Loss of pump primer

[SquamInboards]

After installing my heater the engine began overheating and was wondering if there is anyway that I could have created air pockets in the cooling system preventing the pump from priming. I'm confident the heater is installed correctly so first I'll check the impeller but beyond that, any thoughts?

[ffmedic74]

RE: Loss of pump primer

Are you sure your raw water strainer is not a little loose or did you accidently loose the black gasket in the lake?

[SquamInboards]

RE: Loss of pump primer

Yeah, all the work was done in my shop and I didn't mess with any gaskets as far as I can remember.

[bobchris]

RE: Loss of pump primer

sure sounds like you didn't plumb something right, I would go back and double check the routing of the lines and makes sure you don't have a directinal problem.

[TRBenj]

RE: Loss of pump primer

Theres really not much involved when installing a heater. How long did it take for the boat to overheat after the install? Im betting on a loose hose clamp.

[SquamInboards]

RE: Loss of pump primer

overheated probably after 5 minutes of idleing. Everything seems to be installed right, I've been looking over my PCM manual, but I'm wondering if there is an issue with my "T" off of the block for the hot water output. Check it out --->





It's a bad picture of the "T" because it was raining out at the time and I didnt want to take off the cover to put the hatch all of the way up but hopefully you can get the idea.

[TRBenj]

RE: Loss of pump primer

Im confused what the purpose of the brass T fitting is in the 3rd pic. Your Y on the RWP looks fine. It sounds like you are sucking some air somewhere.

[wake_fun]

RE: Loss of pump primer

Check out a few of my pics on my heater install. They're in my gallery. No problems at all and blows hot!
http://www.planetnautique.com/index....amp;user_id=18

[SquamInboards]

RE: Loss of pump primer

The "T" was used to keep a sensor from the block functioning

[TRBenj]

RE: Loss of pump primer

Id go back through all the hose connections and make sure theyre on tight. Youre sucking air from somewhere and its causing you to overheat.

[MacedayDave]

In your second photo, is your heater hose tee installed on the intake side of the raw water pump? If so, that is probably the problem, since this would cause the raw water pump to pull a vacuum on your heater hoses (and thus pull a vacuum on the cooling water in the engine).

[SquamInboards]

It is but I believe that is how it is meant to be. It should create suction pulling hot water going through the heater to be pulled back out and then sent through the pump. If the "Y" were to be placed after the pump there would be significantly less suction to keep the water flowing through the heater. Maybe I'm wrong so let me know.

[MacedayDave]

You should be utilizing the engine's water pump to circulate the water through the heater. My boat is in storage right now, so I can't get to it for viewing, but it has a factory installed heater. I believe one heater hose is connected to the engine's water pump and the other hose is connected to a water fitting on the intake manifold. You should be able to obtain installation instructions from your heater manufacturer.

[DanielC]

The cooling system on a Ford engine uses cool lake water to displace hot water in the block when the engine gets hot. The way your system is plumbed, the raw water pump sucks hot water through your heater, and back into the engine, and the returned hot water is not able to cool your engine. The hot water going past your raw water pump impeller will also make it very soft, and reduce its pumping ability. The thermostat also opens when the engine gets hot, and the engine wants more cold water to cool. By hooking the heater into the suction side of your raw water pump, you have reduced the amount of water it can pump, you have diluted the cold water with hot, and you have added a whole lot of connections that can possibily leak air when the engine is running, and leak water into your boat when the engine is not. I have seen the heater return hose going to two places on a GT-40. The brass plug that is above the spark plug wires, in the block, in one picture, or the plug that is in the bottom of the elbow on the circulating pump. Get a new piece of hose for the inlet side of your raw water pump. Do not splice it together, it is too important.

[TRBenj]

It looks like you have it plumbed just fine. My heater was installed nearly identical to yours- with the Y fitting in the on the intake side of the RWP and the other line going to the intake manifold. I recently switched intake manifolds and decided to plumb the line to the block instead- but it really shouldnt matter. I have seen many boats with the heater installed this way and have never experienced or heard of a problem. My boat runs a constant 160 with the heater on or off, and I get several years out of an impeller. With the reduced diameter Y fitting, I get good heat even at an idle. This is because the heater is most effective with the return line plumbed just in front of the RWP.

If you are overheating its most likely because you are sucking air somewhere. Go back through and check all the hose connections and make sure theyre tight. Also check the strainer bowl for good measure.