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Question about 2.5 motor and HG failure


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27 replies to this topic

#1 jeryst

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Posted 07 January 2018 - 06:50 PM

I just picked up a 98 Outback with the 2.5 motor without knowing that certain 2.5 motors have an almost 100% HG failure rate. The car runs great, no engine noise, and 124k miles. How can I tell if this is the 2.5 version that has the HG issues, or did all of the 98 Outback wagons come with the bad version?

#2 idosubaru

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Posted 07 January 2018 - 08:41 PM

All 98 wagons came with the most egregious EJ25s made. It’s not a bad engine necessarily but it is subarus worst.

They don’t all fail. They can make high mileages without issues. But now that they’re 20+ years old the chances are low that theyve been meticulously maintained or absent of compromised cooling systems (low coolant, never changed, poorly maintained, leak, blown hose, leaky radiator, etc). So chances are lower than average.

There’s no test that can cost from the initial failure modes at all. Explanation below.

First step is to make sure it hasn’t been swapped to EJ22 - does it have the 4 circles on the plastic timing covers or spark plug wires going through the valve covers? Either of those verify you have the EJ25D engine type it originally and with.

Initial symptoms of the *original* factory installed EJ25D headgaskets are random overheating events followed very shortly by a loss of cabin heat and tiny bubbles in the overflow tank (although bubbles alone aren’t necessariky conclusive without additional info).

Overheating events can be separated by weeks and months with zero indications of problems so it makes them really easy to sell with initial undetectable headgasket issues. While the car is asymptomatic for weeks you can’t test for it.

Over time the overheating events happen more and more frequently until eventually the symptoms are obvious. Overheating boiiing loosing coolant.

The good news is one of the best engines Subaru ever made is a direct plug and okay swap for that engine. I just helped a friend buy an EJ22 swapped 98 outback earlier today for that reason.

#3 idosubaru

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Posted 07 January 2018 - 08:50 PM

claims that they fail at a certain mileage are unwarranted and inaccurate. they were blowing headgaskets at insanely low mileages under warranty and they also can make 200,000 with no issues.

The reasons people assume a mileage are more nuanced and involve correlations that are incorrect.....which is very common.

#4 GeneralDisorder

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Posted 08 January 2018 - 01:14 AM

Replace pistons with 1999 to 2000 SOHC piston. Head gaskets with Subaru 770's. Not if, but when.

GD

#5 jeryst

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Posted 09 January 2018 - 10:03 AM

I was talking to a guy that told me that keeping a lower degree thermostat in the car would significantly increase HG life in the 2.5 motor. Anyone heard about that or believe it?

#6 montana tom

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Posted 09 January 2018 - 11:03 AM

Not heard it... Don't believe it.



#7 idosubaru

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Posted 09 January 2018 - 11:27 AM

I was talking to a guy that told me that keeping a lower degree thermostat in the car would significantly increase HG life in the 2.5 motor. Anyone heard about that or believe it?

 

No. 

 

how many EJ25's has he personally done this too and then followed for a decade and 100,000+ miles? My guess is it's probably an anecdotal amount, if any at all.  he probably works on dodge neons, or knows a friend who works at a shop....

 

someone could say they always use a certain brand of coolant, or always assemble the engine when it's above 50 degrees ambient temps, or they always use crest toothpaste, or always use XYZ brand oil- and never have headgasket failures.  just because it's "true" (for them) or "it happened" or "they saw it" doesn't hold any quantitative significance. 



#8 jeryst

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Posted 09 January 2018 - 12:32 PM

The guy said some relative of his worked for Subaru but I cant remember what he said he did there. He said the lower temps reduce the range of expansion and contraction, which translates to longer life.

I agree that some people's will say anything. I dont know this guy from Adam. We struck up a conversation at a gas station because we both had older Subarus. He asked me if I had my HGs replaced yet. He told me that he had over 300k on his 2.5 and never needed to have his HGs replaced because of using lower temp thermostats. Said the only downside was that the heater did not work all that well.

