seam on the cat.

It 'seems' that, in fact, gas has entered the cooling circuit.

That will be handled by the gas specialist. I will let you know if anything develops.

Best regards, Frank.

So far, it has been running on gasoline without any issues.
Yesterday, the vaporizer was removed and sent for repair.
Best regards, Frank.

Hi.
The vaporizer was refurbished by a specialized workshop and installed by me.
The owner of the car is very knowledgeable and, after installing the vaporizer, filled the tank with gas, switched the system to run on gas, and it's working.
It appears there was indeed a connection from the evaporator/liquefied gas system into the cooling water.
Thank you for the suggestions and advice provided here.
That was a hard lesson for the owner to learn.
Best regards, Frank.

Thank you for your feedback!

Although I've solved the puzzle, I've never heard of such damage before. In my opinion, the crack in the vaporizer is a safety-critical defect. The fact that you're talking about a "repair" instead of a replacement for the vaporizer surprises me. I would have expected the manufacturer of the vaporizer to replace it very generously.

Greetings.
Guste.

Hi.

As I mentioned, this isn't my car, and the owner took the vaporizer to an automotive gas specialist who repaired the removed part.

I have absolutely no idea what exactly was repaired.
Whether that was a repair kit or just a gasket...

If it were mine, I would have disassembled the old one to understand the problem and, lacking precise knowledge, installed a new one.
Liquefied gas in the coolant is not a good thing, and such a defect should be completely eliminated by the manufacturer.

It looks like we might have more challenges ahead.
Best regards, Frank.