Used Subaru Head Gasket and Valve Leak Prognosis

[Subaru_Lurker]

I have been reading around the forum about the common oil leaks in the head gasket and valve covers on many Subaru engines.  It sounds like the usual advice is that if the problem is addressed early enough, it's cheap to fix either DIY or at a mechanic and not a serious threat to the engine.  But if the problem is left alone, especially if the oil isn't refilled, it can destroy the engine.  That all seems reasonable, but I am not sure how to apply it to searching for a used Subaru--what can I look at to figure out if an oil leak is bad enough that it can't be easily fixed, or is so bad that the engine might start misfiring and fail as soon as I drive it away?  I guess some people drive their Subarus around for years without doing anything other than adding oil, so is there any way I can tell whether a small leak is fine or is fatal?

[wtdash]

Hi,

IMHO, your referring to 2 different issues, and there are 2 different versions of the HG leak to consider.

 

Oil leaks are common from various places on ALL Subaru engines:

- Oil pressure sensor/sender

- Cam Seals - front and rear

- Crank / Oil pump seal

- Rear separator plate

- Rear main seal

- Valve (rocker) cover gasket

- Spark plug hole gasket

 - Etc.

 

These aren't necessarily going to cause engine damage, as long as the oil level is maintained. The oil does usually find its way to the exhaust and cause the car to stink of burnt oil.

 

Head gaskets are not to be taken lightly as ignoring them usually leads to more expen$ive repair$. Repeated overheating of the engine causes the bottom-end crankshaft bearings to get worn and causes 'rod knock' and this requires a complete rebuild....unless the rod completely breaks and destroys the engine block - then it's a new(er) engine. 

 

The original '96-'99 engines 2.5L /  EJ25D engines (aka Phase 1)  had the INternal leaks, and most symptoms were indirectly evident, such as overheating and bubbles in the coolant overflow tank, etc.

 

The '99+ EJ251/EJ253 and EJ222 (Phase 2) had the EXternal leaks, and visually could be identified when leaking - although they also had similar symptoms to watch out for.

 

For ANY USED SUBARU w/a 2.5L engine (and to a lesser degree the 2.2L engine), if you can't document the HG repair, you're chances of it failing are......imminent.

 

And there are plenty of posts online about poorly done or just plain bad luck even after getting the HG repaired, w/it either failing again or the rod knock  occurring shortly after the HG repair.  I personally had a '98 EJ25D that had previously had the HG fail twice b4 I bought it. I fixed it and got another 30K miles b4 rod knock took it out of its misery.

 

If you find a Subaru that states: 'New (or newer) engine installed' - Be WARY that it was indeed 'new' and how many miles. If they installed a newer engine, it'll likely need HG @ sometime in its life. Also be wary of the Subaru JDM-replacement engine as it is no guarantee either. HG can fail on those too

 

.... I bought a used 2001 Subaru 2.5L w/100K miles for an Outback that had rod knock. I purposely redid the HG before I installed it to (hopefully) ensure I wouldn't have to touch the engine again....so far, so good after 30K miles.

 

So...Caveat Emptor.

Edited June 25, 2015 by wtdash