* Chris Craft 427 open and closed COOLING SYSTEM diagrams

* Chris Craft 427 open and closed COOLING SYSTEM diagrams

Joined: July 15th, 2005, 8:09 pm

August 3rd, 2005, 8:46 pm #1



Last edited by FEfinaticP on May 16th, 2012, 10:16 pm, edited 1 time in total.
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P
P

September 1st, 2005, 6:57 pm #2


STANDARD (RAW WATER) COOLING SYSTEM


look at the two diagrams and you'll see the standard raw water cooling system tempers the water "before" it sends it to the engine. That's good because running the water through the hot exhaust manifolds serves a purpose: it avoids putting cold water directly into the motor. The hot exhaust manifolds quickly raise the water temp up to the point where it can be run through the motor without causing stress. From here, however, that water is wasted while it's hot, and more cool water comes in to replenish the system. These systems can be run hours on end without overheating, with a little help from the thermostats.



Now look at the closed cooling system (below)



Once under way, the closed cooling system is "closed" so it obviously runs on hot water, and has an inexhaustible supply of hot water. Interesting thing though, why in the heck are they RECIRCULATING all that hot water from the exhaust manifolds. Why isn't that water just dumped like the raw water system does? Sheesh, NO WONDER THE SYSTEM OVERHEATS????

It would appear an easy and simple plumbing change (for the fresh water guys only) would FIX the overheating issue very fast. Now having antifreeze in those exhaust manifolds is a good thing in the winter time, but if you winterize your boat, or for that matter in Tennessee like I do and keep your boat operational all year long, a change in plumbing would appear to fix any overheating problems people have encountered. If you have closed cooling now and you're in salt water, I couldn't recommend you run salt through those expensive and still good cast iron exhaust manifolds. However, if you're in fresh water and have overheating problems, it would appear the removal of the exhaust manifold side of the recirc system would sure bleed off a LOT of heat for you.

Now all of this is in theory, don't anyone start chopping up their system based on this thread. It would appear that you could allow the cold water to come in, directly through the reverse gear cooler and into the heat exchanger just like it does now. That circuit represents the total cooling ability of the system and it also cooling those hot exhaust manifolds too. Now note how water gets to those exhaust manifolds; its the hot water coming from the motor, but when the hot motor water goes through the exhaust manifolds, it just gets that much hotter, and it puts a big load on the heat exchanger to bring it back down again.

Now look at the "Pressure Relief Valve", which sends water to the riser, and then overboard. Why not take water directly from the pressure relief valve and run it into the front side of the exhaust manifold, and then run the hot water out of the exhaust manifold into the riser, and then waste it (rather than sending all that hot exhaust manifold water back to the already hot motor)?

By doing so, it would appear to practically double the cooling ability of the motor with the cost of a little hose. If it affects the function of the pressure relief valve, that could be replaced with a standard valve that is opened up to the extent that would allow the exhaust manifolds, risers, and hoses to get enough water to stay cool. Right now, however, I don't see an issue with those pressure relief valves, unless they're set too tight to allow for adequate flow.

Yeah I know, an inquisitive mind is a terrible thing to waste!

Comments?

regards, Paul

1966 38 Commander Express
Original 427 power (fresh water cooling)
427 spares (closed cooling system)
Last edited by FEfinaticP on May 16th, 2012, 10:07 pm, edited 1 time in total.
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Rob Williams
Rob Williams

September 1st, 2005, 9:33 pm #3

I'm looking at your notes, and I'm going to look at the boat later this week. Right now I don't see any reason why this wouldn't work. As a matter of fact, I may consider doing this with some big ball valves so I can switch back and forth (that seems possible at the momemt, maybe I will wake up from the dream later.

I've had bad results with the heat exchangers, and virtually everyone I talk to who has them on the big block Chris of this era has the same comments "they're good for a boat anchor" or something like that.

