Cooling System Plastics Disintegrating

[keithmuller]

Hi people!
I am from South Africa, and run a workshop specializing in German vehicles. We seem to have more MB vehicles than any other followed by Audi and BMW.

I notice that the plastic pipes, thermostat housings and radiators fail at about the 5 year mark. It has got to the point that when I notice any brittleness in the plastic components I recommend full replacement of ALL cooling system parts. I have seen many cars towed in with overheated engines because a stupid, 'cheap' plastic components have failed. They get brittle, with no outside evidence of the impending failure. It is far better to simply replace these items, at a huge cost.

My question is: Is there any antifreeze that specifically targets this or is it a 'failure mode' we simply have to live with?

I use FUCHS products, because they are high quality, high consistency products. The anti freeze we use is Fuchs PT11 TITAN FRICOFIN S (CONCENTRATE)which, according to Fuchs, is silicate free.

 

[Falcon_LS]

Fuchs certainly make quality products.

I tend to replace the coolant every 40,000 kilometres/1 year in my '05 ML500. A bit extreme, but I also replace the thermostat and radiator cap as well. I just go with the OE Mercedes coolant and distilled water myself. It's only got 70,000 km on the clock, but I haven't experienced any problems yet - touch wood!

BMWs tend to be more prone to failing plastics than MB vehicles from what I have experienced, as the moment the car hits 150,000 kilometres, coolant leaks tend to be common somewhere down the road. Then just replace the entire cooling system as a precautionary measure. Not sure if the higher coolant temperatures (92 C as opposed to the more traditional 82 C) has anything to do with it, but one would imagine the engineers take all this into consideration.

I don't think any special coolant or additive will help prevent plastics from ageing. There are aluminium alternatives, but for some reason they tend to leak worse than the plastic ones!

 

[Gary Allan]

I wonder if there's some coating you could put on the replacement component ..but on the other hand, if it lasts 5 more years, it's probably with a new owner. I also doubt any 3-4 year old MB owner is going to pay to have you drain, coat, and refit/refill a perfectly functioning cooling system.

 

[XS650]

Originally Posted By: Falcon_LS
Not sure if the higher coolant temperatures (92 C as opposed to the more traditional 82 C) has anything to do with it,


An old rule of thumb is that a chemical reaction doubles in speed with every 10C increase in temperature.

 

[keithmuller]

I am not sure how many of you are familiar with the wiring loom debacle that affected 1996 to about 2002 MB vehicles. In these vehicles the plastic disintegrated on the engine wiring harness because it was made of a new bio degradable plastic. Trouble was, the heat of the engine made these degrade a mite early, causing very expensive repairs, not to mention the negative public image done to MB.

I was idly wondering whether the cooling system plastics are not affected in the same way...

To reply to an earlier post Re BMW, my own personal experience has been that the New Mercedes products are the worst. All the cooling pipes on the outside of the engine are plastic, and disturbing anything usually results in a broken pipe, and then a delay as the local agent does not have all the spares..

 

[mechanicx]

I think this Fuchs coolant you are using is an OAT coolant and not exactly the same formula as Mercedes, which I think would be G-05. I don't think that is the reason for the plastic coolant system parts degrading, but these plastic parts need all the help they can get and G-05 might work better. I don't how much if any difference the colant will make though.

 

[keithmuller]

Thats an interesting point, and one i will look up. Interestingly, Fuchs supply MB their coolant as a branded MB coolant, but I will look up the Spec you have mentioned.

 

[HTSS_TR]

My 2000 E430 is 10.5 years old and 110k miles has all OEM cooling parts including pipes, hoses, thermostat and thermostat housings and radiators. They are still in good condition and no sign of pending failure.

The coolant was flushed at dealer once at 4 years old and I flush once 4 years later (about 2.5 years ago) with Zerex G05.

 

[Craig in Canada]

Originally Posted By: Falcon_LS


BMWs tend to be more prone to failing plastics than MB vehicles from what I have experienced, as the moment the car hits 150,000 kilometres, coolant leaks tend to be common somewhere down the road. Then just replace the entire cooling system as a precautionary measure. Not sure if the higher coolant temperatures (92 C as opposed to the more traditional 82 C) has anything to do with it, but one would imagine the engineers take all this into consideration.


Why is 82C "traditional"? And why is 92C "higher"? BMW M62s have been running at 108C since the 90s. All of the designs are running hotter for emissions and efficiency purposes and 92C would be what I'd call "traditional" as it's even been obsolete for a while. 82C is downright "cool".

The 108C V8s are more failure prone (and in a more spectacular fashion) than the 98C or 93C I6s, but this is more to do with system pressure running at 108C than speeding up any chemical reactions in the cooling system.

