2005 2.5 litre (n. a.) engine replacement options ...

[Barry]

The car:
Gen 4 (2005 Model Year) Manual N. A. 2.5 litreOutback.
Sept 04 build date.

Maintenance:
Jan. 2010: 210,000 km. ( ~131,000 miles)
Water pump, belts and pulleys replaced.

Jan 2011:
Current 'Mileage': 257,000 km (~161,000 miles)

Annual 'Mileage: 47,000 km (~30,000 miles )

Issues to consider:


1. When will pulleys, belts , water pump, (other prts next need replacing?

• At 400,000 km (i.e. another 3 years.)
• If less, then what 300,000 km (i.e. another 12 months?)

2. What is the expected life of the engine before a total rebuild would be required?

• 400 / 500 / 600,000 km?
• In particular, would a rebuild be likely to be required within the life of the next set of belts, water pump, etc?
• What additional parts would need replacing at that stage?

3. What are the options in relation to engine replacement?

• '3rd Generation' engine? (The next generation, when it arrives, if I can hold out that long. Would the be compatible with my ECU, other electronics, etc.?)
• A later, more recent, fuel efficient, example of the '2nd generation' engine? (Would this necessitate also changing the ECU, etc.)
• An earlier more bullet proof version of the '2nd Generation' engine, such as the 'closed deck' version. (Would it be legal to run this engine in my model Outback?)

I assume the first 2 alternatives may improve fuel economy, the 3rd would probably have reduced economy.
​

4. Assuming a rebuild of my engine, what would be the obvious improvements to make, especially to maximise torque and fuel economy between 90-100km/h?

Hope all this makes sense.

Don't need to do any of it at the moment, but would like to start developing a plan for the medium term. :iconwink:

 

[Barry]

Placemarker:

Will list the 'solution' as it develops here.

 

[Rally]

Timing belts are set at 3 years/100,000km's, whichever occurs first.
Water pump, pulley's, tensioner and crank and cam seals every 100,000km's
The life expectancy of the engine will be determined by service intervals, quality of service parts, number of short journeys, operational behaviour- such as how hard is it driven- especially when cold, etc. A bloke in the WRX club regularly competes and has seen 300,000km's. Others get nowhere near it. And you can be lucky/unlucky.

Too little is known of the gen 3 engine, but I'd be surprised if mechanically it would not all bolt in. Aftermarket ECU's could help if the computers are not happy. Closed deck engines would not be of much benefit in a low compression, non turbo engine. They tend to have more cooling issues and probably aren't worth it. There should not be legal issues as a closed deck is about the strength of the block, and has nothing to do with safety or combustion.

To change the engine characteristics, changes might need to be made to compression ratio, cams, ecu, exhaust and cylinder head. They used to rally the 2.5 so some of the rally people would have a good idea on specifics.

 

[Barry]

Thanks for that info Rally,
The vast majority of my driving, and likewise that of the previous owner, as I understand it, has been highway / inter-city freeway (off peak direction). Therefore, on balance, not too arduous relative to constant arround town. I try and do the 'wipe off 5' thing most of the time, as much for fuel efficiency as anything else.

Also, I don't 'flog' it when towing, and the number of klms I manage to fit in off road is fairly limited. So, all being equal, I'd be hopefull of getting through at least two more 'belt and pulley' (etc.) changes. On my current mileage that would see me through to about January 2016, by which time the engine will be 11 years old.

I guess by then there will be a bit of data on how much more fuel efficient the Gen 3 engine is, it will probably have been revised once (hopefully dealing with any glitches which might surface) and there should be some available via wreckers.

More immediately, I'll need to do the pulleys etc about Jan next year, so will arrange to fit the Scorpion low ratio gears at the same time. (memo to self: 50 weeks x $40 = $2,000 )