Hi, everyone

Pre-purchase check of the 99 Legacy showed high (20-25ppm) of hydro-carbons in the cooling system. The mechanic advised it is a beginning of head gasket leak; but the owner has a paperwork of the replacement from Feb last year from dealership. He took it back to the dealership and they claim not to detect any leak. Mechanic says it is possible that high ppms are still from the old leak.
My questions:
1) Is it plausible that this is the case?
2) Any way to "clean" cooling system?

The car looks good otherwise but the gasket issue stops me from getting it.

Thanks!!

 

The only way to "clean" the cooling system is to flush out all of the existing coolant and replace it with fresh stuff. If similar levels are detected after it has been driven for a few hundred miles, then it does have a leak.

I'd suggest looking one year newer, because while the SOHC engines do have their share of HG problems, they seem to have a better leak resolution percentage. This is due to better reinforcement of the cylinders in the block and a much thinner gasket. The SOHC also has much better torque.