SBC V8 Water Pump Failure, 3 Styles of Pumps Tested BYPASS THERMOSTAT UPDATE |
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SBC V8 Water Pump Failure, 3 Styles of Pumps Tested BYPASS THERMOSTAT UPDATE |
nick mironov |
May 6 2010, 12:32 PM
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#1
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nickm Group: Members Posts: 204 Joined: 12-June 05 From: San Francisco, CA Member No.: 4,264 |
My Renegade water pump failed yesterday. The pump impeller is stamped steel and the blades all just folded over or sheared off. I understand that the cast impellers are much stronger, but that not all manufacturer's cast models will fit into the Renegade housing. Anybody have experience with cast impeller pumps that will fit into the Renegade housing?
Since there is no bypass in the Renegade system, Renegade instructions are to limit the motor RPM to 3,000, or less, untill the thermostat opens. I have observed this, but the pump still failed after 5,500 miles. Renegade now makes a bypass kit, which I going to try, but I would still like to get a more durable pump. Nick |
nick mironov |
May 26 2010, 10:00 AM
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#2
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nickm Group: Members Posts: 204 Joined: 12-June 05 From: San Francisco, CA Member No.: 4,264 |
This is the Test Setup.
Although the pump housing has two outlets, for convenience, I decided to use one for the pressure gauge and use the other for the output flow. If one were to test both outlets, I would not expect double the flow – maybe only 30% more. That would correspond well to the advertised pump rating of about 40 gpm at 4,000 RPM that I have seen. The motive force for spinning the pumps during testing was a 2,500 RPM hand-drill attached to the protruding bolt on the blue-colored channel that you see in the picture. Unfortunately, the drill could not achieve the full 2,500 RPM under load, so I had to settle for whatever it could do. As a result I had to calculate the resulting water pressures at higher RPMs. The calculated results (list image) do seem to correspond to real conditions, indicating very high pressures at dead head conditions - thermostat is closed during cold engine conditions and not having a bypass. Note that a nearly closed thermostat could be experienced under cruise conditions in very mild weather resulting in the same high pressure effect. Based on my experience and many other posts that I have read about failed pump impellers, the high pressure conditions do happen and that’s what results in catastrophic pump failures. The objective of this testing is to find a pump impeller that is more durable (able to withstand dead head pressures) and to possibly produce less pressure without sacrificing much water flow. Note that the Chrysler big block pumps were used on engines running at about 4,000 rpm, and in my case, my 283 SBC can run to over 6,000 rpm. |
BRAVE_HELIOS |
Nov 1 2010, 01:46 PM
Post
#3
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"Knowledge speaks, wisdom listens" Group: Members Posts: 295 Joined: 25-September 06 From: The Land Of ID! Member No.: 6,920 Region Association: Pacific Northwest |
This is the Test Setup. Although the pump housing has two outlets, for convenience, I decided to use one for the pressure gauge and use the other for the output flow. If one were to test both outlets, I would not expect double the flow – maybe only 30% more. That would correspond well to the advertised pump rating of about 40 gpm at 4,000 RPM that I have seen. The motive force for spinning the pumps during testing was a 2,500 RPM hand-drill attached to the protruding bolt on the blue-colored channel that you see in the picture. Unfortunately, the drill could not achieve the full 2,500 RPM under load, so I had to settle for whatever it could do. As a result I had to calculate the resulting water pressures at higher RPMs. The calculated results (list image) do seem to correspond to real conditions, indicating very high pressures at dead head conditions - thermostat is closed during cold engine conditions and not having a bypass. Note that a nearly closed thermostat could be experienced under cruise conditions in very mild weather resulting in the same high pressure effect. Based on my experience and many other posts that I have read about failed pump impellers, the high pressure conditions do happen and that’s what results in catastrophic pump failures. The objective of this testing is to find a pump impeller that is more durable (able to withstand dead head pressures) and to possibly produce less pressure without sacrificing much water flow. Note that the Chrysler big block pumps were used on engines running at about 4,000 rpm, and in my case, my 283 SBC can run to over 6,000 rpm. Hey Nick, Not quite to the point where I have experienced a water pump failure... but great info non-the-less! I have a few questions pertaining to the installation/configuration of the 2 water pump hoses and where they attach to the engine block. I think you answered one of the questions already with your photo... just need confirmation! Specifically, I am using a Renegade mechanical water pump setup (mounted on the drivers side) and I've seen some conflicting photos of how the two smaller water pump ports are connected to the front of the block(SBC)... in regards to which port on the water pump gets connected to which port on the front side of the engine? Does it matter? It seems like the water pump can be mounted in its bracket in more than one position. I think the whole pump can be rotated 90 degrees at a time until the pump to bracket bolts line up. Does this matter? At this moment, mine is mounted so that, looking at the rear of the pump, one small port is at the 10-11 o'clock position and the other is at the 4-5 o'clock position. The inlet port on the water pump (coming from the radiator) is facing down or at the 6 o'clock position. Is this okay? Once again, any info is greatly appreciated. Thanks again! Tony |
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