My 1999 Z34 has developed an antifreeze leak. The valve cover gasket was replaced two years ago and the water pump about three.

Steam begins coming from the passenger's side, a puddle is building under the main pully, and obviously it smells of burning antifreeze.

I've looked around the water pump and don't see any obvious leaks, also nothing appears to be coming from the intake manifold. Someone told me these cars have a 'thermal bypass', however, I don't know what this does or the routing.

Can someone tell me how the coolant system flows through the car? Obviously I'm aware of the two radiator hoses, water pump, and I can somewhat see the heater core hoses. Besides that, what other pipes or hoses exist that may cause this leak?

Thank you,

Peter

 

Maybe your heater core lines, mine did the same. Look to the left and down of your brake power booster to locate the heater core hoses exiting your firewall. One comes from the firewall and routes above your brake power booster and out by your master cylinder. The other one is routed along your firewall and down the bottom of your right inner fender and back up by your thermostat. that last one is also a hard line that has brackets screwed onto your body. where the brackets are welded to the hardline is where mine rusted through. I removed my passenger tire and splash guard and my leak was where the bracket was welded onto my heater core hose. I replaced my bad section with rubber heater core hose and zip tied it to my inner fender so it wouldnt hit my pulleys. Good luck on finding a way to replace that hardline hose with OEM due to how its routed.

 

if its steam then its more than likely coming from your radiator. i have a 99 lumina and i replaced my intake gasket about a year ago. the pressure created from the faulty gasket made a hairline crack in the side of my radiator causing massive amounts of steam after running my car for about 15-20 mins.... check the sides of your radiator look for dry white spots along small lines. I hope this helps.