Raw Water (Engine Cooling) Plumbing question...

[Lwapo]

Hi Everyone,

Does the water that gets sucked in from the lake need to pass through the manifolds prior to being pumped through the motor?

I know that some do, but it looks like my setup does not. I'm just wondering if something is plumbed incorrectly, or if that is normal in some motors.

My motor is a 1975 Ford 351W.

Thanks in advance!

 

[onsiteservice]

Re: Raw Water (Engine Cooling) Plumbing question...

I've worked on a lot of boats but have never seen an "open" system that pumped thru the manifolds first. Assuming on your style the outdrive is where your raw water impeller is located. If thats the case then it should pump up to the water pump on the engine first then out of the exhaust, usually from the thermostat housing. I may be wrong (happened once in my life lol) but I personally have never seen one like that.

 

[Lwapo]

Re: Raw Water (Engine Cooling) Plumbing question...

I guess let me explain how it is routed and you can tell me if this sounds correct or not. The guy that had the boat before me... well, I don't trust his ability to do things the correct way.

The water comes into the boat from the outdrive.
From there it goes through the oil cooler.
From the oil cooler, it goes into a Neo Vane 505 Pump.
The Neo Vane Pump has 2 outlets. Each goes to a hole on the front of the timing cover.
From there the water comes out of the top of the motor where the thermostat is.
From the thermostat, the water goes into the exhaust manifolds, and out the exhaust of the boat on the outdrive.

Does this sound correct?

From what I read online, the water should come into the boat, then into the exhaust manifolds, and then through my setup, then back into the exhaust and out of the boat. I seem to be missing that first step, but I also don't see extra fittings where I could make that happen.

Thanks in advance!

 

[Maclin]

Re: Raw Water (Engine Cooling) Plumbing question...

You have a Volvo Penta drive with the Ford engine, right? Badged as Commander I think.

The routing is correct on your boat now as you described it. I am not sure what you found online but going thru the exhaust first is not correct for that raw water cooled engine. If you have a link post it here so we can review what context the article has around it.

You should be able to post any questions about your "stuff' in the Volvo forum, I am sure it can be "grandfathered" in so to speak! You may get more specific endorsements there.

 

[Maclin]

Re: Raw Water (Engine Cooling) Plumbing question...

Can u post pics of your setup, I thought about it some more and think the thermostat housing should be a little different that you are describing.

 

[Lwapo]

Re: Raw Water (Engine Cooling) Plumbing question...

Hi Maclin,

Yes, that is my motor setup. Thank you so much for helping me. I know it's a small/simple question, but I have fears of my motor overheating because something was setup incorrectly.

Here is a diagram of my motor. I don't have a picture handy so I put my legendary Microsoft Paint skills to work.

1) Water enters the engine from the lake through the outdrive.
2) Water passes through the oil cooler
3) Water enters the Neo Vane 505 water pump. (Side question below)
4) Water enters the motor on the front near/in the timing cover.
5) Water exits the engine @ the thermostat in the top of the motor.
6) The water enters the exhaust manifolds/risers.
7) The water exits the motor with the exhaust out the back of the boat and through the outdrive.

SIDE QUESTION: I have a Volvo Penta 250 Aquamatic outdrive. Is there an impeller in there or does the entire system just run off of the neo vane pump on the front of the motor? (I intend to check, but I figured I'd ask here while I had your attention in case you knew off the top of your head).

Thank you again for the help, it really helps a lot and is EXTREMELY APPRECIATED!!!

 

[Maclin]

Re: Raw Water (Engine Cooling) Plumbing question...

No impeller in the drive on the Volvos, the raw water vane pump is it.

The thermostat housing is the key here, the raw water not used for cooling needs a way out. The rubber exhaust components also need water in the exhaust mix all the time so they do not melt.

Right now I do not understand the exact nature of your system and plumbing, but I will try to describe the way most inboard engines I have seen work.

On most modern era marine inboard 4 cycle engines the marine specific thermostat housing is a large unit and more like a manifold with ins and outs, and is where the raw water supply is made available to the engine's cooling system. When the thermostat is closed water does not circulate thru the engine and just bypasses directly to the manifolds. As the thermostat opens up this raw water supply is drawn into and circulated thru the engine by the engine's water circulating pump. The thermostat is at the "end" of the cooling cycle and acts more like a lid. When is it closed the engine circulating pump cannot move water thru the engine.

