I have been putting off a head gasket repair for better weather. Looking into the radiator for bubbles and tailpipe and in the engine compartment, it seems that it is leaking to the outside rather than into a cylinder.
Now, I am not sure of the mode of failure. With 170,000 miles, I am wondering if the preload on the bolts is suspect and, if I re-torque them, would it solve the problem. The mode of failure may not mean a bad gasket but loss of preload.
I am really not sure of how a gasket fails. Is it the constant temperature cycles that breaks down the mechanical strength of the material?
As an analogy, tapered roller bearing lose preload after the ends of the rollers burnish in. An early practice was to measure the torque required to turn a race. After a few hundred revolutions, a noticeable change in torque could be detected. In fact, old bearings are typically preloaded to 50% of their original torques. Now, end play is measured. More accurate but also more time consuming.
Anyway, I am thinking of initially retorquing the heads but this leads to the question "What do I torque to?". Since the initial torque also accounts for a squeezing and seating of a new gasket.
Maybe this notion is incorrect.
Now, I am not sure of the mode of failure. With 170,000 miles, I am wondering if the preload on the bolts is suspect and, if I re-torque them, would it solve the problem. The mode of failure may not mean a bad gasket but loss of preload.
I am really not sure of how a gasket fails. Is it the constant temperature cycles that breaks down the mechanical strength of the material?
As an analogy, tapered roller bearing lose preload after the ends of the rollers burnish in. An early practice was to measure the torque required to turn a race. After a few hundred revolutions, a noticeable change in torque could be detected. In fact, old bearings are typically preloaded to 50% of their original torques. Now, end play is measured. More accurate but also more time consuming.
Anyway, I am thinking of initially retorquing the heads but this leads to the question "What do I torque to?". Since the initial torque also accounts for a squeezing and seating of a new gasket.
Maybe this notion is incorrect.