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Hey to anybody in this thread or in the future. If you want to replace your radiator, the ones that I know have worked and fit flawlessly are the DENSO radiators from Rockauto. Super high quality and they *felt* better than the outgoing ones. CSF is good too, but I ALWAYS go out fo my way to order the Denso units for Mercedes. It seems backwards to use a Japanese part in a German car but I'm absolutely not wrong on this. I've seen new Valeos fail at 60k.
ALSO if you have not done a radiator on one of these cars, it has transmission lines that go in. If you do not respect this you end up with all your ATF on the floor... so youll have to re-fill the trans afterwards. This is also just a great chance to do a trans service of which I have done like 50 of.
Don't put this off, if your end-tanks are already kind of leaking, you're only a specific kind of radiator failure away from destroying your transmission. The coolant's glycol soaks in the friction discs and debonds the glue which is an irreparable situation in the worst case scenario.
@ChrisHimself
Thank you Chris for confirming Japanese DENSO quality is superior than original (Valeo) mount.
Back when I still had "extreme heat" I noticed radiator endcaps were sweating coolant around 50kMi.
I am gonna have to install a nice DENSO before mayo waste my 722.9... referral program 5w50 : now inbound !
Last edited by CaliBenzDriver; May 3, 2025 at 04:53 PM.
I honestly cannot take the lab results. Water present, sure.
The explanation? Not a chance.
Need to think about it.
But such explanation sounds like water evaporation is due some being drinking it when nobody is looking.
The radiator inner leak is an old MB favorite:
seals must leak !
It just depend how soon pressure overcome the seal - Same thing with the front timing cover: coolant can leak into oil side when hard seals are overcomed by heatsoak pressure.
The solution... cancel the heatsoaks. Seals will not get challenged by pressure.
Gonna try Amsoil 5w50-SP PAO to remove my piston heat.
I expect Amsoil to be nearly as good as Motul or a hair better.
Last edited by CaliBenzDriver; May 3, 2025 at 05:10 PM.
@ChrisHimself
Thank you Chris for confirming Japanese DENSO quality is superior than original (Valeo) mount.
Back when I still had "extreme heat" I noticed radiator endcaps were sweating coolant around 50kMi.
I am gonna have to install a nice DENSO before mayo waste my 722.9... referral program 5w50 : now inbound !
I was wondering who that was! I appreciate the business bud! I will do anything to continue earning it here on the board
I have the same problem with my 2014 E350 at 77,000 miles. Indy has done multiple flushes, but the rough shifting and slipping still happen. I'd like to know if you've found a solution. Thanks!
I have the same problem with my 2014 E350 at 77,000 miles. Indy has done multiple flushes, but the rough shifting and slipping still happen. I'd like to know if you've found a solution. Thanks!
Did your tranny suffer coolant mix from compromised VALEO radiator heat-exchanger ??
You may need new clutch packs frictions, that means a complete rebuild job, not just valve body.
I have the same problem with my 2014 E350 at 77,000 miles. Indy has done multiple flushes, but the rough shifting and slipping still happen. I'd like to know if you've found a solution. Thanks!
the glycol in the coolant strips the bonding from the friction discs.
Make sure you check your coolant to see if its oily, it might not be too far gone yet if its driving well enough to even slip
Related side note: I learned yesterday that, unlike the W212, the W166 (ML/GLE) has a separate transmission oil cooler attached to the AC condenser, rather than sharing it with the radiator.
I wonder why MB did not do the same for the W212, since they are contemporary designs.
Yes, exactly: radiator inside transmission leaked coolant that mixed with the ATF. Out of nowhere, I had shuddering, bad shifts, slippage, etc.
I don't think it was caught early enough. I'm wondering if I'm better off buying a used transmission (from a donor vehicle) and have my indy swap them out. I know there's some programming involved and of course lots of labor, but it seems to perhaps be the most cost-effective route. I'm not planning to keep the car long term.
Originally Posted by CaliBenzDriver
Did your tranny suffer coolant mix from compromised VALEO radiator heat-exchanger ??
You may need new clutch packs frictions, that means a complete rebuild job, not just valve body.
Okay, in my 350...a "simple trans service" turned into a FREAKING NIGHTMARE at a "Euro" shop who specializes in MB/BMW/Audi. The first time I had what you describe - plus a leak that I had to take the underpan off to see. So, they fixed the leak by making it FAR WORSE and it drove good - until it got to temp, then the car would shudder and I had a smoke screen behind me. Third time after replacing every seal again - and asking a mechanic from another local shop to do the work...it was correct. That "other local show" is now the only shop my cars go to.
So, you may have what I had...great intentions with out the skill set to match them.
Note: UNRELIABLE cars may cause FATALITIES - Personal OPINIONS and INPUTS shared in this forum by non-profesionnal should *NOT* be construed as ADVICE" - Do maintain your vehicle in STOCK condition by seeking PROFESSIONAL services from MB DEALERSHIPS. Any maintenance or experimental modification performed outside of factory network is UNDERTAKEN STRICTLY AT YOUR SOLE RISK
Um....okay, Karen.......LO LO LOL LOL LOL LOL LOOL
Um....okay, Karen.......LO LO LOL LOL LOL LOL LOOL
...thy shall not temper with the setup of excellent "300k.Mi" cars - Nothing new but a long list of standard issues we don't care to enumerate out of sanity. Members are familiar with minefields.
Instead of engineering high quality like Japan, the world engineering masters focus on bottom line. Suppliers compete to incorporate their amazin parts.
Positively nothing wrong with systems setup for failure. Predictablefailures are SAFER than random ones!
> Practical Win-Win:
The workaround is to replace the parts early without waiting for colateral damages.
Replace radiator instead of tranny + tame the accumulated extreme heatsoaks.
AWESOME... 5G roaming everywhere
Last edited by CaliBenzDriver; Nov 7, 2025 at 10:36 PM.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
