What to do without the pressure relief valves

What to do without the pressure relief valves

Joined: August 19th, 2008, 9:34 am

May 14th, 2010, 11:46 am #1

I'm kind of desperate. I need two pressure relief valves. CC # 16.99-07346.
But it seems like they are not manufactured any more.
I have found something called pressure relief valve adaptor kit on the net. Anybody knows if that is a replacement for the valves?

Any ideas of where I can get some valves or what to do if I don't?

I have an 200hp 307QLV that I have made into a 307Q. I am using the Velvet drive from my old Owens engine. The valves was missing when I bought it.
Planning to have it in my Owens Sea Skiff from 1961.

/Gunnar
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Paul
Paul

May 14th, 2010, 1:37 pm #2

I am absolutely sure you can find these at the boat recycling businesses on ebay.

I would look to see who is selling a lot of CC part, go to their listed web site, call them up and you're in business.
These are simple devices and I would think there are a lot of them sitting around in shops now, with very little demand. All they do is direct slow speed water through the engine as a priority, and when speed and pressure increases it just dumps out the riser. Without the PRV you will still get water in the engine, but may be dumping too much out the riser first before the motor really gets what it needs, and therefore the PRV system is associated with overheating motors at slow speeds.

Here is a thread telling all about the PRV, and it has some photos you may want to use to validate what kind of PRV housing you have, since some of them bolt directly to the riser like this one, and some of them are "free standing" with hose connections. Either one works the same.
http://www.network54.com/Forum/424840/m ... regulators





Regards,

Paul
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Brian Tait
Brian Tait

May 20th, 2010, 1:56 pm #3

Paul,
It sounds like I may have this problem with my PRV. I am in the process of rebuilding my Sherwwood Raw Water Pumps and read this. Where exatly are the PRV's located and how many are there. I looked over my engines last night and reviewed the attached pictures and cant seem to identify the locations such as front or rear of the water jackets. I have standard cooling if that matters.
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Paul
Paul

May 20th, 2010, 2:46 pm #4

As far as I know, CC used one PRV design, but used several different housings to hold the PRV. On the Standard Cooling system on the 427 there is a seperate iron casting that holds two PRVs, as you can see in the attached diagram and photos. On the Closed Cooling system, the PRV is held to the riser. On the SBC motor (327F in particular) the PRV shell is bolted to the riser. In all applications, the actual brass PRV itself, is the same unit, functioning in the same way. They're easily cleaned, the tough part is getting the gasket but those are pretty easily made from gasket material and/or Permatex. The problem is....if the Standard Cooling units are stuck in the OPEN position, then the rest of the motor could be starved for cool water at idle, as the cold water takes the path of least resistance right out the riser without getting into the block.

On the Closed Cooling system, ALL the cold water goes directly into the heat exchanger and ALL of that then goes into the riser and is ejected out the tail pipe. On this system the PRV does not seem to serve ANY function I can see and some people have considered removing them on these motors to free up the flow of water by putting less head on the pump.
STANDARD COOLING SYSTEM










~~~~~~~~~~~~~~~~~~~~*~~~~~~~~~~~~~~~~~~~~~~~




CLOSED COOLING SYSTEM
On the Closed Cooling system, the PRV is located in a different location and appears to have less of a function for cooling, and primarily a function for pressure relief.













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Paul
Paul

May 20th, 2010, 2:56 pm #5











At high engine speeds the pumps are putting out so much water it is necessary to relieve the pressure and this valve is forced wide open and allows water to waste directly into the riser. At slow speeds it closes and all water goes through the block first, before being wasted out the tailpipes.




Pretty simple device, long service, reliable, easily checked and cleaned.
Most of the time a 427 sees overheating would be due to the water pump impeller, perhaps a loose belt, perhaps an intake pipe that is admitting a little air on the suction side, perhaps a very worn cam inside the pump itself, or perhaps an internal obstruction somewhere. If the PRV happens to be stuck in the open position, it can short circuit the water flow at slow speeds. If you do not have any PRV units in your system, you could be starving the (Standard Cooled) motor of cooling water at slow speeds.

Regards,

Paul










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Brian Tait
Brian Tait

May 20th, 2010, 7:15 pm #6

As far as I know, CC used one PRV design, but used several different housings to hold the PRV. On the Standard Cooling system on the 427 there is a seperate iron casting that holds two PRVs, as you can see in the attached diagram and photos. On the Closed Cooling system, the PRV is held to the riser. On the SBC motor (327F in particular) the PRV shell is bolted to the riser. In all applications, the actual brass PRV itself, is the same unit, functioning in the same way. They're easily cleaned, the tough part is getting the gasket but those are pretty easily made from gasket material and/or Permatex. The problem is....if the Standard Cooling units are stuck in the OPEN position, then the rest of the motor could be starved for cool water at idle, as the cold water takes the path of least resistance right out the riser without getting into the block.

On the Closed Cooling system, ALL the cold water goes directly into the heat exchanger and ALL of that then goes into the riser and is ejected out the tail pipe. On this system the PRV does not seem to serve ANY function I can see and some people have considered removing them on these motors to free up the flow of water by putting less head on the pump.
STANDARD COOLING SYSTEM










