Ok folks, this one has me stumped. Vehicle is a 98 D1 with 92K, has never given me problems unless touched by idiots. Lately it has been leaking coolant from the vicinity of the right side front wheel well, expansion tank area I am assuming as the puddle is right under it tho there is no evidence of leakage around hose connections, seams, filler cap, radiator... but puddle appears only when the heat is turned on. When I turn the heat off, I can drive pretty much anywhere and have no issues. When I have the heat turned on, I get the puddle after driving just enough to warm the car up. Heat on, drive 5 miles, park, puddle forms in ten minutes on the ground under the area of the expansion tank. Heat off, drive 50 miles, no problem dry as a bone. And can't seem to get it to happen while idling in the driveway. There is no overheating involved, the truck has never overheated and the temp stays rock solid right where it should be, just under halfway up the scale, regardless of the heat settings or puddle formation. Any thoughts on this would be most appreciated, I know how sensitive these things are to overheating and not gonna drive it until this gets sorted out.

 

1. Suspect the coolant cap is venting. Tie some paper towel around it and repeat your tests.

2. The 98 has no heater control valve, so hot coolant is passing thru the core at all times.

3. There is a hose out the bottom of the coolant bottle, might look at that.

4. You can not trust the coolant gauge. Use a scanner to see live data coolant temps.

5. You can rent/loan a pressure tester from a parts store and pump up to 15 PSI and wait about 30 minutes.

 

Will check thanks, tho I cleaned up the area around the cap and have seen no evidence of venting, that was my first thought. Likewise, the hose connections to the bottom of the tank look as dusty and dry as they always have with no signs of leakage. If it is the cap venting, or something else giving way due to pressure, why would turning off the heater have an effect ? 100% repeatable

 

Radiator physics would say that while you have not changed the volume of coolant, or the heat from the engine, you have changed how fast the heat from coolant is discharged by adding the heater fan. So you are slightly cooling the whole mix. Perhaps at that magic temp and pressure is when leak happens, and if so, and it is repeatable, so park over clean card board. Follow the drips to find the Xspurt (X; the unknown, and spurt; a drip under pressure).

On that side of the engine you have the two heater lines (four clamps), the stubby hose from intake to heater metal line (2 clamps), the coolant bottle and clamps, the radiator (lower hose to octopus), and two small lines at top of radiator. Sometimes a leak from the hidden side of a hose clamp can be detected with holding a paper towel or toilet tissue around it, if it comes back wet.....

What we hope is that you don't have a radiator leak, etc. Water pump pulley should be running straight and true, no wobble when viewed from the side (normal leaks out nose of WP).

If it only does it after driving (fully warmed up), when heat fan has been running, seems like the return line from the heater core would be at a slightly cooler temp. So maybe a hose clamp, etc. When not cooled off, it would be slightly warmer and tighter. Of course, if one hose looks bad, the others are racing to catch up.

And of course, you did not say what color the puddle was. So if not coolant perhaps semi-blocked drain for AC, one on each side of tranny. Poke rubber drain with a stick and be prepared for a yuk water shower.

 

puddle is pure coolant, nice and green and fresh. pisses all over the front of the right hand inner wheel well directly under the expansion tank but the expansion tank is clean and dry, and the lower radiator hose is as well, with tight worm clamps

 

See if you can repeat it, over clean card board, and when it has done it use the paper towel or tissues to feel around the back side of hoses, etc. to see if something comes back wet. Engine front cover gasket behind water pump? Return line from throttle body heater?

Could be worse, if you had a Freelander with enough hoses and clamps for a whole parking lot of D1s.

 

That Honda thing ?

 

ok, found it! did the tests you recommended and found the expansion tank ( black) venting from the seam along the back of the tank. I've read allot of bad press about the black tank. are any of the after market ones any good, like the one with cap for 46 bucks that AB carries ? also found a used white one with cap for thirty bucks but concerned about buying someone else's problems.

 

Black one will burst and dump all the coolant before you can pull over and get parked. Aftermarket are good. Ones from donor vehicles, if not black, are also good, I have a boneyard one parked on the spares shelf in the root cellar. $46 seems reasonable.

 

ok thanks, placing order.... and will see if I can negotiate the used one down to twenty bucks for the just - in- case shelf, which grows exponentially the longer I have the rover