What happens when your head gasket fails?

The head of All Drive Subaroo workshop explains:
Head gasket failure is a problem with some Subaru models once they get a few kilometres on the clock, mostly non-turbo models that are factory fitted with a single-layer head gasket. These gaskets simply give up after about 100,000 kilometres, however well maintained the car might be. Multi-layer gaskets used on Subaru turbo models rarely fail, and when they do the failure is usually down to high mileage or poorly maintained cooling systems. Later models don't fare any better than the older ones. In recent times we have seen an increase in external head gasket failures on the 2.5 litre Subaru non-turbo engines.The Subaru dealerships will simply replace the failed single layer gasket with another single layer gasket. All Drive Subaroo delivers a permanent fix for you non-turbo model Subaru.

Call an ADS consultant now on 02 9915 9900 or 0420 319 049


Subaru Internal head gasket leaks

(mainly turbo models EJ 205, 207, 255, and 257
Subaru-Head-Gasket-Issue The head gasket forms a seal between the Subaru engine block and cylinder head. It is the most critical gasket in the engine and the most difficult to diagnose. It seals both the combustion chambers and the coolant passages in a Subaru engine. The Subaru head gasket has to cope with high internal temperatures and combustion gases under high pressure. Due to the extreme range of hot and cold temperatures and pressures on a large surface it is common for head gaskets to leak between chambers over time. These leaks not externally visible. You may see bubbles in the overflow reservoir, or sludgy residue on the walls of the overflow reservoir, or random engine overheating. When a head gasket fails it can either leak engine oil to coolant or coolant to the compression chamber. Either of these may cause engine damage and significant operational problems like burning oil and overheating, which may show up as white exhaust smoke. Occasionally, there will be a compression leak in the gasket, which will have to be replaced, before severe damage occurs. If the gasket fails in this way, a variety of problems can occur, from compression loss (leading to power reduction, or a rough running engine), to exhaust gases being forced into the cooling system, leading to the engine overheating and increased engine wear due to the motor oil being mixed with coolant. Over the years we have not seen many non-turbo models with internal head gasket issues, while we have replaced many turbo WRX, STI, Liberty RS ¬¬, Forester GT/XT head gaskets, and if in the advanced stages, provided exchange engines. However, we have also seen an increase of liberty/Outback H6 EZ engines with internal defective gaskets at about 150 to 200 000km.

Engines EJ 205, 207, 255, and 257 DOHC 4-cylinder turbo from 1991-current, causes and options

Internal head gasket leaks in turbo models are usually caused by problems with one or more of the peripheral components, such as excessive turbo boost, failure of cooling fans, defective wiring, radiator leaks and blocked radiator cores. A blown head gasket in a turbo model usually indicates a replacement engine. There are two reasons for this: one, the OEM pistons consume excessive oil, meaning that replacing the head gasket using the original pistons increases the risk of a future engine failure and two, it is common when a head gasket goes on a turbo model for bearings, crankshafts and other components to be damaged.

Subaru External head gasket leaks

(EJ251, 252, 253) and (EZ30)

Visible leaks and false fixes

These leaks result in coolant and engine oil seeping out past the head gasket and running down the cylinder head, where they are usually visible under careful inspection. They can't be fixed by simply re-torqueing the head. They are sometimes hard to spot, showing only as slight staining where the head bolts onto the block. EJ25 and most EZ30 Subaru non-turbo engines are prone to this type of leak, which will often go undetected for some time as it is only in the advanced stages that coolant loss causes overheating. Customers who are attuned to their Subarus may report unusual smells, caused by coolant residue burning on exhaust pipes, and hot components; however most customers will be unaware of the problem. Additives such as cooling system conditioners, Bars Stop Leak, WWP-99, and Wynn's Stop Leak should never be used as these can compromise the cooling system, causing overheating and serious damage to engine components. The only practicable solution is a proper Subaru head gasket repair, which is one hundred percent effective when done correctly.

Engines EJ251,252,253, SOHC 4-cylinder non-turbo from 1999 to current, Liberty, Forester, Outback, Impreza

Subaru-Head-Gasket-problem In virtually all cases of head gasket failure in non-turbo 4-cylinder engines the cause is the design of the single layer OEM head gasket. If the problem is repaired using another OEM single layer gasket then the same issue will inevitably arise again. The mileage of the vehicle at the time of failure should determine the course of action. If the engine has travelled less than 120,000 kilometres it makes sense to replace the head gasket. At the same time, we advise performing a major service as this will mean a considerable saving in labour costs. If the engine has travelled 150,000 or more, consideration should be given to replacing the engine with a rebuilt or remanufactured engine from Subaru Engines Australia. External head gasket leak problems are rarely reported in turbo models, which are all fitted with the more robust multi-layer gasket.

