Engine Braking
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New User
Joined: Nov 2005
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From: Manteca, CA
Engine Braking
Hello All,
My first Ford HD, so you guys are a Godsend. Bought 2001 F250 used so unclear on history. Bought at 110K, Trans scattered at 121K. "completely" rebuilt. Shifts fine but no engine braking. Trans shop said all OK as far as the trans goes. Maybe the chip. Took to Ford, there was a super chip of some kind, but as no controller came with truck, I had Ford restore to spec. Still no engine braking. The Ford tech mentioned a "one way clutch" which I'm guessing is a " coast clutch. I believe that when I manually drop a gear, the tach should show higher RPM and track slowly down as the truck loses speed. I gotta take it back to the Trannie shop, and it sounds like their going to have to tear it down again. Any comments, insights, advice VERY welcome!
2001 F250 Crew 4WD with 7.3 Diesel
My first Ford HD, so you guys are a Godsend. Bought 2001 F250 used so unclear on history. Bought at 110K, Trans scattered at 121K. "completely" rebuilt. Shifts fine but no engine braking. Trans shop said all OK as far as the trans goes. Maybe the chip. Took to Ford, there was a super chip of some kind, but as no controller came with truck, I had Ford restore to spec. Still no engine braking. The Ford tech mentioned a "one way clutch" which I'm guessing is a " coast clutch. I believe that when I manually drop a gear, the tach should show higher RPM and track slowly down as the truck loses speed. I gotta take it back to the Trannie shop, and it sounds like their going to have to tear it down again. Any comments, insights, advice VERY welcome!
2001 F250 Crew 4WD with 7.3 Diesel
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,696
Likes: 2,618
From: SE Florida
No, that's not how the coast clutch works.
It's NEVER on in 4th gear, because there is always engine braking in 4th. It's very slight due to the trans ratio in 4th, so it isn't really usefull.
The coast clutch will come on in 3rd gear ONLY if the OD off light is on. If the OD light is off the coast clutch stays off in 3rd.
The coast clutch will come on in 2nd gear ONLY if the OD off light is on, or the shifter is in the 2 position. If the OD light is off and the shifter is in D the coast clutch stays off in 2nd.
The coast clutch will come on in 1st gear ONLY if the OD off light is on, or the shifter is in 1. If the OD light is off and the shifter is in D the coast clutch stays off in 1st.
Around 2001 there was a machining problem with the coast clutch drum. The groove for the snap ring that holds the clutch together wasn't machined deep enough and the snap ring would often come out of the groove. When that happens the coast clutch no longer works. Usually, but not every time, it won't break other parts, but sometimes it does.
It's NEVER on in 4th gear, because there is always engine braking in 4th. It's very slight due to the trans ratio in 4th, so it isn't really usefull.
The coast clutch will come on in 3rd gear ONLY if the OD off light is on. If the OD light is off the coast clutch stays off in 3rd.
The coast clutch will come on in 2nd gear ONLY if the OD off light is on, or the shifter is in the 2 position. If the OD light is off and the shifter is in D the coast clutch stays off in 2nd.
The coast clutch will come on in 1st gear ONLY if the OD off light is on, or the shifter is in 1. If the OD light is off and the shifter is in D the coast clutch stays off in 1st.
Around 2001 there was a machining problem with the coast clutch drum. The groove for the snap ring that holds the clutch together wasn't machined deep enough and the snap ring would often come out of the groove. When that happens the coast clutch no longer works. Usually, but not every time, it won't break other parts, but sometimes it does.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,696
Likes: 2,618
From: SE Florida
If your coast clutch is on in 4th gear the trans will be locked up. All three elements of the overdrive gearset will be held to the case, so the input and output shafts will stop turning. That means the wheels are going to stop turning, too. Your coast clutch IS NOT on in 4th gear. It can't happen.
You will have engine braking in 4th gear because the overdrive clutch is on and provides engine braking in 4th gear instead of the coast clutch, which CANNOT be on in 4th.
I think you are mistaking the torque converter clutch for the coast clutch.
You will have engine braking in 4th gear because the overdrive clutch is on and provides engine braking in 4th gear instead of the coast clutch, which CANNOT be on in 4th.
I think you are mistaking the torque converter clutch for the coast clutch.
Last edited by Mark Kovalsky; Nov 7, 2007 at 02:05 PM.
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From: Manteca, CA
So what I think I'm hearing is that the coast clutch, when activated by the OD (OD light is ON) allows the truck to coast without engine braking.
I assume engine braking, in 1st, 2nd or 3rd, will cause my engine to wind up, and through compression, slow or hold my truck to a lower speed so I don't have to burn up my brakes. Every vehicle I have (Explorer, Toyota 4Runner and even car) has this capability.
So when Ford says the problem is likely in the trans, would it be the Coast clutch always on, or the TC clutch. There was a short in the shift stem, (blew fuses when put in OD), and the shift stem was replaced by the guy that rebuilt the trans. Maybe the Coast Clutch is always engaged without the OD lamp lit????
