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Need help with a coolant leak

4K views 17 replies 6 participants last post by  desertboy 
#1 ·
Just came out of the shops to see a puddle of coolant behind the Right Wheel arch (slow drip). Checked the coolant level and it was almost at the bottom of the filler tank. Topped it up and drove the car home watching the temp gauge. The leak has stopped and the level hadn't gone down. Checked the passenger side carpets and they seems to be dry.
Any ideas?
 
#2 ·
If your sure it's the tank just buy a new one, I just replaced mine because I couldn't see through it, I have the old one if you want it no leaks send me a PM and i'll get out to ya.
the new one was only $100.00 bucks or so.

Scotty
 
#3 ·
Denture cleanser and H2O2 works wonders for dirty recovery tanks. :geek:

Plug the hole, fill with H2O2 and drop in 6 or 7 denture tablets. Rinse the next morning and things will be MUCH more clear. :mrgreen:
 
#4 ·
No, its not the tank. It has a 6 month old BMW E30 tank. I hooked up the windshield washer sensor circuit and that is how I knew the coolant was low. Looks like the coolant is coming from inside the car and dripping down the passenger side between the door sill and the wheel arch. I thought the Heater Matrix or O-Ring leaks always ends up with the passenger side carpet getting wet. Unless its running under the carpet.
 
#6 ·
Well, if it's coming from inside the cabin, it is something having to do with the heater core. That's the only reason coolant runs into the cabin. Could be the heater core matrix, just the O-rings, or something having to do with the pipes to and from the core. You'll have to get under there and take a look.

Brett
 
#7 ·
Check to see where your expansion tank vent pipe runs. The standard tank vents directly onto the front valance under the expansion tank. This seems like a possible source which then makes its way down the body work to drip behind the wheel.

But if it is the case what made it vent out so much coolant? Did the car overheat prior to you noticing the puddle?
 
#8 ·
I ordered a couple of O-Rings ($11.95 each daylight robbery from the stealer). I probably could have sourced a cheaper pair but that price for another 140K miles and knowing it is the correct fit is OK by me. My text book symbol has been on since I first got the RR (Oct 2007), I ordered a Core Temperature sensor and will check the blend motors and the flaps when I'm down there.
The number of posts I read here talked about the carpets getting wet and I have know idea where this channel starts. Following the lines on the under carriage, it looks like the Firewall drain channel to me. I'm going to poor some water down the rectangular cutout that is on the plastic wiper trim piece to see where it drains.
 
#9 ·
I checked the Vent line and it is dry. Mine is right behind the expansion/filler tank and the tracks are dry. The car didn't overheat and the temp gauge is steady at 12 O'clock.
 
#10 ·
desertboy said:
I checked the Vent line and it is dry. Mine is right behind the expansion/filler tank and the tracks are dry. The car didn't overheat and the temp gauge is steady at 12 O'clock.
Ah. There is one of the problems. You are looking at the wrong gauge. You should be looking at the coolant temperature gauge - not the clock......... :roll:
 
#11 ·
This one only has one hand and I'm sure it is not used to tell the time. You got me all confused now.
Seriously, you did hit a nerve when you said the expansion tank may have boiled over. I bought this truck with a coolant leak (valley gasket). After I fixed it, it broke a rod without any warning. All within four weeks of ownership. My guess is, the PO must have overheated the engine pretty badly.
The new engine I put in was from a one owner Disco with 80K miles and I babied it for the last 17k miles since Jan 2008. Hence, the BMW tank and level warning circuit.
Like I said, the car was still dripping and the area round the expansion tank was dry.
 
#12 ·
Had same issue last month.
Changed the coolant tank cap and upgraded to E30 BMW tank 2 weeks ago with Little Black Box.
No issues since.
I believe that my tank cap was shot.
 
#13 ·
#14 ·
Drove the car for about 10 miles with a shop towel under the expansion tank outlet hoping to catch some coolant. No leaks nothing.
I'm now leaning towards the Expansion cap opening up and spewing coolant down the wheel arch that one time yesterday. The cap is a genuine RR cap I bought when I first got the car (less than 2 years old and about 17K miles). Now the only snag is, I'm running a RR cap with a BMW tank.
Should I order the BMW cap that goes with the tank and start from fresh? If this is an intermittent problem, I don't want to get caught short by ignoring the issue.
Just to be on the safe side, I will open the passenger side panel and take a peak at the O-Rings and heater core (is that possible?).
 
#15 ·
I used a new RR cap
 
#16 ·
The easiest way to check for leaks is using a cooling system pressure tester. They can be quite expensive but I made a very simple one that only cost me around $20.

Parts required :

Pressure gauge that reads up to 50 psi - got mine from a pneumatic supplier
Four way junction / union or whatever you call it (see pic) with one threaded end for the gauge and the other three to suit 10mm pipe
Standard car tyre tubeless valve which you trim to fit in one end of an 10mm pipe.
A couple of meters of 10mm pipe. Does not have to be anything special - its only going to see 20 psi
A bunch of jubilee clamps.

The radiator to expansion tank pipe is then disconnected at the tank and fitted to the four way union and the opposite side goes to the tank. Basically the tester just fits into the existing system and does not change the operation of the cooling system at all. I think the rest you can see from the pic.

Pressure is then introduce via the tubeless valve and wait and see. Monitor the gauge which should remain static unless there are leaks. You can then examine the car for drips. A lot of engine leaks evaporate before they become visible on a hot engine so this is useful as you can do it cold. There is no danger of over pressurising as the cap will let off any excess pressure and it can be tested by noting when it does vent. I found my heater o ring leak using this tester.
 

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#17 ·
Ghur, That is a pretty clever device and if I don't find the leak this weekend, I may have a go at building that myself.
I have access to a pressure tester through the local Auto parts store's loan a free tool program. Unfortunately, it doesn't come with an adapter for our tanks.
 
#18 ·
I bought a couple of O-Rings and the Core temp sensor from the dealer today. Going to start dismantling panels tomorrow to take a better look. None of the posts mention anything about the passenger side Air Bag, is that something I have to worry about or just disconnecting the battery is good enough? My plan is to take out the Glove box lid, side panel and the HVAC switch panel and go from there.
 
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