Engines EZ30 DOHC 6-cylinder (H6) from 2001 to current

While these models are not as prone to the same problems as the 4-cylinder models, they have their own unique vulnerability, with the heater core. Unlike other models the EZ30 heater does not have a separate tap, and runs in series with the engine cooling system, meaning if the heater core becomes blocked, circulation of coolant is impeded throughout the system and the engine will overheat. The only early warning sign drivers might notice is an intermittent gurgling sound from behind the dashboard. If the heater core is replaced at this stage no further repairs should be required. However, if the early signs are overlooked, the engine will begin within two years to repeatedly overheat and the head gasket will fail, possibly damaging other components such as bearings, rods and crankshafts. The heater cores in these models commonly begin to fail around the 120K kilometre mark.

Advice and warnings from ADS

The earlier the better

The sooner the problem is found and fixed the less expensive it will be. If you have any doubts call us.

Known unacknowledged problem

Subaru have never acknowledged a problem with their single layer head gaskets leaving the only fix up to us.

ADS the only permanent fix

Subaru dealers use only the single layer head gasket. Only ADS use the multi-layer gasket for a permanent fix.

Susceptible models

All of the SOHC non-turbo models have the OEM single-layer gasket, and all will fail. We have the only permanent fix.
Call an ADS consultant now on 02 9915 9900 or 0420 319 049

Early and advanced warning signs of head gasket failure

External head gasket leaks never result in immediate engine failure. It's a slow process, and the attentive Subaru driver can spot the early warning signs and possibly save money on repairs by catching the problem before additional damage occurs. If an external head gasket leak is in its early stages it may be detected visually very easily but if it's in the advanced stage there may be more happening that is not visible. It's hard to know just how advanced a head gasket leak is, from external signs alone. Bring your Subaru in to us as soon as you notice any of the early warning signs. All Drive Subaroo have specialized equipment to test for hydrocarbons in the coolant and if these are detected early enough it might save your engine from a catastrophic failure and save you from a great deal of unnecessary expense. Subaru

Indicators of early stage head gasket failure include:

Indicators of advanced stage failure include:

Subaru If you notice these signs, the head gasket leak is at an advanced stage and it is likely that the engine will have suffered other damage and will need to be replaced.  

What happens if I delay repairs?

  Delaying repairs to a leaking head gasket is a false economy. It might seem like you're getting a few more miles out of your engine before paying for the repair, but continuing to drive with a leaking head gasket will cause more expensive problems to arise including:

Subaru Head Gasket Repair or Replacement from $1799


ADS multi-layer head gasket-the permanent fix

If you're thinking of taking your Subaru to a dealer, be aware that they will fit a replacement single layer head gasket, and eventually the problem will reappear. But that doesn't have to happen. All Drive Subaroo use high strength multi-layer stainless steel head gaskets engineered and proven to ensure many years of reliable operation for all Subaru models and are far more durable than the OEM original item. Over 10 years and hundreds of repairs using the revised gasket, we have never had a re-occurring problem. We have created two head gasket repair packages, one for the most economical yet reliable repair possible and the other, that we recommended, for the best possible repair plus long-term reliability.

Get a Quote

Please select your preferred option below then, complete the quick form and we will get a quote to you ASAP. If we need more detail we will phone you.

Step 1 - Select Your Option

Option 1 -Basic Head Gasket Repair Option

This option is a basic head gasket repair only. We re-use all existing parts (if still serviceable) and we do not perform any additional servicing of your vehicle, other than the included radiator service. If you want long-term service from your Subaru, and you like to keep your vehicle in top condition, we recommend the Option two repair.
  • Supply 1 x 2.5L SOHC Engine Gasket Kit
  • Remove and refit engine (service labour)
  • Dismantle, chemically clean and inspect, report on any findings if required
  • Assemble and reseal the engine using new gaskets and sealants
  • supply all necessary oils, filters, spark plugs, and materials
  • Pressure test radiator and clean if required

