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97 Outback Head Gasket Failure


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Well the 97 Outback that I bought less than 2 months ago blew a head gasket. On the way home last week I took a relatively steep and long hill where shortly after I noticed a lot of heat coming out of the vents. When I looked at the temp guage it was well on its way to the top, luckily I pulled over before it could get to the highest level. Coolant puked out of the overflow reservoir. I let the car cool off and then drove home, less than 5 min without any further overheating.

 

After adding some coolant I went for another test drive and sure enough it overheated again after going up a few long steep hills. Again, all ran well after letting it cool of.

 

The next day I drove to the dealer without incident, no overheat. The mechnic had a look and said head gaskets. There was oil residue in the overflow tank as well as air bubbles.

 

So, I bought this car because I was told by the dealer that the short block was replaced in 2001(with only 46,000km). I figured new block, better gaskets all would be well, no such luck. Now at 112,000Km new head gaskets.

 

The other disturbing thing was the condition of the inside of the engine. The oil was filthy and gelled, so much so that you could barely tell the bolts on the bearing caps were hex head. The PO had changed the oil before I bought the car but apparently not nearly often enough, if ever. What really sucks is that the dearler was going to go to bat for me and see if they could get the local Subaru Atlantic Rep to pay for part of the head gasket repair but once they opened up the engine and saw the sludge they said sorry we can't help.

 

Fortunately, the cams and related bearings look to be OK(of course looking OK and being OK are not always the same). The sludge will be removed and the valve train should operate a heck of a lot better. The heads went to the head shop for a cleaning, inspection and milling.

 

In any case, my confidence in this vehicle has been shattered but given what I have spent thus far I can't get rid of it.

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Even with oil changes every 12,000 km (which is the standard usage schedule from Subaru Canada), I have not seen sludging to the level that you describe.

 

Is it possible that coolant was leaking into the oil for quite some time causing it to break down?

 

Coolant in oil will cause it to look like puke... No other way to describe it.

 

Another possibility is that the oil pump installed on the new short block was not correctly done, causing oil to sludge up because it overheats due to insufficient flow. This could even lead to problems such as a failed head gasket.

 

It is also possible that an older model head gasket was used during the rebuild in 2001.

 

One of my longstanding concerns with solid lifter engines (Subaru's from 1997 onward) is that they don't give much indication of low oil pressure without a guage. With hydraulic lifters, the lifters will clack indicating and oil pressure problem.

 

During the head gasket repair, the oil pump should be inspected. Also be sure to replace any seal or gasket that appears to be leaking and the timing belt as well if oil contaminated. You may just want to change the timing belt anyways, since it is just parts cost at this point.

 

Be sure that both the heads and engine block are straight.

 

You could install new head gaskets and have no further problems, or the crank bearings could let go because of the sludge. Sludging generally occurs on cool parts of the engine, and by bearing caps, I assume you mean the camshaft bearing caps (since Subaru doesn't have crank bearing caps). This is a colder area of the engine and an area prone to sludging.

 

I have changed valve cover gaskets on my 1993 Legacy twice and noted substantial sludge buildup under the valve cover. I changed the oil regularly (every 6000 km or so), and used Mobil 1 full synthetic (one of the best oils around), and still had the sludge when I changed the gaskets, first at 140,000km and then again at 390,000 km. It was a waxy white paste that was thick and had settled on every stationary component in the head.

 

My Legacy was running perfectly until 466,000km on the original engine and transmission (and clutch!!), when a deer came through the windshield bending the A pillar which could not be repaired safely.

 

Do you have sludge build up in both heads, or just the one that failed? Do you have any records indicating why the original short block was changed??

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The short block was done because of piston slap.

 

Coolant did not get in the oil, it was dark but not creamy. I have seen coolant in oil before when I had a cracked head on a Toyota Land Cruiser. This stuff was like jelly and burnt sugar, ulgy!

 

As you said insufficient flow of oil could be the cause of the gasket failure after overheating and the dealer is looking at it the same way. The mechanic and the service manager said they haven't seen that much crap inside that type of engine before and they seemed pretty sincere. Both heads were caked with sludge and the crap could be seen all the way into the block.

 

I questioned the oil pump but the final jusgement was that it was always in the "wet" oil at the bottom of the sump while the sludge was stuck on parts up above. However, I can't help but think the oil pump had to have pumped some crappy oil at some time.

 

The timing belt was replaced just this spring as was a cam shaft sensor and other components ($1,700.00 in repairs). I doubt the mechinic would put a contaminated belt back on.

 

Both heads were milled for a fresh edge, pressure tested and checked for cracks etc.

 

All in all I am not feeling very good about this car.

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Originally posted by Greg S

The short block was done because of piston slap.

 

Unusual that they would change the short block due to piston slap given that Subaru's policy of late has been:

 

"Piston slap is normal when the engine is cold. Get used to it, we are not going to fix it"

 

Perhaps the piston slap not a simple cold engine problem, perhaps the piston or cylinder was defective and it was constant piston slap, both hot and cold.

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