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Heater Hotter


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We were running down the lake at about 3000 rpm yesterday after skiing. Air 70, water 56. This time of year we always run the heater. I noticed that the air coming out of the heater was not really hot. Seems like it used to be hotter. I pulled the heater hoses off of the engine and blew through them and there was no obstruction. Temp is 160. I'm not running a Y. What up?

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Heatercraft used to recommend a 160 degree thermostat in all their heater installs. Seems normal to me.

As for why the heater isn't putting out much heat, I'd check the temp of the hoses going to the heater core & see if their hot.

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We were running down the lake at about 3000 rpm yesterday after skiing. Air 70, water 56. This time of year we always run the heater. I noticed that the air coming out of the heater was not really hot. Seems like it used to be hotter. I pulled the heater hoses off of the engine and blew through them and there was no obstruction. Temp is 160. I'm not running a Y. What up?

Us Northern people would very much enjoy those temps with no heater. :)

If it is like a car, the thermostat could be stuck open, so the engine temp isn't getting hot enough.

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Us Northern people would very much enjoy those temps with no heater. :)

If it is like a car, the thermostat could be stuck open, so the engine temp isn't getting hot enough.

The temperature gauge is running about 165.

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I'd replace the thermostat, it's not opening fully.

That's incorrect.

If the T-stat were not opening fully, you'd have a hot running motor.

It's still a good idea to replace it if it's original. There could be a chance that's it's physically broken open.

But, it sounds like your motor is running at roughly the correct temp.

You should feel the heat of the hoses going to and from the heater core. One should be pretty hot (if the motor is truly at 160*), the other hose should feel a little cooler.

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That's incorrect.

If the T-stat were not opening fully, you'd have a hot running motor.

It's still a good idea to replace it if it's original. There could be a chance that's it's physically broken open.

But, it sounds like your motor is running at roughly the correct temp.

You should feel the heat of the hoses going to and from the heater core. One should be pretty hot (if the motor is truly at 160*), the other hose should feel a little cooler.

Thanks Pistol, I'm going to check the hoses tomorrow.

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Upon further thought about this situation, while driving home from work tonight, it dawned on me that if you're running at 3K rpm in 56* water, the refresh rate in the motor is probably really high with cold lake water.

What that means is, at that speed, the raw water pump is pumping a poop load of cold water into the motor, the water jackets prob. don't have enough time for the heat to transfer in and therefor, the water in the engine is probably a lot cooler than normal under high-speed, low lake water temp. conditions.

So, I wouldn't get too wrapped up about this one particular circumstance unless you're really sure that in the past, under the same conditions, the heater used to put out a lot more heat. BTW, the "Y" update was to provide heat during low speed, idle conditions. And, BTW, I don't have a heater in my boat.

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165 is not abnormal for your boat temp.

Check the temp of the heater hoses. They should be pretty warm. I bet their not.

Did you winterize the boat? Did you hook all the hoses back up too? Any chance 2 of the hoses were switched?

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165 is not abnormal for your boat temp.

Check the temp of the heater hoses. They should be pretty warm. I bet their not.

Did you winterize the boat? Did you hook all the hoses back up too? Any chance 2 of the hoses were switched?

I don't really winterize...Just kind of ski year round on the nice days in Jan and Feb. I will check the hoses tomorrow. Would it matter it the hoses WERE switched? Wouldn't hot water still fill the core?

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Yea, it would be other hoses than the heater causing it. But if you haven't had the water pump hoses apart at all, then it's not the issue.

Check the temp of the core & hoses the next time you notice the problem.

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If you invert the input and output hoses and the input is the top hose there is a chance the core might not fill properly if there is not enough resistance on the output side to ensure the core stays full. Making the water push up through the core gives it a better chance to keep the core full. You might also check to see if the bypass circuit is stuck open and as mentioned, check for any debris buildup in the core itself.

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I'm still going with the T-stat. He said that he blew through the heater hoses with no obstruction. I'm assuming there was water coming out of the engine when you pulled the hoses off. With 56 degree water and running at 3000 rpm there should be lots of heat, at least I have had heat in all of my boats with or without the Y-tube for the past 20 years.

