Who here is the most knowledgeable?

[mikec03]

Someone from Prestone recently posted the production point in 2002 where Subaru started to add the conditioner and extended the warrenty on the head gaskets to 100K miles. They are:

 

Sedan = 2129 vehicles

Wagon= 1972

Outback =5593

 

Now the question: At this point [1] did Subaru just start adding the conditioner AND/OR [2] did Subaru switch over from the 521 HG to the 632 HG? In short, did they also change the type of head gasket at that time. Eventually they went to the 633 gasket, of course.

 

My 2002 sedan was manufactured in Jan 2002 and was the 11.722 sedan made. The head gasket is steel with a black coating which is brittle and peeling off. I don't know if this is the 521 or 632 HG.

 

Extra Credit: what is the difference between the 521, 632, and 633 gaskets? Maybe it's academic, since many of the 03-05 are showing head gasket failures, indicating that the 632 gasket is no better then the 521. It could however be important as a wedge issue to get Subaru to kick in for the HG repair.

[GeneralDisorder]

I just did HG's on an '06 Forester - classic oil weeping from drivers side HG.

 

The issue is the type of sealant they are using on the gasket. These are single layer gaskets that are just a stamped peice of sheet metal. The "glue" they apply to the surface is what holds all the fluids in. That glue breaks down, washes away, and then you have a leak.

 

I really don't know why they don't reinforce the deck and go back to graphite - it's worked well since Subaru started building the all-aluminium boxer engine around 1970. The only reason they went away from it was due to the larger sized, unreinforced bore of the die-cast EJ25 causing fire ring blow-outs. If they would just use the 257 semi-closed deck design for all their engines and go back to the graphite these problems would evaporate.

 

Incidentally - you rarely hear about 255 and 257 HG failures. It seems to be almost exclusively a non-turbo problem. You would think having solved the problem in the turbo engines they would use the same tech on the rest to save themselves from consumer backlash. This HG issue has cost them more customers than any other factor in the last 10 years.

 

GD

[idosubaru]

this:

Maybe it's academic, since many of the 03-05 are showing head gasket failures

 

This HG issue has cost them more customers than any other factor in the last 10 years.

maybe they like their labor and parts volume increases too much?