Heater blowing cold then hot - MG-Rover.org Forums

TonyAKM · 14-01-2009, 11:58

Driving to work this morning it took ages for the heater to warm up, then when it did it blew cold when car slowed down and the temp guage fluctuates between mid guage and hot. Any ideas what maybe prob?

Aftershock · 14-01-2009, 14:52

The same happened to me the other morning then this morning had steam coming out of the header tank on my way to work. Im told i have a leaking radiator that is causing this so i would start there.

creature · 14-01-2009, 15:18

along the same lines happened to me after heavy breaking heaters blew cold air whilst temperature guage showed hot. Ive been told its a sign of HG failure can anyone confirm this?

warwickswinger · 14-01-2009, 15:33

Air in the cooling system would be my guess.

It could be getting in for a variety of reasons, including but not limited to:

Split or perished rad hose
Holed radiator
Leaking gasket (check around the thermostat and water pump)

If you don't sort it then you'll get problems but just because the temperature guage has moved doesn't automatically mean the engine's broken or the head gasket's failed

I had an airlock in my heating system last week (the garage drained the cooling system and didn't refill it properly) so my heaters blew cold and the temperature guage climbed slightly. Bled the cooling system and hey-presto! Problem solved. Touch wood.

There wouldn't be any harm in looking for signs of oil in the water or water in the oil though. They're easy enough to check.

AcC8braman · 27-01-2009, 13:50

I had this problem, no water in the system = blown head = £1300 repair bill for new head etc!! boooo

Carl · 27-01-2009, 21:01

My dad had this type of problem on his 25v , new expansion tank cap solved it - they go faulty quiet often , so it an easy fix they are about £5 from rimmer bros

14-01-2009, 11:58	#1
TonyAKM Registered User Join Date: Jul 2008 Location: Lincoln Car: Rover 45 Posts: 8	Heater blowing cold then hot Driving to work this morning it took ages for the heater to warm up, then when it did it blew cold when car slowed down and the temp guage fluctuates between mid guage and hot. Any ideas what maybe prob?

14-01-2009, 15:33	#4
warwickswinger Supporter Join Date: Feb 2008 Location: Near Brands Car: MG ZS 120+ & Suzuki TL-1000R Posts: 1,512	Air in the cooling system would be my guess. It could be getting in for a variety of reasons, including but not limited to: Split or perished rad hose Holed radiator Leaking gasket (check around the thermostat and water pump) If you don't sort it then you'll get problems but just because the temperature guage has moved doesn't automatically mean the engine's broken or the head gasket's failed I had an airlock in my heating system last week (the garage drained the cooling system and didn't refill it properly) so my heaters blew cold and the temperature guage climbed slightly. Bled the cooling system and hey-presto! Problem solved. Touch wood. There wouldn't be any harm in looking for signs of oil in the water or water in the oil though. They're easy enough to check.

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14-01-2009, 14:52	#2
Aftershock Registered User Join Date: Jul 2007 Location: Scotland Car: MG ZS 120 Posts: 23	The same happened to me the other morning then this morning had steam coming out of the header tank on my way to work. Im told i have a leaking radiator that is causing this so i would start there.

14-01-2009, 15:18	#3
creature Registered User Join Date: Sep 2008 Car: MG ZS Posts: 13	along the same lines happened to me after heavy breaking heaters blew cold air whilst temperature guage showed hot. Ive been told its a sign of HG failure can anyone confirm this?

27-01-2009, 13:50	#5
AcC8braman Registered User Join Date: Jan 2009 Car: MG ZS Posts: 3	I had this problem, no water in the system = blown head = £1300 repair bill for new head etc!! boooo

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