what path does water flow through block?
 

I cannot find a source to explain the exact path water takes as it flows through the block (of an LTR specifically, which i believe is regular cooling). If you can help explain this, I'd really appreciate it..

Seawater intake>Seawater pump>thermostat housing>routes fresh water to both exhaust risers (where it will exit with the exhaust) and also delivers fresh water to circulation pump>???.

What i don't understand if the circulation pump is pumping water into the block that is coming from the thermostat housing, where does this water 'exit' the block?? Does it come up through a hole underneath that thermostat housing and circulate back to the pump over and over? It makes sense that in the 'thermostat housing' would lie the thermostat, which would determine how much circulated water to mix with fresh water to maintain the desired engine temp.. But since I don't see this 'recirculated' water source entering the thermostat housing, I'm assuming the water is coming up from underneath the housing itself, and that indeed the direction of water flow is from up out of the block, through the housing, back to the recirc pump at the front of the engine, and into the engine again..

I did locate a drawing of the LT1 cooling system, which i believe is reverse cooling, and it seemed completely different than the LTR...

Also, I'm amazed the system can 'dump water' into the exhaust exiting the boat. Seems the exhaust would be under more pressure than the water pressure of the cooling system, and at the point that the two 'met', exhaust would try to flow backward through the cooling hoses rather than water flow into the exhaust stream.. But I'm obviously wrong on this because this isn't what happens.. I guess if you're far enough downstream on the exhaust the average pressure is less than the pressure of the cooling system, and this pressure must be low, since it is an 'open' or non-pressurized system...

Anyway, any help with the cooling system explanation would be very appreciated..

dave

Not sure to what extent this applies to the LTR, but it's a general raw water cooling diagram.

http://mccollister.info/cooling diagram.jpg

Thanks for the diagram bigmac, but I still have some unanswered questions.. That diagram doesn't show the circulation pump or the circulation 'path' if you will.. I assume that the circ pump takes water sent to it from the thermostat housing, pushes it into the block and from there it goes up and through the heads and somehow makes its way back to the thermostat housing, and the thermostat housing if the engine is cold will somehow direct ALL off this just circulated water back to the pump again for another time through. If the engine is hot, some of this water will then flow out the exhaust through the risers, and some of it will be mixed with water from the raw water pump and this 'mixture' will again be drawn through the circulation pump. But the circulation pump will continue to circulate water even with a closed thermostat, and I cannot find literature that diagrams the path of the water...

seems like information that should be easy to attain, but I cannot find it for some reason..
dave

bigmac,
i found this diagram.. indeed, water does flow up through the thermostat housing from the block.. What I didn't realize is that it also flows into the top of the circulation pump through a rubber hose connected to the valley.. I guess when the thermostat is closed, all of the water being circulated through the block and heads gets back to the pump through this hose.. It's hard to see on my v drive, can others confirm this is what the LTR looks like??

Basically, the thermostat opens to let water OUT of the engine where it is routed through the thermostat housing and into the exaust risers and out the exhaust. As this hot water leaves the engine, there is then room for sea water to be drawn into the circulation system through the hose that connects the circ pump to the thermostat housing, and this sea water of course comes from the seawater pump.

dave.

now that I think of it, that hose that connects the valley to the recirculation pump is probably the 'heater hose' i hear people talk about.. Automotive applications would use this as the heat source for the heater core I believe.. I haven't seen this hose on my boat, but i didn't look specifically for it last time I saw the engine, and it is hard to see the front of the engine being a V-drive..

The heater inlet hose is usually plumbed to the intake manifold, and the heater outlet hose returns to the circulating pump. There are usually two plumbed fittings on the intake manifold, one of which has the water temp sensor, and the other one is plugged unless you have a heater. If you have a heater, there's often a valve there to close down heater circulation (doesn't work very well, IMHO). Likewise the heater return port on the circulating pump is only plumbed if there's a heater. Some people (and some mfgrs) plumb the heater intake line directly to the raw water intake using a Y fitting, the point of which (AFAIK) is to allow more heat to be extracted by the heater core. In that case the heater return line is connected to the barb on the Y fitting, and the usual return port on the circulating pump is plugged.

http://mccollister.info/yadapter.jpg

so you're saying that because I don't have a heater, i may not have this 'line' running back to my recirc pump.. So I guess, if my thermostat is closed, the thermostat can route the water that just circulated through the engine back to the hose that leads to the recirc pump, and as the thermostat opens fully, it can somehow block the just circulated water from returning back to the pump (forcing it to exit out the exhaust) and allow only raw water to be drawn into the pump... I'd like to see the plumbing on the inside of the thermostat housing to see how this takes place.

dave