I'll give you my comments after I've had a chance to look at the system in person.

cheers,
Rob
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EH
EH

September 18th, 2005, 2:10 pm #4


STANDARD (RAW WATER) COOLING SYSTEM


look at the two diagrams and you'll see the standard raw water cooling system tempers the water "before" it sends it to the engine. That's good because running the water through the hot exhaust manifolds serves a purpose: it avoids putting cold water directly into the motor. The hot exhaust manifolds quickly raise the water temp up to the point where it can be run through the motor without causing stress. From here, however, that water is wasted while it's hot, and more cool water comes in to replenish the system. These systems can be run hours on end without overheating, with a little help from the thermostats.



Now look at the closed cooling system (below)



Once under way, the closed cooling system is "closed" so it obviously runs on hot water, and has an inexhaustible supply of hot water. Interesting thing though, why in the heck are they RECIRCULATING all that hot water from the exhaust manifolds. Why isn't that water just dumped like the raw water system does? Sheesh, NO WONDER THE SYSTEM OVERHEATS????

It would appear an easy and simple plumbing change (for the fresh water guys only) would FIX the overheating issue very fast. Now having antifreeze in those exhaust manifolds is a good thing in the winter time, but if you winterize your boat, or for that matter in Tennessee like I do and keep your boat operational all year long, a change in plumbing would appear to fix any overheating problems people have encountered. If you have closed cooling now and you're in salt water, I couldn't recommend you run salt through those expensive and still good cast iron exhaust manifolds. However, if you're in fresh water and have overheating problems, it would appear the removal of the exhaust manifold side of the recirc system would sure bleed off a LOT of heat for you.

Now all of this is in theory, don't anyone start chopping up their system based on this thread. It would appear that you could allow the cold water to come in, directly through the reverse gear cooler and into the heat exchanger just like it does now. That circuit represents the total cooling ability of the system and it also cooling those hot exhaust manifolds too. Now note how water gets to those exhaust manifolds; its the hot water coming from the motor, but when the hot motor water goes through the exhaust manifolds, it just gets that much hotter, and it puts a big load on the heat exchanger to bring it back down again.

Now look at the "Pressure Relief Valve", which sends water to the riser, and then overboard. Why not take water directly from the pressure relief valve and run it into the front side of the exhaust manifold, and then run the hot water out of the exhaust manifold into the riser, and then waste it (rather than sending all that hot exhaust manifold water back to the already hot motor)?

By doing so, it would appear to practically double the cooling ability of the motor with the cost of a little hose. If it affects the function of the pressure relief valve, that could be replaced with a standard valve that is opened up to the extent that would allow the exhaust manifolds, risers, and hoses to get enough water to stay cool. Right now, however, I don't see an issue with those pressure relief valves, unless they're set too tight to allow for adequate flow.

Yeah I know, an inquisitive mind is a terrible thing to waste!

Comments?

regards, Paul

1966 38 Commander Express
Original 427 power (fresh water cooling)
427 spares (closed cooling system)
There are several factors, the surface area of exposure, the speed at which the medium is exposed (water flow in this case) and the fluid being used (antifreeze on one side, water on the other, sometimes salt water), and the temperature of the incoming water.

When the incoming water temp goes up, that heat exchanger better be a big one. Looking at the CC system, it's pretty obvious the exchange system is limited in size for a large engine that is working hard (talking about the big 300horspower 427). I suppose more flow would work, and it is an interesting idea to not return water from the exhaust manifold, but this will only work in fresh water areas because salt would kill those fast and they're expensive.

EH
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Joined: September 16th, 2005, 3:49 pm

September 18th, 2005, 4:37 pm #5



Up here on the St Lawrence, many people use closed cooling because our water is cold to start with and we just don't see as much overheating as you would, say in the Gulf of Mexico. Closed cooling also gives anti-corrosion protection and protection against that unexpected cold weather that can settle in and stay for a week at a time. Up here, if you have closed cooling you keep it, in other parts of the country on fresh water, you have the option of tossing the system if it's overheating, but like the guys said, only if you are on a fresh water lake or river.

