afternoon,

i've recently had a new rad fitted as the old one was blocked and caused the engine to overheat for a couple of miles.

since i've replaced the rad i cannot get the levels right in the expantion tank; its been fitted about a month and have topped up everytime i've been out, but just half a glass full really which is normal for the first week of a new rad; yesterday did about 40miles, checked the levels this morning and the expantion tank was nearly emply!

any thoughts?

Is there any sign of a leak? Any drips or puddles?

Did the rad come with a new cap?

Head gasket ok?

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Are you making sure that the rad is full right to the top [no air gap]? And as was said a new Mazda filler cap should be used, some after market items have known issues.

 new cap on new rad, no sign anywhere of a leak and car running fine, a friend will do a pressure test tomorrow night for me, it had lost 1.5 pints from expantion tank and half a pint from rad in a 30 mile trip

 Either headgasket failure, or you are filling above min when cold

If you fill above min when cold it will spit out coolant as it expands

 rad always filled right up, i also have the coolent in the expantion tank toped up to max, is this wrong?

pressure test tonight so i'll let you know.

kind regards

 did pressure tests last night, no prob when cold, did chemical test, no prob, warmed the car pressure test again and water dripping out from an area below the engine windscreen end, cant locate it at all even with coil pack out.

still drives well and pulls like a train, apart from the loss of water everything feels fine

any thoughts

Either heater hose no.1 or the smaller coolant hose running from the oil filter housing, under the inlet manifold and around the back of the head on the drivers side has split, they are both pretty tricky to replace but best you hope it is the heater hose as that is the easier of the two to change...

 Be a bit careful if you do have to change the heater hoses.  The metal pipes through the bulkhead are soft metal, (copper I think) and it is very easy to damage them or distort them if you use too much force trying to remove the old hoses.  Best to cut them lengthways at the pipe joints.