Why do the 2.5 boxer motors seem to have head gasket issues. I have a 2008 legacy 2.5i limited (non-turbo). At 131,000 the headgasket blew. Total cost was $1,744.00. The repair shop said this is common they do atleast 4 of these a month and I live in a rural area. Why such a issue.
It is a poor design.
Just my 2 cents, but there is one main reason and that involves a retightening of the cylinder head bolts.
I’ve done countless Subaru head gaskets on various models and I’ve always done it the following way.
Make sure the heads are flat. One would think that a short head would not have a tendency to warp but they do.
Coat the replacement head gaskets with Copper Coat.
After the initial head bolt tightening wait a few hours and retighten them again. Then I allow the engine to sit overnight and retighten the head bolts again the next day. The gaskets have a tendency to relax so to speak after being initially crushed. Ideally, the engine should get a 500 to 1000 miles run-in period before the 3rd head bolt check but that is not always possible.
I have never had a Subaru head gasket job come back yet because of my methodogy.
From the late 70s to the mid 80s Subaru did not have a problem with head gaskets; or at least very few which will be explained. The reason? Subaru used to pay for a 1000 miles head bolt retorque. At one point Subaru stated that a head bolt retorque was no longer necessary on models with auto transmissions.(Same heads, gaskets, head bolts)
Bad move. What happened then is that models with automatic transmissions started leaking at the head gaskets so then Subaru said to retorque them and that solved that. Just my opinion; hope it helps.
I’m guessing here but I assume your use of the word “blew” is not quite correct. They seldom blow; they just weep oil or coolant; or both. Blow may occur when an engine is severely overheated.