2000 Launch Heater Not Working

[ForJP]

I just purchased a 2000 Supra Launch. The boat has a heater that blows air but it's not warm. Any ideas what I should check?

[IndyMatt]

Who did your last winterization? The reason I ask is when I winterize my boat I drain the heater then install a bypass on the motor so I can winterize it. If during your last winterization, the heater was not reconnected properly, hot water would not be cycling from your motor through the heater core. There are two black hoses that run from the motor up to your heater, one comes out from behind the raw water pump (under the thermostat housing) and the return line attaches beneath the manifold riser on the drivers side of the motor, just above the drain/ knock sensor. If those are both installed correctly, make sure there isnt a leak at the heater (if water froze in the heater over the winter, it will split the welds on the core). One sure way to check (lil messy) is with the boat running, loosen the hose clamp & remove the return line, the one on the side of the motor. You should get a steady ejection of water, be careful... its hot. to stop the water either push the line back onto the nipple or shut off the motor. The water is being pumped through by the impeller so it wont leak if the boat is in the water. The only down side is you have to do this with the motor at opperating temp. If its not hot enough to open the thermostat, the heater will not be cycling hot water. You can also remove the cover to the heater core after your boat has been running to see if it feels hot, but since your blower seems to be blowing cold air... it probably isnt.

[ForJP]

Thanks IndyMatt, I'll do some checking on your suggestions.

[ForJP]

I checked the heater core hoses and found that they were not connected to the engine. They've been disconnected and replaced with a single hose for a closed system. Summer is on here in Texas so the heater won't be necessary right now. I'm may look into connecting it back up to see if it works if we decide to do some fall boarding.

[IndyMatt]

Yeah... I disconnect mine when I winterize & replace with the bypass hose... I fill my heater with antifreeze and plug the two hose ends together to protect. Not sure if your mechanic did the same... some just drain and leave them open. It certainly wont hurt anything to leave the bypass in place but you may want to reconnect... never know when you may get caught on a cool morning or evening cruise. Enjoy~

[IndyMatt]

Just one additional thought... make sure when you reinstall you check for leaks (wet carpet around the drivers feet or water in the bilge after running) Sometimes people forget to winterize their heaters & as I said above, if they freeze, it will do damage to the core. Your previous owner may have had this experience and decided to go without the heater rather than replace the core. There are several options regarding repair if needed... but I replaced the heater core in a 2001 Tige for around $70... just somthing to keep in mind.

[Ed Obermeier]

Same problem with my 2000 Legacy, the blower blows cool air. The original issue heater worked great, had a leaking heater core, replaced it and intially it worked but it's quit giving warm air and I don't have a clue why. Both send and return lines are hooked up properly, no leaks anywhere, totally at a loss why it won't give me warm air. I've always winterized it properly. Any ideas? I'm wondering if the thermostat is stuck open but the temp guage reads a steady 160 degrees during normal operation.

[IndyMatt]

I think your thermostat is ok if your running at the 160... if it were stuck open you would be overcooling, and running at lower temps (oil pressure would be high, poor performance, and lower opperating temps. The heater process is a fairly simple opperation, hot water runs through the core (a basic radiator assembly) and the fan blows through it carrying the heat away. How sure are you that hot water is passing through the core? Have you disconnected the back feed to check for hot water? Are the hoses connected correctly? Etc??