Hey everyone,

I'm new to the forum. I've been watching this site for a while now. I have owned my mini for about a year, but let's get to the problem. The problem is I have a coolant leak. If I drive the car like a grandpa it will never leak, but if I go out and do some spirited driving, the next morning I will wake up to find a puddle of coolant resting beneath the car. So here's what I've done to attempt to eliminate the problem. I've taken the Cooper in to my local dealer, paid $120 for them to diagnose the problem. They told me it was a water pump and oil cooler seal. So I purchased all Oem parts from the dealer, went home and replaced the water pump, pump flange and seal, oil cooler gasket, valve cover gasket, knock sensor o ring, and radiator. The next morning the Cooper still had a coolant leak. I cannot find any visible leaks when the car is on the lift. What do you guys think?

Thanks in advance

 

What year/model is your Mini? By your Username I suspect you have an R53.
Was the dealership sure the thermostat housing/gasket were not leaking because that is a very common leak spot. The thermostat leak is sometimes hard to spot because the coolant evaporates on the hot engine. Look for coolant puddling near the thermostat housing and/or white residue (dried coolant) near/below the housing.

 

I have a 2005 Cooper s. They looked and it wasn't leaking, I did all the work on a lift at a shop and didn't see any signs of the thermostat leaking. I'm going to replace it this week for the heck of it. Do you all recommend a own thermostat or a different temperature? The coolant if dripping off the plastic lip under the bumper.

 

Put it up on ramps or a lift and take the plastic shield out. You can look up and
hopefully see where it is or has been leaking. Check out the bottom of the radiator
in particular. I'd stick with the stock thermostat temperature. The old stock
thermostat gaskets were very prone to leaking after a few years, but the current
ones being sold now hold up much better.

 

I'm guessing it has to be that housing, I have replaced everything else 😂 I wonder if I should replace the expansion tank and cap too?

 

Find the leak before you spend another dime. Take your time and search while egine idles and accelerate. Be patient, if there's a leak you will see it eventually.

 

I also suggest sticking with the stock temp thermostat.
If you want to switch to the cooler 180 deg thermo, I have a new one you can have for $10 shipped.

 

Yes, definitely spend the time to diagnose the leak before you keep throwing parts at it unless you feel you want to have those done for preventative measures. We have thermostats here and it's best to stick with the 190 degree. As said, check over the radiator and all associated hoses.

 

I can't seem to locate a leak using a pressure test @ 15 pounds. I let it idle on the lift for 30 mins with no luck. It will only leak after you have driven it hard and let it cool. It's at the Cooper dealer again..

 

First things first: check your thermostat housing. it's on the right side of the cylinder head. Black plastic piece bolted to the head. If it has white crusty at the head, replace the thermostat (not the housing): the new gasket comes with the thermostat.

 

Sure sounds like the Thermostat gasket.

 

How is your expansion tank? They tend to leak at the seam if plastic

 

I would check that also. Tend to crack and leak on the back side ( you can see from the front ).

https://www.northamericanmotoring.co...lant-tank.html

 

Check just behind your engine under the battery compartment, if yours is anything like my 02 r50, there is a 4 way connector with a bleed screw. On mine the plastic split down the middle, and when the car was running it would slowly run out, rev it and it squirted out.










It's right under the power steering reservoir. Good luck!

 

+1 Ah yes! That is a good area to point out. Thread HERE for reference for the OP with info.

 

That's for the R50 R52 Cooper ( NON S ) , we are talking about the R53 " I have a 2005 Cooper s " . But a good point for the Cooper non S threads.

 

That thread also has much better pictures, this was the fixed/new product.

 

The bleeder acre for the r53 is on the upper radiator hose. I picked it up from the dealer yesterday and they said everything is fine. I haven't seen a leak yet but I guess I will know when I drive from nc to Miami on Sunday 👍

 

The mini

 

Nice electric blue with challenge wheels. Very nice. Looks like brembo brakes up front. Chrono pack or nav ?

 

It has the Nav with blue carpet and blue/black seats

 

Nice , it has the lapis blue interior then. Very rare to see anymore