~~~~~~~~~~~~~~~~~~~~*~~~~~~~~~~~~~~~~~~~~~~~




CLOSED COOLING SYSTEM
On the Closed Cooling system, the PRV is located in a different location and appears to have less of a function for cooling, and primarily a function for pressure relief.












Paul,
I dont see these on my 427's at all? still cant do the photo bucket thing? I dont know if you staill have my photos I e mailed you but there is a shot of the rear of my starbord engine and I dont see what you sent me.
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Paul
Paul

May 20th, 2010, 8:48 pm #7

Hi Brian,

Yes indeed I have your photos saved in the archives and they reveal what I think is a forensic clue about why your motors don't have the PRV.

It sure looks like you have the closed cooling motor setup that has been converted to a standard setup. Here is why I think so, compare the two photos below.

FIRST PHOTO, STANDARD COOLING.


Note the following: Sea water pump delivers water to two locations, one goes to the oil coolers and virtually all that water is dumped overboard after it passes by the PRV. When the motor is going slow, the oil does not really need to be cooled so the PRV is closed due to low pressure, and all the water is going into the exhaust logs for preheating, and then into the block, finally dumped into the riser. Key point: two circuits coming from Sea Water pump.



Now we have the Closed Coolins system below, note how the Sea Water pump only has one delivery point. Now for the forensic clue I spotted in your photo (attached below), look at the diagram for the water flow RETURNING from the heat exchanger.......see how that flow enters the Circulating Water Pump. That pump ONLY has a return port like that if it is on a Closed System. Your motor (photo below) has such a return port on the Circulating Pump, and therefore I conclude it was a Closed System once, but had the surge tank and heat exchanger removed, now it's a almost Standard Cooling system, and I don't see any PRV valves.



Your motor photo below:



Here is another view of your motors




I will bet you, that if you look at your Sea Water pump it will have one outlet.
This outlet goes directly to the oil cooler, to the transmission cooler, and then it goes to that line I identified in the photo with the white arrow as your MAIN SEA WATER FEED TO THE MOTOR. If this is so, then your main source of cooling water has already been pre-heated by the oil cooler and the transmission, before it ever gets to the motor. Also, it would appear at higher speeds your are getting a LOT of pressure and flow through the motor with no PRV capability to bleed off excess pressure. check it out and lemme know.

Regards, Paul





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Brian Tait
Brian Tait

May 20th, 2010, 8:57 pm #8

Paul,
I think your right. I'm rebuilding the pumps now. They have one outlet and it goes right to the trans cooler. What do you suggest I do. Can I run it the way it is. Or do I need to repipe and try to find PRV's.
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Paul
Paul

May 20th, 2010, 9:44 pm #9

Brian I'll bet you can find the PRV setup at some of the engine recycler guys up in Michigan or other parts of the country.

I would look for someone parting out a 427, and there are always some of those on ebay it seems, and this is a part they would LOVE to sell someone becuase there is next to NO market for them. If you had a couple of those, it would be easy to bring the system up to original spec. You could put a T in the water pump outlet and be done.

Regards,

Paul
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James Brunette
James Brunette

May 20th, 2010, 10:16 pm #10


Check with Robert at
http://www.chris-craft-parts.com/

Here is a salvage operation on ebay that looks promising
http://stores.ebay.com/ShipWreckSalvage ... -and-Parts

JB
Last edited by FEfinaticP on May 1st, 2016, 12:41 pm, edited 1 time in total.
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