I changed my water pump seal 2500 miles ago because it was weeping out the hole. Cleaned the shaft and installed new seal. I also vented the hole to prevent crap from getting back in. After several months and many miles, all good. However, my dad borrowed it and when I checked it out when I got it back, I noticed there was coolant in the vent tube and the level was half way down in the reservoir bottle. I drained the vent line and topped up the bottle. I have now ran it for a couple of weeks. After 100 hard miles it has not leaked anymore out the weep hole. What would cause coolant to get through the seal, but then stop leaking. The only thing I could think of, was my old man might have been shutting it off hot and not letting the fan cool it first. Could that cause the seal to leak? Suggestions please.

I changed my water pump seal 2500 miles ago because it was weeping out the hole. Cleaned the shaft and installed new seal. I also vented the hole to prevent crap from getting back in. After several months and many miles, all good. However, my dad borrowed it and when I checked it out when I got it back, I noticed there was coolant in the vent tube and the level was half way down in the reservoir bottle. I drained the vent line and topped up the bottle. I have now ran it for a couple of weeks. After 100 hard miles it has not leaked anymore out the weep hole. What would cause coolant to get through the seal, but then stop leaking. The only thing I could think of, was my old man might have been shutting it off hot and not letting the fan cool it first. Could that cause the seal to leak? Suggestions please.