View Full Version : best way to plumb heater on LY6?

10-14-2011, 05:31 PM
Hey guys,
OK...I've read as much as I need to be confused. I have an '07 Prostar 197 with the LY6 motor. Like so many others, I do have occassional overheat issues at idle, so I'd love to get the short story on the solution to that as well...but more immediate is my question on the best way to plumb the heater? I know the stock setup, but it seems many complain the design of this motor with the heater in line where originally installed produces little heat. I don't really care to do things twice and was hoping for some good input before I undertake so that I can take advantage of other's experience. Anyone have this motor that can chime in? I did buy the Y fitting that supposedly improves the temperature of the heater at idle...but now I need to put a plan in play for the entire install. Any help is appreciated.


10-15-2011, 02:29 PM
Ca'mon guys! 55 reads and no help? Anyone?

10-15-2011, 03:25 PM
Ca'mon guys! 55 reads and no help? Anyone?

Who is your dealer???

10-15-2011, 04:24 PM
Ca'mon guys! 55 reads and no help? Anyone?

It's the weekend, everyone is probably at the lake and those 55 that viewed it don't know how to do it.

10-15-2011, 04:52 PM
Valid point....but its windy here today, no reason to be on the water and I'm anxious for an answer:) Anyway....who goes to dealers Jim for stuff you can do yourself? No offense, but if I took my boat to the dealer for everything it ever needed, well....then I couldn't afford to own it. I'm not in the honored group of boat owners who just look to their warranty:(

Wouldn't be warranty work anyway....my boat didn't have it stock. I know I can easily talk to them about how it might have been done at the factory, but we all know that this board is a better place to get the "best" advice. Seems the truth not only comes out here more often, but you get a lot better advice from those that have lived and learned. I don't always want to do things the way the factory intended. Hell....if that were the case, I'd be pumping on hundred's or thousands of pounds of ballast in order to try and create a decent wakeboard wake. Instead, I installed a floating wedge and have to give it to the Bu guys with that option. (I can hear the steam building already;)) I'm just not sure if I now have to change the decals to read "MasterBu"??

Anyway....trying to make my boat the best all around at everything possible....including a comfortable ride when I pull it out next Spring shortly after the ice breaks. If anyone has an LY6 or any knowledge of what might be the best hookup points, I'd greatly appreciate it. Thanks in advance.

10-16-2011, 01:53 AM
I have an LY6 with the factory heater set-up and haven't had any complaints about lack of heat. I'm not saying that's the best way to plumb it, just that I have been happy with it's performance. As for the overheating at idle issue, I've been there. I would be interested in hearing a real fix for that also. My fix is we don't idle a warm engine. As long as you start moving within a few minutes and keep it above 4 or 5mph it will stay at operating temp.

10-16-2011, 08:32 AM
My dealer explained to me that the LY6 doesn't work as well with a heater as the other engines because the thermostat is opposite of the others. Not entirely sure what he meant, maybe Jim can explain.

Holman J.B.F
10-17-2011, 05:32 PM
here is what i did,i know it works but use it at your own risk.

Keep the U hose (original heater tap point) as it is,..DO NOT REMOVE OR BLOCK THIS FLOW!
see pic where to install a T with a 16mm out and the heatercraft Y-pipe

iirc,..the ly6 has a reversed flow,..by cutting the circulating pump hose that goes to the thermosstat housing,you will tap waste water from the engine and re-use it to heat your heater(or in my case the lpg convertors & heater)water is pushed thru heater and ""sucked"" back in thru the Y-Pipe.P.s you can install y-pipe right after the oil cooler(s)
It works for me,the LPG convertors stay hot enough when in idle,...and so is the heater.

Holman J.B.F
10-17-2011, 05:38 PM
pics ,...i will take some pics of the install when i,m at the boat,it is already winterized and stored

10-17-2011, 06:29 PM
Awesome, this is exactly what kind of feedback I was looking for! PM in your inbox. Thanks!

10-17-2011, 06:33 PM
Ps....what year is your LY6? Mine is an '07 and although I'm sure the water flow is the same, one of my hoses (The one in your top photo that runs from the impeller housing up and to the left by the thermostat housing). I'm just wondering if they found it made a difference because the hose on mine is probably twice as long and runs down to the right, then under the front of the motor to the left, and back up to the same connection point. Just curious as to why the change.