I assume engine braking, in 1st, 2nd or 3rd, will cause my engine to wind up, and through compression, slow or hold my truck to a lower speed so I don't have to burn up my brakes. Every vehicle I have (Explorer, Toyota 4Runner and even car) has this capability.
So when Ford says the problem is likely in the trans, would it be the Coast clutch always on, or the TC clutch. There was a short in the shift stem, (blew fuses when put in OD), and the shift stem was replaced by the guy that rebuilt the trans. Maybe the Coast Clutch is always engaged without the OD lamp lit????
Post Fiend
Joined: Feb 2007
Posts: 7,191
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From: Blairsville,Ga
all I know if I am much over 40 mph no matter 45 or 100 when I let completely off the throttle it's like it down shifts to a lower gear and the rpms come up a little
if I touchthe brake it goes to a normal coast,when I let off brake it does the same again
if I lock it in third there is never sny change with throttle on or off
if I touchthe brake it goes to a normal coast,when I let off brake it does the same again
if I lock it in third there is never sny change with throttle on or off
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New User
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From: Manteca, CA
Thanks Guys. I think It's sinking in. I'm a newby to Diesels!! Borrowed my brothers '97 F250 for my frequent trips to AZ and was hooked. Nothing like hauling a truck load of material, and a trailer with the same, up the Kingman Grade like it was going down hill!
So from Ray's input here, looks like if I lock in third, the RPMs should track up and down. What I mean is the RPMs come up as I apply throttle (obvious) but should track down slowly as I let off the throttle (almost like I had a manual trans). As it is, I can be doing 40MPH in third, and when I let off the throttle it falls immediatly back to 1,500 RPM, and coasts to a stop. That ain't right. Worked OK till it blew.
I gotta go back to the trans shop, and need to be crystal clear so I don't get BSd again!
So from Ray's input here, looks like if I lock in third, the RPMs should track up and down. What I mean is the RPMs come up as I apply throttle (obvious) but should track down slowly as I let off the throttle (almost like I had a manual trans). As it is, I can be doing 40MPH in third, and when I let off the throttle it falls immediatly back to 1,500 RPM, and coasts to a stop. That ain't right. Worked OK till it blew.
I gotta go back to the trans shop, and need to be crystal clear so I don't get BSd again!
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Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
Originally Posted by Wayno
So what I think I'm hearing is that the coast clutch, when activated by the OD (OD light is ON) allows the truck to coast without engine braking.
Originally Posted by Wayno
I assume engine braking, in 1st, 2nd or 3rd, will cause my engine to wind up, and through compression, slow or hold my truck to a lower speed so I don't have to burn up my brakes. Every vehicle I have (Explorer, Toyota 4Runner and even car) has this capability.
Originally Posted by Wayno
So when Ford says the problem is likely in the trans, would it be the Coast clutch always on, or the TC clutch.
Originally Posted by Wayno
There was a short in the shift stem, (blew fuses when put in OD), and the shift stem was replaced by the guy that rebuilt the trans. Maybe the Coast Clutch is always engaged without the OD lamp lit????
To test the coast clutch, drive at 40 MPH and take your foot off the go pedal. Move the shifter to 2. If there is engine braking the coast clutch is working. If the engine drops to idle speed then the coast clutch is not working.
Last edited by Mark Kovalsky; Nov 7, 2007 at 05:21 PM.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,696
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From: SE Florida
Originally Posted by rbaker6336
all I know if I am much over 40 mph no matter 45 or 100 when I let completely off the throttle it's like it down shifts to a lower gear and the rpms come up a little
if I touchthe brake it goes to a normal coast,when I let off brake it does the same again
if I lock it in third there is never sny change with throttle on or off
if I touchthe brake it goes to a normal coast,when I let off brake it does the same again
if I lock it in third there is never sny change with throttle on or off
Since your's works with the OD off, your coast clutch is working as it should. Wayno's truck won't do this. His is going to idle speed, which means the coast clutch isn't working. It doesn't tell anything about the torque converter clutch, which is a different clutch.
Cargo Master
Joined: Jan 2007
Posts: 2,243
Likes: 79
From: Roman Forest, TX
I couldn't dispute or add to what Mark said, but wow, that is a wealth of knowledge there! His sig says it all..."Former Ford automatic transmission engineer, 1988-2007." And I have no reason to doubt it. Thanks Mark!
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New User
Joined: Nov 2005
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From: Manteca, CA
Tranny fixed!!! Mark Kovalsky nailed it Replace coast clutch drum (2001 shallow machined groove for snap ring) and now performs great. Drove heck out of it and all is well. I printed up some of the insights provided by members of this forum, and presented to rebuilder along with diagnostics from Ford and after the 3rd teardown, all is well. The rebuilder even restarted my 1 year / 12K warranty! Thanks again!!!!