decending hills with an automatic
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decending hills with an automatic
I just bought 99' F350 PSD. When I decend hills, I get no engine braking unless I'm in OD and then only until 35 MPH. If I have OD turned off or pull the transmission into 2nd - I get NO engine braking. Is this normal?
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decending hills with an automatic
Diesels don't create vacuum when you take your foot off the accelerator like a gas engine does when the throttle plate is closed. Vacuum is what causes the engine brakeing on a gas engine. Turbocharged diesels will have positive pressure on the intake even at idle. So there is no vacuum to hold 'em back.
There are engine brakes made specifically for diesels, but they are not really practical for pickups. They create vacuum by mechanically holding the intake valves closed.
The brakeing effect you experience in OD is from the torque converter being locked up. Below about 35mph it unlocks and behaves the same as in gears 1-3.
What kind of trailer or camper will you be towing with your new PSD?
There are engine brakes made specifically for diesels, but they are not really practical for pickups. They create vacuum by mechanically holding the intake valves closed.
The brakeing effect you experience in OD is from the torque converter being locked up. Below about 35mph it unlocks and behaves the same as in gears 1-3.
What kind of trailer or camper will you be towing with your new PSD?
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decending hills with an automatic
[font size="1" color="#FF0000"]LAST EDITED ON 25-Oct-01 AT 01:04 PM (EST)[/font][p]
That is exactly how diesels operate. There are quite a few different exhaust brakes on the market for these trucks. Everyone I have ever talked that uses one of these brakes swears by it. You may wnat to visit www.ford-diesel.com, they have an extnesive collection diesel enthusiats who do this sort of stuff all day long.
-Rich
Hum.... but my problem is the the engine goes down to idle when decending hills. That doesn't seem right.
-Rich
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From: Iowa
decending hills with an automatic
The guys are right, a diesel has no compression braking. Scared me the first time I drove one...
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
Jason Kendrick
1970 F100 Custom 390/C6
1978 F150 Ranger Lariat Supercab 460/C6
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decending hills with an automatic
Okay... I just got back from driving a 2001 and there is 'engine-braking'! I don't think you guys understood my problem. It's not that there's not a lot of compression braking - the problem is that my truck goes down to an IDLE whenever I take my foot of the fuel pedal. That's right - it coasts. The 2001 with an automatic stayed "in gear" and didn't coast. So I guess there is a problem with my transmission
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decending hills with an automatic
UPDATE on my engine braking problem: The dealer agreed that there was a problem and put in a remanufactured transmission from the factory. I picked up my truck yesterday and.... it's FIXED. It engine brakes in OD, with OD turned off, in 2nd, etc. It's like having a brand new truck when I'm towing and descending down a big hill.
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decending hills with an automatic
You will only have slight engine braking when the TC is locked, once unlocked, you basically freewheel. If you want "true" engine braking, you should look into an exhaust brake, especially if you tow.
-Rich
-Rich
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decending hills with an automatic
Hum... I find your comment about the TC interesting. If this were true, then putting the transmission into 2nd would not slow you down at all when going less than 35 MPH... but with the new transmission downshifting into 2nd does provide a significant amount of engine braking.
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From: Troy USA
decending hills with an automatic
The comment about the Torque Converter only providing braking when it is locked is totally false. If this were the case, you would see your engine go to idle every time you took your foot off of the gas pedal.
Comments like these come from people who dont understand how these things work.
Comments like these come from people who dont understand how these things work.
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decending hills with an automatic
Prove me wrong, I'm a big enough man to admit it, but you must show evidence and facts. I made that statement for the reason that I have been led to believe, by many sources, that the TC unlocks around 35 mph. If you are traveling at 35+ mph, the TC will be locked, whether or not your foot is on the accelerator. Of course there are other factors that come into play here, but for most part this is true. If anyone knows otherwise, please inform me so that I have the correct information.
-Rich
-Rich
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From: Troy USA
decending hills with an automatic
[font size="1" color="#FF0000"]LAST EDITED ON 08-Nov-01 AT 03:06 PM (EST)[/font][p]I do not dispute the fact that the TC unlocks after a certain MPH. My point is that when a TC is 'unlocked' it means that the TC CLUTCH -- not the entire TC is 'unlocked.' The TC clutch is a secondary mechanism inside the TC that 'locks' the engine crankshaft with the transmission input shaft. This does not allow any slippage -- which is what the TC is designed to do. When a TC clutch is unlocked, the TC functions normally. There is slippage... but it is not free-wheeling. Even when the TC clutch is unlocked, there is still a 'connect' between the crank and the tranny input shaft. There is just a little slipping. You will still see/feel the engine slowing you down.
The TC completely disengaging when taking your foot off of the accelerator would not only not make sense, it would be a MAJOR safety issue.
The TC completely disengaging when taking your foot off of the accelerator would not only not make sense, it would be a MAJOR safety issue.