Coolant usage on 530e (G30)

LFCFan · 01-10-2025 03:12PM #1

Does anyone else have a version of this car that drinks coolant like fuel? I have the car around 18 months now and have topped up the coolant at least 8 times now. In all my days of driving, I may have done that once. A random guy at my GAA club approached me about this as he was driving a similar car and had the same issue. Any thoughts? Thanks

BlakeS94 · 01-10-2025 04:56PM

https://www.boards.ie/discussion/2058425838/coolant-usage-on-530e-g30

Sounds like a big leak. Bring it to a garage and have them pressure test it, probably a plastic component cracked thermostat housing, coolant expansion tank or water pump gasket

Orban6 · 01-10-2025 05:11PM

https://www.boards.ie/discussion/2058425838/coolant-usage-on-530e-g30

Is the colour of the oil okay?

If it is, then probably just a leak somewhere.

Gumbo · 01-10-2025 05:38PM

it on the 530e that we have (2017 car) but did have this issue on our old F10 520d and it only appeared after the 2 EGR recalls it got.

kirving · 02-10-2025 02:13AM

I have the same engine (B48) in an F30 330e, and it has a slow coolant leak (on the engine circuit), but I've been unable to find the source of it to be honest - it need a professional test.

It's not going into oil, a replacement cooling cap didn't fix it (despite the original being broken), as far as I can see it's not dripping out of the connection at the top of the engine and evaporating, and it's not dripping anywhere in the engine bay or under the car.

LFCFan · 02-10-2025 05:57PM

Should I see some sort of evidence of a leak? I've had the car parked up for 2 weeks at one stage and no signs of a leak on the ground or would coolant just evaporate before it has a chance to accumulate on the ground?

mk7r · 02-10-2025 06:44PM

https://www.boards.ie/discussion/comment/123871219#Comment_123871219

Cooland very rarely makes it to the ground unless it's a huge leak, once it hits the atmosphere it boils instantly

User1998 · 02-10-2025 08:47PM

https://www.boards.ie/discussion/comment/123871373#Comment_123871373

That's interesting. I have a 330e that's leaking coolant too, but definitely isn't dripping onto the ground

mk7r · 02-10-2025 09:36PM

https://www.boards.ie/discussion/comment/123871734#Comment_123871734

The only thing keeping the coolant from boiling and evaporating is the pressure in the cooling system, once it leaks out the pressure becomes atmospheric and it instantly vaporises. Usually you will see a chalky residue where it is leaking in the colour of the coolant (red is the easiest to spot)

landmarkjohn · 02-10-2025 10:06PM

Certainly a good idea to keep on top of any low coolant issues on these cars.

When I was researching used X5 40E model there were many with issues of the EME (Electrical Management Electronics, or something like that, the electronic bit that controls electric motor). Seemingly the gubbins is cooled with engine coolant and if not it gets cooked and fails. And on some cars this is almost like a horse with a broken leg.

Bargain_Hound · 02-10-2025 10:10PM

I also have an f30 330e (b48) with the same issue. I’ve been through a fair amount of coolant over the last 5 years of ownership. It Needs a good top up every month or two. I can’t find the source or any obvious evidence where it’s going. 212,000kms. I have googled it a few times and see references to weak water pumps but haven’t investigated fully.

last time I made an attempt to investigate I popped a coolant hose connector which required an entire coolant line replacement, and it routed into the gearbox cooler on top of the zf box and in turn broke 3 more replacing the first. The plastic connectors are seriously brittle, ended up having to strip the intake and charge cooler and car off the road for a week to get it back running. That was 2 years ago and I’m obviously hesitant going poking around again.

I’m sure after a hot run I can get a faint whiff of coolant around the engine bay, so it’s likely evaporating at high temperature.

other then that, it runs perfectly, just a nuisance.

kirving · 02-10-2025 10:47PM

Those connectors are notoriously brittle alright. I was lucky (if you can call in that) that the 90° connector on top of the engine broke about 100m from the house, so I could fix it there.

No evidence of residue anywhere that I can find either. It obviously must be leaking, but only when it's hot, and in such a way that it isn't leaving visible residue. A difficult one to debug at home.

mikeecho · 03-10-2025 06:08AM

Probably a hair line crack somewhere, and it's escaping as steam.

Could you put a drop of UV dye into the coolant, and check with a UV lamp.. might give you an indication as to where it's escaping from.

kirving · 03-10-2025 09:08PM

https://www.boards.ie/discussion/comment/123872420#Comment_123872420

Good idea, I actually have a UV lamp, so will give that a go the next time I'm home as a basic check. The car has cost enough, and it's not being driven too far from home really ever, so a small drip out of it is manageable. If I can avoid putting too much money into what is pure labour in finding a leak, I will!

Coolant usage on 530e (G30)

Comments