Reasons for Subaru Legacy Head failure ? - Surrey_Scientist

Have been wondering about buying a Legacy or Outback, and doing a bit of research seems the engines have a reputation for head-gasket failure , certainly the 2.5L engines at least.

I know how to check for this, (mayo, oil in coolant and vice-versa) etc. and that you need tochange oil & coolant regularly to reduce chances of failure.

Can anyone tell me the reason why they are so prone - clearly it must be a design/manufacturing problem ?

are the bores machined too close together, there is premature corrosion between gasket/head/block, or is the machining of head and block not to highenough tolerances for instance ?

I would be glad of anyones knowledge on these cars

Thanks !
Reasons for Subaru Legacy Head failure ? - Aprilia
This problem principally affected the '98, '99 model cars with 2.5L engines and was a worldwide problem.
The main reason is that the block is an 'open deck' design on the EJ25 engine. The cylinders are able to oscillate in an up/down plane (looking at the engine mounted in the car). There was insufficient bracing on the top and bottom of the cylinders.
If you remove the head on one you can see the HG 'fretting' where the cylinders have moved.
The sympton is water getting in oil, and occasional heat 'spikes' caused by hot gas getting into the water and interrupting flow. Failure normally happens after about 60-80k+ of normal use, or lower mileage if the car has been driven hard.
The cure is light head skim and a new gasket (Subaru have redesigned the gaskets). Subaru also suggest use of a 'coolant conditioner' (basically someting like Radweld) at coolant change time.
Bear in mind that some of these cars get driven REALLY hard; either through 'sporty' driving or by lugging a horsebox behind.

Cars made after about 2000- are supposed to be a lot better, and cars from 2003- feature a major engine redesign so should be every bit as reliable as the 2 litre engines. I have not heard of any post-2003 failures.

If you have any questions about these engines then call Subaru Technical in B'ham - they are normally very helpful and not the usual car manufacturer's 'customer service' wonks who know nothing about engines.
Reasons for Subaru Legacy Head failure ? - Surrey_Scientist

Thanks for the info Aprilia

I notice that there are '95, '96 and '97 registered cars advertised with a 2.5 engne - you say this only really affects the 98-99 cars.

are these earlier vehicles a different engine, or just don't seem to suffer the problem (for whatever reason, better assembly) or maybe these have already had their gaskets replaced by now ?

It is these earlier vehicles I am probably looking at price-wise (provided they don't look to thrashed) or is this not a wise move ? Maybe save my money and either look for a lter car when I can afford it or a different make.

(I need a reasonable size estate car, automatic essential, reasaonably tough and reliable, pref japanese.)

Don't suppose you can shed any light onto their mpg... some people I've spoken to say you will be lucky to 20mpg out of these for general driving, and struggle to get 25mpg max on a run..... ?

Thanks
Reasons for Subaru Legacy Head failure ? - Aprilia
Its mainly the '98-on engines that were affected. The block design was a bit different than the earlier 2.5's.

Any 2.5 that is 10+ years old could suffer from 'random' HGF, particularly if the engine has been used hard or the cooling system is below par.

Expecting ANY 2.5 engined automatic estate to get better than 25mpg is being a bit optimistic. I think you would be looking at 20-25 at best.

Really, at that age it comes down to finding a car that has been well looked after and not a workhorse that's only been serviced when its given trouble.
Reasons for Subaru Legacy Head failure ? - MVP
Our Forester II , 2.0x March 2003 had to have a new head gasket at its 2nd year service as the dealer found oil down the back of the block.

I was surprised at this early failure - the car had done less than 9,000 miles.
Reasons for Subaru Legacy Head failure ? - nick
At least he spotted it and fixed it under warranty. Some dealers would have wiped it over with a rag and sent it out again! Unusual on a 2 litre.
Reasons for Subaru Legacy Head failure ? - Aprilia
Our Forester II , 2.0x March 2003 had to have a
new head gasket at its 2nd year service as the dealer
found oil down the back of the block.
I was surprised at this early failure - the car had
done less than 9,000 miles.


That's a completely different kind of failure - sounds like the outer edge of the gasket was missing or damaged (during assembly maybe?) allowing oil to leak out from the gallery.
 

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