Subaru Head Gasket


#1

I have a 1997 subaru legacy with about 120,000 miles which was just diagnosed with a blown head gasket. The quote to replace the one gasket was $1600. However, the car overheated a few different times before the problem was diagnosed. I’m wondering if there may be other damage to the engine from the overheating; if I should have both the head gaskets replaced; and if I pay for the repairs now will I just have more expensive work needed soon? Any thoughts on Subarus and their head gasket issues would be much appreciated.

Thanks -


#2

The price seems a bit high so you might check around on this for a few more estimates.

When one head gasket is done the other should be done at the same time IMHO and it is critical that the cylinder heads be inspected for warpage. The heads are very short in length and logic dictates that a short cylinder head should not be prone to warpage, but the fact remains that warpage is common and they should be resurfaced.

It’s difficult to say about other problems considering the past episodes of overheating.
A lot could depend on whether the engine oil has been contaminated with coolant and just how many and how severe those previous overheating bouts were.
Chronic, and severe overheating can ruin piston rings and cylinder walls. This could cause the engine to use oil excessively, smoke, or possibly even suffer a piston rattle.

Exactly what are the symptoms behind the head gasket diagnosis? Any coolant loss, rough running, etc. or is this someone’s guess at a problem since the car is overheating?

When does the overheating occur; in town, highway only, A/C on, etc?


#3

Thanks for the reply. I just received the “head gasket diagnosis” yesterday in a voice message from the dealership. I have not spoken with the mechanic yet to hear how they diagnosed the problem or what else they may have checked. Prior to this diagnosis, the car experienced three overheating episodes. I rarely drive, except to leave town for the weekend, so all three episodes happened out of town and after a longer drive with some elevation change (without the AC on). Each time the thermostat spiked to H rapidly, but would cool easily when the car was pulled over, or if the heater was turned on. The first time the coolant was low, but the fan was running, and the car sounded fine. I took it to the shop and they replaced the thermostat and flushed the radiator. The second time the coolant level seemed fine, but was clearly warm with some bubbling in the reservoir. This time the shop flushed the radiator again and said it may just be a bubble in the coolant system. The last time the car did not seem hot, was running fine, and did not appear to have lost coolant although pressure in the radiator was high, but the thermostat was fluctuating a lot and drifting from H back down to cool. This time I took the car to the dealer and received the head gasket diagnosis.


#4

Different shops have different methods for determining a head gasket problem.
My preference is that it be a combination of tests which include:
Compression test
Cooling system pressure test
Vacuum gauge check
Hydrocarbon test of the coolant

Subarus are of all aluminum construction and do not take overheating very well at all. However, this does not mean they automatically pop a head gasket every time the temp gauge spikes.

I have no idea how they’ve arrived at the head gasket diagnosis (which could be correct), but the tests I mentioned are something you might ask them about.

If a head gasket/combustion chamber head gasket problem is suspected, you might try this.
Loosen the radiator cap (COLD engine) and allow any residual pressure to escape.
Tighten the cap, start the engine, and let it run for about 30 seconds or so.
Quickly get out and loosen the radiator cap. You should NOT hear any hiss of escaping pressure on a cold engine since the coolant has not had enough time to heat up and expand.
If you do hear a hiss then there is a good chance that you do have a head gasket problem.

Hope that helps and good luck.