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Why does the Boxer diesel motor keep dying ? And how to over come it?

In which cars can we find the Subaru Boxer Diesel?

The subaru boxer diesel motor started to first sell in models such as the impreza which was in the years of 2008. Then they were followed by other models such as Forester, Outback/ Legacy and till the XV model.

So why does the Boxer Diesel Motor keep dying?

Well, its a very hard subject in general. And its tough to say which asnwer is right! But with our expertise and years of experience, we can give you our ideas and thoughts what we think is right.
There is always a saying that Subaru´s are unrealiable and have a problem with oil or water distribution. Ok fine, so they dont like heat. But when someone buys a diesel outback. It´s not just for going shopping around the city, but mostly for long-distance travel. This is where the heat problem starts. Everyone drives 140-170 km/h on the highway these days, and that's not good for a boxer. It then starts to overheat and unfortunately "twists".

Usually the dual mass clutch goes. For example, when its worn out the "pick up of the shift " doesn´t engage properly anymore so the mechanism bangs into the crank of the engine. This results in a piece of the crank bearing in the block often breaking off or the entire crank cracking.
Unfortunately, one of the factors is the quality of Czech diesel and the content of their bio-components. Even diesel fuel has a lot to do with fatigue and clogging of the injectors.

How to service your diesel Subaru.

  • We recommend changing high-quality engine oil at intervals of 10-13,000 km, e.g. Motul
  • After every change, have a mechanic on hand to cut open the oil filter to see if there are any metal filings.
  • Visit an authorized service once in a while and insist on checking the current software of the control unit.
  • Visit an authorized service once in a while and have the injectors calibrated.
  • After every 3rd service, make sure to include the original fuel filter in the replacement.
  • Use quality diesel for example in Europe use petrol stations such as OMV, Benzina and Moll.


Parts we offer for the Boxer Diesel

The extent and type of damage to these engines is repeated and very often in the boxer diesel Subaru. That's why we can offer packages to solve the most common fixes. 

The 1st Variant – Broken Crankshaft


  • Play within the crank
  • The crankcase on the transmission side is leaking
  • Noises or bangs coming from the motor at revs from 1800
  • Car not working


If the engine has high mileage, we recommend checking the piston rings, timing and clutch kit

What to pay attention to during the repair:

  • Check the clearance on the clutch > the dual mass is one of the frequent causes of these destructions.
  • Check the bearing of the gearbox, engine and rear differential > loose silent blocks are caused by the impact of the entire mechanism on the crankshaft and as a result the block bearing breaks.

What not to forget

  • We recommend always having the injectors checked.
  • We recommend always checking the turbo.


In 95% of cases, the block is damaged and the repair takes place in the second option.


2nd Variant – Broken Block


  • Car not working
  • Bangs and any unwanted noises coming from the motor.

Short block Motor:

  • Short block motor 2008-2010 – 10103AC200
  • Short block motor 2010-2012 – 10103AC270 (and above 10103AC210, 10103AC250)
  • Short block motor 2012+ - 10103AC280 (and above 10103AB900)

If the Engine alot of miles on the clock, we recommend checking the timing belt/chain and clutch kit.

Other surprises that we may encounter during the repair

  • Always do a block crack fluid test before ordering any parts.

Please don´t forget these things during the procedure they are vital!

  • We recommend always having the injectors checked.
  • We recommend always having the fuel pump checked.
  • We recommend always checking the turbos.


What is an engine short block?

The short block of the engine could be described as the heart of the engine. It is a set of new parts assembled directly by the factory, the manufacturer, i.e. in our case Subaru.

Short Block Engine Contains:

  • Block Motor EE20Z
  • Crankshaft
  • Connect Rod Bearings
  • Crankshaft Bearings
  • Connecting Rods
  • Connecting Rod screws
  • Pistons
  • Piston Pins
  • Piston Rings

The most reliable repair for a boxer diesel is always the replacement of the entire short block. Customers often ask us why it is not enough to replace only a new block. The reason for this is, money. Here we need to say that the price of a new block, pistons, crank and other necessary components to repair, dramatically exceeds the cost of an entire new short block.

How is it possible that your short block engine costs 40% less than in the Czech and Slovak Subaru?

The answer is simple. We buy original Subaru parts directly from the Subaru factory. As a result, we do not pay any distribution network or re-sellers and only pay for shipping and customs directly from Japan. We often supply shortblocks to authorized and unauthorized services not only in the Czech Republic, but also in Slovakia and Hungary.

Is there any point repairing a Diesel Subaru?

This is a frequent question from our customers. It is always necessary to remember that a car with a damaged engine is worth approximately 20-25,000 crowns and, in principle, the year of manufacture and equipment do not matter. By this I mean that in case of repair it is advisable to keep the vehicle with the new engine. The Subaru Boxer Diesel is currently the most difficult used vehicle to sell on the car market.

Where to Repair Boxer Diesels?

Our customers often ask us where to repair their damaged diesel boxer. Either there isn't an experienced mechanic around them or they simply don't want to work on subaru diesels. We also had to decide who will repair our customer's EE20Z and after many small and large repairs, we already have proven services that we can recommend to you.

Frequent questions

What motor oil should i use in my Legacy Diesel 2010?Peter from Prague

For Subarus we recommend using Motul Oil. And for dieseled engines we prefer to use 5w30/5w40 Motul 8100 X-clean C3 for vehichles with DPFs.

It is possible to convert a dual-mass clutch to a single-mass clutch?Honza from Jihlava

Possible it is, but due to the nature of the engine. We do not recommend it.