Option 2 -Head Gasket Repair And Maintenance Option

Note that this option is the best choice if you are looking for long and reliable service life from your vehicle. It includes many new parts, including the water pump, hoses, and timing belt bearings. In addition we perform a major service on the vehicle to ensure you will have a long period of reliable motoring.
  • Supply 1 x 2.5L SOHC engine gasket kit
  • Remove and refit engine (service labour)
  • Dismantle, chemically clean and inspect, report on any findings if required
  • Re-face cylinder heads
  • Assemble, reseal the engine using new gaskets and seals and sealants
  • Supply all necessary oils, filters, spark plugs, and materials to install engine
  • Supply timing belt bearing kit including timing belt tensioner
  • Supply new water pump
  • Supply 2x Misc. water bypass hoses
  • Supply top and bottom radiator hoses
  • Pressure test radiator and clean if required

you can rely on all Drive subaroo

The earlier the better

The sooner the problem is found and fixed the less expensive it will be. If you have any doubts call us.

Known unacknowledged problem

Subaru have never acknowledged a problem with their single layer head gaskets leaving the only fix up to us.

ADS the only permanent fix

Subaru dealers use only the single layer head gasket. Only ADS use the multi-layer gasket for a permanent fix.

Some Commonly Asked Questions:

Is the external head gasket leak issue also common in Subaru turbo models?

No, in fact turbo models are fitted with Multi –layer gaskets which have proven to be robust.

Can I still drive my Subaru while the head gasket is leaking?

For a while, yes you can. Should you? No, not unless you have a yen to spend a whole lot more money than you need to.

Does the H6 EZ30 and EZ36 Subaru engine suffer from the same problem?

Yes, these models do sometimes have problems, but not as often as the others, and usually caused by the heater.

How long does it normally leak before it damages the engine?

It’s impossible to say, but the range would run from a few weeks to a year approximately, depending on the type of leak, and on how the vehicle is driven.

Is it cheaper to buy a second hand engine or repair my own?

It may be cheaper to get a used engine from a wrecker, but this is usually a false economy. Given the inherent weakness of the head gaskets, it’s virtually certain that all the affected models will fail eventually.

Do all Subaru EJ25 engines suffer from defective head gaskets?

Yes, all EJ25 non turbo Subaru engines up to the current models are fitted with the inherently weak head gaskets.

Do you sell the head gasket separately?

Yes, we can supply head gasket kits. Please visit our online store.

How much does a Subaru SOHC head gasket repair normally cost?

Between $2,000 to $3,500 depending on the additional damage and the auxiliary parts required. Call for free inspection and quote now 02 9915 9900

Do Subaru dealers use the revised head gasket when repairing my vehicle?

No, Subaru dealers will fit the standard head gasket, meaning the problem is highly likely to recur if you own the vehicle long enough.

Is it good practice to replace the timing belt at the same time?

Yes it is good practice but it also depends on the mileage.

Will my check engine light come on if my head gasket was to leak?

No not usually but an O2 or AF sensor catalyst code may appear

Why should I need to repair the bottom end when the issues are in the cylinder head area?

Replacement of big end and main crankshaft bearings may be necessary. This will depend on the mileage the engine has run, and the condition of the bearings. If your engine has high miles, or has overheated or lost oil pressure as a result of the leaking head gasket, the bearings will be damaged and should be replaced.

What are some other parts or services that may be necessary while replacing my head gasket?

There are a number of parts that need to be replaced with your head gasket, and some that may need to be replaced depending on mileage or condition. A list of these follows below.

  • Subaru engine gasket and seal kit
  • Subaru spark plugs
  • All engine oils and fluids (Castrol brand)
  • Subaru water pump and thermoset
  • Subaru engine oil and air filter
  • Heater unit core check and flush
  • Radiator service or replacement depending on inspection results
  • Engine bay and engine water hosing

Our Subaru Service Centre Sydney can fix all Subaru problems, and all questions can be answered by our specialised Subaru mechanics on 02 9915 9900 or 0420 319 049


Watch Step by step repair of Head gasket !!


Find out more information about your cooling system

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For further information use our convenient online enquiry form, and one of our specialised technician will call you to discuss your enquiry. Remember, the more specific details you can provide, the more accurate our assessment will be. Alternatively, call us any time in business hours and talk to Niazi on (02) 9915-9900 or 0420 319 049.

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