blown head gasket

Blown Head Gasket - Advice on this issue...

Here are our own thoughts:

A Blown head gasket is probably one of the most costly repairs to be made to a vehicle and can cause the end of the life of the vehicle itself.

What is a blown headgasket

Well in order to cool your engine there are a series of cavities between the combustion chambers (where the pistons go up and down) and the outside of the engine. They are commonly know as a water jacket as it is like a coating of water cavities, water runs through them to aid the cooling process in your vehicle to stop it from over heating and seizing. At the top of the engine there is a gasket in place which can be made of various materials, cork, card, rubber or metal or a mixture of a few. This head gasket stops the water escaping or the water and oil mixing or getting into the combustion chambers. When the headgasket goes it is usually due to wear and tear on the gasket and the pressure forces a hole in it. Another form of failure can be from a small hole or crack appearing in the head or block both give similar symptoms.

Blown headgasket Symptoms

If your vehicle over heats this is due to a head gasket failure or a hole or crack in the block, the water gets into the combustion chamber which can result in the water boiling instantly a sign of this can be white looking smoke from the exhaust on closer inspection you will see that it is steam. Obviously if this occurs you will notice that the water in your radiator or expansion tank appears to be disappearing or 'going down' at an alarming rate.

You sometimes get a whitish sludge forming on the dipstick or on the inside of the oil filler cap this occurs when the water is getting through into the oil as it emulsifies and appears like PVA glue or porridge. It can be the other way round and the oil gets into the water and in this instance you will see oil floating on top of water in your radiator or expansion tank and also the pva glue looking substance. This problems can be very gradually head gasket failures and your car may servive for months and months and then overheat very suddenly or it could just all happen very suddenly and your head gasket blowns instantly.

What cars are prone to a blown headgasket

Some cars are very prone to head gaskets blowing this consist of all rovers, especially ones with k-series engines fitted in the likes of Rover 214's,216, 218's,Rover 416,418 and 420 and so on also in MGF sports cars and The notorious Freelander 1.8. Smaller engined Fiats are also quite common head gasket failures such as the punto in 1.2 and 1.4 petrol. This should not scare you as usually it is at 70-80 thousand miles however they have been a few horror stories of freelander head gaskets blowing at under 30,000 miles from new! The Range rover petrol 3.8, 4.0, 4.4 and 4.6 are also very common headgasket culprits they can also suffer from pourous blocks and dropped liners which can give very similar symptoms. Diesel vehicles usually fare a lot better than petrols and you usually get a lot more miles out of them a few common ones for blowing head gaskets is the peugeot / renault 1.9 diesel and the diesel toyota surf.

What to do when you have a blown headgasket

When you experience the above symptoms it is likely to be a head gasket failure many people start changing radiators and thermostats with no success. You can take your vehicle for a couple of tests to make sure but are only going to confirm what we already know! The two tests: 1 is a combustion compression test where they remove plugs and test the compression on each cylinder if the compression is low on a cylinder it usually indicates that some pressure is escaping elsewhere. The other test test the cooling system where a device is placed over the filler cap and gas is tested for which may change colour of the chemical in the device.
The cost to repair a blown head gasket depends on the amount of additional damaged caused as usually people carry on running the car till it stops this usually causes more proplems from heat such as warped heads, cracked blocks and valve damaged or seized pistons locked due to the amount of water in there. To prevent this is simple as soon as you notice the symptoms stop driving your car and take action! The costs will vary from £300 to £1200 dependant on damage and the type of engine you have.

There are also many chemicals on the market that can be poured into the cooling systemto fix this problem from the inside if they are to work they need to be introduced early. There are many that do not work that cost a few pounds so be carefull they rely on fillers to bung up the hole but there are only a couple that are worth trying one is a product called steelseal which is available in the uk from We have used this product with great results how it works is simple, where ever the hole is the water passing through creates additional heat which draws the chemmicals in the steelseal into the hole and a chemical reaction takes place and forms a compound that seals the hole shut.

Steelseal is definitely worth a go if steelseal does not work then you know that a mechanical repair can not be avoided and you will need to contact your local mechanic or engine centre.