Under bonnet steam

__chris__ · 2nd November 2012, 13:59

Forgive me if this has previously been covered elsewhere; have done a search and couldn't find a solution to this problem:

When driving along, particularly in slow stop/start traffic, the engine heats up quite quickly with the result that steam soon starts to appear from under the bonnet.

I've put the diagnostic mode on and can tell that it happens shortly after the temp. reaches 108. At this point I start to hear the faint sound of what appear to be water running along pipes and if I don't keep the car moving then steam starts to be generated. Popping the bonnet shows me that water is seemingly leaking from somewhere, hitting the engine block and producing the steam.

The problem is that I don't know where to start to look. It only happens once the temp. has reached 108 so I assume this is part of the key to solving the problem. The wettest area seems to be at the front, between the engine and the radiator. Is there a part of the cooling system there that only opens at this temperature?

The temp. needle in the car never moves above the halfway point and I'm wondering if there is air trapped in the system. I've read one post on the forum that the expansion tank ought to be raised up when refilling the system; can anyone confirm this?

Many thanks.

2nd November 2012, 13:59	#1
__chris__ Avid contributor 2003 MG ZT 190+,(2005 Facelift R75 1.8T SE Conny now consigned to be a donor car) Join Date: Sep 2012 Location: Sidcup Posts: 149 Thanks: 34 Thanked 4 Times in 4 Posts	Under bonnet steam Forgive me if this has previously been covered elsewhere; have done a search and couldn't find a solution to this problem: When driving along, particularly in slow stop/start traffic, the engine heats up quite quickly with the result that steam soon starts to appear from under the bonnet. I've put the diagnostic mode on and can tell that it happens shortly after the temp. reaches 108. At this point I start to hear the faint sound of what appear to be water running along pipes and if I don't keep the car moving then steam starts to be generated. Popping the bonnet shows me that water is seemingly leaking from somewhere, hitting the engine block and producing the steam. The problem is that I don't know where to start to look. It only happens once the temp. has reached 108 so I assume this is part of the key to solving the problem. The wettest area seems to be at the front, between the engine and the radiator. Is there a part of the cooling system there that only opens at this temperature? The temp. needle in the car never moves above the halfway point and I'm wondering if there is air trapped in the system. I've read one post on the forum that the expansion tank ought to be raised up when refilling the system; can anyone confirm this? Many thanks.