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Discussion Starter #1
I just picked up a 2000 Outback Wagon 5-speed last week, and am seeing a lot of info on the net about Subaru head gasket failures. Most common being 2.5L DOHC, but it's still happening (less frequently) with the 2.5L SOHC phase II engines. Apparently this problem was resolved in the 2003 model, but it is likely too early to tell.

There are so many reasons why head gasket failures can be problematic that there is no easy answer here. Several different auto-makers have experienced this problem in the last 10 years or so.

My last car was a 92 Saturn SL1 and I decided to go the Subaru route (for the AWD and the wagon) since the newer Saturns (and other GM's) have had serious engine problems.

My Saturn has 382,000 kms and no HG issues - EVER. The rocker gaskets are now leaking, but no engine problems to ***** about. All original clutch...mostly everything is still original. Only major failures were the wiper transmission assembly, clutch hydraulics, and master brake cylinder. Other than that, the car rarely saw a mechanic, except for regular maintenance. The Saturn is also a light and agile performer, which creates minimal load on the drive-train.

It seems that despite their reputation, Subaru is still having HG failures and rust problems. The HG issue could be related to several factors including faulty gaskets, engineering, manufacturing, hard driving, poor service, etc. Us Subie owners need to be prepared with a mountain of evidence which indicates that the HG issue is problematic in nature - should we become another victim. It might even be worthwhile to approach Subaru as a group to get action. Here in Canada, we have the APA - http://www.apa.ca.

Considering the apparent numbers for these HG failures (does anyone have a guestimate on the number of failures?), it appears as though the issue may be an engineering problem. I have read on the net that Subaru has replaced several 2.5L engines under warranty for severe knocking problems. Knocking/detonation, compression ratios, combustion temperature, and head gasket failures are all inter-related. The 2.5L engines have a 10.5:1 compression ratio, which is higher than normal. The back pressure of the AWD system, the immense weight of the car, accompanied with certain driving conditions (and styles, especially lugging) can put a tremendous amount of pressure on the engine.

I'm no engineer, but I believe the best method to deal with this issue is to do one's best to PREVENT the failure in the first place. The coolant additive fix that Subaru is offering is nothing more than a band-aid fix. At least they offer some extended warranty protection with it. How effective it will be...only time can tell.

Some interesting reading on PREVENTING HEAD GASKET FAILURES can be found at www.babcox.com/nascartech/np50320.htm. According to this article, one of the major problems for head gasket failures is improper load on the gasket. Their are a number of factors which can cause this problem - see the article.

A few tips:
1) Check fluid levels regularly.
2) Check for HG leaks regularly.
3) Watch temperature gauge when driving, especially in hot weather.
4) Use the highest octane gas available.
5) If your engine has consistent knocking problems, have it checked IMMEDIATELY, as knocking/detonation issues cause increased compression which can lead to HG failure.
6) If your engine persists on knocking after using high octane fuel, check the plugs. If they're yellowing (see the back of a Haynes manual for plug diagnosis), try colder plugs - this will lower the combustion temp. and aid in knocking issues and help stabalize compression.
7) Have your sensors tested during tune-ups, especially for the EGR system, as EGR affects combustion temperature.

Some other possibilities...

I blew the head gasket on a 1987 VW Vanagon/Westfalia. A VW mechanic told me that with the aluminum head engines you need to peform a coolant flush every 30,000 (better to do it every year before winter) in order to prevent the corrosion inhibitors from breaking down and leading to an HG failure. The VW problem is known as 'crevice corrosion'. I don't know if this is the case with the Subies though. You can read more about the VW problem at http://www.vanagon.com/problems/head-leaks.html.

More reading about coolants and corrosion at http://www.vanagon.com/info/articles/coolants.html.
 

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Formerly 04 Outback 3.0R VDC, now 2011 Mitsubishi Pajero GLS DiD
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Hmmm perhaps this is why the 3.0R refuses to run low revs in any gear even in full manual mode. The engine feels very capable of pulling from 1000 rpm but it changes down gears once the RPM gets below about 2000 rpm. Also refuses to change up until it knows the next gear will not be running too low an RPM. :cool:
 

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MY99 3rd Gen Outback GX, 2004 Lexus RX330 Sport Luxury
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Jondalar said:
Hmmm perhaps this is why the 3.0R refuses to run low revs in any gear even in full manual mode. The engine feels very capable of pulling from 1000 rpm but it changes down gears once the RPM gets below about 2000 rpm. Also refuses to change up until it knows the next gear will not be running too low an RPM. :cool:

I'm pretty sure this is to avoid lugging the engine, which is hard on rods and cranks.

You've pretty much summed it up, regular coolant changes, keeping an eye on engine temps, avoid hard driving, etc etc.

Btw, the compression ratio of the 2.5L is 10:1, not 10.5:1.
 

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Discussion Starter #4
Addendum: I just discovered that the 2.5L SOHC has no EGR - can anyone confirm this? Also, I'm looking for a Haynes manual for the 2000 Outback Wagon and haven't been able to find one here in Canada so far. Anyone know where I can get one in Canada?
 

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MY99 3rd Gen Outback GX, 2004 Lexus RX330 Sport Luxury
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Unfortunately, there is no Haynes manual for the 2000 Legacy/Outback, full stop. I e-mailed Haynes and they told me they have no plans to make one.

There's two threads regarding a manual in this forum.
 

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Hers - 04 red/beige OBW 2.5, His- 2001 Impreza L Wagon For Sale & 65 Triumph TR4A
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Two things to prevent head gasket failure :

1. Change the coolant every 30K as specified by Subaru
2. Have the coolant changed by a professional who is familiar with filling subaru cooling systems.

When I worked at the dealer, we saw two completely warped 2.5L DOHC engines due to overheating. Both of which were because of improper cooling procedures. One done at Firestone, the other by the owner.

THe thermostat is at the bottom of this engine. Coolant flows up through the radiator. Be sure to fill the engine with coolant at the upper radiator hose until it pours out. THen fill the radiator up to fill and bleed the system. When the cooling fans turn on, and both the upper and lower hoses are hot, the thermostat is open and coolant is flowing. SOmething is wrong if the upper hose never gets hot. You have no coolant in the engine.

One customer drove from Rhode Island almost to PA like that, before it overheated because Firestone didn't fill it correctly. Impressive

Mopar 3.7 and 4.7L engines work the same way.
 
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