From an engineering perspective, I suppose it makes some sense. If you took two pieces of metal and you repeatedly bent one back and forth at a 10 degree angle while you bent the second piece at a 70 degree angle, you could probably bend the 10 degree piece more times before it broke.

I try to keep an open mind, but I was still pretty skeptical, so I was just wondering if anyone else has heard anything like that, or if the guy was just blowing smoke (no pun intended).

#9 idosubaru

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Posted 09 January 2018 - 01:44 PM

one could look into it.  i'd wonder how many miles did it have when he bought it and were the headgaskets or engine replaced before then, etc?   if he bought it new, how does he know it wouldn't have made it that long without the tstat?

 

around here the coolant is cycling between -10 and 180 degrees (or whatever it is) and so with a 160 degree tstat it would still be cycling between -10 and 180 degrees.  that's a 190 degree temp swing compared to a 170 degree temp swing, a rather meager difference. and, it is localized materials temp gradients that matter, not coolant temperatures.   

 

so to use your 'bending clip' example - materials can bend nearly indefinitiely in their elastic range.  they fail when they exceed elastic limits (which is presumed in your example) and enter plastic deformation.  so correspondingly we would need to know what that "elasticity" of the temperature swings are to determine if the range difference matters. 

 

so, maybe, but i think the engineering perspective is more nuanced and less convincing than armchair engineering, as is usually the case.



#10 el_freddo

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Posted 10 January 2018 - 02:36 AM

All 98 wagons came with the most egregious EJ25s made. It’s not a bad engine necessarily but it is subarus worst.


Incorrect. That would be the EA82, period!

Many ways to look after or deal with this potential problem - one could be insuring you're not doing repeated small runs where the engine doesn't spend a lot of time at operating temp. Not flogging the engine could be another way to reduce the occurrence of a dud hg. There are many and also different options for repair or replacement...

Cheers

Bennie

#11 idosubaru

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Posted 10 January 2018 - 06:30 AM

Incorrect. That would be the EA82, period!

cant be incorrect, that’s impossible as its just opinion.

yes if you’re talking about buying and comparing an engine right now then any older engine could be problematic for lots of reasons. I’m comparing the engines only, ignoring age and markets.

EJ25Ds ate headgaskets, rod bearings and tossed rods through block cases while still under warranty. EA82s were not comparable to that in terms of early expensive failures needing updated and revised parts. though EAs are wonky, gutless and less than ideal

quarter century old EA82s are a different topic.
if ill maintained cheap craigslist specials, or the current market, or performance, are your thing you’ll find EA engines problematic.

#12 jeryst

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Posted 10 January 2018 - 08:14 AM

So, is there a comprehensive list somewhere, of engines/production years/car models/engine weaknesses?

I would think something like that would be extremely valuable, at least to me it would be.

#13 idosubaru

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Posted 10 January 2018 - 09:40 AM

So, is there a comprehensive list somewhere, of engines/production years/car models/engine weaknesses?

I would think something like that would be extremely valuable, at least to me it would be.

i haven't seen one. too complicated of a compilation. in terms of major engine specific issues (not maintenance, timing belts, pulleys, alternators, batteries, starters which will all strand you if they fail...). In a sense if you just pay attention to the long block - that's what matters and gets expensive. Intake manifolds are rarely probelmatic and cheap and easy to repair or maintain, so that's benign in my eyes. So personally i pay attention to the long blocks for reliablity, easy of preventative maintenace and cost:

EA engines are great but old and slow. TOD is their big thing. Get one that's never been overheated or oil compromised and they make 200,000 miles easily on typical maintenance items.

ER are great but hard to find parts for and not many people are familiar with them. TOD as well and clean the IAC, and address corrosive CTS terminals.

EG33 are great but hard to find parts for and not many people are familiar with them.

