Hey all

I'm dealing with a slow coolant leak on my 2002 Disco 2 with 105,000 miles on it. Interestingly, there's no coolant on the ground, and I don't detect any burning coolant smell. I have to top off the coolant about once a month, although it never completely drains.

Here's a rundown of what I've checked and done so far:

1. Performed a block test for the head gasket; no color change occurred in the test fluid.
2. Replaced the water pump about 200 miles ago.
3. All hoses are relatively new and appear to be in good condition.
4. Checked the oil; it's clean with no milky appearance.
5. The reservoir cap is holding pressure properly.
6. Ran diagnostics with Nanocom, and no fault codes or cylinder misfires were indicated.

Despite all these checks, I'm still puzzled by this leak. If anyone has encountered a similar issue or has any ideas on what else I could check, your insights would be greatly appreciated!

Thanks in advance for your help!

 

Try changing the reservoir cap.

 

Maybe a tiny leak near the top of the radiator that gets evaporated. Check behind the fan shroud.

 

Buy some coolant system Uv Dye and a UV flashlight - you will find it in a couple of days of driving at most

 

Sure sounds like the kind of slow leak the poorly designed Throttle Body Heater Plate is well known for.

 

Rent the pressure tester from Advance and pressure test it, even if you can't see it you will probably be able to hear it.

 

Extinct beat me to it with this recommendation, but to clarify you can rent a pressure testing kit for $0 net. You pay for the kit when you pick it up and get a full refund when it is returned. And it's not just Advance Auto Parts that does this; AutoZone and O'Reilly's also have loaner tool programs.

 

I built my own pressure tester with an old coolant cap. I got a rubber plug that fits into the opening all the way down, drilled a hole into it, added a valve stem and drilled a hole into the old coolant cap. The coolant cap prevents the plug from popping out due to pressure. Make sure you don't go over 20 psi.

 

Same, got tired of renting the one from Advance.

 

Thanks for the tips. The negative block test was a huge relief, but the rabbit hole is gonna be a PITA...