Thanks for sharing your experience. I am glad they discovered all these leaks, and I am surprised at the number of these leaks.

 

I also dealt with coolant leaks with the P400 motor in a 2023 Defender. Went to the dealer numerous times, and they could never determine the source of the leaks, even after overnight pressure tests. The finally discovered a tiny leak at the water pump. After replacing the water pump, the issue went away.

 

Sorry for your issues. Pretty crappy that after how many years they can’t source and fix the issue. My biggest concern is the extent of the tear down to get to the various leaks and possible issues down the line. 😐

 

Agree that they should really nail down these coolant leak issues. With my 23 Defender, they had a bad supply of defective water pumps.

 

I had a coolant leak repaired this week on my P400 SE. They had to order the hoses and what else I don’t know. Thanks for the info. I had heard this was a chronic issue.

 

My car had a low coolant warning shortly after buying it and they did whatever they did to fix it. Fast forward - now I have 12000 miles on it - and in the cold weather - the coolant warning comes on again. They are getting me a loaner and will address the issue.

 

🤦🏻‍♂️. Ridiculous. Good luck and keep us posted on what it ends up being.

 

Dropped it off this morning - will let everyone know what they find.

 

The turbo coolant lines are a known issue

 

They replaced mine and it still smells of coolant.

 

Turbo lines or water cooler

 

Turbo lines.

 

Seems there is a seal defect on the coolant knob.

https://s3-us-west-2.amazonaws.com/tvin/2b535b09-9140-419f-bc42-2fd44b8af101.mp4?t=1739302589290

s3-us-west-2.amazonaws.com/tvin/2b535b09-9140-419f-bc42-2fd44b8af101.mp4?t=1739302589290

 

what bothered me about this video is that they had not put seat and steering cover on the car

 

I noticed that too. Not going to mention anything though. Maybe they had it there at one point and took it off.
I also got a notification from their loaner department that i had traveled outside of the 100 mile radius allowed for a loaner car and that now I'd be charged $1.50 per mile even though i was just in lower Manhattan (about 9 miles from the Brooklyn dealership). I cleared it up with my service advisor - but how strange is that.

 

I just had to top off on a P400. I cannot see or smell any signs of coolant leaks. The cap? Really? Any others having coolant issues? I'm tempted to diagnose myself with dye vs. taking my entire vehicle apart like they did with @mk23

Mine is a 2023 with 37k on it. I just bought it and did check the service history on it and the only thing done on it was factory interval oil changes. Only 2 oil changes in 37k miles, I guess that's within factory spec but not how I will maintain this vehicle.

 

The car is under warranty. I wouldn’t waste any of your personal time on this. We’ve found that letting the car sit over night, using a pressure pump cranked up into the coolant system is the easiest way to find the leak. The majority of the time, it’s those small turbo lines that are ****.

 

My dealer decided to fill the expansion tank all the way to the top. This is brilliant. I spend less time refilling and now when temps get high enough, we can easily see where the coolant is escaping from.

 

This thread made me check my coolant (25 P400). I assume this ok level?

 

If the level stays the same after a while, should be good. As others have said, when the coolant level gets low, there is a leak somewhere. There is no such thing as “these things burn coolant”. That’s total bull ****.

 

If the level stays the same after a while, should be good. As others have said, when the coolant level gets low, there is a leak somewhere. There is no such thing as “these things burn coolant”. That’s total bull ****.

Exactly! Adding a little distilled water here and there from natural evaporation is normal. But there’s no reason a brand new car should go from full in the expansion tank to low or even worse getting an error message. Anybody having to have coolant topped off has a leak unfortunately. The P 400 is known for this issue. Thankfully, it’s the only known issue that I’ve come across compared to the BMW source the engines which are fraught with errors and issues. Hopefully they remedied this for the 2025 models, but why take a chance? Give it to the dealership and have them figure it out.

 

I had to top mine off also. I only have 6200 miles it’s a 24. But I have been watching

 

Has anyone had a coolant leak with the BMW V8 or the P550e PHEV?

 

The 23MY V8 & I6 were mainly the years with a variety of issues. In 24MY a lot of these were corrected. The 24MY V8 became a MHEV and the P460 & 550 PHEV’s are on the I6 engine, which also pumped up volume in 24MY too. Could there be issues? Possibly, but they’re not as common any more.

 

No leaks detected in my P550e

 

Have you been losing coolant?

 

No I never lost any coolant whatsoever.

 

So update on this thread I started:

Took our Rover in for the 10,000 mile service and amongst other things I noticed, despite having the coolant system supposedly repaired some months back, I had to add a significant amount of coolant in the reservoir just last week to pull it from the minimum cold level to the maximum cold level. I told the dealership about it, and apparently they redid the pressure test on the system and found coolant leaking from the thermostat seal, which I believe they had replaced before. They pressure washed the engine and refilled it so it’s all good to go. But clearly the Achilles’ heel of these ingenium engines seems to be the cooling system.

So again as I had done a PSA to all P 400 owners in the past, keep an eye on your coolant, and if anything other than half a cup of distilled water needs to be added every 6 to 12 months, you have coolant leak somewhere and insist they do a pressure test. Even if you do get yours repaired continue to keep an eye on it.

 

Mine has a slow leak somewhere. I think I am going to put some dye in the coolant system to help me/them identify where it’s leaking. A pressure test just shows it’s leaking somewhere, it won’t tell you where. And when it’s a slow leak it’s hard to see dried coolant.

 

OK, I see. I was assumed when they did a pressure test. They put some dye in to see where coolant is leaking. I did a lot of research on the P400 before I purchased it and these engines have been around for some 8 to 10 years I believe. Overall, the reliability seems to be much better than the BMW source engines. However, seals and rings seem to be where these engines lose coolant and it always seems to be a slow leak. Good luck and keep us posted.