Rough idle
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New User
Joined: Dec 2003
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Rough idle
Hello everyone, I am having problems with rough idle when started or when coming to a stop.Does not do it every time, but when it does it sounds like it is running on 6 or7 cylinders. When I start it I can tach it up to about 1200-1500 RPMs and it idles fine. When coming to a stop I can let out on the clutch a little with it in gear and it will stop. Filters and oil have been changed. Been doing it for about 6 mounths. Truck is a 96 crew cab 7.3 psd turbow with manual transmision. CPS,glow plug relay and battery has been changed also. Thanks for any help or ideas any one can give.
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
Likes: 1
From: Southwest Georgia
Does it CLUNK when you turn off the engine? Your symptoms sound like a DMF (Dual Mass Flywheel) going tango uniform on you. Remove the clutch inspection plate on the bell housing and see if you have any play. If it's bad replace it with a SMF like the LUK from Carolina Clutch (site sponsor) also replace the clutch fork. You also might want to replace your slave and master cylinder with the change out.
Not a bad job, some ramps, a floor jack, some long extentions, socket set, etc. and about four hours by yourself, less with help.
Good Luck.
Not a bad job, some ramps, a floor jack, some long extentions, socket set, etc. and about four hours by yourself, less with help.
Good Luck.
Thread Starter
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New User
Joined: Dec 2003
Posts: 8
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Yes it sounds like the engine is going to fall out when I cut it off. Also have hade to replace bushings and pin on clutch linkage going to master cylinder in the cab. How do I check the play? What is the differance in the DMF and SMF? Thanks for your reply. Any further info would be appreciated.
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
Likes: 1
From: Southwest Georgia
With the BIG CLUNK, you don't need to check for play, it's your DMF going out.
The DMF has a center section isolated from the outer section by springs and a bearing assembly. It is supposed to isolate some of the vibration from the engine. Over time, either the springs break or become loose, or the bearing comes apart and all of the ***** shift to one side causing an imbalance (which mine did).
The SMF is a conventional clutch disk, pressure plate, solid flywheel set up.
LUK makes a good one for stock or slightly above stock applications. South Bend makes several that will handle increasingly more HP, (up to 450 HP I think), and a dual disk set up.
The complete SMF conversion (clutch disk, pressure plate, solid flywheel, bolts, throwout bearing, pilot bearing, alignment tool) will usually cost you about the same as just the DMF and then you still have to by the clutch assembly for the DMF.
With the SMF, next time you just buy the clutch assembly and have the SMF turned at a machine shop, total spent is half the price of the conversion the second time around.
Again I recommend Carolina Clutch (site sponsor) good poeple, helpful, fast service, good prices.
The DMF has a center section isolated from the outer section by springs and a bearing assembly. It is supposed to isolate some of the vibration from the engine. Over time, either the springs break or become loose, or the bearing comes apart and all of the ***** shift to one side causing an imbalance (which mine did).
The SMF is a conventional clutch disk, pressure plate, solid flywheel set up.
LUK makes a good one for stock or slightly above stock applications. South Bend makes several that will handle increasingly more HP, (up to 450 HP I think), and a dual disk set up.
The complete SMF conversion (clutch disk, pressure plate, solid flywheel, bolts, throwout bearing, pilot bearing, alignment tool) will usually cost you about the same as just the DMF and then you still have to by the clutch assembly for the DMF.
With the SMF, next time you just buy the clutch assembly and have the SMF turned at a machine shop, total spent is half the price of the conversion the second time around.
Again I recommend Carolina Clutch (site sponsor) good poeple, helpful, fast service, good prices.
Playing in the Dirt
Joined: Oct 2005
Posts: 2,302
Likes: 1
From: Southwest Georgia
$325, I think. I would just give them a call, thats what I did. Don't forget to replace the clutch fork, and if I had the money I would replace the master and slave cylinder too, I did when I replaced mine.
Post Fiend
Joined: Mar 2006
Posts: 7,841
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From: Vacaville, Ca
I also have this CLUNK and occasional rough idle. Sometimes it sounds like I have rocks in the oil pan when I shut it off. Thank you for the insight. My clutch has 166,000 miles on it. It is about time to replace it anyway and I am always looking for an upgrade.