I have an older M52 which runs at 93C, and the only known cooling leak it has had was an uneventful dripping from the t-stat housing 8 years ago. My dad's 108C M62 blew the side out of the rad. Obviously system pressure is at play in creating the "special effects".

 

[Falcon_LS]

Originally Posted By: Craig in Canada
Why is 82C "traditional"? And why is 92C "higher"? BMW M62s have been running at 108C since the 90s. All of the designs are running hotter for emissions and efficiency purposes and 92C would be what I'd call "traditional" as it's even been obsolete for a while. 82C is downright "cool".


I meant to say more "common" as opposed to "traditional", just didn't get my wording right.

 

[mechanicx]

But wouldn't system pressure be mostly dependent on the pressure cap rating and not on coolant temperature? Higher coolant temperature might increase water ciculation some, but higher heat, OAT coolants and plastic parts is a bad combination.

 

[artificialist]

Seems to me like every American, Japanese, or European has plastic stuff constantly fail, so it shows me that no coolant formulation solves plastic part deterioration.

It is just an instance where the manufacturer was being too cheap, IMO.

 

[mechanicx]

I agree that plastic coolant parts aren't the most durable. It depends on the particular polymer how well it holds up to coolant. Some of the plastic coolant parts on GM seem to hold up to Dexcool. A lot of the newer European and Asian coolants have an OAT formula similar to Dexcool's.

 

[Petersubaru]

BASF state they test the auto manuf. plastic parts in their coolants..read under the title "tough conditions for approval".. http://www.performancechemicals.basf.com...antin/approvals

 

[JHZR2]

Interesting data points, though Ill say that as an owner of four MB cars that are nearly 30 years old now (still own two, and the third now belongs to my SIL), and also a daily user of a 19yo BMW, Ive had no such issues.

Neither the coolant tank or the plastic tops on the radiators have failed, in fact, the MB cars ALL have their original radiators! Same for the BMW. Two of the four MBs have >220k miles, one is over 160k, and the other is at 73k, so we see all ends of the use spectrum. The BMW has over 120k. My father also has a 96 MB diesel that has 220k or so on it, on original plastic cooling system parts.

Now, with Honda and Toyota, that is a different issue. Father's previa, wife's integra and a good friend's integra all had early plastic radiator failures.

But using G05 and G48 in MB and BMW vehicles, Ive seen no issues. The only thing of concern Ive noted is that in my M42 BMW engine, the profile gasket failed after being updated previously. The original was a known failure issue, but I was very suprised/disapointed that using G48 and an updated part still yielded a failure...

 

[Craig in Canada]

Originally Posted By: Falcon_LS
Originally Posted By: Craig in Canada
Why is 82C "traditional"? And why is 92C "higher"? BMW M62s have been running at 108C since the 90s. All of the designs are running hotter for emissions and efficiency purposes and 92C would be what I'd call "traditional" as it's even been obsolete for a while. 82C is downright "cool".


I meant to say more "common" as opposed to "traditional", just didn't get my wording right.

Even so, in the 21st century is 82C actually more common than something in the 90s or 100s C? That was my point in the reply.

 

[JHZR2]

Originally Posted By: Craig in Canada
The 108C V8s are more failure prone (and in a more spectacular fashion) than the 98C or 93C I6s, but this is more to do with system pressure running at 108C than speeding up any chemical reactions in the cooling system.


Reaction rates can increase significantly over 10C!

 

[Craig in Canada]

Originally Posted By: JHZR2
Originally Posted By: Craig in Canada
The 108C V8s are more failure prone (and in a more spectacular fashion) than the 98C or 93C I6s, but this is more to do with system pressure running at 108C than speeding up any chemical reactions in the cooling system.


Reaction rates can increase significantly over 10C!


If there's a reaction taking place....

These rads aren't "dissolving" or turning into powder. The torquey V8 is yanking on the upper hose necks when people go on and off throttle and instead of developing a weeping leak they "explode" due to running well above boiling.

All plastics on the vehicle, not just that in the cooling system, get weak with age and exposure to heat. It's not a phenomenon limited to the cooling system.

 

[mechanicx]

Originally Posted By: Petersubaru
BASF state they test the auto manuf. plastic parts in their coolants..read under the title "tough conditions for approval".. http://www.performancechemicals.basf.com...antin/approvals


Well first off is the OP using the approved coolant for Mercedes? The point remains that OAT coolants tend to be slightly more aggressive with most plastics and automakers will approve a less than idea or perfect durabilty. Coolant manufactures all claim their coolants won't harm gaskets or plastics but that is just not always so.

 

[Steve S]

Plastics best quality is to break.