The water from the drive intake is drawn up to the raw water vane pump, the outlet of this vane pump sends the water to the thermostat housing. The thermosat housing is the ultimate water supply director of this system. It has outlets going to each exhaust manifold. It has a large outlet that goes to the engine's circulating pump. When the thermostat opens water flows (propelled by the engine's water circulating pump) up thru the engine and past the thermostat and then into the exhaust. When the thermostat is closed the water just goes directly into the exhaust.

I do not have a picture to show, but at 00:31 into this video pause it and you will see all the components I refer to.
The vane pump is crank driven and is on the crank pulley. The bottom hose comes from the drive, an oil cooler would be between the pump and the drive if so installed. The top hose goes to the thermostat housing, you can follow the rest from there. This is a GM 350 V8 engine for reference.
http://www.youtube.com/watch?v=BoWHEpDS0Ws&feature=related

I do not know exactly why your vane pump feeds into the engine, and I do not want to try to reverse-engineer anything here, but look at all your components again in light of the example given to see if it makes more sense, or seems even more of a hack...

 

[Lwapo]

Re: Raw Water (Engine Cooling) Plumbing question...

Hey again!

Ok, so after reading your post and looking at the video... what you are describing is NOTHING like my setup

SO, I need to attempt to figure out if I can get my setup to work like your example, or if it is correct the way that it is.

I have pictures...

This is a picture of the thermostat housing that was on the motor when I started. As you can see, it simply blocks off the passage beside the thermostat and has 2 pipes coming off of the thermostat.

This is a picture of a thermostat that I grabbed from Autozone. I know that it is probably not the correct one for my setup, but I wanted to see if it would work. I think I might be able to make this one function the way your example did, but I am guessing that it would take a fair amount of "engineering" to get it there.

Last but not least, here is a picture of the front of the motor itself. This is what I am looking at out in our shop.

So, suggestions? Would I be able to purchase a thermostat housing to make this setup function the way that you are talking or can I make other adjustments to get it to work correctly? I don't want to screw up a motor because the cooling system was funky.

Thanks in advance for ANY help/suggestions!~

 

[Maclin]

Re: Raw Water (Engine Cooling) Plumbing question...

It looks like you have a raw water pump that is also used as the engine circulating pump, and it's full output goes thru the engine, and actual flow is regulated by the thermostat.

I say that because I do not see a standard belt drive water pump on the engine to circulate water through the engine cooling passages. I would say that the way it was plumbed might work, but I do not see how much water would get thru to the exhaust manifolds until the thermostat opened up without some kind of bypass for when the thermostat has not opened yet. Was there a thermostat under the white housing?

I googled up "commander 351" and found a pic or two, they all have the "manifold" type thermostat housing that I described though. Yours is maybe a custom or full race setup or something, not the standard runabout marine cooling system for that engine. But again lwapo, I only know what I have been around and have seen, and while all of that was what I described I know there are other systems out there.

I also went on youtube and searched on "Ford 351 marine engine" and all of those show the large manifold type thermo housing as well. I wish I could help more with what you have but I can only be theoretical at this point.

Commander 351 pic...:

 

[Lwapo]

Re: Raw Water (Engine Cooling) Plumbing question...

Maclin,

I think that if I use the thermostat housing from autozone, I can accomplish what I need to.

This housing has a large neck that the thermostat is located in, but it also has a smaller tube that bypasses the thermostat. If I route that smaller bypass tube to the manifolds, but then take the larger neck and route it either to the manifolds, or out of the boat, it should function as follows.

Water would flow into the boat and into the pump. The pump would push water into the block and up to the thermostat housing. When the motor was cold, the bypass would allow a small amount of water to flow to the exhaust manifolds to cool them. As the engine warmed up, the thermostat would open and water would flow from the larger neck to the exhaust manifolds or out of the boat. (However I plumbed it).

Does this sound reasonable?

 

[Scott Danforth]

Re: Raw Water (Engine Cooling) Plumbing question...

the neovane is a drag boat pump. there is no thermostat in a drag boat, only a restrictor plate

contact the pump manufacturer. they will have proper method of plumbing it. do not try to guess at plumbing, you will end up with something overheated. your sketch shows the correct plumbing using the neovane pump

the thermostat housing you bought from autozone is NOT A BOAT PART. return it. you can not get it to work and maintain coolant flow to the manifolds

what is the motor in? or going in?

if you want a thermostat, you will have to go back to a marinized cooling system. raw water in, thru oil cooler, into marine thermostat housing that then mixes incoming water and discharge water into the circulating pump, thru the engine, and out the T-stat

there will always be coolant flow to the manifolds that way.

