Sudden head gasket failure

martinwiseman2000 · Unread post by **martinwiseman2000** » 17 Mar 2011, 10:44

Hi,

Last Friday evening after driving about 200 miles and with 30 miles to go my Xantia 2.0 16V (W reg) suddenly overheated. I stopped immediately the red light came on and found the top radiator hose had blown off. After about an hour and a half the hose was reattached and the radiator filled. Cranking the engine produced a fountain from the radiator filler at which point the car was declared dead and loaded onto a tow truck.

I now have the head off and was surprised/concerned that the failure is not obvious. I was expecting to see a clear point of failure or physical damage on the gasket but can't.

Is this normal for a HGF and other than having the head pressure tested and checked for flatness should I be looking for anything else?

Prior to the failure there had been no history of overheating and no symptoms of HGF (such as mixing of oil and water).

Thanks,
Martin.

addo · Unread post by **addo** » 17 Mar 2011, 10:51

Very odd! Is there much corrosion to the water passages in its head? How does the thermostat look? Check it's open and shut temperatures if you can cobble up a double boiler with saucepan and basin.

The other weird one (very "old school" in terms of modern engines) is a split bore.

martinwiseman2000 · Unread post by **martinwiseman2000** » 17 Mar 2011, 12:37

addo wrote:Very odd! Is there much corrosion to the water passages in its head?

No evidence of corrosion at all.

addo wrote:How does the thermostat look?

Looks ok, but I'll test it this evening.

addo wrote:The other weird one (very "old school" in terms of modern engines) is a split bore.

I was wondering about that, as it's the only other place a fault could lie. Would it be obvious it would it only be the sort of thing you could find with a pressure test?

Thanks,
Martin.

Unread post by **citroenxm** » 17 Mar 2011, 12:51

Sounds though, more like that fact the gasket hasn't failed, but due to lack of water the head has got too hot... and warped the cylinder head instead..

When you refilled at the side of the road did the car actually start and run?

Paul

citronut · Unread post by **citronut** » 17 Mar 2011, 12:56

or maybe it was just your rad fan/s were not cutting in,

regards malcolm

MikeT · Unread post by **MikeT** » 17 Mar 2011, 13:54

Mine's a TD engine but I had the same issue - over-pressurised coolant from combustion gases. The gasket showed no signs of damage (see my blog pics) so I too was concerned there may be other engine damage but with a repair gasket and head skim, she's still going strong 10Kmiles later.

Unread post by **Peter.N.** » 17 Mar 2011, 14:52

The other possibilty of course is a cracked head

Peter

martinwiseman2000 · Unread post by **martinwiseman2000** » 17 Mar 2011, 16:17

citroenxm wrote:When you refilled at the side of the road did the car actually start and run?

No, it coughed and spluttered, sounding as if was only firing on one or 2 cylinders. I stopped cranking before it actually ran.

When I took it apart there was water in the middle two cylinders. Assuming this was the case when I was cranking it the damp spark plugs would have prevented them from firing. I assume the fault would have initially occurred on one cylinder and that the overheating warped the head allowing a second cylinder to leak.

Martin.

addo · Unread post by **addo** » 17 Mar 2011, 19:10

At a wild guess, I'd say the head's been off before, and there was a pre-existing issue with one or more bolts bridging the centre two bores, then.

Either too tight (entered plastic deformation stage) or not fully tightened (perhaps torqued in wrong order).

martinwiseman2000 · Unread post by **martinwiseman2000** » 20 Mar 2011, 11:44

Update - the engine is back together and so far looking promising. The temperature is stable and there is no evidence of the cooling system pressurising.

Unfortunately there is steam coming off the radiator, so I guess it was damaged by the pressure. More expense. javascript:emoticon(':(')