96 and earlier EJ22's and EJ18's are non interference and routinely make 200,000 miles without blinking on regular maintenance.
Knock sensor is most common failure i used to replace these routinely preventatively, CTS probably second most common

1997+ and all EJ25's and newer gen engines are interference so if timing belt breaks they usually bend valves. Timing belt reliability should include excellent on-time maintenance and OEM parts or an OEM supplier (currently Aisin does for some platforms, but not all).

EJ25's - headgasket issues, knock sensors as well. 1996-1999 EJ25D's are randomly symptomatic and get worse over time. 1999 Phase II's leak externally 00-04 is usually coolant, 05+ is usually oil, but any of those years can do both and they can burn oil internally as well.

EZ engines have higher mileage headgasket issues - usually onset later in life and have the same general predisposition as EJ25D's. No timing belt maintenanace.

Later models starting sometime later in the 2000's start having smaller 7mm oil pumps and worse lubrication issues - like oil control rings in early FB engines.

Edited by idosubaru, 10 January 2018 - 09:42 AM.


#14 GeneralDisorder

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Posted 10 January 2018 - 11:46 AM

Thermostat change on a computer controlled engine will only confuse the computer and potentially create codes. The ECU isn't going to run the fans till it hits 204 regardless of thermostat.

 

GD



#15 el_freddo

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Posted 10 January 2018 - 06:08 PM

EJ25Ds ate headgaskets, rod bearings and tossed rods through block cases while still under warranty.


Hmmm... That list of issues suck and must be a US market issue. In Oz I know head gaskets and rings/pistons were changed under warranty but have not heard of them throwing rods through blocks over here. Odd.

Jeryst, do some searching on the forum. As previously mentioned there are many people/members that have effectively worked with/around the issue. Look after your vehicle, get to know it well and watch out for the signs of an issue or anything abnormal.

Cheers

Bennie

#16 idosubaru

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Posted 10 January 2018 - 11:03 PM

 them throwing rods through blocks

 

one can google various combinations of "thrown rods EJ25 bearings failure" etc - it's widely known and common.

 

on EJ25D's it's related to the random overheats.  car with 30,000 miles overheats and in the 1990's no one was thinking headgaskets, it wasn't known back then and the internet wasn't yet sparkling with insight.  in the early 2000's mechanics were calling me about it because they thought I knew a little bit about Subaru's. Typical scenarios - car overheats, limp it home but it's fine the next day so "bad luck" and keep driving.  overheats a month later and they limp it home.  mechanic finds nothing and changes coolant.  wash-rinse-repeat with various combinations of radiator, thermostat, radiator cap, water pump replacements - and the car has been limped and overheated multiple times when all along it was the head gasket failing. 

 

that overheating compromises the oil which degrades the bearings that fail sometime later. 

 

they can sustain a fair amount of overheating so it's not like they all do that, but it's certainly not uncommon either.  they're all rusting away out here but 10 years ago you could buy blown EJ25 vehicles weekly, if not daily, on craigslist. 



#17 1997reduxe

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Posted 11 January 2018 - 05:33 PM

it would b intresting to see statistics on how thos engines failed over the years, relative to their geo location. i have been living in texas for about 12 years now, and our recent cold snap really brought home to me the hardship on cars that used to bn our pennsylvania winters. its no wonder cars last for ever here in comparison to the salt and cold up there. :)

the reason i was saying that was i have heard this myself lately from someone regarding thermostats, that you should go with a typical sube one from the dealer, etc, and that a higher temp one can cook the engine, probably because while it may have a rating at a certain temp, it may in fact measure higher at least for a little while, and esp in those areas of severe cold, that kind of change in temp cant be a good thing repeatedly.

in comparison you could imaginee the old vw bug engines that were air cooled. what a marvel of eengineering those were. but at any temperature upon starting cold the entire operating mechanisms would reach temp quickly and uniformly. no need to slowly bring to temp in sections of the engine.


Edited by 1997reduxe, 11 January 2018 - 05:36 PM.


#18 Gloyale

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Posted 11 January 2018 - 06:21 PM

Thermostat change on a computer controlled engine will only confuse the computer and potentially create codes. The ECU isn't going to run the fans till it hits 204 regardless of thermostat.

