Diesels and Engine Braking: Ken vs. His Transmission

[TraceyAZ]

Originally Posted by daveb

Our shop suggests that constant shifting is not a good thing to do. They claim the same as Marty just said, especially problems with heat from shifting very often in short periods of time. They recommend down-shifting on long grades, but not in and out all the time. In other words, use the brakes when you can and when you feel a grade might be too much downshift instead. The 7.3 fleet had trannys that had constant problems. They installed a device that keeps the transmission out of overdrive until the speed reaches 50mph. After 50 mph the tranny shifts into overdrive. This helped with the old transmissions. When driving in areas (such as town) you don't want the transmission to run thru the gears and into overdrive with a stop sign in site. The same goes for driving in the hills. Thats why they put the device in, to keep us from forgetting to turn off the overdrive. This is more of an overdrive issue though. I downshift often when needed but also use my brakes for what they are made for whenever possible. Because I pull a SMB trailer most of the time, downshifting is unavoidable. Still, I try to keep it to a minimum whether the tranny can handle it or not.
Dave Boyer
(Although I would like to have electric brakes on the trailer so far I don't think this little trailer needs them).
Dave Boyer

So a question that is related to the overdrive lock out. The 6.0 in mine seems to have a similar issue with shifting and town driving. When driving in town with stop and go traffic I seem to notice a sort of loading up, when I finally get to an on ramp to come up to speed. I get a decent roll of coal coming out, and I notice scan gage says my egt temps will come up quickly. It doesn't happen all the time and when it does it's when it's a lot of stop and go. However if driving through the same conditions with my OD off those conditions don't happen at all. Been doing this for many years. I think it's normal? I'll be the first to admit I'm still learning all about diesels. Any thought on this??
Thank you.

[carringb]

Originally Posted by TraceyAZ

When driving in town with stop and go traffic I seem to notice a sort of loading up, when I finally get to an on ramp to come up to speed. I get a decent roll of coal coming out, and I notice scan gage says my egt temps will come up quickly. It doesn't happen all the time and when it does it's when it's a lot of stop and go. However if driving through the same conditions with my OD off those conditions don't happen at all.

^This actually sounds like sticking turbo vanes, and the OD is only incidental in that it causes lower RPMs. If turning off OD is working for now, you might be able to get by like this for a while (or indefinitely) but you are probably losing some responsiveness and possibly power.

[TraceyAZ]

Originally Posted by carringb

^This actually sounds like sticking turbo vanes, and the OD is only incidental in that it causes lower RPMs. If turning off OD is working for now, you might be able to get by like this for a while (or indefinitely) but you are probably losing some responsiveness and possibly power.

I've thought about that possibility as well, but the turbo has been cleaned and a new updated unison ring installed maybe 15,000 miles ago when all the bullet proofing was being done. I might pull the turbo out just to check.
Thank you
Tracey

[sscott3d]

On my 6.0 I believe the button on the end of the shift lever is actually a tow/ haul mode when engaged. It changes the shift points and holds each gear for higher rpm which would equal higher EGT's. My 7.3 pickup the button is a OD lockout.

[daveb]

I don't have a tow haul on my 6.0 van but my Ford 550 work truck has it and it works much differently. I'm not sure if there is a difference in year models or what Ford offered at the time as far as vans having a TH feature. There was a thread about programming the switch operation but don't recall if you could get both modes.



Just to note, my van was bare bone stock back in 08 but now I'm running a DP tuner and they changed some of the shift points. It's like night and day and am satisfied with the OD on/off switch. I've never noticed any difference when the OD button is on or off other than it won't hunt for OD. The tune made the average transmission temp and EGT's drop along with the ECT & EOT.

[WhitH]

on my 05 the button was an OD lockout

[TraceyAZ]

Originally Posted by carringb

^This actually sounds like sticking turbo vanes, and the OD is only incidental in that it causes lower RPMs. If turning off OD is working for now, you might be able to get by like this for a while (or indefinitely) but you are probably losing some responsiveness and possibly power.

I was gonna look further into this just to be on the safe side, what would you recommend for a good upgrade/replacement unit for it? If it matters I've got all the usual bullet proofing type work done with EGR delete and such. I'm also running a upgraded FICM with a mild upgraded flash.
Also I consider myself a decent shade tree mechanic and have zero issues with tools and such, is this a job that I can preform myself with the basic tools or is there some special ford/Diesal type stuff needed and would be better off in pro hands?
Thank you
Tracey

[JoeH]

Originally Posted by sscott3d

On my 6.0 I believe the button on the end of the shift lever is actually a tow/ haul mode when engaged. It changes the shift points and holds each gear for higher rpm which would equal higher EGT's. My 7.3 pickup the button is a OD lockout.

Yes, the 6.0 does not have OD lockout like the 7.3. But the opposite is true wrt EGTs. Using tow/haul on long grades will lower EGTs and prevent the engine from lugging.

[JoeH]

Originally Posted by WhitH

on my 05 the button was an OD lockout

I believe this was a carryover from the vans with a 7.3. They didn't change the shift levers as they started dropping the 6.0 and 5R100 into the vans but if you replace it (I had mine go out) the replacement lever says tow/haul on it and not OD off. The only way to do it is with a custom tune.

[ShuttlePilot]

My 2005 6.0 is OD lockout. Transmission and handle call out.