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I'm still going with the T-stat. He said that he blew through the heater hoses with no obstruction. I'm assuming there was water coming out of the engine when you pulled the hoses off. With 56 degree water and running at 3000 rpm there should be lots of heat, at least I have had heat in all of my boats with or without the Y-tube for the past 20 years.

That assumption is what I was thinking should be verified by checking the temp of the heater hoses. $10 says their stone cold. So the obstruction would be in the engine, causing heated water to never make it into the core.

If the t-stat was the problem then the engine would either heat way up (jammed shut), or never get heated up at all (jammed open). And since it's making it to 165, it seems to me like the t-stat would be fine.

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I'm still going with the T-stat. He said that he blew through the heater hoses with no obstruction. I'm assuming there was water coming out of the engine when you pulled the hoses off. With 56 degree water and running at 3000 rpm there should be lots of heat, at least I have had heat in all of my boats with or without the Y-tube for the past 20 years.

if it was with the t-stat would the motor no be running cooler....he is showing 160?

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OK, I made four changes and then took it out and skied today.

1. The impeller was flat on one side with bent vanes so I replaced the impeller to push more water through the core.

2. The LX open bow has an open rectangular area towards the floor so I plugged it so that cool air can't enter.

3.Removed the driver's vent hose at the coil end and found that the vent flange had been distorted with a too tight wire tie.

Fixed the flange.

4. The driver's vent hose was extra long so I shortened it about a foot.

Turned on the heater today and:

1. The defroster vent is nice and hot.

2. The hot tube is nice and hot.

3 The driver's vent is not as hot as the other vents. Also, it has the longest vent hose of the three vents.

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Sweet. I'm taking notes as I'm installing a 3 outlet heater this spring. Thumbup.gif

I installed a four outlet heater 3 or 4 years ago on my previous boat. Used one outlet for the driver and three pull-outs. Some photos:

http://rides.webshots.com/album/573990703cWwJKO?vhost=rides

Eyepeeler, taking the floor out was easy on that boat, so I used pipe insulation for both water hoses. I didn't insulate the vent hoses though.

I don't remember if there is one fan or three on the heater. If there are multiple fans, are they all working? You could also try reducing flow through the other vent hoses. That's all I can think off right now :dontknow:

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  • 4 years later...

That assumption is what I was thinking should be verified by checking the temp of the heater hoses. $10 says their stone cold. So the obstruction would be in the engine, causing heated water to never make it into the core.

If the t-stat was the problem then the engine would either heat way up (jammed shut), or never get heated up at all (jammed open). And since it's making it to 165, it seems to me like the t-stat would be fine.

I'm having the same problem. Water temp 70 degrees , Temp gage 165, & heater hose stone cold. How does debris get past the honey comb filter? How do I clean the engine of the debris? What is the best way to clean the heater core?

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Heatercraft used to recommend a 160 degree thermostat in all their heater installs. Seems normal to me.

As for why the heater isn't putting out much heat, I'd check the temp of the hoses going to the heater core & see if their hot.

I think I figured it out. I checked the honeycomb filter going to my transmission cooler and it was full of weeds. When i head to the river in a couple of weeks I will be able to confirm if I solved the problem or not.

This is what it should look like..

That's incorrect.

If the T-stat were not opening fully, you'd have a hot running motor.

It's still a good idea to replace it if it's original. There could be a chance that's it's physically broken open.

But, it sounds like your motor is running at roughly the correct temp.

You should feel the heat of the hoses going to and from the heater core. One should be pretty hot (if the motor is truly at 160*), the other hose should feel a little cooler.

My heater hose was cold.

Edited by LUV2SKI
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Did any one ever figure out the issue for this? Could it be possible the shop switched the hoses? Neither of my hoses leading into the heater are actually hot. I believe I cleaned out the honey comb without a resolution there either. I have good hot water coming from my bottom Y house on starboard side of motor and from the top where I believe it starts.

Edited by TC_2006_VLX
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