I thought I’d start a poll & thread to help those with low coolant issues/concerns see the solutions and hopefully help you identify your low coolant source.

1. For the poll, to help people keep perspective with if this is rare or more widespread. If you have a coolant leak, pick your motor, otherwise select no leak.

2. ONLY post solutions and identify where/how/etc your coolant problem began and what solved it.

3. Please NO asking for help or diagnosing, there’s other threads for that. Hopefully this helps people find the solutions faster.

 

Was smelling coolant for a few weeks on my 2022 110 P300 S (currently at 38,300 miles). I wash my 110 a lot and have never noticed any coolant on the ground or under the hood. I had it in for a oil change and asked them to do a pressure test, they said "no leaks or loss of pressure." They did add a coolant UV dye and didn't see it leaking (green fluid in the pictures below the dye is UV light reactive). I suspect they didn't check the aux radiator. However, the aux radiator is only used when the vehicle get hot and the aux coolant pump is activated,

I did a 3,700 mile trip from FL to NY and back to NY and the coolant smell was strong especially from the driver's side when I arrived home. I think because of the heat in FL (over 90 every day) and the time it was running (over a 20 hour drive) it started to leak more, so I took off the driver's side front tire and the fender liner and found the source. The aux radiator was leaking from a few fins, not the hose fittings, the coolant level in the reservoir tank never really dropped. Took it to the dealer and they replaced the driver's side aux radiator under warrantee.

I have put 300 plus miles on the new driver's side aux rad, no leaks or smells. I can tell it was active during my driving because it was warm to the touch like the main rad. My dealer was able to activate the aux coolant pump during the pressure testing and no issues.

 

funny thing, I dont even think aux radiators are needed for p300, it's global platform leftover stuff.
Auxiliary Radiator Bypass/Delete | Defender Source Forum

 

P400 significant leak with less than 2,000 miles. Dealer states:
"found coolant pooled up on top of engine under engine cover".
Replaced "charge air cooler outlet hose" part number LR147037

Slow leak remains after repair requiring top-off every 3,000-4,000 miles. Cause yet to be determined.

 

Had a leak happen just under 30k miles. Dealership fixed under warranty. Said it was an o-ring in the pipe/hose for turbocharger. Replaced ring and hoses. No problems since.

 

Apparently my leak is from the o-ring on the intercooler for the turbo. Dealer says this has been the most common leak on P400s. Will take that with a grain of salt and I will monitor the reservoir level for some time to ensure it’s fixed.

for history, my leak occurred over a 3-6 month period where I lost about one entire reservoir of fluid. The car passed pressure testing multiple times on two different service visits.

I had to be persistent a bit in refuting the “it past pressure testing” a couple times. And it helped coming prepared by telling the dealer “I measured and tracked the fluid level and x amount has been replaced over x months”. It seemed like that did the trick to get the vehicle looked at closer.

 

After our second leak…my SA said car passed pressure testing (again, as always) and that they are seeing a number of RRs and LRs that are burning and “burping” coolant during these hot 105+ hour Austin temps so far this summer.

And that we should top the coolant off every 3-6 months…not sure that’s a solution, but it was touted to me so I’m passing it along…

 

My 2nd coolant leak was found after quite a bit of hoopla.

the dealer took all skid plates off, drove the vehicle home w/ my permission, then drove it into work straight into the service bay.

with the motor hot and under pressure, after searching for a few hours they found a drip on a coolant pipe clip (down by the PCM) where the ac lines pass through the cowling. A crimp connection for the PCM coolant cooling tube was the culprit. I believe the part number is LR132648

after 5 visits all having passed pressure testing, I finally got their attention to spend some kind of substantial time looking for the leak.

if you are passing pressure testing, be persistent and keep bringing it back. Open up a TA case with LR which gives the dealer more ability o spend longer man hours on the vehicle that they can be reimbursed for.

hopefully this is my last leak. Fingers crossed!

 

Upper radiator hose was replaced (part# LR121446), was leaking where the hose clamps on to the drivers side of engine (P400) with 3600 miles

 

^ This. Added coolant for a while and finally got it fixed at 15K miles.