Commander35
Cape Vincent, NY
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JD
JD

March 21st, 2006, 12:35 am #6


STANDARD (RAW WATER) COOLING SYSTEM


look at the two diagrams and you'll see the standard raw water cooling system tempers the water "before" it sends it to the engine. That's good because running the water through the hot exhaust manifolds serves a purpose: it avoids putting cold water directly into the motor. The hot exhaust manifolds quickly raise the water temp up to the point where it can be run through the motor without causing stress. From here, however, that water is wasted while it's hot, and more cool water comes in to replenish the system. These systems can be run hours on end without overheating, with a little help from the thermostats.



Now look at the closed cooling system (below)



Once under way, the closed cooling system is "closed" so it obviously runs on hot water, and has an inexhaustible supply of hot water. Interesting thing though, why in the heck are they RECIRCULATING all that hot water from the exhaust manifolds. Why isn't that water just dumped like the raw water system does? Sheesh, NO WONDER THE SYSTEM OVERHEATS????

It would appear an easy and simple plumbing change (for the fresh water guys only) would FIX the overheating issue very fast. Now having antifreeze in those exhaust manifolds is a good thing in the winter time, but if you winterize your boat, or for that matter in Tennessee like I do and keep your boat operational all year long, a change in plumbing would appear to fix any overheating problems people have encountered. If you have closed cooling now and you're in salt water, I couldn't recommend you run salt through those expensive and still good cast iron exhaust manifolds. However, if you're in fresh water and have overheating problems, it would appear the removal of the exhaust manifold side of the recirc system would sure bleed off a LOT of heat for you.

Now all of this is in theory, don't anyone start chopping up their system based on this thread. It would appear that you could allow the cold water to come in, directly through the reverse gear cooler and into the heat exchanger just like it does now. That circuit represents the total cooling ability of the system and it also cooling those hot exhaust manifolds too. Now note how water gets to those exhaust manifolds; its the hot water coming from the motor, but when the hot motor water goes through the exhaust manifolds, it just gets that much hotter, and it puts a big load on the heat exchanger to bring it back down again.

Now look at the "Pressure Relief Valve", which sends water to the riser, and then overboard. Why not take water directly from the pressure relief valve and run it into the front side of the exhaust manifold, and then run the hot water out of the exhaust manifold into the riser, and then waste it (rather than sending all that hot exhaust manifold water back to the already hot motor)?

By doing so, it would appear to practically double the cooling ability of the motor with the cost of a little hose. If it affects the function of the pressure relief valve, that could be replaced with a standard valve that is opened up to the extent that would allow the exhaust manifolds, risers, and hoses to get enough water to stay cool. Right now, however, I don't see an issue with those pressure relief valves, unless they're set too tight to allow for adequate flow.

Yeah I know, an inquisitive mind is a terrible thing to waste!

Comments?

regards, Paul

1966 38 Commander Express
Original 427 power (fresh water cooling)
427 spares (closed cooling system)
I run 427s in my 47 (on a lake) and I am tired of dealing with overheating. Can anyone put me onto specific instructions on how to go from a closed to open system? How to do the plumbing?
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Paul
Paul

March 21st, 2006, 5:24 am #7

Hello JD,

On your system, looking at the diagrams and following this with me, your sea water pump sends water directly to the oil cooler first and then through the transmission cooler before it goes through the heat exchanger and is “wasted” into the exhaust system and dumped overboard.


The main difference is the standard cooling system (raw water cooling) has the sea water pump splitting the flow, with a dedicated but pressure relief valve flow restricted route to the oil cooler and transmission cooler. I believe the pressure relief valves allow priority water to the motor at lower speeds, and open up when the motors are spinning faster, since there’s an abundance of water and cooling at speed with this system.

On your system, look where the water flows FROM the heat exchanger and enters the circulating pump. This is the point at which the standard system receives cold water. This is part of the conversion, but it should be easy. The diagrams should give you the idea, but close up photos will do wonders.

I can (and will) take these photos, and I think it would represent a good project for the Commander Forum. I’m on my way to FL in a couple days, and it’s going to be a little while until I can do this. In the interim, if you have photos or questions, please fire away, as there may be some people here that have done this already. I can tell you it’s not a terribly big job. The closed cooling systems were a compromise even at the onset, as they were not engineered with large enough heat exchangers. Debris can get into the system too, causing it to be choked off from being able to bleed off adequate heat.