 

[Maclin]

Re: Raw Water (Engine Cooling) Plumbing question...

I have a couple more observations, but I have to preface it with a disclaimer that this is out of my wheelhouse so to speak, and certainly above my pay grade

I think the outlet tube on the housing in your pics are for heater hose plumbing maybe? Again, I am out of my area here in a couple of ways, 1.) Not familiar with the Ford cooling system routing in general and 2.) I do not recognize the pump and routing you have. I am just not sure how the engine would ever get up to or keep the correct temperature if the water can go thru the engine and bypass the thermostat. If that fitting is for heater hoses then bypassing the thermo would work in an automotive application as the heater core circuit is closed, just routes back thru the engine.

I just know that the marine cooling systems referenced have the raw cooling water "source" outside the engine's circulating system. The raw water pump circuit and the engine's circulating pump circuit have separate pumping units, and plumbing circuits are separate except for where they merge in the thermostat "manifolded" housing. The way the passages work and where the thermostat is inside that housing allow the raw cooling water drawn in from the drive to bypass the engine when it is below temperature, then as the thermo opens the engine's circulating pump is able then to draw in and circulate the raw cooling water on thru the engine with flow regulated by the thermostat. In all cases the water exits thru the exhaust manifolds.

 

[Maclin]

Re: Raw Water (Engine Cooling) Plumbing question...

Thanks Scott, we were typing at the same time. I am glad you could recognize the components lwapo has in play.

 

[Scott Danforth]

Re: Raw Water (Engine Cooling) Plumbing question...

no problem. the small tube on the automotive t-stat housing is a loop that goes back into the automotive water pump (which is no longer there). its primary use is block filling.

My guess is the OP's motor is from a jet boat. They also used the same pumps as drag boats. that is an aluminum timing cover/pump mount. or someone swapped it in the past.

 

[Lwapo]

Re: Raw Water (Engine Cooling) Plumbing question...

Hey Guys,

Thank you so much for the help so far.

The motor is from a 23' Seasport fishing boat. It will be used primarly for salmon fishing.

What I need to peice together now, is how to get this system to function correctly. Should I scap this pump, order a different one and build it from the ground up? Are there components that I can use to get this to function properly? Is there someone I should be contacting for assistance?

Any help you can give me would be great. It seems like my setup is not going to work in the way that I was hoping it would/could.

 

[Maclin]

Re: Raw Water (Engine Cooling) Plumbing question...

What you have now is designed for 1/4 mile bursts.

For reliable cooling I would swap to the marine cooling specs closer to what your boat originally would have had. I think a mid-80's Volvo Penta 5.8 FL would be a good place to start. There would be a Jabsco raw water pump driven off the crank, then a marine spec engine water pump, and the large type water directing thermostat housing. Your exhaust manifolds may not be correct as well, they do not look like the marine ones for the Volvo Penta or Commander engines with the non-race cooling.

 

[Lwapo]

Re: Raw Water (Engine Cooling) Plumbing question...

Ok, so after some research, I think I understand how a cooling system "should" work.

Water comes from the raw water pump into the thermostat housing. (Not the thermostat housing I have, but one that should have 4 hoses coming into it and a thermostat in it.

There should be a water pump, similiar to one that would go on a car, where my neo vane pump is at right now. This pump with circulate water from the thermostat housing, into the 2 holes on the front of my motor and back up to the thermostat.

When the motor is cool, the thermostat is closed and the water stays in the motor and warms up. As the water warms, the thermostat opens and cooler water is pumped into the motor.

The other 2 hoses on the thermostat housing go to the exhaust manifolds to ensure that they are getting waterflow and staying cooled at all times.



Does this sound correct?

Thanks!

 

[Scott Danforth]

Re: Raw Water (Engine Cooling) Plumbing question...

I see two choices

sell the complete motor to obtain a complete factory marinized motor

strip the front timing cover, etc. off the block, sell that, and pick up a pile of cooling parts, timing cover, etc. like Maclin pointed out.

stock timing cover, marine circulating pump, raw water pump, thermostat housing, hoses, etc.

 

[Lwapo]

Re: Raw Water (Engine Cooling) Plumbing question...

The timing cover that is on there also serves as the front engine mounts. How would I go about mounting an engine without this timing cover?

 

[Scott Danforth]

Re: Raw Water (Engine Cooling) Plumbing question...

you would mount off the sides like a standard factory volvo marinized motor. the motor mounts you have are part of the whole Go Fast speed parts setup for a light-weight drag boat or a jet boat