Inline Thermostat Mod

[heartless]

5 hours ago, db***** said:

Seems as if there is some hostility in this thread. Lol. Sorry for trying to explore my options. 

Thanks for all the help!

Don't be sorry, and yeah, sometimes the guys tend to be a little blunt.. us long timers are used to it, but we sometimes forget new folks are not, lol

in all seriousness, the mod you are considering is not something even remotely needed on a daily driver. The correct thermostat, installed properly, will do more for you than putting all kinds of time & effort into something that is completely unnecessary.

a little tip when filling your cooling system... Fill the block first, thru the upper rad hose.. take your time, and make sure you get the block completely full before putting the hose on the radiator, and then filling the radiator. If you have the correct thermostat installed, it will seep coolant through the jiggle pin hole, into the lower rad hose, pushing air out thru the radiator.

having the nose in the air does help, but filling the block thru that upper hose works beautifully nearly every single time.

I have owned several Subarus over the last 18 yrs - from an 89 GL wagon with the EA82, a couple of early-mid 90s Legacies with the EJ22, and currently a 2002 Forester with the EJ251. I have never had a problem with trapped air using the rad hose method of filling the cooling system.

[idosubaru]

8 hours ago, db***** said:

I'm sorry is this post about me?

 

nah nah, joking with carfreak (who i had quoted) about the author of that article...jokingly, eye roll, like we're having a coke and wings at a table in town together. 

Explore away!  There's a ton of great information on EJ25D's on this thread to explore, packed full of excellent data and experience.

Did you know that EJ18's and EJ22's use the exact same (same part number) cooling system components as EJ25D's - water pump, cooling hoses, thermostat, etc - and no overheating or  headgasket issues?

 

[db*****]

My misunderstanding. Thanks for the info

[Mike104]

 Fill the block first, thru the upper rad hose

I have only worked on 4 Subaru's and I find that this method works for me.  I know that the Subaru mech's at my local dealer use a special funnel but filling the block through the upper rad hose has always worked for me

[db*****]

I think I've been misunderstood. I know how to bleed the coolant in an ej

[heartless]

11 hours ago, db***** said:

I think I've been misunderstood. I know how to bleed the coolant in an ej

ok.. if you know how to clear the air from the system, but are still getting air pockets, this would lead one to suggest a head gasket failure that is allowing combustion air into the system.

no thermostat/cooling system mod is going to fix that.

if you are looking at doing this mod "just because" - well.. do what you want - it is your car after all - but i think the general consensus here is you would be wasting time, energy and money doing it.

[db*****]

Never said that it would fix a head gasket, thats a pretty stupid thought. 

I was suggesting that it would help prevent good head gaskets from going bad, while also being easier to replace. 

I'm not trying to prove that this works, just wanted thoughts on it. 

[carfreak85]

2 hours ago, db***** said:

Never said that it would fix a head gasket, thats a pretty stupid thought. 

I was suggesting that it would help prevent good head gaskets from going bad, while also being easier to replace. 

I'm not trying to prove that this works, just wanted thoughts on it. 

The general consensus is that it will not do anything to prevent good head gaskets from going bad.  Besides that, the thermostat is already REALLY easy to get at on EJ engines, you don't even have to raise the car to get at it on our 1999 Forester.

What are your end goals for this engine?

[nvu]

For composite gaskets it wouldn't do much as they fail the rubber/graphite breaking down and eventually coming apart.

Moving the thermostat to the top has the risk of it never opening if there's a pocket of air big enough to dry it out.

[idosubaru]

6 hours ago, db***** said:

I was suggesting that it would help prevent good head gaskets from going bad, while also being easier to replace. 

sure thing.  if it was a "cause" then more than likely EJ18 and EJ22's - which use the exact same part number water pump, thermostat, and cooling system layout would have headgasket issues. but they don't. 

i realize some of this might seem harsh - that "author" you linked to is one of a hundred rabbit trails and iterations of the same thing that's been happening over the 20+ year history of the EJ25D headgasket - various conjectures, theories, or persons have thought they figured it out, knew it, or anecdotally thought they're awesome at owning/repairing/back seating commenting on EJ25D's, or found the magic bullet that no expert or prevailing wisdom came across. 

it was interesting when they first came out and people were trying to learn it and figure it out....15 years ago.   bottom line - the EJ25D is old news and there's about a 0.000000000000005% chance of a random internet person adding anything meaningful now.  so sure, ask, but also keep in mind the reality of the topic being discussed. 

[GeneralDisorder]

The 25D has head gasket issues for one reason only - the bore diameter caused a reduction in the thickness of the cylinder liner support walls where the HG fire ring seats on the block. Due to the thickness of the composition graphite gaskets they started with in 1996 (because of piston height above the deck at TDC) there is insufficient rigidity provided by the cylinder head to prevent the cylinders from moving around due to thermal expansion and contraction and combustion chamber pressure.This movement abrades the fire ring against the block and head leading to pitting, which ultimately leads to failure. Number of heat cycles is the primary indicator of lifespan coupled with any overheating events that add further thermal stress loading. 

It is easy to see this because Subaru solved the problem - you only need to look at what they did to effect a solution. They changed the piston to allow a thinner head gasket, and they beefed up the block around the liners to make them more rigid. For turbocharged applications they incorporated liner gussets to help stop them from moving under high cylinder pressure and temperature.

Also the open deck 1.8 and 2.2 engines do not have this problem despite having the same thickness HG as the earl 25D. Why? Because the cylinder liner support walls are WAY thicker due to smaller bore size. The engineers that designed the EJ never envisioned a 2.5 liter displacement when they modeled in on early computer systems in the mid 1980's. When new engineers were asked to increase the displacement they inadvertently caused a HG issue by the bore size change without considering what that would do to the rigidity of the cylinder. It was an engineering design mistake. Nothing more. 

Nothing you do or do not do as regards the thermostat location will have ANY effect on the HG "problem" associated with this engine. Want to solve it permanently? Resurface the block and the heads, Install 251 pistons, and use the 642 turbo head gasket. They will never blow again. 

GD

Edited November 16, 2018 by GeneralDisorder