Regards, Paul
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Tim Toth
Tim Toth

March 21st, 2006, 11:14 pm #8

I run 427s in my 47 (on a lake) and I am tired of dealing with overheating. Can anyone put me onto specific instructions on how to go from a closed to open system? How to do the plumbing?
Looking for info ,just what is the normal temp. gage reading on a closed cooling 427 set-up at cruising speed ?
What is the over-heat temp. gage range also at cruising .I will be checking a few systems like this later this Spring.
Tim
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Gene Hagland
Gene Hagland

October 26th, 2006, 6:35 pm #9


STANDARD (RAW WATER) COOLING SYSTEM


look at the two diagrams and you'll see the standard raw water cooling system tempers the water "before" it sends it to the engine. That's good because running the water through the hot exhaust manifolds serves a purpose: it avoids putting cold water directly into the motor. The hot exhaust manifolds quickly raise the water temp up to the point where it can be run through the motor without causing stress. From here, however, that water is wasted while it's hot, and more cool water comes in to replenish the system. These systems can be run hours on end without overheating, with a little help from the thermostats.



Now look at the closed cooling system (below)



Once under way, the closed cooling system is "closed" so it obviously runs on hot water, and has an inexhaustible supply of hot water. Interesting thing though, why in the heck are they RECIRCULATING all that hot water from the exhaust manifolds. Why isn't that water just dumped like the raw water system does? Sheesh, NO WONDER THE SYSTEM OVERHEATS????

It would appear an easy and simple plumbing change (for the fresh water guys only) would FIX the overheating issue very fast. Now having antifreeze in those exhaust manifolds is a good thing in the winter time, but if you winterize your boat, or for that matter in Tennessee like I do and keep your boat operational all year long, a change in plumbing would appear to fix any overheating problems people have encountered. If you have closed cooling now and you're in salt water, I couldn't recommend you run salt through those expensive and still good cast iron exhaust manifolds. However, if you're in fresh water and have overheating problems, it would appear the removal of the exhaust manifold side of the recirc system would sure bleed off a LOT of heat for you.

Now all of this is in theory, don't anyone start chopping up their system based on this thread. It would appear that you could allow the cold water to come in, directly through the reverse gear cooler and into the heat exchanger just like it does now. That circuit represents the total cooling ability of the system and it also cooling those hot exhaust manifolds too. Now note how water gets to those exhaust manifolds; its the hot water coming from the motor, but when the hot motor water goes through the exhaust manifolds, it just gets that much hotter, and it puts a big load on the heat exchanger to bring it back down again.

Now look at the "Pressure Relief Valve", which sends water to the riser, and then overboard. Why not take water directly from the pressure relief valve and run it into the front side of the exhaust manifold, and then run the hot water out of the exhaust manifold into the riser, and then waste it (rather than sending all that hot exhaust manifold water back to the already hot motor)?

By doing so, it would appear to practically double the cooling ability of the motor with the cost of a little hose. If it affects the function of the pressure relief valve, that could be replaced with a standard valve that is opened up to the extent that would allow the exhaust manifolds, risers, and hoses to get enough water to stay cool. Right now, however, I don't see an issue with those pressure relief valves, unless they're set too tight to allow for adequate flow.

Yeah I know, an inquisitive mind is a terrible thing to waste!

Comments?

regards, Paul

1966 38 Commander Express
Original 427 power (fresh water cooling)
427 spares (closed cooling system)
We recently moved a freshwater 1972 41 Commander from Lake Erie to the Hudson River area where we will most certainly be encountering salt water from time to time. Everyone tells me that we must convert to a closed cooling system, and we are considering our options for next season. I have read the notes with interest here, and would like some recommendations regarding what or how we should proceed with this conversion.

thank you,
GH

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Dave Mehl
Dave Mehl

October 26th, 2006, 7:37 pm #10


Interesting to see this note, because I have been looking at the cooling kits at marine engine parts. Here is a link I believe you will find of interest.

http://marineengineparts.com/shopsite_s ... age19.html

and another

http://marineengineparts.com/shopsite_s ... page2.html

Dave
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