Exhaust Manifold circulation setup

[John Smith]

I have an Old 72 omc 307 elctr.shift Outdrive boat with a old log style exhaust manifold and an elbow(I just order an center type manifold with a riser, when I described the old cooling system to Tech. who sold me the manif. he said I have a partial close system, because the salt water from impeller goes thru heat exchange, then enter the elbow to the exh. Manif. then out the out drive). Is anyone could show me how to route a complete close system. Tech said it is much better with antifreeze circulating the engine as well as the rest of exh. Manif. What is the advantage and diasadvantage of close and partial close cooling system. <br />You help or input is greatly appreicated

 

[akriverrat]

Re: Exhaust Manifold circulation setup

http://www.marinemechanic.com/New-Folder2/v8-cool-flow-clsd.htm faster engine warm up, much longer manifold life. your current heat exchanger might not handle the extra cooling load, more complicated.

 

[John Smith]

Re: Exhaust Manifold circulation setup

akriverrat,<br />Thanks for the valuable information and attachment. <br />The heat exchanger is about 5" X 24" is about 2 years old, I open the end cape is still very clean. Is there a way to determine if my heat exchanger is big enough to handle the extra heat?<br />from the exh. manif.. before make any modification.

 

[oldboat1]

Re: Exhaust Manifold circulation setup

A partially closed system would send fresh water and coolant through the block, at least. A fully closed system would send coolant through the block and the exhaust manifolds. The risers would still be cooled by raw water, as would the transmission oil cooler, and of course circulating raw water would also be the means by which the heat exhange takes place in the heat exchanger. It's possible that you actually have a fully closed system, and the circulation to the exhaust system is to the risers only.

 

[akriverrat]

Re: Exhaust Manifold circulation setup

after re-reading your description i agree with oldboat1 that you have a fully closed system now. riser/elbow is raw water cooled allways. these guys are supposed to be real helpfull http://www.cool-craft.net/index.htm

 

[John Smith]

Re: Exhaust Manifold circulation setup

akriverrat and oldboat1,<br /><br />Thanks for you input and advise, I still think cooling system in the 307 engine is a partial close only, because antif. only find in the engine, head and part of the heat exchange. <br />The sea water(raw water) circulated first to the heat exch then to the elbow, upper exh.manif., make a U turn at the end of exh.manif. to the lower part exh.manif back to the elbow combines with the exhaust out the leg. When I remove the Exh.manif and elbow, there is absolutely no antif. in the exh. manif or any hose might connect with antif from the engine. <br />The question is back to the present heat exch. if I make the modif follow the diagram from akriverrat, is it able to handle the heat from the exh. manif. plus the engine heat. The impeller is new I just install few months ago and the water pump housing is also new .<br />Any input is greatly appreciated

 

[John Smith]

Re: Exhaust Manifold circulation setup

akriverrat, oldboat1 and any I/O expert:<br /> The new exh. manif and Riser arrived on Thursday, I finally find time on Sunday afternoon put the riser and exh. manif. in this week end (not to mention I spend 2 Hrs to cut and drill to make two stainless steel plates from scratch which I don't mine except my wife think I spend too much time on the boat), from looking at the diagram of http://www.marinemechanic.com/New-Folder2/v8-cool-flow-clsd.htm, I could not determine where in the GM 307 eng. would I find the connection from the engine(Antif.) to exh.manif. and Where the connection of return(under the thermostat). <br />Please Help

 

[akriverrat]

Re: Exhaust Manifold circulation setup

i was going to refer you to kemequipment web site but it is not working. their phone number is 503 692-5012. they have a kit for doing this that 2 friends have used on sb chevy. coolcraft site i posted earlier are experts in this.

 

[oldboat1]

Re: Exhaust Manifold circulation setup

Sorry -- can't help.