gas pre heater on a 165?

[stonyloam]

Re: gas pre heater on a 165?

First off the input can not be coming from the head, because it is filled with antifreeze and you would quickly drain your cooling system, so it MUST be raw water from the heat exchanger. I think the guys that guessed cooling are correct (cure for vapor lock?). I bet if you trace that input line back it connects into the heat exchanger water input line, somewhere around the voltage regulator. I agree it looks like someone did a pretty clever job. Good luck.

 

[Don S]

Re: gas pre heater on a 165?

We don't have any information as to where the water is coming in at Terry. With his last pictures we could see where the water is going out at because we know what the riser is. From his original post, I have no clue where the water is coming in at. Until we see a picture of those connections. I's all just a bunch of guesses. But for sure we know it's not a huge fuel line.

 

[stonyloam]

Re: gas pre heater on a 165?

We don't have any information as to where the water is coming in at

Yeah it is purely speculation, but if it is for cooling the fuel the only place to get cold water is from the heat exchanger inlet hoses. The thing that I would worry about is any water taken from that line would reduce the raw water flow through the exchanger which could reduce its efficiency, not what you want to do on a 470. Would like to know for sure where the water is coming from though.

 

[Pete104]

Re: gas pre heater on a 165?

There is NO Water running thru it at all! It's merely insulation.

Used to run into this alot in the midwest. Merc did address it on engines around 90 & up! The heavy insulation hose they use TBI & MPI engines? Has been around about 20 years!

Disconnect that little hose at the riser & see how much water goes which way.

P/N 32-861304A01 was somebodies theory, and just turned it up a notch! I couldn't find the P/N for just the material but it came in 4 or 5 foot lengths.

 

[5 o'clock Houseboat]

Re: gas pre heater on a 165?

I know I must have started this sounding like an idiot but I didn't have any idea what I was dealing with. This all started when I had to change out the starter and had to take off the cooling hoses to get at it. You have all been so helpful it s amazing. Now that I've read these latest replies I realize it must be a cooling line as it comes from(I thought it went to) the nub that delivers cooling water from the outdrive (you can see the nub sticking out of the outdrive in the one photo taken from right over the engine) to the heat exchanger, just forward of the starter, and it seems to go to the antifreeze reservoir over the starter (see previous pic). If it is for cooling I don't mind or fear it as the boat gets 15 - 20 hours annually in fresh water and is kept on a trailer. I'll go out later and check but it seems that the water going from the top of the gas COOLER (thanks for explaining that) goes into the reservoir and not into the heat exchanger. This is my first and only fresh water cooled inboard - is there raw water circulating in the reservoir area or is it all contained in the heat exchange cylinder that sits in front of the heater?
Thanks again for this info - this forum is priceless to a backyard mechanic with an unfamiliar engine type.

 

[5 o'clock Houseboat]

Re: gas pre heater on a 165?

I am so thankful that you all can explain this to me. I have never dealt with fresh water cooling but was planning on putting it on twin Crusader 350 inboards next year as we will try to go to Canada by the Champlain canal and that will involve salt water for a few days. The fresh water cooling will also give me hot domestic water without the generator running. Here are two more shots - one shows the hose from the outdrive that the cooling line joined by way of a copper nipple setup. The other one is a close up of the nipple. This is the nipple that broke and prompted me to ask for help. I have resoldered it but that was my first soldering on copper in thirty years so I am a little worried about the strength. It looks like it may be a T for an ice maker line for a home fridge with ice maker and I'll check a local plumbing supply house to see if I can get one made like this without the solder. As a cooling line is there any reason not to hhave it on there? I knew the former owner and he is well known as a good redneck mechanic who can keep things going but not always sanely. He has a 29' formula with a blower that he has to put a bag of ice on the blower when he anchors to keep the gas cool so it will start again. Not my way of doing things but this setup onn the 165 has been fine for five years. I haven't touched the engine and let the local Merc dealer change impellers, winterize, and even change a starter two years ago because I was rebuilding our 40' houseboat. Job cutbacks are making me service her boat also and it is new territory so thanks again for your input. Anything you can tell me would be helpful.

 

[stonyloam]

Re: gas pre heater on a 165?

OK it is what we thought, a cooling line. It looks like the po installed the "T" in the cooling water inlet hose just before the water cooled voltage regulator (if it is still there). The water flows from the "T" to the bottom of the "cooling jacket hose" and out the top to the exhaust elbow. It does not go into the antifreeze reservoir, it exits through a plug in the elbow that dumps the water directly into the exhaust. FYI on your 470 the cooling water flows from the outdrive through a hose to the water cooled voltage regulator then to the front of the exchanger. The water flows back and forth through tubes in the exchanger and out of the hose in the back, and up through the power steering cooler (if you have one) and through a hose to a nipple in the exhaust elbow, where it is dumped into the exhaust where it cools the exhaust and protects the rubber parts (shutters & engine bellows) on its way out. Good luck.