 

GD

 

+1

 

without reprogramming or otherwise changing when fans come on, AND adding additional cooling capacity the temps will be nearly excactly the same.

 

thermostat is there to provide a minimum heat level to keep optimum temps for efficiency and heat for passengers. 

 

Once it opens, the high limit is controled by fans, and hte cooling ability of raditor.  If neither of those change, the lower temp thermostat will do nothing. 

 

The engine will prodiuce the same amount of heat, and will not disipate it any better or worse.

 

waste of time.  Just drive it and do the HGs if needed.



#19 idosubaru

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Posted 11 January 2018 - 06:52 PM

Faikure localations close to combustion chambers are experiencing temp swings of hundreds of degrees. The materials at the localized failure points wont reduce the full 20 degrees either. A lower thermostat sounds diminutive to me.

I don’t feel it’s worth pursuing so I don’t care personally but for clarity - GD and Gloyale are suggesting dissimilar reactions to lower Tstat? It will influence ECU or it makes no difference at all?

#20 jeryst

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Posted 11 January 2018 - 07:43 PM

Ok, I'm a little confused. If a thermostat opens at 160 and lets the water circulate through the system, wont the entire engine be cooler than if the themostat opens at 190?

#21 golucky66

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Posted 11 January 2018 - 08:38 PM

Ok, I'm a little confused. If a thermostat opens at 160 and lets the water circulate through the system, wont the entire engine be cooler than if the themostat opens at 190?


When driving down the road, with enough airflow through the radiator. Yes. It will be lower.

But when stopped, or in traffic etc. And minimal to no airflow through the radiator. The upper limit of "204" is the controlled by the fans.

#22 GeneralDisorder

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Posted 12 January 2018 - 02:36 AM

Ok, I'm a little confused. If a thermostat opens at 160 and lets the water circulate through the system, wont the entire engine be cooler than if the themostat opens at 190?


The answer is yes and no. What will happen is that in mixed driving the temperature delta between hot and cold will be larger and that will cause unnecessary thermal stress on the gaskets - potentially leading to even more rapid gasket failure than if it were more tightly controlled and thermal stress was restricted as much as possible to warm up and cool down periods only. Thermal cycling, and head gasket thickness were the primary reasons for failure. Decreasing the operating temperature without also chasnging the software fan set points is pointless and only create more thermal stress on everything.

GD

#23 jeryst

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Posted 12 January 2018 - 06:30 AM

Ok, so next question.

Does it help, hurt, or make no difference if you warm up your car?

I live in PA, and drive 65 mikes to work. Every morning I warm up
the car for 1015 minutes before leaving.

Does that affect HGs in any way?

#24 idosubaru

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Posted 12 January 2018 - 07:11 AM

there is nothing significant you can do to mitigate headgasket issues on that engine so i doubt idling matters.



#25 Bushwick

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Posted 12 January 2018 - 01:38 PM

Excessive idling can hurt the cats over a long period of time, causes engine wear, and also wastes gas, but if being warm is creature comfort you enjoy, then enjoy it! Life is too short!

 

 

As long you aren't flogging it after immediately starting, you can drive it right way and heat will be there in 5 minutes, though nothing worse than windows icing over as the defrost temp is too cold to keep it from forming ;)

 

 

I honestly wouldn't worry too much about your HG, though your timing belt needs routine maintenance which will fail if ignored/neglected to a bad effect. Just keep a vigilant eye on your temp gauge (some people ignore theirs). If it ever starts creeping past the half-way mark, then start being concerned with a cooling issue. TBH, I think these engines are fairly easy to work on thanks in part to being a boxer engine (the little baby 2 cylinder heads are too neat). The real nightmares are the transverse-mounted DOHC V6 and V8's in some FWD platforms where everything from the firewall cylinder head to the front of the engine being 1/2" away from a frame rail, to overly complicated and expensive timing chains are the ones where it's no fun to deal with.






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