10-17-2011, 07:33 PM
I have had the LY6 in my 2007 PS197 and the LY6 in my 2008 PS197. I had constant overheat issues in my 2007 until I made a plumbing change on my engine. To explain the problem I need to first explain the way the raw water pump was plumbed from the factory. If you look at the picture above that is the way mine was plumbed from the factory. The raw water hose that connects to the inlet in the hull ran to the transmission cooler first then to the raw water pump then to the thermostat housing. The problem that I had was that if I had any kind of minor blockage in the tranny cooler the engine would overheat. The lake I skied on was pretty weedy and any kind of weeds that I would suck in would clog the tranny cooler and limit the amount of water getting to the engine. I can't tell you how many times out on the lake I had to pull the hose off the tranny cooler and try to get the little bit of weeds out of there to keep it from over heating.

I fixed the problem by changing the routing of the raw water system to be like it was on my 2003 MCX. I talked to Engine Nut (Indmar Employee) on here to verify that I wasn't going to be creating any other problems. Now the hose from the hull inlet goes straight to the raw water pump. Then on the outlet of the raw water pump it goes to the back of the tranny cooler. Next the hose coming out the front of the tranny cooler goes to the thermostat housing. My idea was that the raw water pump purees the weeds to allow them to pass through the tranny cooler and engine without causing any blockages. Once I made this change all of my overheating issues were gone.

I live in Northern, WI and when the water temp gets down below 60F I tend to start having problems generating enough heat to have an effective heater. It still works, but it definitively drops in performance. I have not tried to fix this issue as I have become much more of a fair weather skier in the past couple of years so it hasn't been that big of an issue.

Due to the way the thermostat and cooling system is in the LY6 the boat engine runs very cool when the water temp is cold. This past weekend I winterize the boat and I had it running in our lake on my rail system for at least 30 minutes and the engine temp never got over about 90 degrees. The lake water temp was in the low 50s. Until a solution can be found to get the engine operating temperature up to where it "should" be the stock heater will not produce much heat.


Holman J.B.F
10-20-2011, 01:11 PM
@ imawreck
took a few pics of the install.
It is easy,...fill the heater core and hoses with water manually,by using a gardenhose or a vacuum oil-change pump,this will reduce the chance of overheating at first use.(closed stat)

10-20-2011, 05:22 PM
Awesome, looks like a rather easy fix. How much of a difference did you notice? Looks like you manufactured your own splitter/barb on the intake line to the heater? I was thinking I'd just pick up a second Y fitting, but I see in the one supplied for the return hose, that the actual "opening" inside the larger diamter tube is only about 3/16". Is this right? I can't believe that little hole is sufficient to encourage decent flow either in or out of the heater?? Would using another one of these on the inlet side be effective, or do I need to retrofit one or have it custom made to get sufficient flow?

Holman J.B.F
10-21-2011, 12:52 PM
The heatercraft Y-Pipe with a 3/16 (4,5mm) hole goes in front of the raw waterpump as a return.
you need a second Y - pipe with a 16MM hole as a send.I made my own.

i can not remember how much of a difference i noticed,..it has been a while(2007).
My main reason was to keep the LPG convertors hot,they were freezing up when idling for 15 minutes across the lake when hooked up at the original tap points.(U shape hose)
With my modification they don,t and the heater gives good heat.
I,ve done this mod ever since on my 08 & 10 x-star including some friends boats with LY6,...and they all work perfect.

Just give it a try,it does not cost anything,you have to cut that hose and if it doesn,t work for you, just use a 32mm piece of stainless pipe and 2 (better 4) hose clamps and you are fine,...or buy a new hose.

make sure you fill the heater hose and heater with water

08-12-2015, 10:21 AM
I have the same issue with a 2007 prostar LY6, boat ran fine to start the season, but had it overheat a couple weeks in after sitting in some shallow water, our lake has gotten progressively more weedy as the summer goes on and so has my overheating issue. I have to stop and hammer the boat in reverse then the temp will immediately drop from 200 to 160 in about 8 seconds. Makes me think something in the transmission is getting plugged. I have the heater and shower installed on this boat as well. I am going to try installing a Sea Strainer, but it will obviously have to go in before the transmission. Not even sure if this is possible. The previous owner of this boat spent 1500 at the dealership and got no where. If anyone has any other ideas let me know. I am ready to trade this thing off.

08-12-2015, 10:35 AM
I have the LY6 and a number of my friends have the smaller motor all with the same issue. I think it is primarily an issue with back pressure that builds in the exhaust at idle. I typically throw it in neutral and rev the motor to flush the exhaust and am golden. If you know you're going to be at idle for a while, I do it before the heat climbs and never have the issue.