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  #1  
Old 02-27-2012, 07:38 PM
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Default Anybody Heard of These?

Something called a Weeper Engine Brake. Clicky Here From the diagram at the bottom it looks to hold the exhaust valve open during compression like a traditional Jake Brake, but it also shows the valve being held open until the actual exhaust stroke. With the valve held open after the compression stroke doesn't that negate the purpose of it?
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Old 02-27-2012, 08:03 PM
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It operates the same as any other engine brake. It is just another company. Jacobs engine brake is just one of several engine brakes on the market. Cummins makes their own with its own name as well. They are just individual companies with the same concept. Maybe half the engines that have engine brakes actually have jacobs or Jakes as they are more commonly referred to. When you order a new rig you used to be able to spec the engine out with the engine brake of your choosing be it Jacobs cummins or one of the other options out there. I have been out of the over the road end of things for nearly 10 years now so I am not sure if this is still an option.
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Last edited by Wild and Free; 02-27-2012 at 08:07 PM.
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Old 02-27-2012, 08:06 PM
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I understand that, but it just seems strange to keep the exhaust valve open for so long. I would think that after you dumped the compression that you would want the valve to close so there will be a vacuum in each cylinder for it to work properly.
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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Old 02-27-2012, 09:11 PM
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Alright I read and read and read all the sparse crap on the net about this and it does indeed leave the exhaust valve open the entire time the brake is on. It never shuts it. I don't know how it gets away with this when the piston would hit it UNLESS it just BARELY opened it. I measured I guess it would be a total of 0.09" if I remember right, I think there was 70 thousandths left after the initial 20 so it could open 0.090 but that is right where it hits the piston, so it would have to be a little less. Anyhow, it seems it would be the same as leaving a 0.070" feeler gauge in there while the engine is running, so it always has the valve open and it opens a lot more on the actual exhaust stroke. So it would draw air in, leaking it out the exhaust slowly, it would compress it acting just like a jake brake, but also leaking it out the exhaust so it wouldn't be as good. Since it is constantly leaking, there would be less air on the power stroke so the rebound effect would be greatly reduced (which of course is the idea to a jake brake). Then the exhaust valve finally opens all the way and lets whatever is left out. It is a "cheap braking method" since it's operation is so simple. It is not as good as a jake or exhaust brake. If you read closely, Pacbrake is a little crafty and says it can be used on any diesel, BUT, they go on to say you should use it with the stock (on 6.7 trucks) exhaust brake. You get more benefit because of the jake brake effect it has in the beginning (though less effective since it is constantly open) and because of the OEM exhaust brake.

In other words, it's a gimmick.
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Last edited by ISX; 02-27-2012 at 09:14 PM.
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Old 02-27-2012, 09:19 PM
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I'm not so sure about it being a gimmick. After looking at the diagrams again it looks like the exhaust valve does close so that the piston pulls against a vacuum.
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Old 02-27-2012, 09:22 PM
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If you mean this diagram then look closer lol. The valve never shuts because it is never flush with the head like the intake is. Even so, I think the engine would pull the valve open before it slowed the truck down with vacuum pressure.
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1997-12V-NV4500-Dana 80/3.54/2wd-350k---21-27mpg
Removed AFC--No Plate--13.5* timing--BHAF--5" Exhaust--Valair Clutch
1994-Jeep Cherokee-5spd-3.07-4wd-202k---16-19mpg
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Old 02-27-2012, 09:38 PM
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The fix for the valve opening by suction is the same as with an exhaust brake.... Heavier springs........
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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Old 02-27-2012, 09:41 PM
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Eh, everything I read said "exhaust valve stays open throughout the entire cycle". Maybe your idea would work but it seems the weeper thing is just a cheap jake brake. Probably just a little solenoid that pushes the valve down slightly or something. I read nothing about vacuum.
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1997-12V-NV4500-Dana 80/3.54/2wd-350k---21-27mpg
Removed AFC--No Plate--13.5* timing--BHAF--5" Exhaust--Valair Clutch
1994-Jeep Cherokee-5spd-3.07-4wd-202k---16-19mpg
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Old 02-27-2012, 09:44 PM
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Here you go.
Quote:
A cheaper, though less effective alternative, is the so-called weeper brake. These brakes operate by cracking open the exhaust valves a small amount and keeping them open throughout operation of the brake. Some braking effect is achieved because the exhaust gases build up pressure and provide a braking effect as they are forced past the slightly cracked open valves. The rebound effect is however removed because the pressure in the cylinders does not build up sufficiently to cause an appreciable rebound effect.
Got that from here.
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1997-12V-NV4500-Dana 80/3.54/2wd-350k---21-27mpg
Removed AFC--No Plate--13.5* timing--BHAF--5" Exhaust--Valair Clutch
1994-Jeep Cherokee-5spd-3.07-4wd-202k---16-19mpg
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  #10  
Old 02-27-2012, 09:47 PM
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Hm! Great info!!
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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