Heater questions

[Aquanut]

I have had my '99 sunsetter VLX for a full year now. Last summer and into the fall the heater worked great, blowing out plenty of warm air. It was winterized (including heater) in the fall and now this spring I can only get cold air to blow even when the engine is warmed up. Any Ideas about what may have happened. Any info on how the heater actually works?

[Bill_AirJunky]

It's just like a car heater. Find the heater core, it's a metal box, usually up under the dash some place, has at least 2 air hoses & 2 water hoses coming out of it. Are the water hoses hooked up? Pull one & start the engine & see if water gushes out. You should be able to just feel the hose & tell if hot water is in it.

So does cool air come out when at any speed? What if you are going 10 or 20 mph?

[Molarbu]

Possibly the thermostat. What does your engine temp say?

[SkySkiKohlers]

Using this thread since I have the same problem.

My boat temp has been running around 130-140 degrees since it has gotten cold here (Lake Lanier Georgia). Air was 34 degrees yesterday, water probably in the 40's but I didn't look. I've got a T valve on one of the heater water hoses to get some hot water for my gloves before I get in the water. The heater seemed to put out hotter air in October-November.

I have the 2001 23 LSV, hammerhead engine with the old digital gauge that has all the engine info, heat, fuel, etc. I asked a boat mechanic if I should change out my thermostat, not sure what else the problem could be. The mechanic seemed to think that the engine was probably warmer than what the gauge was reading mentioning the sending unit placement.

Should I go ahead and change the thermostat? Can I get that at the auto parts store, or should I stick with the DIM or Bakes?

Thanks!

[Ndawg12]

Good for you still getting out!! I'd replace the tstat, I know you bought it this summer so for all you know that tstat is 13 years old. Water temp shouldn't matter as I had the same problem through last summer. Temp wouldn't go above 150 unless running really hard, my tstat had failed open which I believe they're designed to do so you don't overheat. Do you notice any excessive gas fumes out the exhaust? You maybe running a little rich if the engine temp isn't hovering around 160.

Edited January 6, 2014 by Ndawg12

[ahopkins22LSV]

I have found when it is really cold out like you described heaters don't work that well. When I was driving for our polar bear event the heater in the TXi was not worth having on. It did not have the wye pipe installed just the standard inlet and outlet hook ups from the water pump.

My theory? And my disclaimer is that I don't have that much knowledge or experience with this or engines. But with the very cold air and water temps the thermostat doesn't circulate water as frequently so warm water is not passing through the heater core. Again that's just my theory, could be very wrong. The axis we had in the water had an aux heater pump and that was putting out good heat. The wye pipe would probably help too. Bakes carries them.

Someone please correct me if I am way off.

[Baddog]

I have found when it is really cold out like you described heaters don't work that well. When I was driving for our polar bear event the heater in the TXi was not worth having on. It did not have the wye pipe installed just the standard inlet and outlet hook ups from the water pump.

My theory? And my disclaimer is that I don't have that much knowledge or experience with this or engines. But with the very cold air and water temps the thermostat doesn't circulate water as frequently so warm water is not passing through the heater core. Again that's just my theory, could be very wrong. The axis we had in the water had an aux heater pump and that was putting out good heat. The wye pipe would probably help too. Bakes carries them.

Someone please correct me if I am way off.

I think you are right on the money. An engine will only get so warm when the air and water temps are conspiring against that happening.

[Ndawg12]

I think you are right on the money. An engine will only get so warm when the air and water temps are conspiring against that happening.

not if the tstat is functioning properly.

As for the heater, without a wye pipe or auxillary pump, anything less than ~1500 rpm's won't be very hot at all.

[100PercentFooter]

OP, connect your water hoses to the heater...winterizing would have removed hoses and drained heater core....or it'll freeze.

[100PercentFooter]

Oops...answered question from 09.....so for the other guy...auto store won't have the right t stat.

[CedarLakeSkier]

Another thing to check. When I installed my heater I put a small screen in the connection to catch any junk so it wouldn't end up stuck in the heater. You'd be surprised how much junk this little screen collects. This stopped my heater from blowing hot air. I just pull the screen and rinse it.

If you have a screen it may be clogged, pull it out and rinse it.

If you don't the junk may be stuck in the heater. See if you can disconnect the pipes and reverse the flow through the heater so send the gunk back out.

[SkySkiKohlers]

Ordered a tstat and the y valve. I should have them in this weekend and will let you know if that fixed everything. If that doesn't work I'll try cleaning out the heater. Thanks everyone!

[NHolladay]

On my jet boat in the fall My engine won't warm up at all. No tstat so I just installed a valve on the dump to the exhaust and it holds the water I'm the engine longer to warm it up. I Suspect it is just to cold Ro out out that much heat. That water runs through the engine fast. I would be curios if all the new closed loop cooling would be different. Any ideas?.

[SkySkiKohlers]

Installed the tstat and boat now runs at 160-165, heater is much warmer and the wife is happy. I bought the y valve also but haven't installed it yet. Hope to put it in this week. Thanks everyone!

[ahopkins22LSV]

Installed the tstat and boat now runs at 160-165, heater is much warmer and the wife is happy. I bought the y valve also but haven't installed it yet. Hope to put it in this week. Thanks everyone!

Good to hear! The wye valve will be awesome for you. You will never not have heat at idle again.

[SkySkiKohlers]

Installed the y valve and wife was too hot! Air temp in the low 50's. Thanks again everyone!

[TallRedRider]

Glad you got a solution.

My local (non-Malibu) dealership had my boat in for a few other things, and decided that he did not like the heater hose configuration and took out my Wye (I think it is actually called a Venturi fitting). He didn't even tell me and threw the 'work' in for free.

I found the heater to not be working so well, and then found the problem. I was then hot and ready to go ballistic. Luckily, they had not thrown away the fitting and he put it back for free. A classic example of a dealership that does not subscribe to 'the Malibu crew', or he would have been smarter about these things.

So I have actually had my heater both ways, and with the Venturi fitting on the intake takes care of any idle speed heater woes.

[klinger]

I know this is an old post, but thought I'd share another thing to check if you don't have heat at any RPM. 

In that "Y" fitting, as noted above, there is a small hole for the heater return line. In my case, this small hole got plugged with some scaling usually found when draining the engine block. This lead to no heat no matter what. Thinking about it after the fact, it seems like a good first place to check if your thermostat is working properly. It seems very likely to plug this hole before you would ever plug the heater core itself, in my opinion. But, it was of course the last place I looked (isn't every solution?? :-) ) Good luck and happy boating or more likely winterizing.

 

Kevin