I have a diesel Impreza 2009 and i have to buy half of an engine. And I've heard that I can use a newer model because its more durable?Adam from Prague

Thanks Adam for asking. Unfortunately you cannot proceed within the first bethod because the block are completely different. But if i were you i would think about whether you would really want to invest an amount of 150,000 (Czech Crowns) in an 11- year-old diesel car.

If you replace the short block within the engine, what is then the life-span of the car and engine itself?Joseph from Liberec

Good day Joseph, if the person takes care of the car properly as required. There shouldn’t be any problems with the engine. We have several clients which have these motors driven over 150,000 km after half of the engine was rebuilt. And nothing has gone wrong, its all about how well the person takes care of the car.

Can I use a 0.95mm gasket on one side of the engine and a 1.05mm gasket on the other side?Kamil from Brno

Yes you can. It all depends on the bending of the heads and the block.

How often should and what is the requirement to change the timing belt? Is it even necessary to change them? And do you guys sell any kits?Ondrej from Olomouc

Thanks for the question Ondrej. Unfortunately, very often customers change the timings belt even with a new half motor engine work. The exchange requirement is 120,000 km.

Is it true that motors within the years of 2011 between 2012 will handle alot more and have a longer life-span than the years of 2008-2009?Peter from Uničov

Thanks for the question. To be honest if we look at the statistics at both years that you have provided us with, both years with the same parts give at the same time. So there isn’t any right or wrong answer for both versions. If you really want to go into detail, it all depends on how the engines differ, ecology and a few channels.

Do you guys offer the service of grinding the crankshaft rod and main journals? Or do you sell them already serviced like this?Joseph from Mikulov

Thanks for your question Joseph. The service of grinding the crankshaft and etc, we can provide. But we always try to talk our customers out of it because after this procedure. They usually break/snap and it doesn’t have the orginal weight as before and durability. So overall after this procedure it just weakens the crankshaft.

What is your opinion on boosting up the performance on a diesel boxer?Stanislav from Opočno

Thanks for your question Stanislav. But you have to take in consideration that the Subaru diesel’s are holding up as they are bog standard let alone, you want to even increase the power.

Can I swap a gasket kit for 2008-2010 engines with a 2010 and newer kit?Peter from Olomouc

Thats a good question and thanks for the question. To answser your question, yes. It's common for guys to switch sets. The newer kit does not have a compatible intake manifold gasket. Which is fine.

Can you guys refurbish injectors? And if so what is the price range?Roman from Bíteš

Denso launched a repair program this year when it finally began supplying the parts needed to repair Subaru diesel injectors. We recommend checking the injectors every time the engine is overhauled. The overhaul of Subaru injectors is normally handled by most professional companies that deal with this issue. The normal price of overhauling one injector is around 4,500,- excluding VAT. A new injector costs around 11,000 without VAT.

What do you guys do after rebuilding a new diesel engine?Roman from Plzen

The first steps after rebuilding a new diesel Subaru engine. You should take it to someone who owns and knows how to operate original Subaru diagnostics. The most important step after installing a new engine is to calibrate the injectors.

Lately we've had a DPF flickering a lot, is there a "reasonable" solution? Alternatively, I can remove the Subaru DPF? Daniel from Benešov

Unfortunately, this is a common problem for diesel Subaru owners. One of the causes of DPF clogging is the use of unsuitable oil and its long change intervals. If the filter flashes, throws errors, in most cases, cleaning at a professional company will help. However, if cleaning does not help, unfortunately, replacement follows. Here, we know from experience that only the original part works without problems. Unfortunately, Valeo, Bosch and etc. They have not proven themselves in long-term use for our customers. We do not recommend removing it, as it is very difficult to negotiate with the car.

I have a blown piston, what do you suggest as a solution? Stanislav from Praha

Thanks for the question. It depends if the cylinder wall is scratched so much that it would be necessary to put new pistons with a larger size or if the wall is undamaged. In the event that the block survived the destruction of the piston without damage, you can replace only one piston. Otherwise, the block needs to be remeasured, possibly over-honed or completely reground and replace all pistons with larger ones. Be sure to check the injectors. I would look for the cause here.

Unfortunately, we have a cracked block in the place of the cylinder liner, can we replace the engine? (Legacy Diesel 2011)John from Třinec

Hello John, thanks for your question. A few of our customers had the block lined, unfortunately, in the long run, most of these repaired engines did not last longer. For us, unfortunately, we will recommend a new engine block or the entire short block

Can i buy a turbo for a diesel from you guys. Im asking for it to be for a Forester (2011). John from Blansko

Our response: Of course you can, designated turbos for your model will be in this link provided 14411AA720. WE offer both Subaru or IHI which are identical but its’s up to you. Delivery is within 5 days, IHI will be supplied if so but it doesn’t come in the Subaru box but IHI. We have one in stock at the moment..

Hello SubaruSTI.cz, is it possible to get a price estimate for the repair of a 2012 Subaru Outback Diesel engine with a manual transmission? Mileage 212,000 km. Oil is leaking between the gearbox and the engine. Apparently the worst scenario?Petra, Litomyšl

We have sent you a price estimate for the repair by e-mail. With permission, we will display it here as a PDF for inspiration.

Something clicks in my car when I turn the wheels while driving, as if from the engine, is it the crank? I hope I don't need to change the engine. Impreza 2009 EE20ZDan from Hrádek nad Nisou

Thanks for the question dan. Now let’s assess the situation. It is most likely not a problem with the engine. But may i ask, is the inter-axle of the differential starting to annoy you? If so, try to get someone to listen to your car from the outside while driving. Because we think this may be your problem.

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