Replace 2.5 HG prophylactically ie before failure

[hugho]

Would it be wise to replace the 2.5 HG prophylactically on a perfect running legacy outback, ie hasn't overheated or leaked etc. Would that eliminate the HG problem or are there other design issues which make it a waste of time?

[brus brother]

I did just that on my 08 at the tb change at 105K miles. 

In truth, it had overheated once due to coolant leak from lower radiator hose but this was my intention anyways.

My 05 started with hg leaks about 10K after the tb change so I considered the HG change a matter of maintenance.

Now , barely 5K miles later, I am getting the damn P0420 code on the 08 just as I did on the 05.

I am not going to waste time tracking this down again. I will just reset the code before inspection every other year since I don't use cruise control which becomes inactive when check engine light is on.

[idosubaru]

Would it be wise to replace the 2.5 HG prophylactically on a perfect running legacy outback, ie hasn't overheated or leaked etc. Would that eliminate the HG problem or are there other design issues which make it a waste of time?

 

Waste of time IMO if there's no compelling reason to change them.  They can easily run 100,000 miles, just look at all the subaru's on the road around you and many of them have gobs of miles on their headgaskets. 

 

I guess if you're time rich and bored and watch 10 hours of TV every week then yeah do something more productive and do it. 

 

To be more precise: 

Which EJ25 are you talking about?

How long have you owned it?

How do you know they've never been replaced before?

[hugho]

Thanks idosubaru. I have a 2.2 96 OB which is flawless and low miles but a bit small so I am thinking about the bigger legacys from 96 to say 99. The choice then is to find a low mile 2.2 and throw it in(unlikely) or do due dilligence and fix the 2.5 before it conks out. I have just finished doing  my own rebuild on my 2001 corolla with 290K because of oil burning. It runs flawlessly with lots of power from 1.8 L and gets 45-50 mpg but is 2wd and we live in DEEP snow country(Wyoming) and 4wd comes in handy and is required if you ride the passes so just looking for an economical  winter 4x4. My wife drives the Impreza and I am stuck with my 2wd corolla or driving one of the big Cummins pick em ups which are terrible in snow and ice and lousy commuter cars. They were meant for pulling cattle trailers which is how I use them. If fixing a 2.5 that hasn't broke yet really doesn't fix it, I wont bother trying. We are an empty state with long spaces between help and breakdowns in winter can be serious so I want reliability.  Is throwing in a 2.2 a better option? Finding mid 90 2.2's with less than 150K at junkyards seems impossible. Your thoughts? BTW your posts are superb and I have read almost every one.

[idosubaru]

I would do an EJ22 swap all day long.  They're awesome engines...I'd spend the time and money looking for a good low mileage one if you can. 

They're getting harder to find particular in high demand areas.  Some people say they lack power, I don't really care I'll just rev it an EJ22 can take it.

 

The 96-99 EJ25D's are annoying because when they fail there's no warning, no planning - they initially overheat completely and entirely randomly with no warning. 

 

It's also quite likely they've been overheated or replaced already...further raising questions about how bad they were overheated previously, etc.  because overheating is the first symptom and people often are stranded - they're prone to be "limped home" and run hot too much which doesn't do good things to the longevity of the rod bearings.  "i replaced EJ25 headgaskets and now have rod knock" isn't exactly rare. 

 

Later 2000+ EJ25's are better as they usually don't randomly overheat but leak extenerally so they're easy to plan ahead for a repair and not get stranded.  so they're a better option for reliable, long term, high mileage commuting. 

[Mike104]

"Later 2000+ EJ25's are better as they usually don't randomly overheat but leak extenerally so they're easy to plan ahead for a repair and not get stranded.  so they're a better option for reliable, long term, high mileage commuting." 

 

Especially if you routinely check the oil and radiator for coolant level!

[idosubaru]

 

Especially if you routinely check the oil and radiator for coolant level!

 

what - aren't there lights or an APP or a gas station attendant or social media that can tell me, i actually have to like pop the hood open and look at something mechanical...? eeewwww.....

[Fairtax4me]

what - aren't there lights or an APP or a gas station attendant or social media that can tell me, i actually have to like pop the hood open and look at something mechanical...? eeewwww.....

Don't worry, there's an app for that somewhere!

 

As per the 2.5 in the 96-99 Legacy, no there's no real reason to change head gaskets unless you have signs of failure - mystery loss of coolant, coolant/ air bubbles pushing out into the overflow container, temp rising on highway trips or when going up long grades.

You'll almost never see any smoke, or coolant mixing with the oil, with the failure mode that these gaskets exhibit.

[GeneralDisorder]

It's ALWAYS better to plan and budget your downtime rather than wait for catastrophe. But obviously I'm not the majority here. 

 

That said, those engines don't just need HG's, and you can't assume that they won't be thunderf*cked inside when you open them up for said repair. Too old, and too many variables. Contemplating what you may or may not have to do with a car that's potentially 20+ years old - cross that bridge when you come to it. You are going to have to work within the confines of what is available but I would strongly suggest moving into the Phase-II engine, and if you can into the AVLS version starting in 2006. With some careful pre-purchase inspection, etc - you can find something that's untouched by amateurs and do the HG's proper.   

 

GD