weird cooling problem

[lurch_917]

 now this will test you on my 300 tdi sometimes the temp gauge shoots right up and i loos heat in the heater this lasts about2 mins when driving then the heat comes back and the gauge drops to normal in about 20 seconds so far ive changed the cap on the header tank and both heater pipes as they looked iffy any other ideas please  :?

[craigiow]

Sounds similar to the problem I had , Have you Bled the coolant as sounds like a airlock

[Range Rover Blues]

Is it using any water? how long hjas this been happening? the heater problem is air in the heater, the overheating a lack of circulating water but why are they coming and going?

Faulty thermostat, faulty head gasket?  overheating and loss of water is what I get when a head gasket goes badly enough to let combustioin gas into the water.

[lurch_917]

 no she dosnt use any water and its a brand new termostat its also only 3 months since i done the head gasket im wondering if ive got a gremlin as it has done this a few times now ??

[Sharpshooter]

no she dosnt use any water and its a brand new termostat its also only 3 months since i done the head gasket im wondering if ive got a gremlin as it has done this a few times now ??

If it goes and comes back, its probably the air lock. When the air passes through the heater matrix, it will cool of very quickly. Quicker than water. And the opposite for when it passes the temp sender. It will read high.

If you run it up from cold, then squeze all the coolant hoses with the rad cap off. You should hear a gurgling noise. And your water level should drop. Keep ding it until its warmed up. Make sure you have plenty of water in the header tank to take the air's place. And you must have the heater set to hot when you do it. And be careful. The engine and hoses can get very hot.

Hope this helps.

[Range Rover Blues]

no she dosnt use any water and its a brand new termostat its also only 3 months since i done the head gasket im wondering if ive got a gremlin as it has done this a few times now ??

Me too, new head gasket, new head, water pump, thermostat et al.

Cylinder head is on my bench, coolant is all over the M1   just because it's new is no guarantee it's ok.