Changing coolant at 10 years - should I change the radiator?

[gusferlizi]

In another turn on this, it seems MB have stopped selling the blue 325.0 coolant (which is what was in my system - see the blue trace in the jug photo). MB 325.0 is a G48 coolant, and e.g. Comma xstream G48 is approved by Merc according to Bevo and still available.

Apparently due to environmental concerns, the boron in the Merc 325.0 is the issue, and all G48 coolants are to not be used in Merc workshops?

325.0 was replaced with 325.5, and then 325.6, which is pink G40 type coolant.

Possible service bulletin from Merc confirms these Merc supplied fluids can both be mixed in any quantities without issue (I wouldn't trust other brands). I've noticed (and hence why I looked at this) there seems to be zero MB325.0 for sale online anywhere.

What coolant would people use on these cars now? Something Merc approved for 325.0 from Bevo?

View attachment 166056

My local dealer recommends a full drain and flush before switching over to pink.

 

[OneForTheRoad]

My local dealer recommends a full drain and flush before switching over to pink.

Anywhere would tbh.

 

[Pontoneer]

Because to my understanding, to change all the aux belt and tensioners, the radiator and fan need to come out to give a hope in hell's chance of giving enough room from above. I therefore need to put new coolant in. As I'm there, for another £120, I could put a new rad in. But if the consensus is put the old rad back in as it will have years left, then I can do that.

I’d certainly replace all the 10 year old hoses around the radiator and thermostat once I’d disturbed them , but as others have said , I’d inspect the radiator and go with what I find .

Incidentally, is your car automatic ? If so the ATF cooler will likely be in the bottom of the radiator . The pipes , especially the short flexible ones at the front , often corrode , so be prepared to replace these too .

Also , when was your gearbox last serviced ? ATF and filter chance might be as well to do since you’d be disturbing that too .

Funny how jobs can grow arms and legs …

 

[MrGreedy]

I’d certainly replace all the 10 year old hoses around the radiator and thermostat once I’d disturbed them , but as others have said , I’d inspect the radiator and go with what I find .

Incidentally, is your car automatic ? If so the ATF cooler will likely be in the bottom of the radiator . The pipes , especially the short flexible ones at the front , often corrode , so be prepared to replace these too .

Also , when was your gearbox last serviced ? ATF and filter chance might be as well to do since you’d be disturbing that too .

Funny how jobs can grow arms and legs …

ATF will be changed by Merc specialist on Friday

The top, short 'U' shaped oil line at the front, that goes from near the top of the back of the rad to the additional oil cooler is in the worst condition on the body of the pipe itself although isn't too bad, and the connections (covered by the translucent white caps in the image below) into the rad and the oil cooler are perfect. At another £100, I'll reuse this. Part No. A2045280924 (80 in the diagram).

 

[MrGreedy]

Got a box of all my new bits this morning, so hopefully it thaws a little today and gets a degree or two above freezing and I can get them fitted.

This time, I'm going to apply a corrosion protection spray to the metalwork to hopefully slow down the corrosion that is on every one of the original hose collars!

 

[StMarks]

Got a box of all my new bits this morning, so hopefully it thaws a little today and gets a degree or two above freezing and I can get them fitted.

This time, I'm going to apply a corrosion protection spray to the metalwork to hopefully slow down the corrosion that is on every one of the original hose collars!

Can't go wrong with a coating of ACF50 on any exposed unprotected metalwork imho.

 

[MrGreedy]

Pleased to report I reassembled everything last night in 'only' 4 hours (wriggling around on the frozen ground).
I didn't measure how much coolant I got out, but I put between 9 and 10 litres back in.
I poured the first ~8L in early (over several pours) whilst I was putting other bits back together, and it was surprising, given an hour or so, how much went back in without even turning the engine on. Just slow glug-glugs of coolant making it's way into the radiator.

Once assembled, it was so cold I couldn't get the coolant up to full temp (got to about 80-82°C), and it did require maybe 1L top-up whilst the engine was warming in addition to the volume I could get in whilst stone cold with engine off.
I'll need to take it out for a run tonight to get the temp up - it will be interesting to see if it actually needs any more coolant.
I've got about 1L left, pre-diluted with deionised water.


I also took the opportunity to replace the majority of the front undertray securing clips, which are called:
Mercedes Body Chassis Clip Nut Fastener Fixing A0049943145
Only a pound something each from Merc which I thought was pretty decent.

 

[MrGreedy]

I can report (I think) you don't need to get up to full temp to ensure there is enough coolant in the system. I think time (if you have it and are DIYing) is more important than temp, and just leaving the car to sit for a few hours will get very nearly all the coolant in you need. What a great design by Merc!

Before I took the car out for a spin, I opened the cold expansion tank, and it needed about another 1cm of coolant after sitting all night (this wasn't needed last night).

After getting back from a decent run, there was a reasonable amount of heat expansion pressure in the system when I cracked the lid open (not blowing the doors off or anything), and the hot coolant was about 1.5cm above the min line.

I'll crack it again in the morning, and expect it to be back at the max fill line when it's cool.

In other news, I'd left a couple of securing bolts off the bumper, so needed to faff around under the car putting those back in before I drove. Interestingly, it was so cold at 5pm, my gravel driveway had turn rock solid (probably not actually defrosted after last night, with a high of 1⁰C today), like it was a gravel layer set into concrete! Completely silent and easier to wriggle around on the floor than on loose gravel. Fingers were very numb with cold pretty quickly despite gloves!

 

[MrGreedy]

In another update on this, I'm going to change all the radiator hoses on this. On removal, the steel collar of all of them where they plug into the radiator looks in very bad condition. Just over £100 for the three hoses, top right (down to bottom front of engine), top left to thermostat, and right middle (smaller hose) that goes to the bottom of the expansion tank.

View attachment 166041

I was hoping to maybe fettle these up and recover a few pennies to go back towards the cost, but they are too far gone.

The retaining 'bump' has lost too much metal, and it has a hole in it. It probably wasn't too many months from high risk of letting go!

Might be worth others checking theirs if they happen to have some coolant drained.