7.3 idi engine brake
Fleet Mechanic
Joined: Jan 2014
Posts: 1,506
Likes: 73
From: Staunton, VA
Based on the RPM band you stated, I do believe you're hearing the exhaust note that the IDI's make when in the higher RPM band. As previously stated, it wouldn't be the best option to throw actual Jakes on the 6.9s due to their higher compression numbers.
Is what you're hearing sound about like this video?
i ain't rite
Joined: Mar 2005
Posts: 65,481
Likes: 5,542
From: Marlboro Mental Hospital.
this gives a bit better example of what the exhaust note sounds like, only this guy is trying to blow his trans by pulling it down into second gear from drive to get the sound.
Cargo Master
Joined: Dec 2010
Posts: 2,123
Likes: 5
From: Fort Worth, TX
From what I have been reading, it sounds like downshifting into manual 2nd is a legitimate way to engine brake the truck. I'm not sure about long-term effects but even TransGo prescribes it in their manual for testing after the Tugger kit is installed. Even Mark confirmed it. See post #16 https://www.ford-trucks.com/forums/1...d-today-4.html
Not sure I am ready to try it on my truck, though.
Not sure I am ready to try it on my truck, though.
Elder User
Joined: May 2018
Posts: 695
Likes: 22
Right, there's no way Jacobs Engine Brake Co. could dream up and design a Jake brake on an IDI. First, there's no injector rocker arms to trigger each 8 cylinder head mounted solenoid assembly to pop off each exhaust valve at TDC compression stroke. Second, if it was possible to design one similar to Jake brakes on class 8 diesels there'd probably about $250,000 in R&D. Then probably about $3000+ cost to the customer. There's a LOT of parts and switches to an engine brake.
Cargo Master
Joined: Dec 2010
Posts: 2,123
Likes: 5
From: Fort Worth, TX
Right, there's no way Jacobs Engine Brake Co. could dream up and design a Jake brake on an IDI. First, there's no injector rocker arms to trigger each 8 cylinder head mounted solenoid assembly to pop off each exhaust valve at TDC compression stroke. Second, if it was possible to design one similar to Jake brakes on class 8 diesels there'd probably about $250,000 in R&D. Then probably about $3000+ cost to the customer. There's a LOT of parts and switches to an engine brake.
Elder User
Joined: May 2018
Posts: 695
Likes: 22
Don't know anything about the valves floating, but a Jake brake has nothing at all in common with an exhaust brake. Totally different mechanism, a Jake brake has nothing to do with the exhaust system other than momentarily pressing on the each cylinder's exhaust rocker arm at TDC compression stroke releasing compression. Then with no compression and both valves closed that's where you get the powerful engine breaking. Rather than a firing power stroke, it's more or less turned into a "suction" stroke as the piston comes down.
Cargo Master
Joined: Dec 2010
Posts: 2,123
Likes: 5
From: Fort Worth, TX
Don't know anything about the valves floating, but a Jake brake has nothing at all in common with an exhaust brake. Totally different mechanism, a Jake brake has nothing to do with the exhaust system other than momentarily pressing on the each cylinder's exhaust rocker arm at TDC compression stroke releasing compression. Then with no compression and both valves closed that's where you get the powerful engine breaking. Rather than a firing power stroke, it's more or less turned into a "suction" stroke as the piston comes down.
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New User
Joined: May 2018
Posts: 18
Likes: 0
Hey guys I've been off line for a while I appreciate all the input you have all given ( especially the videos) that is what it sounds like so you guys are probably right on it being the compression. My truck is a five speed so that is a no on the transmission idea. As for the wires and the switch I still don't know but its not for the brake box because that is there and the harness for it is intact and far from those wires. I will be pulling the valve covers in the future but I have other projects that take priority at the moment when I pull them I let you know what I find.
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Elder User
Joined: May 2018
Posts: 695
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Hey guys I've been off line for a while I appreciate all the input you have all given ( especially the videos) that is what it sounds like so you guys are probably right on it being the compression. My truck is a five speed so that is a no on the transmission idea. As for the wires and the switch I still don't know but its not for the brake box because that is there and the harness for it is intact and far from those wires. I will be pulling the valve covers in the future but I have other projects that take priority at the moment when I pull them I let you know what I find.
https://www.google.com/imgres?imgurl...act=mrc&uact=8
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New User
Joined: May 2018
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Likes: 0
I was just following a suggestion and figured the engine could probably benefit from the gaskets being changed. I also figured there something not normal visable if there was. But I won't dig in any deep just to prove or disprove a theory
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GaryJ
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Feb 14, 2005 12:15 AM
Senscient Tortoise
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Jul 4, 2004 09:11 PM