Buzzing...flywheel?

[SKimballC]

I bought my current rig a few months ago, and its had a buzzing/vibration at idle that I haven't been too worrried about...until it just got slightly worse, or at least my sensitivity to it has gotten worse since I got all the other stuff that was bugging me straightened out. It happens from idle to about 1200 rpm, clutch depressed or not, and in or out of gear. Clutch has about 20K on it and works fine and I don't have any clutch slippage, but there is some shudder in reverse, but only sometimes. I searched the forum and found everything I could about the DMF, but it didn't really answer my questions. I am also thinking it could be motor mounts, trans mounts, or engine/bellhousing bolts. So I will check all those. Is checking the flywheel through the inspection cover possible, or is total removal required to check the play between the DMF sections? Any other recommendations or ideas? Also, I have no idea yet what clutch or flywheel setup is on it now as PO had it installed, though most service on the truck was done at a Ford dealership.

 

[Agnem]

One thing is for sure. If it is the DMF, it's going to get much worse. Post an audio clip of it, and be sure to include the sound at shut down.

 

[towcat]

Is checking the flywheel through the inspection cover possible, or is total removal required to check the play between the DMF sections?

best to remove the dustcover. 1/2" rotational play is nominal, 5/8" play is max.
diagnose with caution. Many DMF's have been unnecesiarially(sp) replaced due to bad IP's.

 

[EvergreenRanch]

that shudder in reverse sounds familiar..... towcat what was the name of that bearing assembly on my driveshaft towards the rear of the vehicle that we looked at and discussed replacing.... that was the source of my shudder.

 

[SKimballC]

One thing is for sure. If it is the DMF, it's going to get much worse. Post an audio clip of it, and be sure to include the sound at shut down.

I have absolutely no idea how to go about doing that. I know mycell phone can record voice memos but I also know they sound like s#!%. The sound is mostly heard in the cab. I can't really place it if I'm under the truck. The engine is way too loud for that. I turned the idle up about 100 rpm and I can feel the vibration more, though the sound is slightly less grating, but the windows are buzzing.
Towcat, what's that about a bad IP causing it? Please eleborate. I have no reason to think anything is amiss up there. Power, economy, and smoke are all good and its dry underneath it. I guess I am going to take the crossover pipe and cover off and see if anything is apparent.

 

[Black dawg]

are you sure it isnt just noise/vibration transfer, from under the hood? on alot of the 87-91 trucks there is an a/c hose that rubs on the wiper motor and hood, makes a fair amount of noise in the cab, makes the dash kind of buzz. at idle and lower rpm.

 

[SKimballC]

I don't think so, its too loud for that, but I'll check. It does make me think it could be a motor mount or something. I pooped the hood and it is noticeable outside the cab too. I can't really place it. I stopped by my dad's and he came out and poked his old engineer's ears around, and noticed that it is very loud if you listen at the air intake scoop. I pulled the new K&N out of the air box and the sound became less noticeable in the engine bay, but still as loud in the cab and the same amount of dash vibration. I did notice that a little smoke is coming out of the air intake when running. What is up with that?!? The more I try to find the source of the vibration the more questions I have. But again, everything is working really good right now, so besides the increased noise and vibration I have no other real symptoms so I guess I shouldn't worry too much. When I get some time I'm pulling the inspection cover.

 

[towcat]

that shudder in reverse sounds familiar..... towcat what was the name of that bearing assembly on my driveshaft towards the rear of the vehicle that we looked at and discussed replacing.... that was the source of my shudder.

center support bearing

 

[Agnem]

Sometimes called a carrier bearing.

 

[SKimballC]

The vibration has gotten worse. I layed under the truck while running and its definately coming from the bellhousing so I assume its the DMF. I checked NAPA and they don't have the LUK SMF kit. Where, other than Carolina Clutch, can I get it?

 

[SKimballC]

I removed the flywheel inspection cover, and put a 3/8" wrench on one of the pressure plate bolts and turned the p plate and flywheel around til the engine compression kept the flywheel from turning. Trans is in neutral, clutch is engaged. At this point I can turn the pressure plate about an inch in either direction, with distinct stops at either end of the play. Is this accurate enough to tell me that this exceeds the 1/2"(?) allowable play in the DMF?

 

[Mont91]

Sure sounds like the springs are shot.

Do you know if it was a new flywheel 20k ago or did they just put a new pressure plate and disk in on a sufaced flywheel?

 

[SKimballC]

I don't know. All the guy could tell me was new clutch, no reciept or anything. It was his Dad's truck.

 

[towcat]

an inch is a little extreme. take a look at the engine side of the flywheel and see if the dampner springs have ate up the sheet metal retainer area caging them in.

 

[Agnem]

If you are ready to go SMF, why not try the lucky mod? Less than 5 bucks and you have a SMF that's just as good as any other.