Leaky head gasket. Blue devil or wait?
Asked by Kellie May 30, 2018 at 01:42 AM about the 2000 Subaru Legacy L Wagon AWD
Question type: Maintenance & Repair
It has a small external leak at front corner. Cant get
it fixed. I got blue devil, should i use it now as a
preemptive or wait, knowing its an 18yo car that
will leak and keep an eye on it?
6 Answers
Is the head gasket or the valve cover? Oil or coolant leaking?
TheSubaruGuruBoston answered 6 years ago
Coolant from the valve cover?! Are you sure? If it's not from the HG you can try a half bottle of premixed Bar's Leaks and see if it abates in a day or three. If not just carry a jug of premix coolant with you as you're indeed on the death curve.
If the leak is small you could go for a long time. I have used Subaru's brand of antileak with good results.
TheSubaruGuruBoston answered 6 years ago
NO ADDITIVE will stem a coolant leak from the head gaskets! Subaru's "red stuff" was an attempt to seal internal leaks...and will work on minor leaks around low pressure junctions, just as Bar's leaks will, but no additive works for HGs. Hence my comment re the "death curve", as your chariot is probably too old to be worth the $1.5k repair cost. You MIGHT be able to limp along for a completely indeterminate time, being very careful to add coolant to the expansion tank...and the radiator first if the tank is allowed to run dry. But eventually the driveway will start to show puddles, and/or the opposite side HG will start to leak OILI, which is difficult to tolerate as it drips onto and then smokes off the cat conv, affecting your breathing and health. Under no circumstances allow the system to overheat, after which the HG leak will become much worse. We've been through this scenario many thousands of times with the 2.5i SOHC motor used from 2000-09; in 2010-2012 Subaru finally found a three-ply HG that holds up much better. That's what you'll get if you reseal the motor...as well a careful test of the heads by a pro machinist. Do NOT ignore this part of the repair, as a warped head will NOT stay sealed with ANY new gasket. So it may be time to say goodbye....
